CMake: create output directory before building docs.

Previously trying to run rst2man.py with an output file in a nonexistent
directory resulted in the following build error:

  $ cmake --preset=linux-gcc-debug-ootree-skeleton-full
  $ cmake --build --preset=linux-gcc-debug-ootree-skeleton-full
  ...
  [  1%] Generating src/msg/help.cc
  Unable to open destination file for writing:
    OutputError: [Errno 2] No such file or directory:
      '[...]/linux-gcc-debug-ootree-skeleton-full/src/msg/help.cc.1'

CMakePresets.json

@@ -53,7 +53,7 @@
     {
       "name": "linux-gcc-ubsan-ootree-full",
       "displayName": "Linux x86_64: GCC / Ubsan / Out of tree (full)",
-      "inherits": ["linux-gcc-ubsan-ootree-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "linux-gcc-ubsan-ootree-fast"]
     },
     {
       "name": "linux-gcc-asan-ootree-fast",
@@ -71,7 +71,7 @@
     {
       "name": "linux-gcc-asan-ootree-full",
       "displayName": "Linux x86_64: GCC / Asan / Out of tree (full)",
-      "inherits": ["linux-gcc-asan-ootree-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "linux-gcc-asan-ootree-fast"]
     },
     {
       "name": "linux-gcc-debug-ootree-skeleton-fast",
@@ -89,7 +89,7 @@
     {
       "name": "linux-gcc-debug-ootree-skeleton-full",
       "displayName": "Linux x86_64: GCC / Debug / Skeleton / Out of tree (full)",
-      "inherits": ["linux-gcc-debug-ootree-skeleton-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "linux-gcc-debug-ootree-skeleton-fast"]
     },
     {
       "name": "linux-gcc-debug-intree-m32-skeleton-fast",
@@ -113,7 +113,7 @@
     {
       "name": "linux-gcc-debug-intree-m32-skeleton-full",
       "displayName": "Linux x86: GCC / Debug / Skeleton / In tree (full)",
-      "inherits": ["linux-gcc-debug-intree-m32-skeleton-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "linux-gcc-debug-intree-m32-skeleton-fast"]
     },
     {
       "name": "linux-gcc-release-ootree-skeleton-fast",
@@ -129,7 +129,7 @@
     {
       "name": "linux-gcc-release-ootree-skeleton-full",
       "displayName": "Linux x86_64: GCC / Release / Skeleton / Out of tree (full)",
-      "inherits": ["linux-gcc-release-ootree-skeleton-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "linux-gcc-release-ootree-skeleton-fast"]
     },
 
 
@@ -167,7 +167,7 @@
     {
       "name": "macos-clang-debug-ootree-skeleton-full",
       "displayName": "macOS x86_64: Clang / Debug / Skeleton / Out of tree (full)",
-      "inherits": ["macos-clang-debug-ootree-skeleton-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "macos-clang-debug-ootree-skeleton-fast"]
     },
     {
       "name": "macos-clang-debug-intree-skeleton-fast",
@@ -185,7 +185,7 @@
     {
       "name": "macos-clang-debug-intree-skeleton-full",
       "displayName": "macOS x86_64: Clang / Debug / Skeleton / In tree (full)",
-      "inherits": ["macos-clang-debug-intree-skeleton-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "macos-clang-debug-intree-skeleton-fast"]
     },
     {
       "name": "macos-clang-release-ootree-skeleton-fast",
@@ -201,7 +201,7 @@
     {
       "name": "macos-clang-release-ootree-skeleton-full",
       "displayName": "macOS x86_64: CLang / Release / Skeleton / Out of tree (full)",
-      "inherits": ["macos-clang-release-ootree-skeleton-fast", "default-full-configuration"]
+      "inherits": ["default-full-configuration", "macos-clang-release-ootree-skeleton-fast"]
     },
 
 
@@ -237,7 +237,7 @@
     {
       "name": "windows-msvc-debug-ootree-full",
       "displayName": "Windows x86_64: MSVC / Debug / Out of tree (full)",
-      "inherits": ["windows-msvc-debug-ootree-fast", "default-full-configuration"],
+      "inherits": ["default-full-configuration", "windows-msvc-debug-ootree-fast"],
       "cacheVariables": {
         "RE2C_REBUILD_DOCS": false
       }
@@ -256,7 +256,7 @@
     {
       "name": "windows-msvc-debug-intree-full",
       "displayName": "Windows x86_64: MSVC / Debug / In tree (full)",
-      "inherits": ["windows-msvc-debug-intree-fast", "default-full-configuration"],
+      "inherits": ["default-full-configuration", "windows-msvc-debug-intree-fast"],
       "cacheVariables": {
         "RE2C_REBUILD_DOCS": false
       }
@@ -275,7 +275,7 @@
     {
       "name": "windows-msvc-release-ootree-full",
       "displayName": "Windows x86_64: MSVC / Release / Out of tree (full)",
-      "inherits": ["windows-msvc-release-ootree-fast", "default-full-configuration"],
+      "inherits": ["default-full-configuration", "windows-msvc-release-ootree-fast"],
       "cacheVariables": {
         "RE2C_REBUILD_DOCS": false
       }

bootstrap/src/parse/lex.h

@@ -1,4 +1,4 @@
-/* Generated by re2c 2.1.1 on Fri Jul 16 08:52:38 2021 */
+/* Generated by re2c 2.2 on Mon Nov 22 21:59:42 2021 */
 
 #ifndef _RE2C_PARSE_LEX_
 #define _RE2C_PARSE_LEX_

cmake/Re2cGenDocs.cmake

@@ -1,8 +1,10 @@
 function(re2c_gen_manpage source target bootstrap lang)
     if(RE2C_REBUILD_DOCS)
+        get_filename_component(targetdir "${target}" DIRECTORY)
         set(source_l "${source}.${lang}")
         add_custom_command(
             OUTPUT "${target}"
+            COMMAND "${CMAKE_COMMAND}" -E make_directory ${targetdir}
             COMMAND "${re2c_splitman}" "${source}" "${source_l}" "${lang}"
             COMMAND "${RST2MAN}" --tab-width=4 "${source_l}" "${target}"
             COMMAND "${CMAKE_COMMAND}" -E copy_if_different "${target}" "${bootstrap}"
@@ -23,8 +25,10 @@ endfunction()
 
 function(re2c_gen_help source target bootstrap)
     if(RE2C_REBUILD_DOCS)
+        get_filename_component(targetdir "${target}" DIRECTORY)
         add_custom_command(
             OUTPUT "${target}"
+            COMMAND "${CMAKE_COMMAND}" -E make_directory ${targetdir}
             COMMAND "${RST2MAN}" "${source}" "${target}.1"
             COMMAND "${re2c_genhelp}" "${target}.1" "${target}"
             COMMAND "${CMAKE_COMMAND}" -E copy_if_different "${target}" "${bootstrap}"

examples/c/conditions/parse_u32_blocks.c

@@ -5,9 +5,6 @@
 #include <assert.h>
 
 static const uint64_t ERROR = ~0lu;
-enum YYCONDTYPE {
-};
-
 
 template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
 {

examples/c/conditions/parse_u32_blocks.re

@@ -4,7 +4,6 @@
 #include <assert.h>
 
 static const uint64_t ERROR = ~0lu;
-/*!types:re2c*/
 
 template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
 {

examples/go/conditions/parse_u32_blocks.go

@@ -1,5 +1,5 @@
 // Code generated by re2c, DO NOT EDIT.
-//go:generate re2go -c $INPUT -o $OUTPUT -i
+//go:generate re2go $INPUT -o $OUTPUT -i
 package main
 
 import (

examples/go/conditions/parse_u32_blocks.re

@@ -1,4 +1,4 @@
-//go:generate re2go -c $INPUT -o $OUTPUT -i
+//go:generate re2go $INPUT -o $OUTPUT -i
 package main
 
 import (

examples/go/includes/include.go

@@ -1,5 +1,5 @@
 // Code generated by re2c, DO NOT EDIT.
-//go:generate re2go -c $INPUT -o $OUTPUT -i
+//go:generate re2go $INPUT -o $OUTPUT -i
 package main
 
 import "testing"

examples/go/includes/include.re

@@ -1,4 +1,4 @@
-//go:generate re2go -c $INPUT -o $OUTPUT -i
+//go:generate re2go $INPUT -o $OUTPUT -i
 package main
 
 import "testing"

src/adfa/adfa.cc

@@ -510,10 +510,6 @@ void DFA::calc_stats(OutputBlock &out)
         out.stags.insert(stagnames.begin(), stagnames.end());
         out.mtags.insert(mtagnames.begin(), mtagnames.end());
     }
-
-    if (!cond.empty()) {
-        out.conds.push_back(cond);
-    }
 }
 
 static bool can_hoist_tags(const State *s, const opt_t *opts)

src/adfa/adfa.h

@@ -21,7 +21,7 @@
 namespace re2c {
 
 class Msg;
-class Output;
+struct Output;
 struct dfa_t;
 struct opt_t;
 struct Label;
@@ -130,7 +130,6 @@ struct DFA {
     void reorder();
     void prepare(const opt_t *opts);
     void calc_stats(OutputBlock &out);
-    void emit_body(Output &output, CodeList *program) const;
     void emit_dot(Output &output, CodeList *program) const;
 
 private:

src/codegen/code.h

@@ -9,6 +9,7 @@
 #include <string>
 #include <sstream>
 #include <vector>
+#include <map>
 
 #include "src/constants.h"
 #include "src/dfa/tcmd.h"
@@ -16,7 +17,6 @@
 #include "src/msg/location.h"
 #include "src/util/forbid_copy.h"
 #include "src/util/slab_allocator.h"
-#include "src/util/uniq_vector.h"
 #include "src/util/smart_ptr.h"
 #include "src/util/string_utils.h"
 
@@ -30,8 +30,8 @@ struct opt_t;
 struct Code;
 struct CodeGo;
 struct CodeGoIf;
-class Output;
-class OutputBlock;
+struct Output;
+struct OutputBlock;
 struct State;
 struct DFA;
 typedef std::vector<smart_ptr<DFA> > dfas_t;
@@ -315,6 +315,7 @@ struct Code {
         CodeVar        var;
         CodeFmt        fmt;
         CodeLabel      label;
+        CodeList      *loop;
         loc_t          loc;
     };
 
@@ -374,6 +375,13 @@ inline Code *code_stmt(code_alc_t &alc, const char *text)
     return x;
 }
 
+inline Code *code_loop(code_alc_t &alc, CodeList *loop)
+{
+    Code *x = new_code(alc, CODE_LOOP);
+    x->loop = loop;
+    return x;
+}
+
 inline Code *code_text(code_alc_t &alc, const char *text)
 {
     Code *x = new_code(alc, CODE_TEXT);
@@ -463,6 +471,11 @@ inline Code *code_yyaccept_def(code_alc_t &alc)
     return new_code(alc, CODE_YYACCEPT);
 }
 
+inline Code *code_yystate_def(code_alc_t &alc)
+{
+    return new_code(alc, CODE_YYSTATE);
+}
+
 inline Code *code_line_info_output(code_alc_t &alc)
 {
     return new_code(alc, CODE_LINE_INFO_OUTPUT);
@@ -628,12 +641,10 @@ struct CodegenCtxGlobal {
     Scratchbuf &scratchbuf;
     Msg &msg;
     const opt_t *opts;
+    const blocks_t &cblocks;
+    const blocks_t &hblocks;
     const blocks_t *pblocks;
-    uniq_vector_t<std::string> conds;
-    tagnames_t stags;
-    tagnames_t mtags;
-    size_t max_fill;
-    size_t max_nmatch;
+    mutable blocks_t tmpblocks; // temporary buffer for block lists in directives
     const bool warn_cond_ord;
 };
 
@@ -662,6 +673,14 @@ struct OutputFragment {
     uint32_t  indent;
 };
 
+struct StartCond {
+    std::string name;
+    uint32_t number;
+};
+typedef std::vector<StartCond> StartConds;
+
+typedef std::map<uint32_t, CodeList*> storable_states_t;
+
 struct OutputBlock {
     InputBlockKind kind;
     std::string name;
@@ -669,7 +688,7 @@ struct OutputBlock {
     std::vector<OutputFragment> fragments;
     bool used_yyaccept;
     bool have_user_code;
-    std::vector<std::string> conds;
+    StartConds conds;
     tagnames_t stags;
     tagnames_t mtags;
     const opt_t *opts;
@@ -678,25 +697,23 @@ struct OutputBlock {
     size_t max_nmatch; // YYMAXNMATCH
 
     // Used in the state switch (with `-f --storable-state` option).
-    Label *start_label;        // label of the DFA start state
-    uint32_t fill_index_start; // start of YYFILL index range
-    uint32_t fill_index_end;   // end of YYFILL index range (not included)
-    std::vector<CodeList*> fill_goto; // transitions to YYFILL states
+    Label *start_label; // label of the DFA start state
+    uint32_t fill_index; // next free index in YYFILL state enumeration
+    uint32_t fill_state; // index of the most recent YYFILL state
+    storable_states_t fill_goto; // transitions to YYFILL states
 
     OutputBlock(InputBlockKind kind, const std::string &name, const loc_t &loc);
     ~OutputBlock();
     FORBID_COPY(OutputBlock);
 };
 
-class Output {
+struct Output {
     blocks_t cblocks; /* .c file */
     blocks_t hblocks; /* .h file */
     blocks_t *pblocks; /* selector */
-
-public:
     uint32_t label_counter;
     bool state_goto;
-    bool cond_enum_in_hdr;
+    bool cond_enum_autogen; // true unless an explicit `types:re2c` directive is used
     bool cond_goto;
     bool warn_condition_order;
     bool need_header;
@@ -746,6 +763,9 @@ void gen_goto(Output &output, const DFA &dfa, CodeList *stmts, const State *from
     const CodeJump &jump);
 const char *gen_lessthan(Scratchbuf &o, const opt_t *opts, size_t n);
 void gen_code(Output &output, dfas_t &dfas);
+void gen_dfa_as_blocks_with_labels(Output &output, const DFA &dfa, CodeList *stmts);
+void gen_dfa_as_switch_cases(Output &output, DFA &dfa, CodeCases *cases);
+void wrap_dfas_in_loop_switch(Output &output, CodeList *stmts, CodeCases *cases);
 
 void expand_pass_1(CodegenCtxPass1 &ctx, Code *code);
 void expand_pass_2(CodegenCtxPass2 &ctx, Code *code);

src/codegen/code_goto.cc

@@ -12,7 +12,7 @@
 namespace re2c {
 
 static CodeGoIf *code_goif(code_alc_t &alc, CodeGoIf::Kind kind, const Span *sp,
-    uint32_t nsp, State *next, bool skip, uint32_t eof);
+    uint32_t nsp, State *next, bool skip, uint32_t eof, const opt_t *opts);
 
 static bool is_eof(uint32_t eof, uint32_t ub)
 {
@@ -97,7 +97,7 @@ static CodeCmp *code_cmp(code_alc_t &alc, const char *cmp, uint32_t val)
 }
 
 static CodeGoIfB *code_goifb(code_alc_t &alc, const Span *s, uint32_t n, State *next,
-    bool skip, uint32_t eof)
+    bool skip, uint32_t eof, const opt_t *opts)
 {
     const uint32_t l = n / 2;
     const uint32_t h = n - l;
@@ -106,13 +106,13 @@ static CodeGoIfB *code_goifb(code_alc_t &alc, const Span *s, uint32_t n, State *
 
     CodeGoIfB *x = alc.alloct<CodeGoIfB>(1);
     x->cond = code_cmp(alc, "<=", s[l - 1].ub - 1);
-    x->gothen = code_goif(alc, tkind, &s[0], l, next, skip, eof);
-    x->goelse = code_goif(alc, ekind, &s[l], h, next, skip, eof);
+    x->gothen = code_goif(alc, tkind, &s[0], l, next, skip, eof, opts);
+    x->goelse = code_goif(alc, ekind, &s[l], h, next, skip, eof, opts);
     return x;
 }
 
 static void add_branch(CodeGoIfL *go, const CodeCmp *cond, State *to, State *next,
-    const Span &sp, bool skip, uint32_t eof)
+    const Span &sp, bool skip, uint32_t eof, const opt_t *opts)
 {
     CodeGoIfL::Branch &b = go->branches[go->nbranches++];
     b.cond = cond;
@@ -121,11 +121,16 @@ static void add_branch(CodeGoIfL *go, const CodeCmp *cond, State *to, State *nex
     b.jump.tags  = sp.tags;
     b.jump.skip  = skip && consume(sp.to);
     b.jump.eof   = is_eof(eof, sp.ub);
-    b.jump.elide = !to;
+    // TODO: support transition elision with --loop-switch option. This requires
+    // used-label analysis before the start of code generation phase, because in Rust
+    // there is no fallthrough between cases and we can only elide a transition if we can
+    // elide the whole case, which is only possible if there are no other transitions into
+    // this state (so its label is unused).
+    b.jump.elide = !opts->loop_switch && !to;
 }
 
 static CodeGoIfL *code_goifl(code_alc_t &alc, const Span *s, uint32_t n, State *next,
-    bool skip, uint32_t eof)
+    bool skip, uint32_t eof, const opt_t *opts)
 {
     CodeGoIfL *x = alc.alloct<CodeGoIfL>(1);
     x->nbranches = 0;
@@ -134,17 +139,17 @@ static CodeGoIfL *code_goifl(code_alc_t &alc, const Span *s, uint32_t n, State *
 
     for (;;) {
         if (n == 1 && s[0].to == next) {
-            add_branch(x, NULL, NULL, next, s[0], skip, eof);
+            add_branch(x, NULL, NULL, next, s[0], skip, eof, opts);
             break;
         }
         else if (n == 1) {
-            add_branch(x, NULL, s[0].to, next, s[0], skip, eof);
+            add_branch(x, NULL, s[0].to, next, s[0], skip, eof, opts);
             break;
         }
         else if (n == 2 && s[0].to == next) {
             CodeCmp *cmp = code_cmp(alc, ">=", s[0].ub);
-            add_branch(x, cmp, s[1].to, next, s[1], skip, eof);
-            add_branch(x, NULL, NULL, next, s[0], skip, eof);
+            add_branch(x, cmp, s[1].to, next, s[1], skip, eof, opts);
+            add_branch(x, NULL, NULL, next, s[0], skip, eof, opts);
             break;
         }
         else if (n == 3
@@ -153,8 +158,8 @@ static CodeGoIfL *code_goifl(code_alc_t &alc, const Span *s, uint32_t n, State *
                 && s[2].to == s[0].to
                 && s[2].tags == s[0].tags) {
             CodeCmp *cmp = code_cmp(alc, "!=", s[0].ub);
-            add_branch(x, cmp, s[0].to, next, s[0], skip, eof);
-            add_branch(x, NULL, NULL, next, s[1], skip, eof);
+            add_branch(x, cmp, s[0].to, next, s[0], skip, eof, opts);
+            add_branch(x, NULL, NULL, next, s[1], skip, eof, opts);
             break;
         }
         else if (n >= 3
@@ -162,13 +167,13 @@ static CodeGoIfL *code_goifl(code_alc_t &alc, const Span *s, uint32_t n, State *
                 && s[2].to == s[0].to
                 && s[2].tags == s[0].tags) {
             CodeCmp *cmp = code_cmp(alc, "==", s[0].ub);
-            add_branch(x, cmp, s[1].to, next, s[1], skip, eof);
+            add_branch(x, cmp, s[1].to, next, s[1], skip, eof, opts);
             n -= 2;
             s += 2;
         }
         else {
             CodeCmp *cmp = code_cmp(alc, "<=", s[0].ub - 1);
-            add_branch(x, cmp, s[0].to, next, s[0], skip, eof);
+            add_branch(x, cmp, s[0].to, next, s[0], skip, eof, opts);
             n -= 1;
             s += 1;
         }
@@ -178,35 +183,35 @@ static CodeGoIfL *code_goifl(code_alc_t &alc, const Span *s, uint32_t n, State *
 }
 
 static CodeGoIf *code_goif(code_alc_t &alc, CodeGoIf::Kind kind, const Span *sp,
-    uint32_t nsp, State *next, bool skip, uint32_t eof)
+    uint32_t nsp, State *next, bool skip, uint32_t eof, const opt_t *opts)
 {
     CodeGoIf *x = alc.alloct<CodeGoIf>(1);
     x->kind = kind;
     if (kind == CodeGoIf::BINARY) {
-        x->goifb = code_goifb(alc, sp, nsp, next, skip, eof);
+        x->goifb = code_goifb(alc, sp, nsp, next, skip, eof, opts);
     }
     else {
-        x->goifl = code_goifl(alc, sp, nsp, next, skip, eof);
+        x->goifl = code_goifl(alc, sp, nsp, next, skip, eof, opts);
     }
     return x;
 }
 
 static CodeGoSwIf *code_goswif(code_alc_t &alc, const Span *sp, uint32_t nsp,
-    State *next, bool sflag, bool skip, uint32_t eof)
+    State *next, bool skip, uint32_t eof, const opt_t *opts)
 {
     CodeGoSwIf *x = alc.alloct<CodeGoSwIf>(1);
-    if ((!sflag && nsp > 2)
+    if ((!opts->sFlag && nsp > 2)
             || (nsp > 8 && (sp[nsp - 2].ub - sp[0].ub <= 3 * (nsp - 2)))) {
         x->kind = CodeGoSwIf::SWITCH;
         x->gosw = code_gosw(alc, sp, nsp, skip, eof);
     }
     else if (nsp > 5) {
         x->kind = CodeGoSwIf::IF;
-        x->goif = code_goif(alc, CodeGoIf::BINARY, sp, nsp, next, skip, eof);
+        x->goif = code_goif(alc, CodeGoIf::BINARY, sp, nsp, next, skip, eof, opts);
     }
     else {
         x->kind = CodeGoSwIf::IF;
-        x->goif = code_goif(alc, CodeGoIf::LINEAR, sp, nsp, next, skip, eof);
+        x->goif = code_goif(alc, CodeGoIf::LINEAR, sp, nsp, next, skip, eof, opts);
     }
     return x;
 }
@@ -241,7 +246,7 @@ static uint32_t unmap(Span *new_span, const Span *old_span, uint32_t old_nspans,
 
 static CodeGoBm *code_gobm(code_alc_t &alc, const Span *span, uint32_t nSpans,
     const Span *hspan, uint32_t hSpans, const CodeBmState *bm, State *next,
-    bool sflag, uint32_t eof)
+    uint32_t eof, const opt_t *opts)
 {
     CodeGoBm *x = alc.alloct<CodeGoBm>(1);
     x->bitmap = bm;
@@ -251,11 +256,11 @@ static CodeGoBm *code_gobm(code_alc_t &alc, const Span *span, uint32_t nSpans,
     Span *bspan = allocate<Span>(nSpans); // temporary
     uint32_t bSpans = unmap (bspan, span, nSpans, bm->state);
     x->lgo = bSpans == 0 ? NULL
-        : code_goswif(alc, bspan, bSpans, next, sflag, false, eof);
+        : code_goswif(alc, bspan, bSpans, next, false, eof, opts);
     // if there are any low spans, then next state for high spans
     // must be NULL to trigger explicit goto generation in linear 'if'
     x->hgo = hSpans == 0 ? NULL
-        : code_goswif(alc, hspan, hSpans, x->lgo ? NULL : next, sflag, false, eof);
+        : code_goswif(alc, hspan, hSpans, x->lgo ? NULL : next, false, eof, opts);
     x->bitmap->state->label->used = true;
     operator delete(bspan);
 
@@ -282,11 +287,11 @@ static CodeGoCpTable *code_gocp_table(code_alc_t &alc, const Span * span, uint32
 }
 
 static CodeGoCp *code_gocp(code_alc_t &alc, const Span *span, uint32_t nSpans,
-    const Span *hspan, uint32_t hSpans, State *next, bool sflag, uint32_t eof)
+    const Span *hspan, uint32_t hSpans, State *next, uint32_t eof, const opt_t *opts)
 {
     CodeGoCp *x = alc.alloct<CodeGoCp>(1);
     x->hgo = hSpans == 0 ? NULL
-        : code_goswif(alc, hspan, hSpans, next, sflag, false, eof);
+        : code_goswif(alc, hspan, hSpans, next, false, eof, opts);
     x->table = code_gocp_table(alc, span, nSpans);
     return x;
 }
@@ -356,18 +361,18 @@ void code_go(code_alc_t &alc, CodeGo *go, const State *from, const opt_t *opts,
             && !low_spans_have_tags) {
         go->kind = CodeGo::CPGOTO;
         go->gocp = code_gocp(alc, go->span, go->nspans, hspan, hSpans, from->next,
-            opts->sFlag, eof);
+            eof, opts);
     }
     else if (opts->bFlag && !part_skip && nBitmaps > 0) {
         go->kind = CodeGo::BITMAP;
         go->gobm = code_gobm(alc, go->span, go->nspans, hspan, hSpans, bm,
-            from->next, opts->sFlag, eof);
+            from->next, eof, opts);
         bitmap->used = true;
     }
     else {
         go->kind = CodeGo::SWITCH_IF;
-        go->goswif = code_goswif(alc, go->span, go->nspans, from->next, opts->sFlag,
-            part_skip, eof);
+        go->goswif = code_goswif(alc, go->span, go->nspans, from->next,
+            part_skip, eof, opts);
     }
 }
 

src/codegen/gen_delayed.cc

@@ -9,18 +9,44 @@
 
 namespace re2c {
 
-static const OutputBlock *find_block_with_name(CodegenCtxPass1 &ctx,
-    const char *name, const char *where)
+static OutputBlock *find_block_with_name(CodegenCtxPass1 &ctx, const char *name)
 {
-    const blocks_t &blocks = *ctx.global->pblocks;
-    for (size_t i = 0; i < blocks.size(); ++i) {
-        const OutputBlock *b = blocks[i];
-        if (b->name.compare(name) == 0) return b;
+    const blocks_t &cblocks = ctx.global->cblocks;
+    for (size_t i = 0; i < cblocks.size(); ++i) {
+        if (cblocks[i]->name.compare(name) == 0) return cblocks[i];
+    }
+    const blocks_t &hblocks = ctx.global->hblocks;
+    for (size_t i = 0; i < hblocks.size(); ++i) {
+        if (hblocks[i]->name.compare(name) == 0) return hblocks[i];
     }
-    error("cannot find block '%s' listed in `%s` directive", name, where);
     return NULL;
 }
 
+static void find_blocks(CodegenCtxPass1 &ctx, const BlockNameList *names,
+    blocks_t &blocks, const char *directive)
+{
+    blocks.clear();
+    for (const BlockNameList *p = names; p; p = p->next) {
+        OutputBlock *b = find_block_with_name(ctx, p->name);
+        if (b) {
+            blocks.push_back(b);
+        } else {
+            error("cannot find block '%s' listed in `%s` directive", p->name, directive);
+            exit(1);
+        }
+    }
+}
+
+static std::string output_cond_get(const opt_t *opts)
+{
+    return opts->cond_get + (opts->cond_get_naked ? "" : "()");
+}
+
+static std::string output_state_get(const opt_t *opts)
+{
+    return opts->state_get + (opts->state_get_naked ? "" : "()");
+}
+
 void gen_tags(Scratchbuf &buf, const opt_t *opts, Code *code, const tagnames_t &tags)
 {
     DASSERT(code->kind == CODE_STAGS || code->kind == CODE_MTAGS);
@@ -49,6 +75,18 @@ void gen_tags(Scratchbuf &buf, const opt_t *opts, Code *code, const tagnames_t &
     code->raw.data = buf.flush();
 }
 
+static void add_tags_from_blocks(const blocks_t &blocks, tagnames_t &tags, bool multival)
+{
+    for (size_t i = 0; i < blocks.size(); ++i) {
+        const OutputBlock &block = *blocks[i];
+        if (multival) {
+            tags.insert(block.mtags.begin(), block.mtags.end());
+        } else {
+            tags.insert(block.stags.begin(), block.stags.end());
+        }
+    }
+}
+
 static void expand_tags_directive(CodegenCtxPass1 &ctx, Code *code)
 {
     DASSERT(code->kind == CODE_STAGS || code->kind == CODE_MTAGS);
@@ -58,31 +96,24 @@ static void expand_tags_directive(CodegenCtxPass1 &ctx, Code *code)
     }
 
     Scratchbuf &buf = ctx.global->scratchbuf;
-    bool oneval = (code->kind == CODE_STAGS);
+    bool multival = (code->kind == CODE_MTAGS);
 
+    tagnames_t tags;
     if (code->fmt.block_names == NULL) {
-        // Use the global set of tags accumulated from all blocks.
-        gen_tags(buf, ctx.block->opts, code,
-            oneval ? ctx.global->stags : ctx.global->mtags);
+        // Gather tags from all blocks in the output and header files.
+        add_tags_from_blocks(ctx.global->cblocks, tags, multival);
+        add_tags_from_blocks(ctx.global->hblocks, tags, multival);
     } else {
         // Gather tags from the blocks on the list.
-        const char *directive = oneval ? "stags:re2c" : "mtags:re2c";
-        tagnames_t tags;
-        for (BlockNameList *p = code->fmt.block_names; p; p = p->next) {
-            const OutputBlock *b = find_block_with_name(ctx, p->name, directive);
-            if (!b) exit(1);
-            if (oneval) {
-                tags.insert(b->stags.begin(), b->stags.end());
-            } else {
-                tags.insert(b->mtags.begin(), b->mtags.end());
-            }
-        }
-        gen_tags(buf, ctx.block->opts, code, tags);
+        const char *directive = multival ? "mtags:re2c" : "stags:re2c";
+        find_blocks(ctx, code->fmt.block_names, ctx.global->tmpblocks, directive);
+        add_tags_from_blocks(ctx.global->tmpblocks, tags, multival);
     }
+    gen_tags(buf, ctx.block->opts, code, tags);
 }
 
-static void gen_cond_enum(Scratchbuf &buf, code_alc_t &alc, Code *code,
-    const opt_t *opts, const uniq_vector_t<std::string> &conds)
+static void gen_cond_enum(Scratchbuf &buf, code_alc_t &alc, Code *code, const opt_t *opts,
+    const StartConds &conds)
 {
     DASSERT(opts->target == TARGET_CODE);
 
@@ -93,10 +124,11 @@ static void gen_cond_enum(Scratchbuf &buf, code_alc_t &alc, Code *code,
         for (size_t i = 0; i < conds.size(); ++i) {
             if (i > 0 && sep) buf.cstr(sep);
             std::ostringstream s(fmt);
-            // The main substitution (the one allowing unnamed sigil) must go
-            // last, or else it will erroneously substitute all the named ones.
-            argsubst(s, opts->api_sigil, "num", false, i);
-            argsubst(s, opts->api_sigil, "cond", true, conds[i]);
+            // The main substitution (the one allowing unnamed sigil) must go last, or
+            // else it will erroneously substitute all the named ones.
+            size_t cid = opts->loop_switch ? conds[i].number : i;
+            argsubst(s, opts->api_sigil, "num", false, cid);
+            argsubst(s, opts->api_sigil, "cond", true, conds[i].name);
             buf.str(s.str());
         }
         buf.cstr("\n");
@@ -106,7 +138,7 @@ static void gen_cond_enum(Scratchbuf &buf, code_alc_t &alc, Code *code,
         code->raw.data = buf.flush();
 
     } else {
-        const char *text, *start = NULL, *end = NULL;
+        const char *start = NULL, *end = NULL;
         CodeList *stmts = code_list(alc);
         CodeList *block = code_list(alc);
 
@@ -114,15 +146,23 @@ static void gen_cond_enum(Scratchbuf &buf, code_alc_t &alc, Code *code,
             start = buf.cstr("enum ").str(opts->yycondtype).cstr(" {").flush();
             end = "};";
             for (size_t i = 0; i < conds.size(); ++i) {
-                text = buf.str(conds[i]).cstr(",").flush();
-                append(block, code_text(alc, text));
+                buf.str(conds[i].name);
+                if (opts->loop_switch) {
+                    buf.cstr(" = ").u32(conds[i].number);
+                }
+                append(block, code_text(alc, buf.cstr(",").flush()));
             }
         } else if (opts->lang == LANG_GO) {
             start = buf.cstr("const (").flush();
             end = ")";
             for (size_t i = 0; i < conds.size(); ++i) {
-                text = buf.str(conds[i]).cstr(i == 0 ? " = iota" : "").flush();
-                append(block, code_text(alc, text));
+                buf.str(conds[i].name);
+                if (opts->loop_switch) {
+                    buf.cstr(" = ").u32(conds[i].number);
+                } else if (i == 0) {
+                    buf.cstr(" = iota");
+                }
+                append(block, code_text(alc, buf.flush()));
             }
         }
 
@@ -136,6 +176,43 @@ static void gen_cond_enum(Scratchbuf &buf, code_alc_t &alc, Code *code,
     }
 }
 
+static void add_condition_from_block(const OutputBlock &block, StartConds &conds,
+    const StartCond &cond)
+{
+    // Condition prefix is specific to the block that defines it. If a few blocks define
+    // conditions with the same name, but a different prefix, they should have different
+    // enum entries.
+    StartCond sc = cond;
+    sc.name = block.opts->condEnumPrefix + sc.name;
+
+    for (size_t i = 0; i < conds.size(); ++i) {
+        if (conds[i].name == sc.name) {
+            if (conds[i].number == sc.number) {
+                // A duplicate condition, it's not an error but don't add it.
+                return;
+            } else {
+                // An error: conditions with idetical names but different numbers.
+                error("cannot generate condition enumeration: conditon '%s' has "
+                    "different numbers in different blocks (use `re2c:condenumprefix` "
+                    "configuration to set per-block prefix)", sc.name.c_str());
+                exit(1);
+            }
+        }
+    }
+
+    conds.push_back(sc);
+}
+
+static void add_conditions_from_blocks(const blocks_t &blocks, StartConds &conds)
+{
+    for (size_t i = 0; i < blocks.size(); ++i) {
+        const OutputBlock &block = *blocks[i];
+        for (size_t i = 0; i < block.conds.size(); ++i) {
+            add_condition_from_block(block, conds, block.conds[i]);
+        }
+    }
+}
+
 static void expand_cond_enum(CodegenCtxPass1 &ctx, Code *code)
 {
     Scratchbuf &buf = ctx.global->scratchbuf;
@@ -151,37 +228,34 @@ static void expand_cond_enum(CodegenCtxPass1 &ctx, Code *code)
         return;
     }
 
+    StartConds conds;
     if (code->fmt.block_names == NULL) {
-        // Use the global set of conditions accumulated from all blocks.
-        gen_cond_enum(buf, alc, code, globopts, ctx.global->conds);
+        // Gather conditions from all blocks in the output and header files.
+        add_conditions_from_blocks(ctx.global->cblocks, conds);
+        add_conditions_from_blocks(ctx.global->hblocks, conds);
     } else {
         // Gather conditions from the blocks on the list.
-        uniq_vector_t<std::string> conds;
-        for (BlockNameList *p = code->fmt.block_names; p; p = p->next) {
-            const OutputBlock *b = find_block_with_name(ctx, p->name, "types:re2c");
-            if (!b) exit(1);
-            for (size_t i = 0; i < b->conds.size(); ++i) {
-                // Condition prefix is specific to the block that defines it.
-                // If a few blocks define conditions with the same name, but a
-                // different prefix, they result in different enum entries.
-                conds.find_or_add(b->opts->condEnumPrefix + b->conds[i]);
-            }
-        }
-        gen_cond_enum(buf, alc, code, globopts, conds);
+        find_blocks(ctx, code->fmt.block_names, ctx.global->tmpblocks, "types:re2c");
+        add_conditions_from_blocks(ctx.global->tmpblocks, conds);
     }
+
+    // Do not generate empty condition enum. Some compilers or language standards
+    // allow it, but generally it's more likely to indicate an error in user code.
+    if (conds.empty()) {
+        code->kind = CODE_EMPTY;
+        return;
+    }
+
+    gen_cond_enum(buf, alc, code, globopts, conds);
 }
 
 static void gen_state_goto_cases(CodegenCtxPass1 &ctx, CodeCases *cases,
     const OutputBlock *block)
 {
     code_alc_t &alc = ctx.global->allocator;
-
-    uint32_t index_count = block->fill_index_end - block->fill_index_start;
-    DASSERT(index_count <= block->fill_goto.size());
-
-    for (uint32_t i = 0; i < index_count; ++i) {
-        append(cases, code_case_number(alc, block->fill_goto[i],
-            static_cast<int32_t>(i + block->fill_index_start)));
+    for (storable_states_t::const_iterator i = block->fill_goto.begin();
+            i != block->fill_goto.end(); ++i) {
+        append(cases, code_case_number(alc, i->second, static_cast<int32_t>(i->first)));
     }
 }
 
@@ -200,6 +274,10 @@ static void gen_state_goto(CodegenCtxPass1 &ctx, Code *code)
         return;
     }
 
+    // Loop/switch approach is handled differently (by appending special cases
+    // to the state switch).
+    DASSERT(!globopts->loop_switch);
+
     Scratchbuf &o = ctx.global->scratchbuf;
     code_alc_t &alc = ctx.global->allocator;
     const char *text;
@@ -245,19 +323,18 @@ static void gen_state_goto(CodegenCtxPass1 &ctx, Code *code)
         }
     } else {
         // Generate a switch for all specified named blocks.
-        for (BlockNameList *p = code->fmt.block_names; p; p = p->next) {
-            const OutputBlock *b = find_block_with_name(ctx, p->name, "getstate:re2c");
-            if (!b) exit(1);
+        blocks_t &blocks = ctx.global->tmpblocks;
+        find_blocks(ctx, code->fmt.block_names, blocks, "getstate:re2c");
+        for (size_t i = 0; i < blocks.size(); ++i) {
+            const OutputBlock *b = blocks[i];
             if (!b->start_label) {
                 error("block '%s' does not generate code, so it should not be"
-                    " listed in `getstate:re2c` directive", p->name);
+                    " listed in `getstate:re2c` directive", b->name.c_str());
                 exit(1);
             }
-
-            gen_state_goto_cases(ctx, cases, b);
-
             // Use start label of the first block on the list.
             if (!bstart) bstart = b;
+            gen_state_goto_cases(ctx, cases, b);
         }
     }
 
@@ -283,7 +360,7 @@ static void gen_state_goto(CodegenCtxPass1 &ctx, Code *code)
     }
 
     CodeList *stmts = code_list(alc);
-    text = o.str(globopts->state_get).cstr(globopts->state_get_naked ? "" : "()").flush();
+    text = o.str(output_state_get(globopts)).flush();
     append(stmts, code_switch(alc, text, cases));
 
     if (globopts->bUseStateNext) {
@@ -322,6 +399,45 @@ static void gen_yyaccept_def(const opt_t *opts, Code *code, bool used_yyaccept)
     }
 }
 
+static void gen_yystate_def(CodegenCtxPass1 &ctx, Code *code)
+{
+    const opt_t *opts = ctx.block->opts;
+    Scratchbuf &o = ctx.global->scratchbuf;
+
+    if (opts->loop_switch) {
+        code->kind = CODE_VAR;
+        code->var.name = o.str(opts->yystate).flush();
+        if (opts->fFlag) {
+            // With storable state `yystate` should be initialized to YYGETSTATE.
+            // Since there is a -1 case, `yystate` should have a signed type.
+            // If conditions are also used, YYGETSTATE takes priority over YYGETCONDITION,
+            // because the lexer may be reentered after an YYFILL invocation. In that case
+            // we use YYSETSTATE instead of YYSETCONDITION in the final states.
+            code->var.type = "int";
+            code->var.init = o.str(output_state_get(opts)).flush();
+        } else if (opts->cFlag) {
+            // Else with start conditions yystate should be initialized to YYGETCONDITION.
+            code->var.type = "unsigned int";
+            code->var.init = o.str(output_cond_get(opts)).flush();
+        } else {
+            // Else it should be the start DFA state (always case 0 with --loop-switch).
+            code->var.type = "unsigned int";
+            code->var.init = "0";
+        }
+    } else {
+        code->kind = CODE_EMPTY;
+    }
+}
+
+static size_t max_among_blocks(const blocks_t &blocks, size_t max, CodeKind kind)
+{
+    for (size_t i = 0; i < blocks.size(); ++i) {
+        const OutputBlock &block = *blocks[i];
+        max = std::max(max, kind == CODE_MAXFILL ? block.max_fill : block.max_nmatch);
+    }
+    return max;
+}
+
 static void gen_yymax(CodegenCtxPass1 &ctx, Code *code)
 {
     const opt_t *opts = ctx.block->opts;
@@ -332,22 +448,19 @@ static void gen_yymax(CodegenCtxPass1 &ctx, Code *code)
         return;
     }
 
-    bool is_maxfill = (code->kind == CODE_MAXFILL);
-    const char *dirname = is_maxfill ? "max:re2c" : "maxnmatch:re2c";
-    const char *varname = is_maxfill ? "YYMAXFILL" : "YYMAXNMATCH";
+    CodeKind kind = code->kind;
+    const char *dirname = kind == CODE_MAXFILL ? "max:re2c" : "maxnmatch:re2c";
+    const char *varname = kind == CODE_MAXFILL ? "YYMAXFILL" : "YYMAXNMATCH";
 
-    size_t max;
+    size_t max = 1;
     if (code->fmt.block_names == NULL) {
-        // Global maximum in the file.
-        max = is_maxfill ? ctx.global->max_fill : ctx.global->max_nmatch;
+        // Gather max value from all blocks in the output and header files.
+        max = max_among_blocks(ctx.global->cblocks, max, kind);
+        max = max_among_blocks(ctx.global->hblocks, max, kind);
     } else {
         // Maximum among the blocks listed in the directive.
-        max = 0;
-        for (BlockNameList *p = code->fmt.block_names; p; p = p->next) {
-            const OutputBlock *b = find_block_with_name(ctx, p->name, dirname);
-            if (!b) exit(1);
-            max = std::max(max, is_maxfill ? b->max_fill : b->max_nmatch);
-        }
+        find_blocks(ctx, code->fmt.block_names, ctx.global->tmpblocks, dirname);
+        max = max_among_blocks(ctx.global->tmpblocks, max, kind);
     }
 
     if (code->fmt.format) {
@@ -388,65 +501,59 @@ static void gen_yymax(CodegenCtxPass1 &ctx, Code *code)
  *       dispatch shrinks to unconditional jump
  */
 
-static std::string output_cond_get(const opt_t *opts)
+static CodeList *gen_cond_goto_binary(CodegenCtxPass1 &ctx, size_t lower, size_t upper)
 {
-    return opts->cond_get + (opts->cond_get_naked ? "" : "()");
-}
+    const opt_t *opts = ctx.block->opts;
+    code_alc_t &alc = ctx.global->allocator;
+    Scratchbuf &o = ctx.global->scratchbuf;
 
-static CodeList *gen_cond_goto_binary(Scratchbuf &o, code_alc_t &alc,
-    const std::vector<std::string> &conds, const opt_t *opts,
-    size_t lower, size_t upper)
-{
     CodeList *stmts = code_list(alc);
-    const char *text;
-
     if (lower == upper) {
-        text = o.cstr("goto ").str(opts->condPrefix).str(conds[lower]).flush();
-        append(stmts, code_stmt(alc, text));
-    }
-    else {
+        o.cstr("goto ").str(opts->condPrefix).str(ctx.block->conds[lower].name);
+        append(stmts, code_stmt(alc, o.flush()));
+    } else {
         const size_t middle = lower + (upper - lower + 1) / 2;
-        text = o.str(output_cond_get(opts)).cstr(" < ").u64(middle).flush();
-        CodeList *if_then = gen_cond_goto_binary(o, alc, conds, opts, lower, middle - 1);
-        CodeList *if_else = gen_cond_goto_binary(o, alc, conds, opts, middle, upper);
-        append(stmts, code_if_then_else(alc, text, if_then, if_else));
+        CodeList *if_then = gen_cond_goto_binary(ctx, lower, middle - 1);
+        CodeList *if_else = gen_cond_goto_binary(ctx, middle, upper);
+        o.str(output_cond_get(opts)).cstr(" < ").u64(middle);
+        append(stmts, code_if_then_else(alc, o.flush(), if_then, if_else));
     }
-
     return stmts;
 }
 
-static void gen_cond_goto(Scratchbuf &o, code_alc_t &alc, Code *code,
-    const std::vector<std::string> &conds, const opt_t *opts, Msg &msg,
-    bool warn_cond_ord, const loc_t &loc)
+static void gen_cond_goto(CodegenCtxPass1 &ctx, Code *code)
 {
+    const opt_t *opts = ctx.block->opts;
+    code_alc_t &alc = ctx.global->allocator;
+    Scratchbuf &o = ctx.global->scratchbuf;
+    const StartConds &conds = ctx.block->conds;
+    bool warn_cond_ord = ctx.global->warn_cond_ord;
+
     const size_t ncond = conds.size();
     CodeList *stmts = code_list(alc);
     const char *text;
 
     if (opts->target == TARGET_DOT) {
         for (size_t i = 0; i < ncond; ++i) {
-            const std::string &cond = conds[i];
+            const std::string &cond = conds[i].name;
             text = o.cstr("0 -> ").str(cond).cstr(" [label=\"state=").str(cond)
                 .cstr("\"]").flush();
             append(stmts, code_text(alc, text));
         }
-    }
-    else {
+    } else {
         if (opts->gFlag) {
             text = o.cstr("goto *").str(opts->yyctable).cstr("[")
                 .str(output_cond_get(opts)).cstr("]").flush();
             append(stmts, code_stmt(alc, text));
-        }
-        else if (opts->sFlag) {
+        } else if (opts->sFlag) {
             warn_cond_ord &= ncond > 1;
-            append(stmts, gen_cond_goto_binary(o, alc, conds, opts, 0, ncond - 1));
-        }
-        else {
+            append(stmts, gen_cond_goto_binary(ctx, 0, ncond - 1));
+        } else {
             warn_cond_ord = false;
 
             CodeCases *ccases = code_cases(alc);
             for (size_t i = 0; i < ncond; ++i) {
-                const std::string &cond = conds[i];
+                const std::string &cond = conds[i].name;
 
                 CodeList *body = code_list(alc);
                 text = o.cstr("goto ").str(opts->condPrefix).str(cond).flush();
@@ -462,7 +569,7 @@ static void gen_cond_goto(Scratchbuf &o, code_alc_t &alc, Code *code,
         // see note [condition order]
         warn_cond_ord &= opts->header_file.empty();
         if (warn_cond_ord) {
-            msg.warn.condition_order(loc);
+            ctx.global->msg.warn.condition_order(ctx.block->loc);
         }
     }
 
@@ -471,22 +578,23 @@ static void gen_cond_goto(Scratchbuf &o, code_alc_t &alc, Code *code,
     code->block.fmt = CodeBlock::RAW;
 }
 
-static void gen_cond_table(Scratchbuf &o, code_alc_t &alc, Code *code,
-    const std::vector<std::string> &conds, const opt_t *opts)
+static void gen_cond_table(CodegenCtxPass1 &ctx, Code *code)
 {
+    const opt_t *opts = ctx.block->opts;
+    code_alc_t &alc = ctx.global->allocator;
+    Scratchbuf &o = ctx.global->scratchbuf;
+    const StartConds &conds = ctx.block->conds;
     const size_t ncond = conds.size();
 
     CodeList *stmts = code_list(alc);
-    const char *text;
 
-    text = o.cstr("static void *").str(opts->yyctable).cstr("[").u64(ncond)
-        .cstr("] = {").flush();
-    append(stmts, code_text(alc, text));
+    o.cstr("static void *").str(opts->yyctable).cstr("[").u64(ncond).cstr("] = {");
+    append(stmts, code_text(alc, o.flush()));
 
     CodeList *block = code_list(alc);
     for (size_t i = 0; i < ncond; ++i) {
-        text = o.cstr("&&").str(opts->condPrefix).str(conds[i]).cstr(",").flush();
-        append(block, code_text(alc, text));
+        o.cstr("&&").str(opts->condPrefix).str(conds[i].name).cstr(",");
+        append(block, code_text(alc, o.flush()));
     }
     append(stmts, code_block(alc, block, CodeBlock::INDENTED));
 
@@ -508,9 +616,6 @@ static void expand_pass_1_list(CodegenCtxPass1 &ctx, CodeList *stmts)
 void expand_pass_1(CodegenCtxPass1 &ctx, Code *code)
 {
     const opt_t *opts = ctx.block->opts;
-    Scratchbuf &buf = ctx.global->scratchbuf;
-    code_alc_t &alc = ctx.global->allocator;
-
     switch (code->kind) {
         case CODE_BLOCK:
             expand_pass_1_list(ctx, code->block.stmts);
@@ -524,6 +629,9 @@ void expand_pass_1(CodegenCtxPass1 &ctx, Code *code)
                 expand_pass_1_list(ctx, x->body);
             }
             break;
+        case CODE_LOOP:
+            expand_pass_1_list(ctx, code->loop);
+            break;
         case CODE_STAGS:
         case CODE_MTAGS:
             expand_tags_directive(ctx, code);
@@ -538,15 +646,17 @@ void expand_pass_1(CodegenCtxPass1 &ctx, Code *code)
         case CODE_YYACCEPT:
             gen_yyaccept_def(opts, code, ctx.block->used_yyaccept);
             break;
+        case CODE_YYSTATE:
+            gen_yystate_def(ctx, code);
+            break;
         case CODE_COND_ENUM:
             expand_cond_enum(ctx, code);
             break;
         case CODE_COND_GOTO:
-            gen_cond_goto(buf, alc, code, ctx.block->conds, opts,
-                ctx.global->msg, ctx.global->warn_cond_ord, ctx.block->loc);
+            gen_cond_goto(ctx, code);
             break;
         case CODE_COND_TABLE:
-            gen_cond_table(buf, alc, code, ctx.block->conds, opts);
+            gen_cond_table(ctx, code);
             break;
         case CODE_STATE_GOTO:
             gen_state_goto(ctx, code);
@@ -618,6 +728,9 @@ void expand_pass_2(CodegenCtxPass2 &ctx, Code *code)
                 expand_pass_2_list(ctx, x->body);
             }
             break;
+        case CODE_LOOP:
+            expand_pass_2_list(ctx, code->loop);
+            break;
         case CODE_LABEL:
             gen_label(ctx.scratchbuf, ctx.opts, code);
             break;

src/codegen/gen_dfa.cc

@@ -40,7 +40,9 @@ static void emit_state(Output &output, const State *s, CodeList *stmts)
     Scratchbuf &o = output.scratchbuf;
     const char *text;
 
-    append(stmts, code_nlabel(alc, s->label));
+    if (!opts->loop_switch) {
+        append(stmts, code_nlabel(alc, s->label));
+    }
 
     if (opts->dFlag && (s->action.type != Action::INITIAL)) {
         text = o.str(opts->yydebug).cstr("(").label(*s->label).cstr(", ")
@@ -49,31 +51,84 @@ static void emit_state(Output &output, const State *s, CodeList *stmts)
     }
 }
 
-void DFA::emit_body(Output &output, CodeList *stmts) const
+static void gen_storable_state_cases(Output &output, CodeCases *cases)
+{
+    OutputBlock &block = output.block();
+    const opt_t *opts = block.opts;
+    code_alc_t &alc = output.allocator;
+
+    if (!opts->fFlag || !opts->loop_switch) return;
+
+    // TODO: If `re2c:eof` is not used, some of these cases are redundant (they contain a
+    // single transition to the DFA state that has the corresponding YYFILL invocation).
+    for (storable_states_t::const_iterator i = block.fill_goto.begin();
+            i != block.fill_goto.end(); ++i) {
+        append(cases, code_case_number(alc, i->second, static_cast<int32_t>(i->first)));
+    }
+
+    CodeList *start_case = code_list(alc);
+    if (opts->lang == LANG_GO) {
+        append(start_case, code_stmt(alc, "fallthrough"));
+    }
+    prepend(cases, code_case_number(alc, start_case, -1));
+}
+
+void gen_dfa_as_blocks_with_labels(Output &output, const DFA &dfa, CodeList *stmts)
 {
     const opt_t *opts = output.block().opts;
     code_alc_t &alc = output.allocator;
     Scratchbuf &o = output.scratchbuf;
-    const char *text;
 
-    gen_settags(output, stmts, *this, tags0, false /* delayed */);
+    gen_settags(output, stmts, dfa, dfa.tags0, /*delayed*/ false);
 
-    // If DFA has transitions to initial state, then initial state
-    // has a piece of code that advances input position. Wee must
-    // skip it when entering DFA.
-    if (head->label->used) {
-        initial_label->used = true;
-        text = o.cstr("goto ").str(opts->labelPrefix).label(*initial_label).flush();
-        append(stmts, code_stmt(alc, text));
+    // If DFA has transitions into the initial state and --eager-skip option is not used,
+    // then the initial state must have a YYSKIP statement that must be bypassed when
+    // first entering the DFA. With --loop-switch that would be impossible, because there
+    // can be no transitions in the middle of a state.
+    DASSERT(!opts->loop_switch);
+    if (dfa.head->label->used && !opts->eager_skip) {
+        dfa.initial_label->used = true;
+        o.cstr("goto ").str(opts->labelPrefix).label(*dfa.initial_label);
+        append(stmts, code_stmt(alc, o.flush()));
     }
 
-    for (State * s = head; s; s = s->next) {
+    for (State *s = dfa.head; s; s = s->next) {
         emit_state(output, s, stmts);
-        emit_action(output, *this, s, stmts);
-        gen_go(output, *this, &s->go, s, stmts);
+        emit_action(output, dfa, s, stmts);
+        gen_go(output, dfa, &s->go, s, stmts);
     }
 }
 
+void gen_dfa_as_switch_cases(Output &output, DFA &dfa, CodeCases *cases)
+{
+    const opt_t *opts = output.block().opts;
+    code_alc_t &alc = output.allocator;
+
+    DASSERT(opts->loop_switch);
+    DASSERT(dfa.tags0 == TCID0);
+
+    for (State *s = dfa.head; s; s = s->next) {
+        CodeList *body = code_list(alc);
+        emit_state(output, s, body);
+        emit_action(output, dfa, s, body);
+        gen_go(output, dfa, &s->go, s, body);
+        append(cases, code_case_number(alc, body, static_cast<int32_t>(s->label->index)));
+    }
+}
+
+void wrap_dfas_in_loop_switch(Output &output, CodeList *stmts, CodeCases *cases)
+{
+    const opt_t *opts = output.block().opts;
+    code_alc_t &alc = output.allocator;
+
+    DASSERT(opts->loop_switch);
+
+    CodeList* loop = code_list(alc);
+    gen_storable_state_cases(output, cases);
+    append(loop, code_switch(alc, opts->yystate.c_str(), cases));
+    append(stmts, code_loop(alc, loop));
+}
+
 void DFA::emit_dot(Output &output, CodeList *program) const
 {
     code_alc_t &alc = output.allocator;
@@ -143,28 +198,50 @@ void gen_code(Output &output, dfas_t &dfas)
         const bool first = i == b;
         DFA &dfa = *(*i);
 
-        if (first) {
-            if (opts->startlabel_force) {
-                // User-enforced start label.
-                dfa.start_label = new_label(alc, output.label_counter++);
-                dfa.start_label->used = true;
-            } else if (opts->fFlag) {
-                // Start label is needed in `-f` mode: it points to state 0 (the
-                // beginning of block, before condition dispatch in `-c` mode).
-                dfa.start_label = new_label(alc, output.label_counter++);
-            }
-            oblock.start_label = dfa.start_label;
+        if (opts->loop_switch && (first || opts->target == TARGET_SKELETON)) {
+            // With loop/switch there are no labels, and each block has its own state
+            // switch where all conditions are joined. Restart state counter from zero so
+            // that cases start from zero. With skeleton conditions are separate.
+            output.label_counter = 0;
         }
 
-        // Initial label points to the beginning of the DFA (after condition
-        // dispatch in `-c` mode).
-        dfa.initial_label = new_label(alc, output.label_counter++);
-        dfa.head->action.set_initial();
-
+        if (!opts->loop_switch) {
+            if (first) {
+                if (opts->startlabel_force) {
+                    // User-enforced start label.
+                    dfa.start_label = new_label(alc, output.label_counter++);
+                    dfa.start_label->used = true;
+                } else if (opts->fFlag) {
+                    // Start label is needed in `-f` mode: it points to state 0 (the
+                    // beginning of block, before condition dispatch in `-c` mode).
+                    dfa.start_label = new_label(alc, output.label_counter++);
+                }
+                oblock.start_label = dfa.start_label;
+            }
+            // Initial label points to the beginning of the DFA (after condition
+            // dispatch in `-c` mode).
+            dfa.initial_label = new_label(alc, output.label_counter++);
+            dfa.head->action.set_initial();
+        }
         for (State *s = dfa.head; s; s = s->next) {
             s->label = new_label(alc, output.label_counter++);
         }
 
+        // With loop/switch storable states need their own cases in the state switch, as
+        // they have some logic on top of transition to the state that invoked YYFILL.
+        // Give them continuous indices after the last state index.
+        if (opts->loop_switch && opts->fFlag) {
+            oblock.fill_index = output.label_counter;
+        }
+
+        if (!dfa.cond.empty()) {
+            // If loop/switch is used, condition numbers are the numeric indices of their
+            // initial DFA state. Otherwise we do not assign explicit numbers, and
+            // conditions are implicitly assigned consecutive numbers starting from zero.
+            StartCond sc = {dfa.cond, opts->loop_switch ? dfa.head->label->index : 0};
+            oblock.conds.push_back(sc);
+        }
+
         if (opts->bFlag) {
             dfa.bitmap = code_bitmap(alc, std::min(dfa.ubChar, 256u));
             for (State *s = dfa.head; s; s = s->next) {
@@ -205,6 +282,7 @@ void gen_code(Output &output, dfas_t &dfas)
 
         const char *text;
         CodeList *program1 = code_list(alc);
+        CodeCases *cases = code_cases(alc);
         for (i = b; i != e; ++i) {
             const bool first = i == b;
             DFA &dfa = *(*i);
@@ -220,6 +298,9 @@ void gen_code(Output &output, dfas_t &dfas)
                 append(program1, code_yych_decl(alc));
                 append(program1, code_yyaccept_def(alc));
             }
+            if (first) {
+                append(program1, code_yystate_def(alc));
+            }
 
             if (!is_cond_block && bms) {
                 append(program1, bms);
@@ -229,7 +310,7 @@ void gen_code(Output &output, dfas_t &dfas)
                 append(program1, code_cond_table(alc));
             }
 
-            if (opts->fFlag && !output.state_goto) {
+            if (opts->fFlag && !output.state_goto && !opts->loop_switch) {
                 append(program1, code_state_goto(alc,
                     block_list_for_implicit_state_goto(alc, oblock)));
                 output.state_goto = true;
@@ -246,12 +327,11 @@ void gen_code(Output &output, dfas_t &dfas)
                 append(program1, code_slabel(alc, text));
             }
 
-            if (is_cond_block && !output.cond_goto) {
-                append(program1, code_cond_goto(alc));
-                output.cond_goto = true;
-            }
-
-            if (is_cond_block && !dfa.cond.empty()) {
+            if (is_cond_block && !opts->loop_switch) {
+                if (!output.cond_goto) {
+                    append(program1, code_cond_goto(alc));
+                    output.cond_goto = true;
+                }
                 if (opts->condDivider.length()) {
                     o.str(opts->condDivider);
                     argsubst(o.stream(), opts->condDividerParam, "cond", true, dfa.cond);
@@ -261,20 +341,29 @@ void gen_code(Output &output, dfas_t &dfas)
                 append(program1, code_slabel(alc, text));
             }
 
-            // generate code for DFA
-            CodeList *body = code_list(alc);
-            dfa.emit_body(output, body);
-
-            if (is_cond_block && bms) {
-                CodeList *block = code_list(alc);
-                append(block, bms);
-                append(block, body);
-                append(program1, code_block(alc, block, CodeBlock::WRAPPED));
-            }
-            else {
-                append(program1, body);
+            if (!opts->loop_switch) {
+                // In the goto/label mode, generate DFA states as blocks of code preceded
+                // with labels, and `goto` transitions between states.
+                CodeList *body = code_list(alc);
+                gen_dfa_as_blocks_with_labels(output, dfa, body);
+                if (is_cond_block && bms) {
+                    CodeList *block = code_list(alc);
+                    append(block, bms);
+                    append(block, body);
+                    append(program1, code_block(alc, block, CodeBlock::WRAPPED));
+                } else {
+                    append(program1, body);
+                }
+            } else {
+                // In the loop/switch mode append all DFA states as cases of the `yystate`
+                // switch. Merge DFAs for different conditions together in one switch.
+                DASSERT(!bms);
+                gen_dfa_as_switch_cases(output, dfa, cases);
             }
         }
+        if (opts->loop_switch) {
+            wrap_dfas_in_loop_switch(output, program1, cases);
+        }
 
         const bool prolog = (opts->fFlag && opts->gFlag)
             || (!opts->fFlag && (oblock.used_yyaccept || opts->bEmitYYCh))

src/codegen/gen_program.cc

@@ -14,7 +14,6 @@
 #include "src/util/file_utils.h"
 #include "src/util/string_utils.h"
 #include "src/util/temp_file.h"
-#include "src/util/uniq_vector.h"
 
 
 namespace re2c {
@@ -59,8 +58,8 @@ OutputBlock::OutputBlock(InputBlockKind kind, const std::string &name,
     , max_fill(1)
     , max_nmatch(1)
     , start_label(NULL)
-    , fill_index_start(0)
-    , fill_index_end(0)
+    , fill_index(0)
+    , fill_state(0)
     , fill_goto()
 {}
 
@@ -75,7 +74,7 @@ Output::Output(Msg &msg)
     , pblocks(&cblocks)
     , label_counter(0)
     , state_goto(false)
-    , cond_enum_in_hdr(false)
+    , cond_enum_autogen(true)
     , cond_goto(false)
     , warn_condition_order(true)
     , need_header(false)
@@ -169,8 +168,7 @@ void Output::new_block(Opt &opts, InputBlockKind kind, const std::string &name,
 
     b->opts = opts.snapshot();
 
-    b->fill_index_start = total_fill_index;
-    b->fill_index_end   = total_fill_index;
+    b->fill_index = total_fill_index;
 
     pblocks->push_back(b);
 
@@ -183,7 +181,7 @@ void Output::gather_info_from_block()
 {
     DASSERT(!pblocks->empty());
     const OutputBlock *b = pblocks->back();
-    total_fill_index = b->fill_index_end;
+    total_fill_index = b->fill_index;
 }
 
 static void fix_first_block_opts(const blocks_t &blocks)
@@ -276,23 +274,6 @@ bool Output::emit_blocks(const std::string &fname, const CodegenCtxGlobal &globa
     return true;
 }
 
-static void add_symbols(const OutputBlock &block, CodegenCtxGlobal &ctx)
-{
-    DASSERT(!block.name.empty());
-
-    const std::string &condenumprefix = block.opts->condEnumPrefix;
-    for (size_t j = 0; j < block.conds.size(); ++j) {
-        ctx.conds.find_or_add(condenumprefix + block.conds[j]);
-    }
-
-    const tagnames_t &st = block.stags, &mt = block.mtags;
-    ctx.stags.insert(st.begin(), st.end());
-    ctx.mtags.insert(mt.begin(), mt.end());
-
-    ctx.max_fill = std::max(ctx.max_fill, block.max_fill);
-    ctx.max_nmatch = std::max(ctx.max_nmatch, block.max_nmatch);
-}
-
 bool Output::emit()
 {
     if (msg.warn.error()) return false;
@@ -302,42 +283,31 @@ bool Output::emit()
         , scratchbuf
         , msg
         , total_opts
+        , cblocks
+        , hblocks
         , /*pblocks*/ NULL
-        , /*conditions*/ uniq_vector_t<std::string>()
-        , /*stags*/ tagnames_t()
-        , /*mtags*/ tagnames_t()
-        , /*max_fill*/ 1
-        , /*max_nmatch*/ 1
+        , /*tmpblocks*/ blocks_t()
         , warn_condition_order
         };
 
-    // gather global data accumulated across all blocks and files
-    for (uint32_t i = 0; i < cblocks.size(); ++i) {
-        add_symbols (*cblocks[i], ctx);
-    }
-    for (uint32_t i = 0; i < hblocks.size(); ++i) {
-        add_symbols (*hblocks[i], ctx);
-    }
-
     // global options are last block's options
     const opt_t *opts = block().opts;
     bool ok = true;
 
-    // emit .h file
+    // Emit header file.
     if (!opts->header_file.empty() || need_header) {
-        // old-style -t, --type-headers usage implies condition generation
-        if (!ctx.conds.empty() && !this->cond_enum_in_hdr) {
+        if (opts->cFlag && this->cond_enum_autogen) {
+            // Old-style -t, --type-headers usage implies condition enum.
             header_mode(true);
             wdelay_stmt(0, code_newline(allocator));
             wdelay_stmt(0, code_fmt(allocator, CODE_COND_ENUM, NULL, NULL, NULL));
             header_mode(false);
         }
-
         ctx.pblocks = &hblocks;
         ok &= emit_blocks(opts->header_file, ctx);
     }
 
-    // emit .c file
+    // Emit output file.
     ctx.pblocks = &cblocks;
     ok &= emit_blocks(opts->output_file, ctx);
 

src/codegen/gen_state.cc

@@ -226,54 +226,7 @@ void emit_accept(Output &output, CodeList *stmts, const DFA &dfa, const accept_t
     append(stmts, code_switch(alc, text, cases));
 }
 
-void emit_rule(Output &output, CodeList *stmts, const DFA &dfa, size_t rule_idx)
-{
-    const opt_t *opts = output.block().opts;
-    const Rule &rule = dfa.rules[rule_idx];
-    const SemAct *semact = rule.semact;
-    const std::string &cond = semact->cond;
-    code_alc_t &alc = output.allocator;
-    Scratchbuf &o = output.scratchbuf;
-    std::string s;
-    const char *text;
-
-    gen_fintags(output, stmts, dfa, rule);
-
-    if (opts->target == TARGET_SKELETON) {
-        emit_skeleton_action(output, stmts, dfa, rule_idx);
-    }
-    else {
-        if (!cond.empty() && dfa.cond != cond) {
-            o.str(opts->cond_set);
-            argsubst(o.stream(), opts->cond_set_arg, "cond", true,
-                opts->condEnumPrefix + cond);
-            if (opts->cond_set_naked) {
-                append(stmts, code_text(alc, o.flush()));
-            } else {
-                o.cstr("(").str(opts->condEnumPrefix).str(cond).cstr(")");
-                append(stmts, code_stmt(alc, o.flush()));
-            }
-        }
-        if (!semact->autogen) {
-            if (!dfa.setup.empty()) {
-                text = o.str(dfa.setup).flush();
-                append(stmts, code_text(alc, text));
-            }
-            append(stmts, code_line_info_input(alc, semact->loc));
-            text = o.str(semact->text).flush();
-            append(stmts, code_text(alc, text));
-            append(stmts, code_line_info_output(alc));
-        }
-        else if (!cond.empty()) {
-            o.str(opts->condGoto);
-            argsubst(o.stream(), opts->condGotoParam, "cond", true,
-                opts->condPrefix + cond);
-            append(stmts, code_text(alc, o.flush()));
-        }
-    }
-}
-
-static void gen_setstate(Output &output, CodeList *stmts, uint32_t fillidx)
+static void gen_setstate(Output &output, CodeList *stmts, const char *fillidx)
 {
     const opt_t *opts = output.block().opts;
     code_alc_t &alc = output.allocator;
@@ -284,11 +237,85 @@ static void gen_setstate(Output &output, CodeList *stmts, uint32_t fillidx)
     if (opts->state_set_naked) {
         append(stmts, code_text(alc, o.flush()));
     } else {
-        o.cstr("(").u32(fillidx).cstr(")");
+        o.cstr("(").cstr(fillidx).cstr(")");
         append(stmts, code_stmt(alc, o.flush()));
     }
 }
 
+static void gen_setcondition(Output &output, CodeList *stmts, const char *cond)
+{
+    const opt_t *opts = output.block().opts;
+    code_alc_t &alc = output.allocator;
+    Scratchbuf &o = output.scratchbuf;
+
+    o.str(opts->cond_set);
+    argsubst(o.stream(), opts->cond_set_arg, "cond", true, cond);
+    if (opts->cond_set_naked) {
+        append(stmts, code_text(alc, o.flush()));
+    } else {
+        o.cstr("(").cstr(cond).cstr(")");
+        append(stmts, code_stmt(alc, o.flush()));
+    }
+}
+
+void emit_rule(Output &output, CodeList *stmts, const DFA &dfa, size_t rule_idx)
+{
+    const opt_t *opts = output.block().opts;
+    const Rule &rule = dfa.rules[rule_idx];
+    const SemAct *semact = rule.semact;
+    code_alc_t &alc = output.allocator;
+    Scratchbuf &o = output.scratchbuf;
+
+    gen_fintags(output, stmts, dfa, rule);
+
+    if (opts->target == TARGET_SKELETON) {
+        emit_skeleton_action(output, stmts, dfa, rule_idx);
+        return;
+    }
+
+    bool is_cond_block = !dfa.cond.empty();
+    const std::string &cond = semact->cond.empty() ? dfa.cond : semact->cond;
+    const char *next = is_cond_block
+        ? o.str(opts->condEnumPrefix).str(cond).flush() : "0";
+
+    if (opts->loop_switch && opts->fFlag) {
+        // With loop/switch and storable state we need YYSETSTATE in the final state,
+        // because the user may enclose lexer in an outer loop and expect the next
+        // iteration to start from the initial DFA state. Since `yystate` is initialized
+        // to YYGETSTATE, we need to do YYSETSTATE before the user-defined action.
+        //
+        // If both storable state and start conditions are used, only one of YYGETSTATE
+        // and YYGETCONDITION can be used to initialize `yystate`. It must be YYGETSTATE
+        // because the lexer may be reentered after an YYFILL invocation. Consequently we
+        // need to use YYSETSTATE instead of YYSETCONDITION in the final state to match
+        // YYGETSTATE in `yystate` initialization.
+        gen_setstate(output, stmts, next);
+    } else if (is_cond_block && cond != dfa.cond) {
+        // Omit YYSETCONDITION if the current condition is the same as the new one.
+        gen_setcondition(output, stmts, next);
+    }
+
+    if (!semact->autogen) {
+        // User-defined semantic action.
+        if (!dfa.setup.empty()) append(stmts, code_text(alc, o.str(dfa.setup).flush()));
+        append(stmts, code_line_info_input(alc, semact->loc));
+        append(stmts, code_text(alc, o.str(semact->text).flush()));
+        append(stmts, code_line_info_output(alc));
+    } else if (opts->loop_switch) {
+        // Autogenerated action for the :=> rule, loop/switch mode: set `yystate` to the
+        // initial state of the next condition and continue to the head of the loop.
+        o.str(opts->yystate).cstr(" = ").cstr(next);
+        append(stmts, code_stmt(alc, o.flush()));
+        append(stmts, code_stmt(alc, "continue"));
+    } else {
+        // Autogenerated action for the :=> rule, goto/label mode: emit `cond:goto`
+        // configuration with `cond:goto@cond` replaced by the next condition label.
+        o.str(opts->condGoto);
+        argsubst(o.stream(), opts->condGotoParam, "cond", true, opts->condPrefix + cond);
+        append(stmts, code_text(alc, o.flush()));
+    }
+}
+
 static CodeList *gen_fill_falllback(Output &output, const DFA &dfa,
     const State *from, const State *to)
 {
@@ -330,8 +357,14 @@ static CodeList *gen_fill_falllback(Output &output, const DFA &dfa,
 
         // go to fallback state
         fallback->label->used = true;
-        append(fallback_trans, code_stmt(alc, output.scratchbuf.cstr("goto ")
-            .str(opts->labelPrefix).label(*fallback->label).flush()));
+        if (!opts->loop_switch) {
+            append(fallback_trans, code_stmt(alc, output.scratchbuf.cstr("goto ")
+                .str(opts->labelPrefix).label(*fallback->label).flush()));
+        } else {
+            append(fallback_trans, code_stmt(alc, output.scratchbuf.str(opts->yystate)
+                .cstr(" = ").label(*fallback->label).flush()));
+            append(fallback_trans, code_stmt(alc, "continue"));
+        }
     }
     else {
         // Transition can be elided, because control flow "falls through" to an
@@ -346,7 +379,7 @@ static void gen_fill(Output &output, CodeList *stmts, const DFA &dfa,
 {
     const opt_t *opts = output.block().opts;
     const bool eof_rule = opts->eof != NOEOF;
-    const uint32_t fillidx = output.block().fill_index_end - 1;
+    const uint32_t fillidx = output.block().fill_index - 1;
     const size_t need = eof_rule ? 1 : from->fill;
     code_alc_t &alc = output.allocator;
     Scratchbuf &o = output.scratchbuf;
@@ -356,13 +389,19 @@ static void gen_fill(Output &output, CodeList *stmts, const DFA &dfa,
 
     // Transition to YYFILL label from the initial state dispatch.
     CodeList *goto_fill = code_list(alc);
-    const char *flabel = gen_fill_label(output, fillidx);
-    append(goto_fill, code_stmt(alc, o.cstr("goto ").cstr(flabel).flush()));
+    if (!opts->loop_switch) {
+        const char *flabel = gen_fill_label(output, fillidx);
+        append(goto_fill, code_stmt(alc, o.cstr("goto ").cstr(flabel).flush()));
+    } else {
+        o.str(opts->yystate).cstr(" = ").u32(output.block().fill_state);
+        append(goto_fill, code_stmt(alc, o.flush()));
+        append(goto_fill, code_stmt(alc, "continue"));
+    }
 
     CodeList *fill = code_list(alc);
 
     if (opts->fFlag) {
-        gen_setstate(output, eof_rule ? fill : stmts, fillidx);
+        gen_setstate(output, eof_rule ? fill : stmts, o.u32(fillidx).flush());
     }
 
     if (opts->fill_use) {
@@ -407,7 +446,7 @@ static void gen_fill(Output &output, CodeList *stmts, const DFA &dfa,
         }
     }
     if (opts->fFlag) {
-        output.block().fill_goto.push_back(goto_fill);
+        output.block().fill_goto[fillidx] = goto_fill;
     }
 
     if (opts->fill_check && fill->head) {
@@ -429,7 +468,8 @@ void gen_fill_and_label(Output &output, CodeList *stmts, const DFA &dfa, const S
     const bool need_fill_label = need_fill_on_trans || (need_fill_in_state && opts->fFlag);
 
     if (need_fill_label) {
-        ++output.block().fill_index_end;
+        ++output.block().fill_index;
+        output.block().fill_state = s->label->index;
     }
 
     if (need_fill_in_state) {
@@ -445,8 +485,8 @@ void gen_fill_and_label(Output &output, CodeList *stmts, const DFA &dfa, const S
         gen_settags(output, stmts, dfa, s->go.tags, opts->stadfa /* delayed */);
     }
 
-    if (need_fill_label) {
-        const char *flabel = gen_fill_label(output, output.block().fill_index_end - 1);
+    if (need_fill_label && !opts->loop_switch) {
+        const char *flabel = gen_fill_label(output, output.block().fill_index - 1);
         append(stmts, code_slabel(output.allocator, flabel));
     }
 }
@@ -475,8 +515,14 @@ void gen_goto(Output &output, const DFA &dfa, CodeList *stmts, const State *from
 
     if (!jump.elide) {
         jump.to->label->used = true;
-        text = o.cstr("goto ").str(opts->labelPrefix).label(*jump.to->label).flush();
-        append(stmts, code_stmt(alc, text));
+        if (!opts->loop_switch) {
+            text = o.cstr("goto ").str(opts->labelPrefix).label(*jump.to->label).flush();
+            append(stmts, code_stmt(alc, text));
+        } else {
+            text = o.str(opts->yystate).cstr(" = ").label(*jump.to->label).flush();
+            append(stmts, code_stmt(alc, text));
+            append(stmts, code_stmt(alc, "continue"));
+        }
     }
     else {
         // Goto can be elided, because control flow "falls through" to the

src/codegen/render.cc

@@ -334,6 +334,31 @@ static void render_func(RenderContext &rctx, const CodeFunc *func)
     ++rctx.line;
 }
 
+static void render_loop(RenderContext &rctx, const CodeList *loop)
+{
+    std::ostringstream &os = rctx.os;
+    const opt_t *opts = rctx.opts;
+
+    os << indent(rctx.ind, opts->indString);
+    switch (opts->lang) {
+    case LANG_C:
+        os << "for (;;) {";
+        break;
+    case LANG_GO:
+        os << "for {";
+        break;
+    }
+    os << std::endl;
+    ++rctx.line;
+
+    ++rctx.ind;
+    render_list(rctx, loop);
+    --rctx.ind;
+
+    os << indent(rctx.ind, opts->indString) << "}" << std::endl;
+    ++rctx.line;
+}
+
 static inline void yych_conv(std::ostream &os, const opt_t *opts)
 {
     if (opts->yychConversion) {
@@ -509,6 +534,9 @@ void render(RenderContext &rctx, const Code *code)
         case CODE_FUNC:
             render_func(rctx, &code->func);
             break;
+        case CODE_LOOP:
+            render_loop(rctx, code->loop);
+            break;
         case CODE_TEXT_RAW:
             os << code->text << std::endl;
             line += count_lines_text(code->text) + 1;
@@ -576,6 +604,7 @@ void render(RenderContext &rctx, const Code *code)
         case CODE_MAXNMATCH:
         case CODE_YYCH:
         case CODE_YYACCEPT:
+        case CODE_YYSTATE:
         case CODE_COND_ENUM:
         case CODE_COND_GOTO:
         case CODE_COND_TABLE:

src/compile.cc

@@ -204,6 +204,14 @@ void compile(Scanner &input, Output &output, Opt &opts)
 
     output.total_opts = accum_opts ? accum_opts : rblocks.last_opts();
 
+    // For special targets (skeleton and .dot) merge header into the output file.
+    if (globopts->target != TARGET_CODE && output.need_header) {
+        output.need_header = false;
+        blocks_t &cblocks = output.cblocks, &hblocks = output.hblocks;
+        cblocks.insert(cblocks.end(), hblocks.begin(), hblocks.end());
+        hblocks.clear();
+    }
+
     if (globopts->target == TARGET_SKELETON) {
         output.wdelay_stmt(0, emit_skeleton_epilog(output));
     }

src/compile.h

@@ -6,7 +6,7 @@ namespace re2c {
 
 class Scanner;
 struct Opt;
-class Output;
+struct Output;
 
 void compile(Scanner &input, Output &output, Opt &opts);
 

src/constants.h

@@ -97,8 +97,10 @@ enum CodeKind {
     CODE_MAXNMATCH,
     CODE_YYCH,
     CODE_YYACCEPT,
+    CODE_YYSTATE,
     CODE_VAR,
     CODE_STMT,
+    CODE_LOOP,
     CODE_TEXT,
     CODE_TEXT_RAW,
     CODE_RAW,

src/options/opt.cc

@@ -16,10 +16,6 @@ static void fix_conopt(conopt_t &glob)
         glob.iFlag = true;
     }
 
-    if (!glob.lookahead) {
-        glob.eager_skip = true;
-    }
-
     // append directory separator '/' to all paths that do not have it
     for (size_t i = 0; i < glob.incpaths.size(); ++i) {
         std::string &p = glob.incpaths[i];
@@ -29,6 +25,13 @@ static void fix_conopt(conopt_t &glob)
         }
     }
 
+    if (!glob.lookahead || glob.loop_switch) {
+        // for loop-switch enable eager-skip always (not only in cases when
+        // YYFILL labels are used) to avoid special handling of initial state
+        // when there are transitions into it.
+        glob.eager_skip = true;
+    }
+
     if (!glob.dep_file.empty() && glob.output_file.empty()) {
         error("cannot generate dep file, output file not specified");
         exit(1);
@@ -120,6 +123,7 @@ static void fix_mutopt(const conopt_t &glob, const mutopt_t &defaults,
         real.yych = defaults.yych;
         real.bEmitYYCh = defaults.bEmitYYCh;
         real.yychConversion = defaults.yychConversion;
+        real.yystate = defaults.yystate;
         real.fill = defaults.fill;
         real.fill_use = defaults.fill_use;
         real.fill_check = defaults.fill_check;
@@ -248,6 +252,14 @@ static void fix_mutopt(const conopt_t &glob, const mutopt_t &defaults,
     if (real.fill_naked) {
         real.fill_arg_use = false;
     }
+    if (glob.loop_switch) {
+        // With --loop-switch there is no `goto`.
+        real.yyctable = defaults.yyctable;
+        real.condDivider = defaults.condDivider;
+        real.condDividerParam = defaults.condDividerParam;
+        real.condGoto = defaults.condGoto;
+        real.condGotoParam = defaults.condGotoParam;
+    }
 
     // errors
     if (glob.target == TARGET_SKELETON && glob.lang != LANG_C) {
@@ -310,6 +322,25 @@ static void fix_mutopt(const conopt_t &glob, const mutopt_t &defaults,
         error("storable state requires YYFILL to be enabled");
         exit(1);
     }
+    if (glob.loop_switch) {
+        if (real.gFlag) {
+            error("cannot combine loop switch and computed gotos");
+            exit(1);
+        }
+        if (real.bFlag) {
+            // TODO: generate bitmaps before the joined loop/switch for all conditions.
+            error("bitmaps with loop switch are not supported");
+            exit(1);
+        }
+        if (!glob.lookahead) {
+            // The problem here is that TDFA(0) may have initial register operations that
+            // should be executed on DFA entry. With loop/switch these operations would
+            // need to go in a special initial state (they can't go before the `yystate`
+            // loop because that would not work with start conditions).
+            error("TDFA(0) with loop switch is not supported");
+            exit(1);
+        }
+    }
 }
 
 Opt::Opt(const conopt_t &globopts)

src/options/opt.h

@@ -70,11 +70,12 @@ class Msg;
     CONSTOPT (posix_prectable_alg_t, posix_prectable, POSIX_PRECTABLE_COMPLEX) \
     CONSTOPT (fixed_tags_t, fixed_tags, FIXTAG_ALL) \
     CONSTOPT (bool, lookahead, true) \
-    CONSTOPT (bool, eager_skip, false) \
     CONSTOPT (bool, optimize_tags, true) \
     CONSTOPT (bool, backward, false) \
     CONSTOPT (bool, stadfa, false) \
     CONSTOPT (bool, nested_negative_tags, true) \
+    CONSTOPT (bool, eager_skip, false) \
+    CONSTOPT (bool, loop_switch, false) \
     /* debug */ \
     CONSTOPT (bool, dump_nfa, false) \
     CONSTOPT (bool, dump_dfa_raw, false) \
@@ -136,6 +137,7 @@ class Msg;
     MUTOPT (bool, yybmHexTable, false) \
     MUTOPT (bool, gFlag, false) \
     MUTOPT (bool, case_ranges, false) \
+    MUTOPT (std::string, yystate, "yystate") \
     MUTOPT (std::string, yytarget, "yytarget") \
     MUTOPT (uint32_t, cGotoThreshold, 9) \
     MUTOPT (uint32_t, eof, NOEOF) \

src/options/parse_opts.re

@@ -167,6 +167,8 @@ opt_long:
     "no-generation-date"    end { globopts.bNoGenerationDate = true; goto opt; }
     "no-version"            end { globopts.version = false;          goto opt; }
     "skeleton"              end { globopts.target = TARGET_SKELETON; goto opt; }
+    "eager-skip"            end { globopts.eager_skip = true;        goto opt; }
+    "loop-switch"           end { globopts.loop_switch = true;      goto opt; }
 
     "bit-vectors"           end { opts.set_bFlag (true);             goto opt; }
     "debug-output"          end { opts.set_dFlag (true);             goto opt; }
@@ -209,7 +211,6 @@ opt_long:
     "fixed-tags"            end { NEXT_ARG("--fixed-tags",       opt_fixed_tags); }
     "no-lookahead"          end { globopts.lookahead = false;     goto opt; }
     "no-optimize-tags"      end { globopts.optimize_tags = false; goto opt; }
-    "eager-skip"            end { globopts.eager_skip = true;     goto opt; }
     "stadfa"                end { globopts.stadfa = true;         goto opt; }
 
     // debug options

src/options/symtab.h

@@ -9,7 +9,7 @@ namespace re2c {
 
 struct AST;
 struct loc_t;
-struct Msg;
+class Msg;
 
 typedef std::map<std::string, const AST*> symtab_t;
 

src/parse/ast.h

@@ -13,7 +13,7 @@
 namespace re2c {
 
 struct SemAct;
-template <class _Ty> class free_list;
+template <class Ty> class free_list;
 
 struct ASTChar {
     uint32_t chr;

src/parse/lex.re

@@ -189,7 +189,7 @@ loop:
     }
 
     "/*!types:re2c" {
-        out.cond_enum_in_hdr = out.in_header();
+        out.cond_enum_autogen = false;
         out.warn_condition_order = false; // see note [condition order]
         uint32_t allow = DCONF_FORMAT | DCONF_SEPARATOR;
         if (!lex_block(out, CODE_COND_ENUM, opts->topIndent, allow)) return INPUT_ERROR;
@@ -202,6 +202,12 @@ loop:
             msg.error(cur_loc(), "`getstate:re2c` without `-f --storable-state` option");
             return INPUT_ERROR;
         }
+        if (opts->loop_switch) {
+            msg.error(cur_loc(), "`getstate:re2c` is incompatible with the --loop-switch "
+                "option, as it requires cross-block transitions that are unsupported "
+                "without the `goto` statement");
+            return INPUT_ERROR;
+        }
         if (!lex_block(out, CODE_STATE_GOTO, opts->topIndent, 0)) return INPUT_ERROR;
         goto next;
     }
@@ -209,7 +215,7 @@ loop:
     "/*!header:re2c:on" {
         out.wraw(tok, ptr);
         out.header_mode(true);
-        out.need_header = opts->target == TARGET_CODE;
+        out.need_header = true;
         if (!lex_block_end(out)) return INPUT_ERROR;
         goto next;
     }

src/parse/lex_conf.re

@@ -119,6 +119,7 @@ void Scanner::lex_conf(Opt &opts)
         return;
     }
     "variable:yytarget" { opts.set_yytarget (lex_conf_string ()); return; }
+    "variable:yystate"  { opts.set_yystate  (lex_conf_string ()); return; }
 
     "define:YYCURSOR"    { opts.set_yycursor    (lex_conf_string ()); return; }
     "define:YYMARKER"    { opts.set_yymarker    (lex_conf_string ()); return; }

src/parse/scanner.h

@@ -21,7 +21,7 @@
 namespace re2c {
 
 class Msg;
-class Output;
+struct Output;
 struct AST;
 struct ASTChar;
 struct BlockNameList;

src/regexp/re.h

@@ -14,7 +14,7 @@ namespace re2c {
 
 struct AST;
 struct ASTRule;
-struct Msg;
+class Msg;
 struct Rule;
 struct opt_t;
 

src/skeleton/generate_code.cc

@@ -152,7 +152,7 @@ static void emit_skeleton_defines(Output &output, CodeList *code, const DFA &dfa
     append(code, code_textraw(alc, "#define YYSHIFT(o) cursor += o"));
     append(code, code_textraw(alc, "#define YYLESSTHAN(n) (limit - cursor) < n"));
     append(code, code_textraw(alc, opts->eof == NOEOF
-        ? "#define YYFILL(n) { break; }"
+        ? "#define YYFILL(n) { goto loop_end; }"
         : "#define YYFILL(n) 1 /* fail */"));
     append(code, code_newline(alc));
 }
@@ -610,8 +610,17 @@ static void emit_skeleton_function_lex(Output &output, CodeList *code, DFA &dfa)
 
     append(block, code_textraw(alc, ""));
 
-    append(block, code_text(alc,
-        "for (i = 0; status == 0 && cursor < eof && i < keys_count;) {"));
+    // Don't use `for` loops or `while` loops: the generated code may contain an
+    // inner loop if the --loop-switch option is used, and then `continue` and
+    // `break` statements may result in unexpected control flow. Use `goto` loop.
+    append(block, code_stmt(alc, "i = 0"));
+    append(block, code_slabel(alc, "loop"));
+
+    block2 = code_list(alc);
+    append(block2, code_stmt(alc, "goto loop_end"));
+    append(block, code_if_then_else(alc,
+        "!(status == 0 && cursor < eof && i < keys_count)", block2, NULL));
+
     block2 = code_list(alc);
     append(block2, code_stmt(alc, "token = cursor"));
     if (dfa.need_backup) {
@@ -624,6 +633,9 @@ static void emit_skeleton_function_lex(Output &output, CodeList *code, DFA &dfa)
     if (dfa.need_accept) {
         append(block2, code_stmt(alc, "unsigned int yyaccept = 0"));
     }
+    if (opts->loop_switch) {
+        append(block2, code_stmt(alc, o.cstr("unsigned int yystate = 0").flush()));
+    }
     // autogenerated stag variables
     if (!dfa.stagnames.empty()) {
         text = o.cstr("\n").str(indent(2, opts->indString))
@@ -676,11 +688,20 @@ static void emit_skeleton_function_lex(Output &output, CodeList *code, DFA &dfa)
     }
     append(block2, code_textraw(alc, ""));
 
-    dfa.emit_body(output, block2);
+    if (!opts->loop_switch) {
+        gen_dfa_as_blocks_with_labels(output, dfa, block2);
+    } else {
+        // With loop/switch there are no labels, and each block has its own state switch.
+        // Restart state counter from zero so that cases start from zero.
+        output.label_counter = 0;
+        CodeCases *cases = code_cases(alc);
+        gen_dfa_as_switch_cases(output, dfa, cases);
+        wrap_dfas_in_loop_switch(output, block2, cases);
+    }
     append(block2, code_textraw(alc, ""));
 
-    append(block, code_block(alc, block2, CodeBlock::INDENTED));
-    append(block, code_text(alc, "}"));
+    append(block, code_block(alc, block2, CodeBlock::WRAPPED));
+    append(block, code_slabel(alc, "loop_end"));
 
     if_code = code_list(alc);
 
@@ -837,7 +858,7 @@ void emit_skeleton_action(Output &output, CodeList *code, const DFA &dfa, size_t
 
     append(code, code_block(alc, hangafter, CodeBlock::INDENTED));
 
-    append(code, code_stmt(alc, "continue"));
+    append(code, code_stmt(alc, "goto loop"));
 }
 
 } // namespace re2c

src/util/free_list.h

@@ -6,25 +6,25 @@
 
 namespace re2c {
 
-template<class _Ty>
-class free_list: protected std::set<_Ty>
+template<class Ty>
+class free_list: protected std::set<Ty>
 {
 public:
-    typedef typename std::set<_Ty>::iterator   iterator;
-    typedef typename std::set<_Ty>::size_type  size_type;
-    typedef typename std::set<_Ty>::key_type   key_type;
+    typedef typename std::set<Ty>::iterator   iterator;
+    typedef typename std::set<Ty>::size_type  size_type;
+    typedef typename std::set<Ty>::key_type   key_type;
     
     free_list(): in_clear(false)
     {
     }
     
-    using std::set<_Ty>::insert;
+    using std::set<Ty>::insert;
 
     size_type erase(const key_type& key)
     {
         if (!in_clear)
         {
-            return std::set<_Ty>::erase(key);
+            return std::set<Ty>::erase(key);
         }
         return 0;
     }
@@ -37,7 +37,7 @@ public:
         {
             delete *it;
         }
-        std::set<_Ty>::clear();
+        std::set<Ty>::clear();
         
         in_clear = false;
     }

test/bug152.c

@@ -2,8 +2,6 @@
 #line 1 "bug152.re"
 // re2c $INPUT -o $OUTPUT -c
 #line 5 "bug152.c"
-enum YYCONDTYPE {
-};
 #line 2 "bug152.re"
 
 

test/codegen/loop_switch/c/basic.c

@@ -0,0 +1,54 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --case-ranges --loop-switch -i
+
+int lex(const char *YYCURSOR) {       // C/C++ code
+
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			switch (yych) {
+			case 'A' ... 'Z':
+			case 'a' ... 'z':
+				yystate = 3;
+				continue;
+			default:
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return 1; }
+		case 3:
+			yych = *YYCURSOR;
+			yystate = 4;
+			continue;
+		case 4:
+			switch (yych) {
+			case '0' ... '9':
+			case 'A' ... 'Z':
+			case 'a' ... 'z':
+				++YYCURSOR;
+				yystate = 3;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 5:
+			{ return 0; }
+		}
+	}
+}
+
+}                                     //
+                                      //
+int main() {                          // C/C++ code
+    return lex("qwerty42");           //
+}                                     //

test/codegen/loop_switch/c/basic.re

@@ -0,0 +1,18 @@
+// re2c $INPUT -o $OUTPUT --case-ranges --loop-switch -i
+
+int lex(const char *YYCURSOR) {       // C/C++ code
+/*!re2c
+    re2c:define:YYCTYPE = char;       // configurations
+    re2c:yyfill:enable  = 0;          //
+                                      //
+    alpha = [a-zA-Z];                 // named definitions
+    ident = alpha (alpha | [0-9])*;   //
+                                      //
+    ident { return 0; }               // rules
+    *     { return 1; }               //
+*/
+}                                     //
+                                      //
+int main() {                          // C/C++ code
+    return lex("qwerty42");           //
+}                                     //

test/codegen/loop_switch/c/bounds_checking.c

@@ -0,0 +1,121 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define YYMAXFILL 1
+
+
+// expect YYMAXFILL-padded string
+static int lex(const char *str, unsigned int len)
+{
+    const char *YYCURSOR = str, *YYLIMIT = str + len + YYMAXFILL;
+    int count = 0;
+
+loop:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			if (YYLIMIT <= YYCURSOR) return -1;
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case ' ':
+				yystate = 5;
+				continue;
+			case '\'':
+				yystate = 8;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return YYCURSOR + YYMAXFILL - 1 == YYLIMIT ? count : -1; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return -1; }
+		case 5:
+			if (YYLIMIT <= YYCURSOR) return -1;
+			yych = *YYCURSOR;
+			yystate = 6;
+			continue;
+		case 6:
+			switch (yych) {
+			case ' ':
+				++YYCURSOR;
+				yystate = 5;
+				continue;
+			default:
+				yystate = 7;
+				continue;
+			}
+		case 7:
+			{ goto loop; }
+		case 8:
+			if (YYLIMIT <= YYCURSOR) return -1;
+			yych = *YYCURSOR;
+			yystate = 9;
+			continue;
+		case 9:
+			++YYCURSOR;
+			switch (yych) {
+			case '\'':
+				yystate = 10;
+				continue;
+			case '\\':
+				yystate = 12;
+				continue;
+			default:
+				yystate = 8;
+				continue;
+			}
+		case 10:
+			yystate = 11;
+			continue;
+		case 11:
+			{ ++count; goto loop; }
+		case 12:
+			if (YYLIMIT <= YYCURSOR) return -1;
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			yystate = 8;
+			continue;
+		}
+	}
+}
+
+}
+
+// make a copy of the string with YYMAXFILL zeroes at the end
+static void test(const char *str, unsigned int len, int res)
+{
+    char *s = (char*) malloc(len + YYMAXFILL);
+    memcpy(s, str, len);
+    memset(s + len, 0, YYMAXFILL);
+    int r = lex(s, len);
+    free(s);
+    assert(r == res);
+}
+
+#define TEST(s, r) test(s, sizeof(s) - 1, r)
+int main()
+{
+    TEST("", 0);
+    TEST("'qu\0tes' 'are' 'fine: \\'' ", 3);
+    TEST("'unterminated\\'", -1);
+    return 0;
+}

test/codegen/loop_switch/c/bounds_checking.re

@@ -0,0 +1,46 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*!max:re2c*/
+
+// expect YYMAXFILL-padded string
+static int lex(const char *str, unsigned int len)
+{
+    const char *YYCURSOR = str, *YYLIMIT = str + len + YYMAXFILL;
+    int count = 0;
+
+loop:
+    /*!re2c
+    re2c:api:style = free-form;
+    re2c:define:YYCTYPE = char;
+    re2c:define:YYFILL = "return -1;";
+
+    *                           { return -1; }
+    [\x00]                      { return YYCURSOR + YYMAXFILL - 1 == YYLIMIT ? count : -1; }
+    ['] ([^'\\] | [\\][^])* ['] { ++count; goto loop; }
+    [ ]+                        { goto loop; }
+
+    */
+}
+
+// make a copy of the string with YYMAXFILL zeroes at the end
+static void test(const char *str, unsigned int len, int res)
+{
+    char *s = (char*) malloc(len + YYMAXFILL);
+    memcpy(s, str, len);
+    memset(s + len, 0, YYMAXFILL);
+    int r = lex(s, len);
+    free(s);
+    assert(r == res);
+}
+
+#define TEST(s, r) test(s, sizeof(s) - 1, r)
+int main()
+{
+    TEST("", 0);
+    TEST("'qu\0tes' 'are' 'fine: \\'' ", 3);
+    TEST("'unterminated\\'", -1);
+    return 0;
+}

test/codegen/loop_switch/c/eof_rule.c

@@ -0,0 +1,134 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+
+// expect a null-terminated string
+static int lex(const char *str, unsigned int len)
+{
+    const char *YYCURSOR = str, *YYLIMIT = str + len, *YYMARKER;
+    int count = 0;
+
+loop:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case ' ':
+				++YYCURSOR;
+				yystate = 3;
+				continue;
+			case '\'':
+				++YYCURSOR;
+				yystate = 6;
+				continue;
+			default:
+				if (YYLIMIT <= YYCURSOR) {
+					yystate = 12;
+					continue;
+				}
+				++YYCURSOR;
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return -1; }
+		case 3:
+			yych = *YYCURSOR;
+			yystate = 4;
+			continue;
+		case 4:
+			switch (yych) {
+			case ' ':
+				++YYCURSOR;
+				yystate = 3;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 5:
+			{ goto loop; }
+		case 6:
+			YYMARKER = YYCURSOR;
+			yych = *YYCURSOR;
+			if (yych >= 0x01) {
+				yystate = 8;
+				continue;
+			}
+			if (YYLIMIT <= YYCURSOR) {
+				yystate = 2;
+				continue;
+			}
+			++YYCURSOR;
+			yystate = 7;
+			continue;
+		case 7:
+			yych = *YYCURSOR;
+			yystate = 8;
+			continue;
+		case 8:
+			switch (yych) {
+			case '\'':
+				++YYCURSOR;
+				yystate = 9;
+				continue;
+			case '\\':
+				++YYCURSOR;
+				yystate = 11;
+				continue;
+			default:
+				if (YYLIMIT <= YYCURSOR) {
+					yystate = 13;
+					continue;
+				}
+				++YYCURSOR;
+				yystate = 7;
+				continue;
+			}
+		case 9:
+			yystate = 10;
+			continue;
+		case 10:
+			{ ++count; goto loop; }
+		case 11:
+			yych = *YYCURSOR;
+			if (yych <= 0x00) {
+				if (YYLIMIT <= YYCURSOR) {
+					yystate = 13;
+					continue;
+				}
+				++YYCURSOR;
+				yystate = 7;
+				continue;
+			}
+			++YYCURSOR;
+			yystate = 7;
+			continue;
+		case 12:
+			{ return count; }
+		case 13:
+			YYCURSOR = YYMARKER;
+			yystate = 2;
+			continue;
+		}
+	}
+}
+
+}
+
+#define TEST(s, r) assert(lex(s, sizeof(s) - 1) == r)
+int main()
+{
+    TEST("", 0);
+    TEST("'qu\0tes' 'are' 'fine: \\'' ", 3);
+    TEST("'unterminated\\'", -1);
+    return 0;
+}

test/codegen/loop_switch/c/eof_rule.re

@@ -0,0 +1,31 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+
+// expect a null-terminated string
+static int lex(const char *str, unsigned int len)
+{
+    const char *YYCURSOR = str, *YYLIMIT = str + len, *YYMARKER;
+    int count = 0;
+
+loop:
+    /*!re2c
+    re2c:define:YYCTYPE = char;
+    re2c:yyfill:enable = 0;
+    re2c:eof = 0;
+
+    *                           { return -1; }
+    $                           { return count; }
+    ['] ([^'\\] | [\\][^])* ['] { ++count; goto loop; }
+    [ ]+                        { goto loop; }
+
+    */
+}
+
+#define TEST(s, r) assert(lex(s, sizeof(s) - 1) == r)
+int main()
+{
+    TEST("", 0);
+    TEST("'qu\0tes' 'are' 'fine: \\'' ", 3);
+    TEST("'unterminated\\'", -1);
+    return 0;
+}

test/codegen/loop_switch/c/fill_1.c

@@ -0,0 +1,207 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#define SIZE 4096
+
+typedef struct {
+    FILE *file;
+    char buf[SIZE + 1], *lim, *cur, *mar, *tok;
+    int eof;
+} Input;
+
+static int fill(Input *in)
+{
+    if (in->eof) {
+        return 1;
+    }
+    const size_t free = in->tok - in->buf;
+    if (free < 1) {
+        return 2;
+    }
+    memmove(in->buf, in->tok, in->lim - in->tok);
+    in->lim -= free;
+    in->cur -= free;
+    in->mar -= free;
+    in->tok -= free;
+    in->lim += fread(in->lim, 1, free, in->file);
+    in->lim[0] = 0;
+    in->eof |= in->lim < in->buf + SIZE;
+    return 0;
+}
+
+static void init(Input *in, FILE *file)
+{
+    in->file = file;
+    in->cur = in->mar = in->tok = in->lim = in->buf + SIZE;
+    in->eof = 0;
+    fill(in);
+}
+
+static int lex(Input *in)
+{
+    int count = 0;
+loop:
+    in->tok = in->cur;
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *in->cur;
+			switch (yych) {
+			case ' ':
+				++in->cur;
+				yystate = 3;
+				continue;
+			case '\'':
+				++in->cur;
+				yystate = 6;
+				continue;
+			default:
+				if (in->lim <= in->cur) {
+					if (fill(in) == 0) {
+						yystate = 0;
+						continue;
+					}
+					yystate = 12;
+					continue;
+				}
+				++in->cur;
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return -1; }
+		case 3:
+			yych = *in->cur;
+			yystate = 4;
+			continue;
+		case 4:
+			switch (yych) {
+			case ' ':
+				++in->cur;
+				yystate = 3;
+				continue;
+			default:
+				if (in->lim <= in->cur) {
+					if (fill(in) == 0) {
+						yystate = 3;
+						continue;
+					}
+				}
+				yystate = 5;
+				continue;
+			}
+		case 5:
+			{ goto loop; }
+		case 6:
+			in->mar = in->cur;
+			yych = *in->cur;
+			if (yych >= 0x01) {
+				yystate = 8;
+				continue;
+			}
+			if (in->lim <= in->cur) {
+				if (fill(in) == 0) {
+					yystate = 6;
+					continue;
+				}
+				yystate = 2;
+				continue;
+			}
+			++in->cur;
+			yystate = 7;
+			continue;
+		case 7:
+			yych = *in->cur;
+			yystate = 8;
+			continue;
+		case 8:
+			switch (yych) {
+			case '\'':
+				++in->cur;
+				yystate = 9;
+				continue;
+			case '\\':
+				++in->cur;
+				yystate = 11;
+				continue;
+			default:
+				if (in->lim <= in->cur) {
+					if (fill(in) == 0) {
+						yystate = 7;
+						continue;
+					}
+					yystate = 13;
+					continue;
+				}
+				++in->cur;
+				yystate = 7;
+				continue;
+			}
+		case 9:
+			yystate = 10;
+			continue;
+		case 10:
+			{ ++count; goto loop; }
+		case 11:
+			yych = *in->cur;
+			if (yych <= 0x00) {
+				if (in->lim <= in->cur) {
+					if (fill(in) == 0) {
+						yystate = 11;
+						continue;
+					}
+					yystate = 13;
+					continue;
+				}
+				++in->cur;
+				yystate = 7;
+				continue;
+			}
+			++in->cur;
+			yystate = 7;
+			continue;
+		case 12:
+			{ return count; }
+		case 13:
+			in->cur = in->mar;
+			yystate = 2;
+			continue;
+		}
+	}
+}
+
+}
+
+int main()
+{
+    const char *fname = "input";
+    const char str[] = "'qu\0tes' 'are' 'fine: \\'' ";
+    FILE *f;
+    Input in;
+
+    // prepare input file: a few times the size of the buffer,
+    // containing strings with zeroes and escaped quotes
+    f = fopen(fname, "w");
+    for (int i = 0; i < SIZE; ++i) {
+        fwrite(str, 1, sizeof(str) - 1, f);
+    }
+    fclose(f);
+
+    f = fopen(fname, "r");
+    init(&in, f);
+    assert(lex(&in) == SIZE * 3);
+    fclose(f);
+
+    remove(fname);
+    return 0;
+}

test/codegen/loop_switch/c/fill_1.re

@@ -0,0 +1,86 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#define SIZE 4096
+
+typedef struct {
+    FILE *file;
+    char buf[SIZE + 1], *lim, *cur, *mar, *tok;
+    int eof;
+} Input;
+
+static int fill(Input *in)
+{
+    if (in->eof) {
+        return 1;
+    }
+    const size_t free = in->tok - in->buf;
+    if (free < 1) {
+        return 2;
+    }
+    memmove(in->buf, in->tok, in->lim - in->tok);
+    in->lim -= free;
+    in->cur -= free;
+    in->mar -= free;
+    in->tok -= free;
+    in->lim += fread(in->lim, 1, free, in->file);
+    in->lim[0] = 0;
+    in->eof |= in->lim < in->buf + SIZE;
+    return 0;
+}
+
+static void init(Input *in, FILE *file)
+{
+    in->file = file;
+    in->cur = in->mar = in->tok = in->lim = in->buf + SIZE;
+    in->eof = 0;
+    fill(in);
+}
+
+static int lex(Input *in)
+{
+    int count = 0;
+loop:
+    in->tok = in->cur;
+    /*!re2c
+    re2c:eof = 0;
+    re2c:api:style = free-form;
+    re2c:define:YYCTYPE  = char;
+    re2c:define:YYCURSOR = in->cur;
+    re2c:define:YYMARKER = in->mar;
+    re2c:define:YYLIMIT  = in->lim;
+    re2c:define:YYFILL   = "fill(in) == 0";
+
+    *                           { return -1; }
+    $                           { return count; }
+    ['] ([^'\\] | [\\][^])* ['] { ++count; goto loop; }
+    [ ]+                        { goto loop; }
+
+    */
+}
+
+int main()
+{
+    const char *fname = "input";
+    const char str[] = "'qu\0tes' 'are' 'fine: \\'' ";
+    FILE *f;
+    Input in;
+
+    // prepare input file: a few times the size of the buffer,
+    // containing strings with zeroes and escaped quotes
+    f = fopen(fname, "w");
+    for (int i = 0; i < SIZE; ++i) {
+        fwrite(str, 1, sizeof(str) - 1, f);
+    }
+    fclose(f);
+
+    f = fopen(fname, "r");
+    init(&in, f);
+    assert(lex(&in) == SIZE * 3);
+    fclose(f);
+
+    remove(fname);
+    return 0;
+}

test/codegen/loop_switch/c/fill_2.c

@@ -0,0 +1,161 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#define YYMAXFILL 1
+
+#define SIZE 4096
+
+typedef struct {
+    FILE *file;
+    char buf[SIZE + YYMAXFILL], *lim, *cur, *mar, *tok;
+    int eof;
+} Input;
+
+static int fill(Input *in, size_t need)
+{
+    if (in->eof) {
+        return 1;
+    }
+    const size_t free = in->tok - in->buf;
+    if (free < need) {
+        return 2;
+    }
+    memmove(in->buf, in->tok, in->lim - in->tok);
+    in->lim -= free;
+    in->cur -= free;
+    in->mar -= free;
+    in->tok -= free;
+    in->lim += fread(in->lim, 1, free, in->file);
+    if (in->lim < in->buf + SIZE) {
+        in->eof = 1;
+        memset(in->lim, 0, YYMAXFILL);
+        in->lim += YYMAXFILL;
+    }
+    return 0;
+}
+
+static void init(Input *in, FILE *file)
+{
+    in->file = file;
+    in->cur = in->mar = in->tok = in->lim = in->buf + SIZE;
+    in->eof = 0;
+    fill(in, 1);
+}
+
+static int lex(Input *in)
+{
+    int count = 0;
+loop:
+    in->tok = in->cur;
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			if (in->lim <= in->cur) if (fill(in, 1) != 0) return -1;
+			yych = *in->cur;
+			++in->cur;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case ' ':
+				yystate = 5;
+				continue;
+			case '\'':
+				yystate = 8;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return (in->lim - in->cur == YYMAXFILL - 1) ? count : -1; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return -1; }
+		case 5:
+			if (in->lim <= in->cur) if (fill(in, 1) != 0) return -1;
+			yych = *in->cur;
+			yystate = 6;
+			continue;
+		case 6:
+			switch (yych) {
+			case ' ':
+				++in->cur;
+				yystate = 5;
+				continue;
+			default:
+				yystate = 7;
+				continue;
+			}
+		case 7:
+			{ goto loop; }
+		case 8:
+			if (in->lim <= in->cur) if (fill(in, 1) != 0) return -1;
+			yych = *in->cur;
+			yystate = 9;
+			continue;
+		case 9:
+			++in->cur;
+			switch (yych) {
+			case '\'':
+				yystate = 10;
+				continue;
+			case '\\':
+				yystate = 12;
+				continue;
+			default:
+				yystate = 8;
+				continue;
+			}
+		case 10:
+			yystate = 11;
+			continue;
+		case 11:
+			{ ++count; goto loop; }
+		case 12:
+			if (in->lim <= in->cur) if (fill(in, 1) != 0) return -1;
+			yych = *in->cur;
+			++in->cur;
+			yystate = 8;
+			continue;
+		}
+	}
+}
+
+}
+
+int main()
+{
+    const char *fname = "input";
+    const char str[] = "'qu\0tes' 'are' 'fine: \\'' ";
+    FILE *f;
+    Input in;
+
+    // prepare input file: a few times the size of the buffer,
+    // containing strings with zeroes and escaped quotes
+    f = fopen(fname, "w");
+    for (int i = 0; i < SIZE; ++i) {
+        fwrite(str, 1, sizeof(str) - 1, f);
+    }
+    fclose(f);
+
+    f = fopen(fname, "r");
+    init(&in, f);
+    assert(lex(&in) == SIZE * 3);
+    fclose(f);
+
+    remove(fname);
+    return 0;
+}

test/codegen/loop_switch/c/fill_2.re

@@ -0,0 +1,89 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+/*!max:re2c*/
+#define SIZE 4096
+
+typedef struct {
+    FILE *file;
+    char buf[SIZE + YYMAXFILL], *lim, *cur, *mar, *tok;
+    int eof;
+} Input;
+
+static int fill(Input *in, size_t need)
+{
+    if (in->eof) {
+        return 1;
+    }
+    const size_t free = in->tok - in->buf;
+    if (free < need) {
+        return 2;
+    }
+    memmove(in->buf, in->tok, in->lim - in->tok);
+    in->lim -= free;
+    in->cur -= free;
+    in->mar -= free;
+    in->tok -= free;
+    in->lim += fread(in->lim, 1, free, in->file);
+    if (in->lim < in->buf + SIZE) {
+        in->eof = 1;
+        memset(in->lim, 0, YYMAXFILL);
+        in->lim += YYMAXFILL;
+    }
+    return 0;
+}
+
+static void init(Input *in, FILE *file)
+{
+    in->file = file;
+    in->cur = in->mar = in->tok = in->lim = in->buf + SIZE;
+    in->eof = 0;
+    fill(in, 1);
+}
+
+static int lex(Input *in)
+{
+    int count = 0;
+loop:
+    in->tok = in->cur;
+    /*!re2c
+    re2c:api:style = free-form;
+    re2c:define:YYCTYPE  = char;
+    re2c:define:YYCURSOR = in->cur;
+    re2c:define:YYMARKER = in->mar;
+    re2c:define:YYLIMIT  = in->lim;
+    re2c:define:YYFILL   = "if (fill(in, @@) != 0) return -1;";
+
+    *                           { return -1; }
+    [\x00]                      { return (in->lim - in->cur == YYMAXFILL - 1) ? count : -1; }
+    ['] ([^'\\] | [\\][^])* ['] { ++count; goto loop; }
+    [ ]+                        { goto loop; }
+
+    */
+}
+
+int main()
+{
+    const char *fname = "input";
+    const char str[] = "'qu\0tes' 'are' 'fine: \\'' ";
+    FILE *f;
+    Input in;
+
+    // prepare input file: a few times the size of the buffer,
+    // containing strings with zeroes and escaped quotes
+    f = fopen(fname, "w");
+    for (int i = 0; i < SIZE; ++i) {
+        fwrite(str, 1, sizeof(str) - 1, f);
+    }
+    fclose(f);
+
+    f = fopen(fname, "r");
+    init(&in, f);
+    assert(lex(&in) == SIZE * 3);
+    fclose(f);
+
+    remove(fname);
+    return 0;
+}

test/codegen/loop_switch/c/generic_api_eof_rule.c

@@ -0,0 +1,146 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+// expect a string without terminating null
+static int lex(const char *str, unsigned int len)
+{
+    const char *cur = str, *lim = str + len, *mar;
+    int count = 0;
+
+loop:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = cur < lim ? *cur : 0;
+			switch (yych) {
+			case ' ':
+				++cur;
+				yystate = 3;
+				continue;
+			case '\'':
+				++cur;
+				yystate = 6;
+				continue;
+			default:
+				if (cur >= lim) {
+					yystate = 12;
+					continue;
+				}
+				++cur;
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return -1; }
+		case 3:
+			yych = cur < lim ? *cur : 0;
+			yystate = 4;
+			continue;
+		case 4:
+			switch (yych) {
+			case ' ':
+				++cur;
+				yystate = 3;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 5:
+			{ goto loop; }
+		case 6:
+			mar = cur;
+			yych = cur < lim ? *cur : 0;
+			if (yych >= 0x01) {
+				yystate = 8;
+				continue;
+			}
+			if (cur >= lim) {
+				yystate = 2;
+				continue;
+			}
+			++cur;
+			yystate = 7;
+			continue;
+		case 7:
+			yych = cur < lim ? *cur : 0;
+			yystate = 8;
+			continue;
+		case 8:
+			switch (yych) {
+			case '\'':
+				++cur;
+				yystate = 9;
+				continue;
+			case '\\':
+				++cur;
+				yystate = 11;
+				continue;
+			default:
+				if (cur >= lim) {
+					yystate = 13;
+					continue;
+				}
+				++cur;
+				yystate = 7;
+				continue;
+			}
+		case 9:
+			yystate = 10;
+			continue;
+		case 10:
+			{ ++count; goto loop; }
+		case 11:
+			yych = cur < lim ? *cur : 0;
+			if (yych <= 0x00) {
+				if (cur >= lim) {
+					yystate = 13;
+					continue;
+				}
+				++cur;
+				yystate = 7;
+				continue;
+			}
+			++cur;
+			yystate = 7;
+			continue;
+		case 12:
+			{ return count; }
+		case 13:
+			cur = mar;
+			yystate = 2;
+			continue;
+		}
+	}
+}
+
+}
+
+// make a copy of the string without terminating null
+static void test(const char *str, unsigned int len, int res)
+{
+    char *s = (char*) malloc(len);
+    memcpy(s, str, len);
+    int r = lex(s, len);
+    free(s);
+    assert(r == res);
+}
+
+#define TEST(s, r) test(s, sizeof(s) - 1, r)
+int main()
+{
+    TEST("", 0);
+    TEST("'qu\0tes' 'are' 'fine: \\'' ", 3);
+    TEST("'unterminated\\'", -1);
+    return 0;
+}

test/codegen/loop_switch/c/generic_api_eof_rule.re

@@ -0,0 +1,50 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+// expect a string without terminating null
+static int lex(const char *str, unsigned int len)
+{
+    const char *cur = str, *lim = str + len, *mar;
+    int count = 0;
+
+loop:
+    /*!re2c
+    re2c:yyfill:enable = 0;
+    re2c:eof = 0;
+    re2c:flags:input = custom;
+    re2c:api:style = free-form;
+    re2c:define:YYCTYPE    = char;
+    re2c:define:YYLESSTHAN = "cur >= lim";
+    re2c:define:YYPEEK     = "cur < lim ? *cur : 0";  // fake null
+    re2c:define:YYSKIP     = "++cur;";
+    re2c:define:YYBACKUP   = "mar = cur;";
+    re2c:define:YYRESTORE  = "cur = mar;";
+
+    *                           { return -1; }
+    $                           { return count; }
+    ['] ([^'\\] | [\\][^])* ['] { ++count; goto loop; }
+    [ ]+                        { goto loop; }
+
+    */
+}
+
+// make a copy of the string without terminating null
+static void test(const char *str, unsigned int len, int res)
+{
+    char *s = (char*) malloc(len);
+    memcpy(s, str, len);
+    int r = lex(s, len);
+    free(s);
+    assert(r == res);
+}
+
+#define TEST(s, r) test(s, sizeof(s) - 1, r)
+int main()
+{
+    TEST("", 0);
+    TEST("'qu\0tes' 'are' 'fine: \\'' ", 3);
+    TEST("'unterminated\\'", -1);
+    return 0;
+}

test/codegen/loop_switch/c/generic_api_sentinel.c

@@ -0,0 +1,152 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+// expect a string without terminating null
+static int lex(const char *str, unsigned int len)
+{
+    const char *cur = str, *lim = str + len;
+    int count = 0;
+
+loop:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = cur < lim ? *cur : 0;
+			++cur;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case ' ':
+				yystate = 5;
+				continue;
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				yystate = 8;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return count; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return -1; }
+		case 5:
+			yych = cur < lim ? *cur : 0;
+			yystate = 6;
+			continue;
+		case 6:
+			switch (yych) {
+			case ' ':
+				++cur;
+				yystate = 5;
+				continue;
+			default:
+				yystate = 7;
+				continue;
+			}
+		case 7:
+			{ goto loop; }
+		case 8:
+			yych = cur < lim ? *cur : 0;
+			yystate = 9;
+			continue;
+		case 9:
+			switch (yych) {
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				++cur;
+				yystate = 8;
+				continue;
+			default:
+				yystate = 10;
+				continue;
+			}
+		case 10:
+			{ ++count; goto loop; }
+		}
+	}
+}
+
+}
+
+// make a copy of the string without terminating null
+static void test(const char *str, unsigned int len, int res)
+{
+    char *s = (char*) malloc(len);
+    memcpy(s, str, len);
+    int r = lex(s, len);
+    free(s);
+    assert(r == res);
+}
+
+#define TEST(s, r) test(s, sizeof(s) - 1, r)
+int main()
+{
+    TEST("", 0);
+    TEST("one two three ", 3);
+    TEST("f0ur", -1);
+    return 0;
+}

test/codegen/loop_switch/c/generic_api_sentinel.re

@@ -0,0 +1,47 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+// expect a string without terminating null
+static int lex(const char *str, unsigned int len)
+{
+    const char *cur = str, *lim = str + len;
+    int count = 0;
+
+loop:
+    /*!re2c
+    re2c:yyfill:enable = 0;
+    re2c:flags:input = custom;
+    re2c:api:style = free-form;
+    re2c:define:YYCTYPE    = char;
+    re2c:define:YYLESSTHAN = "cur >= lim";
+    re2c:define:YYPEEK     = "cur < lim ? *cur : 0";  // fake null
+    re2c:define:YYSKIP     = "++cur;";
+
+    *      { return -1; }
+    [\x00] { return count; }
+    [a-z]+ { ++count; goto loop; }
+    [ ]+   { goto loop; }
+
+    */
+}
+
+// make a copy of the string without terminating null
+static void test(const char *str, unsigned int len, int res)
+{
+    char *s = (char*) malloc(len);
+    memcpy(s, str, len);
+    int r = lex(s, len);
+    free(s);
+    assert(r == res);
+}
+
+#define TEST(s, r) test(s, sizeof(s) - 1, r)
+int main()
+{
+    TEST("", 0);
+    TEST("one two three ", 3);
+    TEST("f0ur", -1);
+    return 0;
+}

test/codegen/loop_switch/c/parse_u32_blocks.c

@@ -0,0 +1,366 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT -i --loop-switch
+#include <stdint.h>
+#include <limits.h>
+#include <assert.h>
+
+static const uint64_t ERROR = ~0lu;
+
+template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
+{
+    u = u * BASE + d;
+    if (u > UINT32_MAX) u = ERROR;
+}
+
+static uint64_t parse_u32(const char *s)
+{
+    const char *YYMARKER;
+    uint64_t u = 0;
+
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case '0':
+				yystate = 3;
+				continue;
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+				yystate = 5;
+				continue;
+			default:
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return ERROR; }
+		case 3:
+			YYMARKER = s;
+			yych = *s;
+			switch (yych) {
+			case 'B':
+			case 'b':
+				++s;
+				yystate = 7;
+				continue;
+			case 'X':
+			case 'x':
+				++s;
+				yystate = 9;
+				continue;
+			default:
+				yystate = 4;
+				continue;
+			}
+		case 4:
+			{ goto oct; }
+		case 5:
+			yystate = 6;
+			continue;
+		case 6:
+			s -= 1;
+			{ goto dec; }
+		case 7:
+			yych = *s;
+			switch (yych) {
+			case '0':
+			case '1':
+				++s;
+				yystate = 10;
+				continue;
+			default:
+				yystate = 8;
+				continue;
+			}
+		case 8:
+			s = YYMARKER;
+			yystate = 4;
+			continue;
+		case 9:
+			yych = *s;
+			switch (yych) {
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+			case 'A':
+			case 'B':
+			case 'C':
+			case 'D':
+			case 'E':
+			case 'F':
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+				++s;
+				yystate = 12;
+				continue;
+			default:
+				yystate = 8;
+				continue;
+			}
+		case 10:
+			yystate = 11;
+			continue;
+		case 11:
+			s -= 1;
+			{ goto bin; }
+		case 12:
+			yystate = 13;
+			continue;
+		case 13:
+			s -= 1;
+			{ goto hex; }
+		}
+	}
+}
+
+bin:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case '0':
+			case '1':
+				yystate = 5;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return u; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return ERROR; }
+		case 5:
+			yystate = 6;
+			continue;
+		case 6:
+			{ adddgt<2>(u, s[-1] - '0'); goto bin; }
+		}
+	}
+}
+
+oct:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+				yystate = 5;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return u; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return ERROR; }
+		case 5:
+			yystate = 6;
+			continue;
+		case 6:
+			{ adddgt<8>(u, s[-1] - '0'); goto oct; }
+		}
+	}
+}
+
+dec:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+				yystate = 5;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return u; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return ERROR; }
+		case 5:
+			yystate = 6;
+			continue;
+		case 6:
+			{ adddgt<10>(u, s[-1] - '0'); goto dec; }
+		}
+	}
+}
+
+hex:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+				yystate = 5;
+				continue;
+			case 'A':
+			case 'B':
+			case 'C':
+			case 'D':
+			case 'E':
+			case 'F':
+				yystate = 7;
+				continue;
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+				yystate = 9;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return u; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return ERROR; }
+		case 5:
+			yystate = 6;
+			continue;
+		case 6:
+			{ adddgt<16>(u, s[-1] - '0');      goto hex; }
+		case 7:
+			yystate = 8;
+			continue;
+		case 8:
+			{ adddgt<16>(u, s[-1] - 'A' + 10); goto hex; }
+		case 9:
+			yystate = 10;
+			continue;
+		case 10:
+			{ adddgt<16>(u, s[-1] - 'a' + 10); goto hex; }
+		}
+	}
+}
+
+}
+
+int main()
+{
+    assert(parse_u32("1234567890") == 1234567890);
+    assert(parse_u32("0b1101") == 13);
+    assert(parse_u32("0x7Fe") == 2046);
+    assert(parse_u32("0644") == 420);
+    assert(parse_u32("9999999999") == ERROR);
+    assert(parse_u32("") == ERROR);
+    return 0;
+}

test/codegen/loop_switch/c/parse_u32_blocks.re

@@ -0,0 +1,69 @@
+// re2c $INPUT -o $OUTPUT -i --loop-switch
+#include <stdint.h>
+#include <limits.h>
+#include <assert.h>
+
+static const uint64_t ERROR = ~0lu;
+
+template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
+{
+    u = u * BASE + d;
+    if (u > UINT32_MAX) u = ERROR;
+}
+
+static uint64_t parse_u32(const char *s)
+{
+    const char *YYMARKER;
+    uint64_t u = 0;
+
+    /*!re2c
+    re2c:yyfill:enable = 0;
+    re2c:define:YYCTYPE = char;
+    re2c:define:YYCURSOR = s;
+
+    end = "\x00";
+
+    '0b' / [01]        { goto bin; }
+    "0"                { goto oct; }
+    "" / [1-9]         { goto dec; }
+    '0x' / [0-9a-fA-F] { goto hex; }
+    *                  { return ERROR; }
+    */
+bin:
+    /*!re2c
+    end   { return u; }
+    [01]  { adddgt<2>(u, s[-1] - '0'); goto bin; }
+    *     { return ERROR; }
+    */
+oct:
+    /*!re2c
+    end   { return u; }
+    [0-7] { adddgt<8>(u, s[-1] - '0'); goto oct; }
+    *     { return ERROR; }
+    */
+dec:
+    /*!re2c
+    end   { return u; }
+    [0-9] { adddgt<10>(u, s[-1] - '0'); goto dec; }
+    *     { return ERROR; }
+    */
+hex:
+    /*!re2c
+    end   { return u; }
+    [0-9] { adddgt<16>(u, s[-1] - '0');      goto hex; }
+    [a-f] { adddgt<16>(u, s[-1] - 'a' + 10); goto hex; }
+    [A-F] { adddgt<16>(u, s[-1] - 'A' + 10); goto hex; }
+    *     { return ERROR; }
+    */
+}
+
+int main()
+{
+    assert(parse_u32("1234567890") == 1234567890);
+    assert(parse_u32("0b1101") == 13);
+    assert(parse_u32("0x7Fe") == 2046);
+    assert(parse_u32("0644") == 420);
+    assert(parse_u32("9999999999") == ERROR);
+    assert(parse_u32("") == ERROR);
+    return 0;
+}

test/codegen/loop_switch/c/parse_u32_conditions.c

@@ -0,0 +1,340 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT -ci --loop-switch
+#include <stdint.h>
+#include <limits.h>
+#include <assert.h>
+
+static const uint64_t ERROR = ~0lu;
+enum YYCONDTYPE {
+	yycinit = 0,
+	yycbin = 14,
+	yycdec = 21,
+	yychex = 28,
+	yycoct = 39,
+};
+
+
+template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
+{
+    u = u * BASE + d;
+    if (u > UINT32_MAX) u = ERROR;
+}
+
+static uint64_t parse_u32(const char *s)
+{
+    const char *YYMARKER;
+    int c = yycinit;
+    uint64_t u = 0;
+
+loop:
+    
+{
+	char yych;
+	unsigned int yystate = c;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case '0':
+				yystate = 3;
+				continue;
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+				yystate = 5;
+				continue;
+			default:
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return ERROR; }
+		case 3:
+			YYMARKER = s;
+			yych = *s;
+			switch (yych) {
+			case 'B':
+			case 'b':
+				++s;
+				yystate = 7;
+				continue;
+			case 'X':
+			case 'x':
+				++s;
+				yystate = 9;
+				continue;
+			default:
+				yystate = 4;
+				continue;
+			}
+		case 4:
+			c = yycoct;
+			yystate = yycoct;
+			continue;
+		case 5:
+			yystate = 6;
+			continue;
+		case 6:
+			s -= 1;
+			c = yycdec;
+			yystate = yycdec;
+			continue;
+		case 7:
+			yych = *s;
+			switch (yych) {
+			case '0':
+			case '1':
+				++s;
+				yystate = 10;
+				continue;
+			default:
+				yystate = 8;
+				continue;
+			}
+		case 8:
+			s = YYMARKER;
+			yystate = 4;
+			continue;
+		case 9:
+			yych = *s;
+			switch (yych) {
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+			case 'A':
+			case 'B':
+			case 'C':
+			case 'D':
+			case 'E':
+			case 'F':
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+				++s;
+				yystate = 12;
+				continue;
+			default:
+				yystate = 8;
+				continue;
+			}
+		case 10:
+			yystate = 11;
+			continue;
+		case 11:
+			s -= 1;
+			c = yycbin;
+			yystate = yycbin;
+			continue;
+		case 12:
+			yystate = 13;
+			continue;
+		case 13:
+			s -= 1;
+			c = yychex;
+			yystate = yychex;
+			continue;
+		case 14:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 15;
+				continue;
+			case '0':
+			case '1':
+				yystate = 19;
+				continue;
+			default:
+				yystate = 17;
+				continue;
+			}
+		case 15:
+			yystate = 16;
+			continue;
+		case 16:
+			{ return u; }
+		case 17:
+			yystate = 18;
+			continue;
+		case 18:
+			{ return ERROR; }
+		case 19:
+			yystate = 20;
+			continue;
+		case 20:
+			{ adddgt<2> (u, s[-1] - '0');      goto loop; }
+		case 21:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 22;
+				continue;
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+				yystate = 26;
+				continue;
+			default:
+				yystate = 24;
+				continue;
+			}
+		case 22:
+			yystate = 23;
+			continue;
+		case 23:
+			{ return u; }
+		case 24:
+			yystate = 25;
+			continue;
+		case 25:
+			{ return ERROR; }
+		case 26:
+			yystate = 27;
+			continue;
+		case 27:
+			{ adddgt<10>(u, s[-1] - '0');      goto loop; }
+		case 28:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 29;
+				continue;
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+			case '8':
+			case '9':
+				yystate = 33;
+				continue;
+			case 'A':
+			case 'B':
+			case 'C':
+			case 'D':
+			case 'E':
+			case 'F':
+				yystate = 35;
+				continue;
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+				yystate = 37;
+				continue;
+			default:
+				yystate = 31;
+				continue;
+			}
+		case 29:
+			yystate = 30;
+			continue;
+		case 30:
+			{ return u; }
+		case 31:
+			yystate = 32;
+			continue;
+		case 32:
+			{ return ERROR; }
+		case 33:
+			yystate = 34;
+			continue;
+		case 34:
+			{ adddgt<16>(u, s[-1] - '0');      goto loop; }
+		case 35:
+			yystate = 36;
+			continue;
+		case 36:
+			{ adddgt<16>(u, s[-1] - 'A' + 10); goto loop; }
+		case 37:
+			yystate = 38;
+			continue;
+		case 38:
+			{ adddgt<16>(u, s[-1] - 'a' + 10); goto loop; }
+		case 39:
+			yych = *s;
+			++s;
+			switch (yych) {
+			case 0x00:
+				yystate = 40;
+				continue;
+			case '0':
+			case '1':
+			case '2':
+			case '3':
+			case '4':
+			case '5':
+			case '6':
+			case '7':
+				yystate = 44;
+				continue;
+			default:
+				yystate = 42;
+				continue;
+			}
+		case 40:
+			yystate = 41;
+			continue;
+		case 41:
+			{ return u; }
+		case 42:
+			yystate = 43;
+			continue;
+		case 43:
+			{ return ERROR; }
+		case 44:
+			yystate = 45;
+			continue;
+		case 45:
+			{ adddgt<8> (u, s[-1] - '0');      goto loop; }
+		}
+	}
+}
+
+}
+
+int main()
+{
+    assert(parse_u32("1234567890") == 1234567890);
+    assert(parse_u32("0b1101") == 13);
+    assert(parse_u32("0x7Fe") == 2046);
+    assert(parse_u32("0644") == 420);
+    assert(parse_u32("9999999999") == ERROR);
+    assert(parse_u32("") == ERROR);
+    return 0;
+}

test/codegen/loop_switch/c/parse_u32_conditions.re

@@ -0,0 +1,57 @@
+// re2c $INPUT -o $OUTPUT -ci --loop-switch
+#include <stdint.h>
+#include <limits.h>
+#include <assert.h>
+
+static const uint64_t ERROR = ~0lu;
+/*!types:re2c*/
+
+template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
+{
+    u = u * BASE + d;
+    if (u > UINT32_MAX) u = ERROR;
+}
+
+static uint64_t parse_u32(const char *s)
+{
+    const char *YYMARKER;
+    int c = yycinit;
+    uint64_t u = 0;
+
+loop:
+    /*!re2c
+    re2c:yyfill:enable = 0;
+    re2c:api:style = free-form;
+    re2c:define:YYCTYPE = char;
+    re2c:define:YYCURSOR = s;
+    re2c:define:YYGETCONDITION = "c";
+    re2c:define:YYSETCONDITION = "c = @@;";
+
+    <*> * { return ERROR; }
+
+    <init> '0b' / [01]        :=> bin
+    <init> "0"                :=> oct
+    <init> "" / [1-9]         :=> dec
+    <init> '0x' / [0-9a-fA-F] :=> hex
+
+    <bin, oct, dec, hex> "\x00" { return u; }
+
+    <bin> [01]  { adddgt<2> (u, s[-1] - '0');      goto loop; }
+    <oct> [0-7] { adddgt<8> (u, s[-1] - '0');      goto loop; }
+    <dec> [0-9] { adddgt<10>(u, s[-1] - '0');      goto loop; }
+    <hex> [0-9] { adddgt<16>(u, s[-1] - '0');      goto loop; }
+    <hex> [a-f] { adddgt<16>(u, s[-1] - 'a' + 10); goto loop; }
+    <hex> [A-F] { adddgt<16>(u, s[-1] - 'A' + 10); goto loop; }
+    */
+}
+
+int main()
+{
+    assert(parse_u32("1234567890") == 1234567890);
+    assert(parse_u32("0b1101") == 13);
+    assert(parse_u32("0x7Fe") == 2046);
+    assert(parse_u32("0644") == 420);
+    assert(parse_u32("9999999999") == ERROR);
+    assert(parse_u32("") == ERROR);
+    return 0;
+}

test/codegen/loop_switch/c/reuse.c

@@ -0,0 +1,229 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --input-encoding utf8 --loop-switch -i
+
+// This example supports multiple input encodings: UTF-8 and UTF-32.
+// Both lexers are generated from the same rules block, and the use
+// blocks add only encoding-specific configurations.
+
+#include <assert.h>
+#include <stdint.h>
+
+
+
+static int lex_utf8(const uint8_t *YYCURSOR)
+{
+    const uint8_t *YYMARKER;
+    
+{
+	uint8_t yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			switch (yych) {
+			case 0xE2:
+				yystate = 3;
+				continue;
+			default:
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return 1; }
+		case 3:
+			YYMARKER = YYCURSOR;
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 0x88:
+				++YYCURSOR;
+				yystate = 4;
+				continue;
+			default:
+				yystate = 2;
+				continue;
+			}
+		case 4:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 0x80:
+				++YYCURSOR;
+				yystate = 6;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 5:
+			YYCURSOR = YYMARKER;
+			yystate = 2;
+			continue;
+		case 6:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 'x':
+				++YYCURSOR;
+				yystate = 7;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 7:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case ' ':
+				++YYCURSOR;
+				yystate = 8;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 8:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 0xE2:
+				++YYCURSOR;
+				yystate = 9;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 9:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 0x88:
+				++YYCURSOR;
+				yystate = 10;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 10:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 0x83:
+				++YYCURSOR;
+				yystate = 11;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 11:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 'y':
+				++YYCURSOR;
+				yystate = 12;
+				continue;
+			default:
+				yystate = 5;
+				continue;
+			}
+		case 12:
+			yystate = 13;
+			continue;
+		case 13:
+			{ return 0; }
+		}
+	}
+}
+
+}
+
+static int lex_utf32(const uint32_t *YYCURSOR)
+{
+    const uint32_t *YYMARKER;
+    
+{
+	uint32_t yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			if (yych == 0x00002200) {
+				yystate = 3;
+				continue;
+			}
+			yystate = 1;
+			continue;
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return 1; }
+		case 3:
+			YYMARKER = YYCURSOR;
+			yych = *YYCURSOR;
+			if (yych != 'x') {
+				yystate = 2;
+				continue;
+			}
+			++YYCURSOR;
+			yystate = 4;
+			continue;
+		case 4:
+			yych = *YYCURSOR;
+			if (yych == ' ') {
+				++YYCURSOR;
+				yystate = 6;
+				continue;
+			}
+			yystate = 5;
+			continue;
+		case 5:
+			YYCURSOR = YYMARKER;
+			yystate = 2;
+			continue;
+		case 6:
+			yych = *YYCURSOR;
+			if (yych != 0x00002203) {
+				yystate = 5;
+				continue;
+			}
+			++YYCURSOR;
+			yystate = 7;
+			continue;
+		case 7:
+			yych = *YYCURSOR;
+			if (yych != 'y') {
+				yystate = 5;
+				continue;
+			}
+			++YYCURSOR;
+			yystate = 8;
+			continue;
+		case 8:
+			yystate = 9;
+			continue;
+		case 9:
+			{ return 0; }
+		}
+	}
+}
+
+}
+
+int main()
+{
+    static const uint8_t s8[] = // UTF-8
+        { 0xe2, 0x88, 0x80, 0x78, 0x20, 0xe2, 0x88, 0x83, 0x79 };
+
+    static const uint32_t s32[] = // UTF32
+        { 0x00002200, 0x00000078, 0x00000020, 0x00002203, 0x00000079 };
+
+    assert(lex_utf8(s8) == 0);
+    assert(lex_utf32(s32) == 0);
+    return 0;
+}
+

test/codegen/loop_switch/c/reuse.re

@@ -0,0 +1,48 @@
+// re2c $INPUT -o $OUTPUT --input-encoding utf8 --loop-switch -i
+
+// This example supports multiple input encodings: UTF-8 and UTF-32.
+// Both lexers are generated from the same rules block, and the use
+// blocks add only encoding-specific configurations.
+
+#include <assert.h>
+#include <stdint.h>
+
+/*!rules:re2c
+    re2c:yyfill:enable = 0;
+
+    "∀x ∃y" { return 0; }
+    *       { return 1; }
+*/
+
+static int lex_utf8(const uint8_t *YYCURSOR)
+{
+    const uint8_t *YYMARKER;
+    /*!use:re2c
+    re2c:define:YYCTYPE = uint8_t;
+    re2c:flags:8 = 1;
+    */
+}
+
+static int lex_utf32(const uint32_t *YYCURSOR)
+{
+    const uint32_t *YYMARKER;
+    /*!use:re2c
+    re2c:define:YYCTYPE = uint32_t;
+    re2c:flags:8 = 0;
+    re2c:flags:u = 1;
+    */
+}
+
+int main()
+{
+    static const uint8_t s8[] = // UTF-8
+        { 0xe2, 0x88, 0x80, 0x78, 0x20, 0xe2, 0x88, 0x83, 0x79 };
+
+    static const uint32_t s32[] = // UTF32
+        { 0x00002200, 0x00000078, 0x00000020, 0x00002203, 0x00000079 };
+
+    assert(lex_utf8(s8) == 0);
+    assert(lex_utf32(s32) == 0);
+    return 0;
+}
+

test/codegen/loop_switch/c/sentinel.c

@@ -0,0 +1,137 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+
+// expect a null-terminated string
+static int lex(const char *YYCURSOR)
+{
+    int count = 0;
+loop:
+    
+{
+	char yych;
+	unsigned int yystate = 0;
+	for (;;) {
+		switch (yystate) {
+		case 0:
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			switch (yych) {
+			case 0x00:
+				yystate = 1;
+				continue;
+			case ' ':
+				yystate = 5;
+				continue;
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				yystate = 8;
+				continue;
+			default:
+				yystate = 3;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			{ return count; }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			{ return -1; }
+		case 5:
+			yych = *YYCURSOR;
+			yystate = 6;
+			continue;
+		case 6:
+			switch (yych) {
+			case ' ':
+				++YYCURSOR;
+				yystate = 5;
+				continue;
+			default:
+				yystate = 7;
+				continue;
+			}
+		case 7:
+			{ goto loop; }
+		case 8:
+			yych = *YYCURSOR;
+			yystate = 9;
+			continue;
+		case 9:
+			switch (yych) {
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				++YYCURSOR;
+				yystate = 8;
+				continue;
+			default:
+				yystate = 10;
+				continue;
+			}
+		case 10:
+			{ ++count; goto loop; }
+		}
+	}
+}
+
+}
+
+int main()
+{
+    assert(lex("") == 0);
+    assert(lex("one two three") == 3);
+    assert(lex("f0ur") == -1);
+    return 0;
+}

test/codegen/loop_switch/c/sentinel.re

@@ -0,0 +1,27 @@
+// re2c $INPUT -o $OUTPUT --loop-switch -i
+#include <assert.h>
+
+// expect a null-terminated string
+static int lex(const char *YYCURSOR)
+{
+    int count = 0;
+loop:
+    /*!re2c
+    re2c:define:YYCTYPE = char;
+    re2c:yyfill:enable = 0;
+
+    *      { return -1; }
+    [\x00] { return count; }
+    [a-z]+ { ++count; goto loop; }
+    [ ]+   { goto loop; }
+
+    */
+}
+
+int main()
+{
+    assert(lex("") == 0);
+    assert(lex("one two three") == 3);
+    assert(lex("f0ur") == -1);
+    return 0;
+}

test/codegen/loop_switch/c/storable_state.c

@@ -0,0 +1,298 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT -f --loop-switch -i
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#define DEBUG    1
+#define LOG(...) if (DEBUG) fprintf(stderr, __VA_ARGS__);
+#define BUFSIZE  10
+
+typedef struct {
+    FILE *file;
+    char buf[BUFSIZE + 1], *lim, *cur, *mar, *tok;
+    unsigned yyaccept;
+    int state;
+} Input;
+
+static void init(Input *in, FILE *f)
+{
+    in->file = f;
+    in->cur = in->mar = in->tok = in->lim = in->buf + BUFSIZE;
+    in->lim[0] = 0; // append sentinel symbol
+    in->yyaccept = 0;
+    in->state = -1;
+}
+
+typedef enum {END, READY, WAITING, BAD_PACKET, BIG_PACKET} Status;
+
+static Status fill(Input *in)
+{
+    const size_t shift = in->tok - in->buf;
+    const size_t free = BUFSIZE - (in->lim - in->tok);
+
+    if (free < 1) return BIG_PACKET;
+
+    memmove(in->buf, in->tok, BUFSIZE - shift);
+    in->lim -= shift;
+    in->cur -= shift;
+    in->mar -= shift;
+    in->tok -= shift;
+
+    const size_t read = fread(in->lim, 1, free, in->file);
+    in->lim += read;
+    in->lim[0] = 0; // append sentinel symbol
+
+    return READY;
+}
+
+static Status lex(Input *in, unsigned int *recv)
+{
+    char yych;
+loop:
+    
+
+	int yystate = in->state;
+	for (;;) {
+		switch (yystate) {
+		case -1:
+		case 0:
+			yych = *in->cur;
+			switch (yych) {
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				++in->cur;
+				yystate = 3;
+				continue;
+			default:
+				if (in->lim <= in->cur) {
+					in->state = 10;
+					return WAITING;
+				}
+				++in->cur;
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			in->state = 0;
+			{ return BAD_PACKET; }
+		case 3:
+			in->mar = in->cur;
+			yych = *in->cur;
+			switch (yych) {
+			case ';':
+				++in->cur;
+				yystate = 4;
+				continue;
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				++in->cur;
+				yystate = 6;
+				continue;
+			default:
+				if (in->lim <= in->cur) {
+					in->state = 11;
+					return WAITING;
+				}
+				yystate = 2;
+				continue;
+			}
+		case 4:
+			yystate = 5;
+			continue;
+		case 5:
+			in->state = 0;
+			{ *recv = *recv + 1; in->tok = in->cur; goto loop; }
+		case 6:
+			yych = *in->cur;
+			yystate = 7;
+			continue;
+		case 7:
+			switch (yych) {
+			case ';':
+				++in->cur;
+				yystate = 4;
+				continue;
+			case 'a':
+			case 'b':
+			case 'c':
+			case 'd':
+			case 'e':
+			case 'f':
+			case 'g':
+			case 'h':
+			case 'i':
+			case 'j':
+			case 'k':
+			case 'l':
+			case 'm':
+			case 'n':
+			case 'o':
+			case 'p':
+			case 'q':
+			case 'r':
+			case 's':
+			case 't':
+			case 'u':
+			case 'v':
+			case 'w':
+			case 'x':
+			case 'y':
+			case 'z':
+				++in->cur;
+				yystate = 6;
+				continue;
+			default:
+				if (in->lim <= in->cur) {
+					in->state = 12;
+					return WAITING;
+				}
+				yystate = 8;
+				continue;
+			}
+		case 8:
+			in->cur = in->mar;
+			yystate = 2;
+			continue;
+		case 9:
+			in->state = 0;
+			{ return END; }
+		case 10:
+			if (in->lim <= in->cur) {
+				yystate = 9;
+				continue;
+			}
+			yystate = 0;
+			continue;
+		case 11:
+			if (in->lim <= in->cur) {
+				yystate = 2;
+				continue;
+			}
+			yystate = 3;
+			continue;
+		case 12:
+			if (in->lim <= in->cur) {
+				yystate = 8;
+				continue;
+			}
+			yystate = 6;
+			continue;
+		}
+	}
+
+}
+
+void test(const char **packets, Status status)
+{
+    const char *fname = "pipe";
+    FILE *fw = fopen(fname, "w");
+    FILE *fr = fopen(fname, "r");
+    setvbuf(fw, NULL, _IONBF, 0);
+    setvbuf(fr, NULL, _IONBF, 0);
+
+    Input in;
+    init(&in, fr);
+    Status st;
+    unsigned int send = 0, recv = 0;
+
+    for (;;) {
+        st = lex(&in, &recv);
+        if (st == END) {
+            LOG("done: got %u packets\n", recv);
+            break;
+        } else if (st == WAITING) {
+            LOG("waiting...\n");
+            if (*packets) {
+                LOG("sent packet %u\n", send);
+                fprintf(fw, "%s", *packets++);
+                ++send;
+            }
+            st = fill(&in);
+            LOG("queue: '%s'\n", in.buf);
+            if (st == BIG_PACKET) {
+                LOG("error: packet too big\n");
+                break;
+            }
+            assert(st == READY);
+        } else {
+            assert(st == BAD_PACKET);
+            LOG("error: ill-formed packet\n");
+            break;
+        }
+    }
+
+    LOG("\n");
+    assert(st == status);
+    if (st == END) assert(recv == send);
+
+    fclose(fw);
+    fclose(fr);
+    remove(fname);
+}
+
+int main()
+{
+    const char *packets1[] = {0};
+    const char *packets2[] = {"zero;", "one;", "two;", "three;", "four;", 0};
+    const char *packets3[] = {"zer0;", 0};
+    const char *packets4[] = {"goooooooooogle;", 0};
+
+    test(packets1, END);
+    test(packets2, END);
+    test(packets3, BAD_PACKET);
+    test(packets4, BIG_PACKET);
+
+    return 0;
+}

test/codegen/loop_switch/c/storable_state.re

@@ -0,0 +1,132 @@
+// re2c $INPUT -o $OUTPUT -f --loop-switch -i
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#define DEBUG    1
+#define LOG(...) if (DEBUG) fprintf(stderr, __VA_ARGS__);
+#define BUFSIZE  10
+
+typedef struct {
+    FILE *file;
+    char buf[BUFSIZE + 1], *lim, *cur, *mar, *tok;
+    unsigned yyaccept;
+    int state;
+} Input;
+
+static void init(Input *in, FILE *f)
+{
+    in->file = f;
+    in->cur = in->mar = in->tok = in->lim = in->buf + BUFSIZE;
+    in->lim[0] = 0; // append sentinel symbol
+    in->yyaccept = 0;
+    in->state = -1;
+}
+
+typedef enum {END, READY, WAITING, BAD_PACKET, BIG_PACKET} Status;
+
+static Status fill(Input *in)
+{
+    const size_t shift = in->tok - in->buf;
+    const size_t free = BUFSIZE - (in->lim - in->tok);
+
+    if (free < 1) return BIG_PACKET;
+
+    memmove(in->buf, in->tok, BUFSIZE - shift);
+    in->lim -= shift;
+    in->cur -= shift;
+    in->mar -= shift;
+    in->tok -= shift;
+
+    const size_t read = fread(in->lim, 1, free, in->file);
+    in->lim += read;
+    in->lim[0] = 0; // append sentinel symbol
+
+    return READY;
+}
+
+static Status lex(Input *in, unsigned int *recv)
+{
+    char yych;
+loop:
+    /*!re2c
+        re2c:eof = 0;
+        re2c:api:style = free-form;
+        re2c:define:YYCTYPE    = "char";
+        re2c:define:YYCURSOR   = "in->cur";
+        re2c:define:YYMARKER   = "in->mar";
+        re2c:define:YYLIMIT    = "in->lim";
+        re2c:define:YYGETSTATE = "in->state";
+        re2c:define:YYSETSTATE = "in->state = @@;";
+        re2c:define:YYFILL     = "return WAITING;";
+
+        packet = [a-z]+[;];
+
+        *      { return BAD_PACKET; }
+        $      { return END; }
+        packet { *recv = *recv + 1; in->tok = in->cur; goto loop; }
+    */
+}
+
+void test(const char **packets, Status status)
+{
+    const char *fname = "pipe";
+    FILE *fw = fopen(fname, "w");
+    FILE *fr = fopen(fname, "r");
+    setvbuf(fw, NULL, _IONBF, 0);
+    setvbuf(fr, NULL, _IONBF, 0);
+
+    Input in;
+    init(&in, fr);
+    Status st;
+    unsigned int send = 0, recv = 0;
+
+    for (;;) {
+        st = lex(&in, &recv);
+        if (st == END) {
+            LOG("done: got %u packets\n", recv);
+            break;
+        } else if (st == WAITING) {
+            LOG("waiting...\n");
+            if (*packets) {
+                LOG("sent packet %u\n", send);
+                fprintf(fw, "%s", *packets++);
+                ++send;
+            }
+            st = fill(&in);
+            LOG("queue: '%s'\n", in.buf);
+            if (st == BIG_PACKET) {
+                LOG("error: packet too big\n");
+                break;
+            }
+            assert(st == READY);
+        } else {
+            assert(st == BAD_PACKET);
+            LOG("error: ill-formed packet\n");
+            break;
+        }
+    }
+
+    LOG("\n");
+    assert(st == status);
+    if (st == END) assert(recv == send);
+
+    fclose(fw);
+    fclose(fr);
+    remove(fname);
+}
+
+int main()
+{
+    const char *packets1[] = {0};
+    const char *packets2[] = {"zero;", "one;", "two;", "three;", "four;", 0};
+    const char *packets3[] = {"zer0;", 0};
+    const char *packets4[] = {"goooooooooogle;", 0};
+
+    test(packets1, END);
+    test(packets2, END);
+    test(packets3, BAD_PACKET);
+    test(packets4, BIG_PACKET);
+
+    return 0;
+}

test/codegen/loop_switch/c/storable_state_error_getstate.c

@@ -0,0 +1 @@
+codegen/loop_switch/c/storable_state_error_getstate.re:3:16: error: `getstate:re2c` is incompatible with the --loop-switch option, as it requires cross-block transitions that are unsupported without the `goto` statement

test/codegen/loop_switch/c/storable_state_error_getstate.re

@@ -0,0 +1,3 @@
+// re2c $INPUT -o $OUTPUT -f --loop-switch
+
+/*!getstate:re2c*/

test/codegen/loop_switch/c/storable_state_two_blocks.c

@@ -0,0 +1,88 @@
+/* Generated by re2c */
+// re2c $INPUT -o $OUTPUT -fi --loop-switch
+
+
+
+	int yystate = YYGETSTATE();
+	for (;;) {
+		switch (yystate) {
+		case -1:
+		case 0:
+			YYSETSTATE(5);
+			if (YYLIMIT <= YYCURSOR) YYFILL(1);
+			yych = *YYCURSOR;
+			++YYCURSOR;
+			switch (yych) {
+			case 'a':
+				yystate = 3;
+				continue;
+			default:
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			YYSETSTATE(0);
+			{ * }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			YYSETSTATE(0);
+			{ a }
+		case 5:
+			yystate = 0;
+			continue;
+		}
+	}
+
+
+
+
+	int yystate = YYGETSTATE();
+	for (;;) {
+		switch (yystate) {
+		case -1:
+		case 0:
+			yych = *YYCURSOR;
+			switch (yych) {
+			case 'b':
+				++YYCURSOR;
+				yystate = 3;
+				continue;
+			default:
+				if (YYLIMIT <= YYCURSOR) {
+					YYSETSTATE(6);
+					YYFILL();
+				}
+				++YYCURSOR;
+				yystate = 1;
+				continue;
+			}
+		case 1:
+			yystate = 2;
+			continue;
+		case 2:
+			YYSETSTATE(0);
+			{ * }
+		case 3:
+			yystate = 4;
+			continue;
+		case 4:
+			YYSETSTATE(0);
+			{ b }
+		case 5:
+			YYSETSTATE(0);
+			{ $ }
+		case 6:
+			if (YYLIMIT <= YYCURSOR) {
+				yystate = 5;
+				continue;
+			}
+			yystate = 0;
+			continue;
+		}
+	}
+

test/codegen/loop_switch/c/storable_state_two_blocks.re

@@ -0,0 +1,13 @@
+// re2c $INPUT -o $OUTPUT -fi --loop-switch
+
+/*!re2c
+    [a] { a }
+    *   { * }
+*/
+
+/*!re2c
+    re2c:eof = 0;
+    [b] { b }
+    $   { $ }
+    *   { * }
+*/

test/codegen/loop_switch/go/basic.go

@@ -0,0 +1,59 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+
+package main                              //
+                                          //
+func lex(str string) {                    // Go code
+    var cursor int                        //
+                                          //
+
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			if (yych <= '0') {
+				yystate = 1
+				continue
+			}
+			if (yych <= '9') {
+				yystate = 3
+				continue
+			}
+			yystate = 1
+			continue
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ panic("error!"); }
+		case 3:
+			yych = str[cursor]
+			yystate = 4
+			continue
+		case 4:
+			if (yych <= '/') {
+				yystate = 5
+				continue
+			}
+			if (yych <= '9') {
+				cursor += 1
+				yystate = 3
+				continue
+			}
+			yystate = 5
+			continue
+		case 5:
+			{ return }
+		}
+	}
+}
+
+}                                         //
+                                          //
+func main() {                             // Go code
+    lex("1234\x00")                       //
+}                                         //

test/codegen/loop_switch/go/basic.re

@@ -0,0 +1,24 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+
+package main                              //
+                                          //
+func lex(str string) {                    // Go code
+    var cursor int                        //
+                                          //
+/*!re2c
+    re2c:define:YYCTYPE = byte;           //
+    re2c:define:YYPEEK = "str[cursor]";   //
+    re2c:define:YYSKIP = "cursor += 1";   // configurations
+    re2c:yyfill:enable = 0;               //
+    re2c:flags:nested-ifs = 1;            //
+                                          //
+    number = [1-9][0-9]*;                 // named definition
+                                          //
+    number { return }                     // rules
+    *      { panic("error!"); }           //
+*/
+}                                         //
+                                          //
+func main() {                             // Go code
+    lex("1234\x00")                       //
+}                                         //

test/codegen/loop_switch/go/bounds_checking.go

@@ -0,0 +1,149 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+var YYMAXFILL int = 1
+
+
+// Expects YYMAXFILL-padded string.
+func lex(str string) int {
+	var cursor int
+	limit := len(str)
+	count := 0
+loop:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			if (limit - cursor < 1) {
+				return -1
+			}
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case ' ':
+				yystate = 5
+				continue
+			case '\'':
+				yystate = 8
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{
+		if limit - cursor == YYMAXFILL - 1 {
+			return count
+		} else {
+			return -1
+		}
+	}
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{
+		return -1
+	}
+		case 5:
+			if (limit - cursor < 1) {
+				return -1
+			}
+			yych = str[cursor]
+			yystate = 6
+			continue
+		case 6:
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 5
+				continue
+			default:
+				yystate = 7
+				continue
+			}
+		case 7:
+			{
+		goto loop
+	}
+		case 8:
+			if (limit - cursor < 1) {
+				return -1
+			}
+			yych = str[cursor]
+			yystate = 9
+			continue
+		case 9:
+			cursor += 1
+			switch (yych) {
+			case '\'':
+				yystate = 10
+				continue
+			case '\\':
+				yystate = 12
+				continue
+			default:
+				yystate = 8
+				continue
+			}
+		case 10:
+			yystate = 11
+			continue
+		case 11:
+			{
+		count += 1;
+		goto loop
+	}
+		case 12:
+			if (limit - cursor < 1) {
+				return -1
+			}
+			yych = str[cursor]
+			cursor += 1
+			yystate = 8
+			continue
+		}
+	}
+}
+
+}
+
+// Pad string with YYMAXFILL zeroes at the end.
+func pad(str string) string {
+	return str + strings.Repeat("\000", YYMAXFILL)
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(pad(x.str))
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/bounds_checking.re

@@ -0,0 +1,67 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+/*!max:re2c*/
+
+// Expects YYMAXFILL-padded string.
+func lex(str string) int {
+	var cursor int
+	limit := len(str)
+	count := 0
+loop:
+	/*!re2c
+	re2c:define:YYCTYPE    = byte;
+	re2c:define:YYPEEK     = "str[cursor]";
+	re2c:define:YYSKIP     = "cursor += 1";
+	re2c:define:YYLESSTHAN = "limit - cursor < @@{len}";
+	re2c:define:YYFILL     = "return -1";
+
+	* {
+		return -1
+	}
+	[\x00] {
+		if limit - cursor == YYMAXFILL - 1 {
+			return count
+		} else {
+			return -1
+		}
+	}
+	['] ([^'\\] | [\\][^])* ['] {
+		count += 1;
+		goto loop
+	}
+	[ ]+ {
+		goto loop
+	}
+	*/
+}
+
+// Pad string with YYMAXFILL zeroes at the end.
+func pad(str string) string {
+	return str + strings.Repeat("\000", YYMAXFILL)
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(pad(x.str))
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/eof_rule.go

@@ -0,0 +1,146 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// Expects a null-terminated string.
+func lex(str string) int {
+	var cursor, marker int
+	limit := len(str) - 1 // limit points at the terminating null
+	count := 0
+loop:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 3
+				continue
+			case '\'':
+				cursor += 1
+				yystate = 6
+				continue
+			default:
+				if (limit <= cursor) {
+					yystate = 12
+					continue
+				}
+				cursor += 1
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return -1 }
+		case 3:
+			yych = str[cursor]
+			yystate = 4
+			continue
+		case 4:
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 3
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 5:
+			{ goto loop }
+		case 6:
+			marker = cursor
+			yych = str[cursor]
+			if (yych >= 0x01) {
+				yystate = 8
+				continue
+			}
+			if (limit <= cursor) {
+				yystate = 2
+				continue
+			}
+			cursor += 1
+			yystate = 7
+			continue
+		case 7:
+			yych = str[cursor]
+			yystate = 8
+			continue
+		case 8:
+			switch (yych) {
+			case '\'':
+				cursor += 1
+				yystate = 9
+				continue
+			case '\\':
+				cursor += 1
+				yystate = 11
+				continue
+			default:
+				if (limit <= cursor) {
+					yystate = 13
+					continue
+				}
+				cursor += 1
+				yystate = 7
+				continue
+			}
+		case 9:
+			yystate = 10
+			continue
+		case 10:
+			{ count += 1; goto loop }
+		case 11:
+			yych = str[cursor]
+			if (yych <= 0x00) {
+				if (limit <= cursor) {
+					yystate = 13
+					continue
+				}
+				cursor += 1
+				yystate = 7
+				continue
+			}
+			cursor += 1
+			yystate = 7
+			continue
+		case 12:
+			{ return count }
+		case 13:
+			cursor = marker
+			yystate = 2
+			continue
+		}
+	}
+}
+
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, "\000"},
+		{3, "'qu\000tes' 'are' 'fine: \\'' \000"},
+		{-1, "'unterminated\\'\000"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/eof_rule.re

@@ -0,0 +1,47 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// Expects a null-terminated string.
+func lex(str string) int {
+	var cursor, marker int
+	limit := len(str) - 1 // limit points at the terminating null
+	count := 0
+loop:
+	/*!re2c
+	re2c:yyfill:enable = 0;
+	re2c:eof = 0;
+	re2c:define:YYCTYPE    = byte;
+	re2c:define:YYPEEK     = "str[cursor]";
+	re2c:define:YYSKIP     = "cursor += 1";
+	re2c:define:YYBACKUP   = "marker = cursor";
+	re2c:define:YYRESTORE  = "cursor = marker";
+	re2c:define:YYLESSTHAN = "limit <= cursor";
+
+	*                           { return -1 }
+	$                           { return count }
+	['] ([^'\\] | [\\][^])* ['] { count += 1; goto loop }
+	[ ]+                        { goto loop }
+	*/
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, "\000"},
+		{3, "'qu\000tes' 'are' 'fine: \\'' \000"},
+		{-1, "'unterminated\\'\000"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/fill_1.go

@@ -0,0 +1,249 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"os"
+	"testing"
+)
+
+// Intentionally small to trigger buffer refill.
+const SIZE int = 16
+
+type Input struct {
+	file   *os.File
+	data   []byte
+	cursor int
+	marker int
+	token  int
+	limit  int
+	eof    bool
+}
+
+func fill(in *Input) int {
+	// If nothing can be read, fail.
+	if in.eof {
+		return 1
+	}
+
+	// Check if at least some space can be freed.
+	if in.token == 0 {
+		// In real life can reallocate a larger buffer.
+		panic("fill error: lexeme too long")
+	}
+
+	// Discard everything up to the start of the current lexeme,
+	// shift buffer contents and adjust offsets.
+	copy(in.data[0:], in.data[in.token:in.limit])
+	in.cursor -= in.token
+	in.marker -= in.token
+	in.limit -= in.token
+	in.token = 0
+
+	// Read new data (as much as possible to fill the buffer).
+	n, _ := in.file.Read(in.data[in.limit:SIZE])
+	in.limit += n
+	in.data[in.limit] = 0
+
+	// If read less than expected, this is the end of input.
+	in.eof = in.limit < SIZE
+
+	// If nothing has been read, fail.
+	if n == 0 {
+		return 1
+	}
+
+	return 0
+}
+
+func lex(in *Input) int {
+	count := 0
+loop:
+	in.token = in.cursor
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = in.data[in.cursor]
+			switch (yych) {
+			case ' ':
+				in.cursor += 1
+				yystate = 3
+				continue
+			case '\'':
+				in.cursor += 1
+				yystate = 6
+				continue
+			default:
+				if (in.limit <= in.cursor) {
+					if (fill(in) == 0) {
+						yystate = 0
+						continue
+					}
+					yystate = 12
+					continue
+				}
+				in.cursor += 1
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return -1 }
+		case 3:
+			yych = in.data[in.cursor]
+			yystate = 4
+			continue
+		case 4:
+			switch (yych) {
+			case ' ':
+				in.cursor += 1
+				yystate = 3
+				continue
+			default:
+				if (in.limit <= in.cursor) {
+					if (fill(in) == 0) {
+						yystate = 3
+						continue
+					}
+				}
+				yystate = 5
+				continue
+			}
+		case 5:
+			{ goto loop }
+		case 6:
+			in.marker = in.cursor
+			yych = in.data[in.cursor]
+			if (yych >= 0x01) {
+				yystate = 8
+				continue
+			}
+			if (in.limit <= in.cursor) {
+				if (fill(in) == 0) {
+					yystate = 6
+					continue
+				}
+				yystate = 2
+				continue
+			}
+			in.cursor += 1
+			yystate = 7
+			continue
+		case 7:
+			yych = in.data[in.cursor]
+			yystate = 8
+			continue
+		case 8:
+			switch (yych) {
+			case '\'':
+				in.cursor += 1
+				yystate = 9
+				continue
+			case '\\':
+				in.cursor += 1
+				yystate = 11
+				continue
+			default:
+				if (in.limit <= in.cursor) {
+					if (fill(in) == 0) {
+						yystate = 7
+						continue
+					}
+					yystate = 13
+					continue
+				}
+				in.cursor += 1
+				yystate = 7
+				continue
+			}
+		case 9:
+			yystate = 10
+			continue
+		case 10:
+			{ count += 1; goto loop }
+		case 11:
+			yych = in.data[in.cursor]
+			if (yych <= 0x00) {
+				if (in.limit <= in.cursor) {
+					if (fill(in) == 0) {
+						yystate = 11
+						continue
+					}
+					yystate = 13
+					continue
+				}
+				in.cursor += 1
+				yystate = 7
+				continue
+			}
+			in.cursor += 1
+			yystate = 7
+			continue
+		case 12:
+			{ return count }
+		case 13:
+			in.cursor = in.marker
+			yystate = 2
+			continue
+		}
+	}
+}
+
+}
+
+// Prepare a file with the input text and run the lexer.
+func test(data string) (result int) {
+	tmpfile := "input.txt"
+
+	f, _ := os.Create(tmpfile)
+	f.WriteString(data)
+	f.Seek(0, 0)
+
+	defer func() {
+		if r := recover(); r != nil {
+			result = -2
+		}
+		f.Close()
+		os.Remove(tmpfile)
+	}()
+
+	in := &Input{
+		file:   f,
+		data:   make([]byte, SIZE+1),
+		cursor: SIZE,
+		marker: SIZE,
+		token:  SIZE,
+		limit:  SIZE,
+		eof:    false,
+	}
+
+	return lex(in)
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{2, "'one' 'two'"},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+		{-2, "'loooooooooooong'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := test(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/fill_1.re

@@ -0,0 +1,128 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"os"
+	"testing"
+)
+
+// Intentionally small to trigger buffer refill.
+const SIZE int = 16
+
+type Input struct {
+	file   *os.File
+	data   []byte
+	cursor int
+	marker int
+	token  int
+	limit  int
+	eof    bool
+}
+
+func fill(in *Input) int {
+	// If nothing can be read, fail.
+	if in.eof {
+		return 1
+	}
+
+	// Check if at least some space can be freed.
+	if in.token == 0 {
+		// In real life can reallocate a larger buffer.
+		panic("fill error: lexeme too long")
+	}
+
+	// Discard everything up to the start of the current lexeme,
+	// shift buffer contents and adjust offsets.
+	copy(in.data[0:], in.data[in.token:in.limit])
+	in.cursor -= in.token
+	in.marker -= in.token
+	in.limit -= in.token
+	in.token = 0
+
+	// Read new data (as much as possible to fill the buffer).
+	n, _ := in.file.Read(in.data[in.limit:SIZE])
+	in.limit += n
+	in.data[in.limit] = 0
+
+	// If read less than expected, this is the end of input.
+	in.eof = in.limit < SIZE
+
+	// If nothing has been read, fail.
+	if n == 0 {
+		return 1
+	}
+
+	return 0
+}
+
+func lex(in *Input) int {
+	count := 0
+loop:
+	in.token = in.cursor
+	/*!re2c
+	re2c:eof = 0;
+	re2c:define:YYCTYPE    = byte;
+	re2c:define:YYPEEK     = "in.data[in.cursor]";
+	re2c:define:YYSKIP     = "in.cursor += 1";
+	re2c:define:YYBACKUP   = "in.marker = in.cursor";
+	re2c:define:YYRESTORE  = "in.cursor = in.marker";
+	re2c:define:YYLESSTHAN = "in.limit <= in.cursor";
+	re2c:define:YYFILL     = "fill(in) == 0";
+
+	*                           { return -1 }
+	$                           { return count }
+	['] ([^'\\] | [\\][^])* ['] { count += 1; goto loop }
+	[ ]+                        { goto loop }
+	*/
+}
+
+// Prepare a file with the input text and run the lexer.
+func test(data string) (result int) {
+	tmpfile := "input.txt"
+
+	f, _ := os.Create(tmpfile)
+	f.WriteString(data)
+	f.Seek(0, 0)
+
+	defer func() {
+		if r := recover(); r != nil {
+			result = -2
+		}
+		f.Close()
+		os.Remove(tmpfile)
+	}()
+
+	in := &Input{
+		file:   f,
+		data:   make([]byte, SIZE+1),
+		cursor: SIZE,
+		marker: SIZE,
+		token:  SIZE,
+		limit:  SIZE,
+		eof:    false,
+	}
+
+	return lex(in)
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{2, "'one' 'two'"},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+		{-2, "'loooooooooooong'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := test(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/fill_2.go

@@ -0,0 +1,227 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+var YYMAXFILL int = 1
+
+
+// Intentionally small to trigger buffer refill.
+const SIZE int = 16
+
+type Input struct {
+	file   *os.File
+	data   []byte
+	cursor int
+	marker int
+	token  int
+	limit  int
+	eof    bool
+}
+
+func fill(in *Input, need int) int {
+	// End of input has already been reached, nothing to do.
+	if in.eof {
+		return -1 // Error: unexpected EOF
+	}
+
+	// Check if after moving the current lexeme to the beginning
+	// of buffer there will be enough free space.
+	if SIZE-(in.cursor-in.token) < need {
+		return -2 // Error: lexeme too long
+	}
+
+	// Discard everything up to the start of the current lexeme,
+	// shift buffer contents and adjust offsets.
+	copy(in.data[0:], in.data[in.token:in.limit])
+	in.cursor -= in.token
+	in.marker -= in.token
+	in.limit -= in.token
+	in.token = 0
+
+	// Read new data (as much as possible to fill the buffer).
+	n, _ := in.file.Read(in.data[in.limit:SIZE])
+	in.limit += n
+
+	// If read less than expected, this is the end of input.
+	in.eof = in.limit < SIZE
+
+	// If end of input, add padding so that the lexer can read
+	// the remaining characters at the end of buffer.
+	if in.eof {
+		for i := 0; i < YYMAXFILL; i += 1 {
+			in.data[in.limit+i] = 0
+		}
+		in.limit += YYMAXFILL
+	}
+
+	return 0
+}
+
+func lex(in *Input) int {
+	count := 0
+loop:
+	in.token = in.cursor
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			if (in.limit-in.cursor < 1) {
+				if r := fill(in, 1); r != 0 { return r }
+			}
+			yych = in.data[in.cursor]
+			in.cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case ' ':
+				yystate = 5
+				continue
+			case '\'':
+				yystate = 8
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{
+		if in.limit - in.cursor == YYMAXFILL - 1 {
+			return count
+		} else {
+			return -1
+		}
+	}
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{
+		return -1
+	}
+		case 5:
+			if (in.limit-in.cursor < 1) {
+				if r := fill(in, 1); r != 0 { return r }
+			}
+			yych = in.data[in.cursor]
+			yystate = 6
+			continue
+		case 6:
+			switch (yych) {
+			case ' ':
+				in.cursor += 1
+				yystate = 5
+				continue
+			default:
+				yystate = 7
+				continue
+			}
+		case 7:
+			{
+		goto loop
+	}
+		case 8:
+			if (in.limit-in.cursor < 1) {
+				if r := fill(in, 1); r != 0 { return r }
+			}
+			yych = in.data[in.cursor]
+			yystate = 9
+			continue
+		case 9:
+			in.cursor += 1
+			switch (yych) {
+			case '\'':
+				yystate = 10
+				continue
+			case '\\':
+				yystate = 12
+				continue
+			default:
+				yystate = 8
+				continue
+			}
+		case 10:
+			yystate = 11
+			continue
+		case 11:
+			{
+		count += 1;
+		goto loop
+	}
+		case 12:
+			if (in.limit-in.cursor < 1) {
+				if r := fill(in, 1); r != 0 { return r }
+			}
+			yych = in.data[in.cursor]
+			in.cursor += 1
+			yystate = 8
+			continue
+		}
+	}
+}
+
+}
+
+// Prepare a file with the input text and run the lexer.
+func test(data string) (result int) {
+	tmpfile := "input.txt"
+
+	f, _ := os.Create(tmpfile)
+	f.WriteString(data)
+	f.Seek(0, 0)
+
+	defer func() {
+		if r := recover(); r != nil {
+			fmt.Println(r)
+			result = -2
+		}
+		f.Close()
+		os.Remove(tmpfile)
+	}()
+
+	in := &Input{
+		file:   f,
+		data:   make([]byte, SIZE+YYMAXFILL),
+		cursor: SIZE,
+		marker: SIZE,
+		token:  SIZE,
+		limit:  SIZE,
+		eof:    false,
+	}
+
+	return lex(in)
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{2, "'one' 'two'"},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+		{-2, "'loooooooooooong'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := test(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/fill_2.re

@@ -0,0 +1,147 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+/*!max:re2c*/
+
+// Intentionally small to trigger buffer refill.
+const SIZE int = 16
+
+type Input struct {
+	file   *os.File
+	data   []byte
+	cursor int
+	marker int
+	token  int
+	limit  int
+	eof    bool
+}
+
+func fill(in *Input, need int) int {
+	// End of input has already been reached, nothing to do.
+	if in.eof {
+		return -1 // Error: unexpected EOF
+	}
+
+	// Check if after moving the current lexeme to the beginning
+	// of buffer there will be enough free space.
+	if SIZE-(in.cursor-in.token) < need {
+		return -2 // Error: lexeme too long
+	}
+
+	// Discard everything up to the start of the current lexeme,
+	// shift buffer contents and adjust offsets.
+	copy(in.data[0:], in.data[in.token:in.limit])
+	in.cursor -= in.token
+	in.marker -= in.token
+	in.limit -= in.token
+	in.token = 0
+
+	// Read new data (as much as possible to fill the buffer).
+	n, _ := in.file.Read(in.data[in.limit:SIZE])
+	in.limit += n
+
+	// If read less than expected, this is the end of input.
+	in.eof = in.limit < SIZE
+
+	// If end of input, add padding so that the lexer can read
+	// the remaining characters at the end of buffer.
+	if in.eof {
+		for i := 0; i < YYMAXFILL; i += 1 {
+			in.data[in.limit+i] = 0
+		}
+		in.limit += YYMAXFILL
+	}
+
+	return 0
+}
+
+func lex(in *Input) int {
+	count := 0
+loop:
+	in.token = in.cursor
+	/*!re2c
+	re2c:define:YYCTYPE    = byte;
+	re2c:define:YYPEEK     = "in.data[in.cursor]";
+	re2c:define:YYSKIP     = "in.cursor += 1";
+	re2c:define:YYBACKUP   = "in.marker = in.cursor";
+	re2c:define:YYRESTORE  = "in.cursor = in.marker";
+	re2c:define:YYLESSTHAN = "in.limit-in.cursor < @@{len}";
+	re2c:define:YYFILL     = "if r := fill(in, @@{len}); r != 0 { return r }";
+
+	* {
+		return -1
+	}
+	[\x00] {
+		if in.limit - in.cursor == YYMAXFILL - 1 {
+			return count
+		} else {
+			return -1
+		}
+	}
+	['] ([^'\\] | [\\][^])* ['] {
+		count += 1;
+		goto loop
+	}
+	[ ]+ {
+		goto loop
+	}
+	*/
+}
+
+// Prepare a file with the input text and run the lexer.
+func test(data string) (result int) {
+	tmpfile := "input.txt"
+
+	f, _ := os.Create(tmpfile)
+	f.WriteString(data)
+	f.Seek(0, 0)
+
+	defer func() {
+		if r := recover(); r != nil {
+			fmt.Println(r)
+			result = -2
+		}
+		f.Close()
+		os.Remove(tmpfile)
+	}()
+
+	in := &Input{
+		file:   f,
+		data:   make([]byte, SIZE+YYMAXFILL),
+		cursor: SIZE,
+		marker: SIZE,
+		token:  SIZE,
+		limit:  SIZE,
+		eof:    false,
+	}
+
+	return lex(in)
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{2, "'one' 'two'"},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+		{-2, "'loooooooooooong'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := test(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/generic_api_eof_rule.go

@@ -0,0 +1,155 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// Returns "fake" terminating null if cursor has reached limit.
+func peek(str string, cursor int, limit int) byte {
+	if cursor >= limit {
+		return 0 // fake null
+	} else {
+		return str[cursor]
+	}
+}
+
+// Expects a string without terminating null.
+func lex(str string) int {
+	var cursor, marker int
+	limit := len(str)
+	count := 0
+loop:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = peek(str, cursor, limit)
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 3
+				continue
+			case '\'':
+				cursor += 1
+				yystate = 6
+				continue
+			default:
+				if (cursor >= limit) {
+					yystate = 12
+					continue
+				}
+				cursor += 1
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return -1 }
+		case 3:
+			yych = peek(str, cursor, limit)
+			yystate = 4
+			continue
+		case 4:
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 3
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 5:
+			{ goto loop }
+		case 6:
+			marker = cursor
+			yych = peek(str, cursor, limit)
+			if (yych >= 0x01) {
+				yystate = 8
+				continue
+			}
+			if (cursor >= limit) {
+				yystate = 2
+				continue
+			}
+			cursor += 1
+			yystate = 7
+			continue
+		case 7:
+			yych = peek(str, cursor, limit)
+			yystate = 8
+			continue
+		case 8:
+			switch (yych) {
+			case '\'':
+				cursor += 1
+				yystate = 9
+				continue
+			case '\\':
+				cursor += 1
+				yystate = 11
+				continue
+			default:
+				if (cursor >= limit) {
+					yystate = 13
+					continue
+				}
+				cursor += 1
+				yystate = 7
+				continue
+			}
+		case 9:
+			yystate = 10
+			continue
+		case 10:
+			{ count += 1; goto loop }
+		case 11:
+			yych = peek(str, cursor, limit)
+			if (yych <= 0x00) {
+				if (cursor >= limit) {
+					yystate = 13
+					continue
+				}
+				cursor += 1
+				yystate = 7
+				continue
+			}
+			cursor += 1
+			yystate = 7
+			continue
+		case 12:
+			{ return count }
+		case 13:
+			cursor = marker
+			yystate = 2
+			continue
+		}
+	}
+}
+
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/generic_api_eof_rule.re

@@ -0,0 +1,56 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// Returns "fake" terminating null if cursor has reached limit.
+func peek(str string, cursor int, limit int) byte {
+	if cursor >= limit {
+		return 0 // fake null
+	} else {
+		return str[cursor]
+	}
+}
+
+// Expects a string without terminating null.
+func lex(str string) int {
+	var cursor, marker int
+	limit := len(str)
+	count := 0
+loop:
+	/*!re2c
+	re2c:yyfill:enable = 0;
+	re2c:eof = 0;
+	re2c:define:YYCTYPE    = byte;
+	re2c:define:YYLESSTHAN = "cursor >= limit";
+	re2c:define:YYPEEK     = "peek(str, cursor, limit)";
+	re2c:define:YYSKIP     = "cursor += 1";
+	re2c:define:YYBACKUP   = "marker = cursor";
+	re2c:define:YYRESTORE  = "cursor = marker";
+
+	*                           { return -1 }
+	$                           { return count }
+	['] ([^'\\] | [\\][^])* ['] { count += 1; goto loop }
+	[ ]+                        { goto loop }
+	*/
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{3, "'qu\000tes' 'are' 'fine: \\'' "},
+		{-1, "'unterminated\\'"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/generic_api_sentinel.go

@@ -0,0 +1,211 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// Returns "fake" terminating null if cursor has reached limit.
+func peek(str string, cursor int, limit int) byte {
+	if cursor >= limit {
+		return 0 // fake null
+	} else {
+		return str[cursor]
+	}
+}
+
+// Expects a string without terminating null.
+func lex(str string) int {
+	var cursor int
+	limit := len(str)
+	count := 0
+loop:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = peek(str, cursor, limit)
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case ' ':
+				yystate = 5
+				continue
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				yystate = 8
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return count }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{ return -1 }
+		case 5:
+			yych = peek(str, cursor, limit)
+			yystate = 6
+			continue
+		case 6:
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 5
+				continue
+			default:
+				yystate = 7
+				continue
+			}
+		case 7:
+			{ goto loop }
+		case 8:
+			yych = peek(str, cursor, limit)
+			yystate = 9
+			continue
+		case 9:
+			switch (yych) {
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				cursor += 1
+				yystate = 8
+				continue
+			default:
+				yystate = 10
+				continue
+			}
+		case 10:
+			{ count += 1; goto loop }
+		}
+	}
+}
+
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{3, "one two three"},
+		{-1, "f0ur"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/generic_api_sentinel.re

@@ -0,0 +1,53 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// Returns "fake" terminating null if cursor has reached limit.
+func peek(str string, cursor int, limit int) byte {
+	if cursor >= limit {
+		return 0 // fake null
+	} else {
+		return str[cursor]
+	}
+}
+
+// Expects a string without terminating null.
+func lex(str string) int {
+	var cursor int
+	limit := len(str)
+	count := 0
+loop:
+	/*!re2c
+	re2c:yyfill:enable = 0;
+	re2c:define:YYCTYPE    = byte;
+	re2c:define:YYLESSTHAN = "cursor >= limit";
+	re2c:define:YYPEEK     = "peek(str, cursor, limit)";
+	re2c:define:YYSKIP     = "cursor += 1";
+
+	*      { return -1 }
+	[\x00] { return count }
+	[a-z]+ { count += 1; goto loop }
+	[ ]+   { goto loop }
+	*/
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, ""},
+		{3, "one two three"},
+		{-1, "f0ur"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/parse_u32_blocks.go

@@ -0,0 +1,463 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"errors"
+	"testing"
+)
+
+var (
+	eSyntax   = errors.New("syntax error")
+	eOverflow = errors.New("overflow error")
+)
+
+const u32Limit uint64 = 1<<32
+
+func parse_u32(str string) (uint32, error) {
+	var cursor, marker int
+	result := uint64(0)
+
+	add_digit := func(base uint64, offset byte) {
+		result = result * base + uint64(str[cursor-1] - offset)
+		if result >= u32Limit {
+			result = u32Limit
+		}
+	}
+
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case '0':
+				yystate = 3
+				continue
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				yystate = 5
+				continue
+			default:
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ goto err }
+		case 3:
+			marker = cursor
+			yych = str[cursor]
+			switch (yych) {
+			case 'B':
+				fallthrough
+			case 'b':
+				cursor += 1
+				yystate = 7
+				continue
+			case 'X':
+				fallthrough
+			case 'x':
+				cursor += 1
+				yystate = 9
+				continue
+			default:
+				yystate = 4
+				continue
+			}
+		case 4:
+			{ goto oct }
+		case 5:
+			yystate = 6
+			continue
+		case 6:
+			cursor += -1
+			{ goto dec }
+		case 7:
+			yych = str[cursor]
+			switch (yych) {
+			case '0':
+				fallthrough
+			case '1':
+				cursor += 1
+				yystate = 10
+				continue
+			default:
+				yystate = 8
+				continue
+			}
+		case 8:
+			cursor = marker
+			yystate = 4
+			continue
+		case 9:
+			yych = str[cursor]
+			switch (yych) {
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				fallthrough
+			case 'A':
+				fallthrough
+			case 'B':
+				fallthrough
+			case 'C':
+				fallthrough
+			case 'D':
+				fallthrough
+			case 'E':
+				fallthrough
+			case 'F':
+				fallthrough
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				cursor += 1
+				yystate = 12
+				continue
+			default:
+				yystate = 8
+				continue
+			}
+		case 10:
+			yystate = 11
+			continue
+		case 11:
+			cursor += -1
+			{ goto bin }
+		case 12:
+			yystate = 13
+			continue
+		case 13:
+			cursor += -1
+			{ goto hex }
+		}
+	}
+}
+
+bin:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				yystate = 5
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ goto end }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{ goto err }
+		case 5:
+			yystate = 6
+			continue
+		case 6:
+			{ add_digit(2, '0'); goto bin }
+		}
+	}
+}
+
+oct:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				yystate = 5
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ goto end }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{ goto err }
+		case 5:
+			yystate = 6
+			continue
+		case 6:
+			{ add_digit(8, '0'); goto oct }
+		}
+	}
+}
+
+dec:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				yystate = 5
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ goto end }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{ goto err }
+		case 5:
+			yystate = 6
+			continue
+		case 6:
+			{ add_digit(10, '0'); goto dec }
+		}
+	}
+}
+
+hex:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				yystate = 5
+				continue
+			case 'A':
+				fallthrough
+			case 'B':
+				fallthrough
+			case 'C':
+				fallthrough
+			case 'D':
+				fallthrough
+			case 'E':
+				fallthrough
+			case 'F':
+				yystate = 7
+				continue
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				yystate = 9
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ goto end }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{ goto err }
+		case 5:
+			yystate = 6
+			continue
+		case 6:
+			{ add_digit(16, '0');    goto hex }
+		case 7:
+			yystate = 8
+			continue
+		case 8:
+			{ add_digit(16, 'A'-10); goto hex }
+		case 9:
+			yystate = 10
+			continue
+		case 10:
+			{ add_digit(16, 'a'-10); goto hex }
+		}
+	}
+}
+
+end:
+	if result < u32Limit {
+		return uint32(result), nil
+	} else {
+		return 0, eOverflow
+	}
+err:
+	return 0, eSyntax
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		num uint32
+		str string
+		err error
+	}{
+		{1234567890, "1234567890\000", nil},
+		{13, "0b1101\000", nil},
+		{0x7fe, "0x007Fe\000", nil},
+		{0644, "0644\000", nil},
+		{0, "9999999999\000", eOverflow},
+		{0, "123??\000", eSyntax},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			num, err := parse_u32(x.str)
+			if !(num == x.num && err == x.err) {
+				t.Errorf("got %d, want %d", num, x.num)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/parse_u32_blocks.re

@@ -0,0 +1,102 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"errors"
+	"testing"
+)
+
+var (
+	eSyntax   = errors.New("syntax error")
+	eOverflow = errors.New("overflow error")
+)
+
+const u32Limit uint64 = 1<<32
+
+func parse_u32(str string) (uint32, error) {
+	var cursor, marker int
+	result := uint64(0)
+
+	add_digit := func(base uint64, offset byte) {
+		result = result * base + uint64(str[cursor-1] - offset)
+		if result >= u32Limit {
+			result = u32Limit
+		}
+	}
+
+	/*!re2c
+	re2c:yyfill:enable = 0;
+	re2c:define:YYCTYPE   = byte;
+	re2c:define:YYPEEK    = "str[cursor]";
+	re2c:define:YYSKIP    = "cursor += 1";
+	re2c:define:YYSHIFT   = "cursor += @@{shift}";
+	re2c:define:YYBACKUP  = "marker = cursor";
+	re2c:define:YYRESTORE = "cursor = marker";
+
+	end = "\x00";
+
+	'0b' / [01]        { goto bin }
+	"0"                { goto oct }
+	""   / [1-9]       { goto dec }
+	'0x' / [0-9a-fA-F] { goto hex }
+	*                  { goto err }
+	*/
+bin:
+	/*!re2c
+	end   { goto end }
+	[01]  { add_digit(2, '0'); goto bin }
+	*     { goto err }
+	*/
+oct:
+	/*!re2c
+	end   { goto end }
+	[0-7] { add_digit(8, '0'); goto oct }
+	*     { goto err }
+	*/
+dec:
+	/*!re2c
+	end   { goto end }
+	[0-9] { add_digit(10, '0'); goto dec }
+	*     { goto err }
+	*/
+hex:
+	/*!re2c
+	end   { goto end }
+	[0-9] { add_digit(16, '0');    goto hex }
+	[a-f] { add_digit(16, 'a'-10); goto hex }
+	[A-F] { add_digit(16, 'A'-10); goto hex }
+	*     { goto err }
+	*/
+end:
+	if result < u32Limit {
+		return uint32(result), nil
+	} else {
+		return 0, eOverflow
+	}
+err:
+	return 0, eSyntax
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		num uint32
+		str string
+		err error
+	}{
+		{1234567890, "1234567890\000", nil},
+		{13, "0b1101\000", nil},
+		{0x7fe, "0x007Fe\000", nil},
+		{0644, "0644\000", nil},
+		{0, "9999999999\000", eOverflow},
+		{0, "123??\000", eSyntax},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			num, err := parse_u32(x.str)
+			if !(num == x.num && err == x.err) {
+				t.Errorf("got %d, want %d", num, x.num)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/parse_u32_conditions.go

@@ -0,0 +1,454 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go -c $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"errors"
+	"testing"
+)
+
+var (
+	eSyntax   = errors.New("syntax error")
+	eOverflow = errors.New("overflow error")
+)
+
+const (
+	yycinit = 0
+	yycbin = 14
+	yycdec = 21
+	yychex = 28
+	yycoct = 39
+)
+
+
+const u32Limit uint64 = 1<<32
+
+func parse_u32(str string) (uint32, error) {
+	var cursor, marker int
+	result := uint64(0)
+	cond := yycinit
+
+	add_digit := func(base uint64, offset byte) {
+		result = result * base + uint64(str[cursor-1] - offset)
+		if result >= u32Limit {
+			result = u32Limit
+		}
+	}
+
+loop:
+	
+{
+	var yych byte
+	yystate := cond
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case '0':
+				yystate = 3
+				continue
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				yystate = 5
+				continue
+			default:
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return 0, eSyntax }
+		case 3:
+			marker = cursor
+			yych = str[cursor]
+			switch (yych) {
+			case 'B':
+				fallthrough
+			case 'b':
+				cursor += 1
+				yystate = 7
+				continue
+			case 'X':
+				fallthrough
+			case 'x':
+				cursor += 1
+				yystate = 9
+				continue
+			default:
+				yystate = 4
+				continue
+			}
+		case 4:
+			cond = yycoct
+			yystate = yycoct
+			continue
+		case 5:
+			yystate = 6
+			continue
+		case 6:
+			cursor += -1
+			cond = yycdec
+			yystate = yycdec
+			continue
+		case 7:
+			yych = str[cursor]
+			switch (yych) {
+			case '0':
+				fallthrough
+			case '1':
+				cursor += 1
+				yystate = 10
+				continue
+			default:
+				yystate = 8
+				continue
+			}
+		case 8:
+			cursor = marker
+			yystate = 4
+			continue
+		case 9:
+			yych = str[cursor]
+			switch (yych) {
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				fallthrough
+			case 'A':
+				fallthrough
+			case 'B':
+				fallthrough
+			case 'C':
+				fallthrough
+			case 'D':
+				fallthrough
+			case 'E':
+				fallthrough
+			case 'F':
+				fallthrough
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				cursor += 1
+				yystate = 12
+				continue
+			default:
+				yystate = 8
+				continue
+			}
+		case 10:
+			yystate = 11
+			continue
+		case 11:
+			cursor += -1
+			cond = yycbin
+			yystate = yycbin
+			continue
+		case 12:
+			yystate = 13
+			continue
+		case 13:
+			cursor += -1
+			cond = yychex
+			yystate = yychex
+			continue
+		case 14:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 15
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				yystate = 19
+				continue
+			default:
+				yystate = 17
+				continue
+			}
+		case 15:
+			yystate = 16
+			continue
+		case 16:
+			{
+		if result < u32Limit {
+			return uint32(result), nil
+		} else {
+			return 0, eOverflow
+		}
+	}
+		case 17:
+			yystate = 18
+			continue
+		case 18:
+			{ return 0, eSyntax }
+		case 19:
+			yystate = 20
+			continue
+		case 20:
+			{ add_digit(2, '0');     goto loop }
+		case 21:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 22
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				yystate = 26
+				continue
+			default:
+				yystate = 24
+				continue
+			}
+		case 22:
+			yystate = 23
+			continue
+		case 23:
+			{
+		if result < u32Limit {
+			return uint32(result), nil
+		} else {
+			return 0, eOverflow
+		}
+	}
+		case 24:
+			yystate = 25
+			continue
+		case 25:
+			{ return 0, eSyntax }
+		case 26:
+			yystate = 27
+			continue
+		case 27:
+			{ add_digit(10, '0');    goto loop }
+		case 28:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 29
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				fallthrough
+			case '8':
+				fallthrough
+			case '9':
+				yystate = 33
+				continue
+			case 'A':
+				fallthrough
+			case 'B':
+				fallthrough
+			case 'C':
+				fallthrough
+			case 'D':
+				fallthrough
+			case 'E':
+				fallthrough
+			case 'F':
+				yystate = 35
+				continue
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				yystate = 37
+				continue
+			default:
+				yystate = 31
+				continue
+			}
+		case 29:
+			yystate = 30
+			continue
+		case 30:
+			{
+		if result < u32Limit {
+			return uint32(result), nil
+		} else {
+			return 0, eOverflow
+		}
+	}
+		case 31:
+			yystate = 32
+			continue
+		case 32:
+			{ return 0, eSyntax }
+		case 33:
+			yystate = 34
+			continue
+		case 34:
+			{ add_digit(16, '0');    goto loop }
+		case 35:
+			yystate = 36
+			continue
+		case 36:
+			{ add_digit(16, 'A'-10); goto loop }
+		case 37:
+			yystate = 38
+			continue
+		case 38:
+			{ add_digit(16, 'a'-10); goto loop }
+		case 39:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 40
+				continue
+			case '0':
+				fallthrough
+			case '1':
+				fallthrough
+			case '2':
+				fallthrough
+			case '3':
+				fallthrough
+			case '4':
+				fallthrough
+			case '5':
+				fallthrough
+			case '6':
+				fallthrough
+			case '7':
+				yystate = 44
+				continue
+			default:
+				yystate = 42
+				continue
+			}
+		case 40:
+			yystate = 41
+			continue
+		case 41:
+			{
+		if result < u32Limit {
+			return uint32(result), nil
+		} else {
+			return 0, eOverflow
+		}
+	}
+		case 42:
+			yystate = 43
+			continue
+		case 43:
+			{ return 0, eSyntax }
+		case 44:
+			yystate = 45
+			continue
+		case 45:
+			{ add_digit(8, '0');     goto loop }
+		}
+	}
+}
+
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		num uint32
+		str string
+		err error
+	}{
+		{1234567890, "1234567890\000", nil},
+		{13, "0b1101\000", nil},
+		{0x7fe, "0x007Fe\000", nil},
+		{0644, "0644\000", nil},
+		{0, "9999999999\000", eOverflow},
+		{0, "123??\000", eSyntax},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			num, err := parse_u32(x.str)
+			if !(num == x.num && err == x.err) {
+				t.Errorf("got %d, want %d", num, x.num)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/parse_u32_conditions.re

@@ -0,0 +1,88 @@
+//go:generate re2go -c $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"errors"
+	"testing"
+)
+
+var (
+	eSyntax   = errors.New("syntax error")
+	eOverflow = errors.New("overflow error")
+)
+
+/*!types:re2c*/
+
+const u32Limit uint64 = 1<<32
+
+func parse_u32(str string) (uint32, error) {
+	var cursor, marker int
+	result := uint64(0)
+	cond := yycinit
+
+	add_digit := func(base uint64, offset byte) {
+		result = result * base + uint64(str[cursor-1] - offset)
+		if result >= u32Limit {
+			result = u32Limit
+		}
+	}
+
+loop:
+	/*!re2c
+	re2c:yyfill:enable = 0;
+	re2c:define:YYCTYPE        = byte;
+	re2c:define:YYPEEK         = "str[cursor]";
+	re2c:define:YYSKIP         = "cursor += 1";
+	re2c:define:YYSHIFT        = "cursor += @@{shift}";
+	re2c:define:YYBACKUP       = "marker = cursor";
+	re2c:define:YYRESTORE      = "cursor = marker";
+	re2c:define:YYGETCONDITION = "cond";
+	re2c:define:YYSETCONDITION = "cond = @@";
+
+	<*> * { return 0, eSyntax }
+
+	<init> '0b' / [01]        :=> bin
+	<init> "0"                :=> oct
+	<init> ""   / [1-9]       :=> dec
+	<init> '0x' / [0-9a-fA-F] :=> hex
+
+	<bin, oct, dec, hex> "\x00" {
+		if result < u32Limit {
+			return uint32(result), nil
+		} else {
+			return 0, eOverflow
+		}
+	}
+
+	<bin> [01]  { add_digit(2, '0');     goto loop }
+	<oct> [0-7] { add_digit(8, '0');     goto loop }
+	<dec> [0-9] { add_digit(10, '0');    goto loop }
+	<hex> [0-9] { add_digit(16, '0');    goto loop }
+	<hex> [a-f] { add_digit(16, 'a'-10); goto loop }
+	<hex> [A-F] { add_digit(16, 'A'-10); goto loop }
+	*/
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		num uint32
+		str string
+		err error
+	}{
+		{1234567890, "1234567890\000", nil},
+		{13, "0b1101\000", nil},
+		{0x7fe, "0x007Fe\000", nil},
+		{0644, "0644\000", nil},
+		{0, "9999999999\000", eOverflow},
+		{0, "123??\000", eSyntax},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			num, err := parse_u32(x.str)
+			if !(num == x.num && err == x.err) {
+				t.Errorf("got %d, want %d", num, x.num)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/reuse.go

@@ -0,0 +1,226 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --input-encoding utf8 --loop-switch -i
+
+// This example supports multiple input encodings: UTF-8 and UTF-32.
+// Both lexers are generated from the same rules block, and the use
+// blocks add only encoding-specific configurations.
+
+package main
+
+import "testing"
+
+
+
+func lexUTF8(str []uint8) int {
+	var cursor, marker int
+	
+{
+	var yych uint8
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0xE2:
+				yystate = 3
+				continue
+			default:
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return 1; }
+		case 3:
+			marker = cursor
+			yych = str[cursor]
+			switch (yych) {
+			case 0x88:
+				cursor += 1
+				yystate = 4
+				continue
+			default:
+				yystate = 2
+				continue
+			}
+		case 4:
+			yych = str[cursor]
+			switch (yych) {
+			case 0x80:
+				cursor += 1
+				yystate = 6
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 5:
+			cursor = marker
+			yystate = 2
+			continue
+		case 6:
+			yych = str[cursor]
+			switch (yych) {
+			case 'x':
+				cursor += 1
+				yystate = 7
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 7:
+			yych = str[cursor]
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 8
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 8:
+			yych = str[cursor]
+			switch (yych) {
+			case 0xE2:
+				cursor += 1
+				yystate = 9
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 9:
+			yych = str[cursor]
+			switch (yych) {
+			case 0x88:
+				cursor += 1
+				yystate = 10
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 10:
+			yych = str[cursor]
+			switch (yych) {
+			case 0x83:
+				cursor += 1
+				yystate = 11
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 11:
+			yych = str[cursor]
+			switch (yych) {
+			case 'y':
+				cursor += 1
+				yystate = 12
+				continue
+			default:
+				yystate = 5
+				continue
+			}
+		case 12:
+			yystate = 13
+			continue
+		case 13:
+			{ return 0; }
+		}
+	}
+}
+
+}
+
+func lexUTF32(str []uint32) int {
+	var cursor, marker int
+	
+{
+	var yych uint32
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			if (yych == 0x00002200) {
+				yystate = 3
+				continue
+			}
+			yystate = 1
+			continue
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return 1; }
+		case 3:
+			marker = cursor
+			yych = str[cursor]
+			if (yych != 'x') {
+				yystate = 2
+				continue
+			}
+			cursor += 1
+			yystate = 4
+			continue
+		case 4:
+			yych = str[cursor]
+			if (yych == ' ') {
+				cursor += 1
+				yystate = 6
+				continue
+			}
+			yystate = 5
+			continue
+		case 5:
+			cursor = marker
+			yystate = 2
+			continue
+		case 6:
+			yych = str[cursor]
+			if (yych != 0x00002203) {
+				yystate = 5
+				continue
+			}
+			cursor += 1
+			yystate = 7
+			continue
+		case 7:
+			yych = str[cursor]
+			if (yych != 'y') {
+				yystate = 5
+				continue
+			}
+			cursor += 1
+			yystate = 8
+			continue
+		case 8:
+			yystate = 9
+			continue
+		case 9:
+			{ return 0; }
+		}
+	}
+}
+
+}
+
+func TestLex(t *testing.T) {
+	s8 := []uint8{0xe2, 0x88, 0x80, 0x78, 0x20, 0xe2, 0x88, 0x83, 0x79};
+	if lexUTF8(s8) != 0 {
+		t.Errorf("utf8 failed")
+	}
+
+	s32 := []uint32{0x2200, 0x78, 0x20, 0x2203, 0x79};
+	if lexUTF32(s32) != 0 {
+		t.Errorf("utf32 failed")
+	}
+}

test/codegen/loop_switch/go/reuse.re

@@ -0,0 +1,48 @@
+//go:generate re2go $INPUT -o $OUTPUT --input-encoding utf8 --loop-switch -i
+
+// This example supports multiple input encodings: UTF-8 and UTF-32.
+// Both lexers are generated from the same rules block, and the use
+// blocks add only encoding-specific configurations.
+
+package main
+
+import "testing"
+
+/*!rules:re2c
+	re2c:yyfill:enable = 0;
+	re2c:define:YYPEEK    = "str[cursor]";
+	re2c:define:YYSKIP    = "cursor += 1";
+	re2c:define:YYBACKUP  = "marker = cursor";
+	re2c:define:YYRESTORE = "cursor = marker";
+
+	"∀x ∃y" { return 0; }
+	*       { return 1; }
+*/
+
+func lexUTF8(str []uint8) int {
+	var cursor, marker int
+	/*!use:re2c
+	re2c:flags:8 = 1;
+	re2c:define:YYCTYPE = uint8;
+	*/
+}
+
+func lexUTF32(str []uint32) int {
+	var cursor, marker int
+	/*!use:re2c
+	re2c:flags:u = 1;
+	re2c:define:YYCTYPE = uint32;
+	*/
+}
+
+func TestLex(t *testing.T) {
+	s8 := []uint8{0xe2, 0x88, 0x80, 0x78, 0x20, 0xe2, 0x88, 0x83, 0x79};
+	if lexUTF8(s8) != 0 {
+		t.Errorf("utf8 failed")
+	}
+
+	s32 := []uint32{0x2200, 0x78, 0x20, 0x2203, 0x79};
+	if lexUTF32(s32) != 0 {
+		t.Errorf("utf32 failed")
+	}
+}

test/codegen/loop_switch/go/sentinel.go

@@ -0,0 +1,201 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// expect a null-terminated string
+func lex(str string) int {
+	var cursor int
+	count := 0
+loop:
+	
+{
+	var yych byte
+	yystate := 0
+	for {
+		switch (yystate) {
+		case 0:
+			yych = str[cursor]
+			cursor += 1
+			switch (yych) {
+			case 0x00:
+				yystate = 1
+				continue
+			case ' ':
+				yystate = 5
+				continue
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				yystate = 8
+				continue
+			default:
+				yystate = 3
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			{ return count }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			{ return -1 }
+		case 5:
+			yych = str[cursor]
+			yystate = 6
+			continue
+		case 6:
+			switch (yych) {
+			case ' ':
+				cursor += 1
+				yystate = 5
+				continue
+			default:
+				yystate = 7
+				continue
+			}
+		case 7:
+			{ goto loop }
+		case 8:
+			yych = str[cursor]
+			yystate = 9
+			continue
+		case 9:
+			switch (yych) {
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				cursor += 1
+				yystate = 8
+				continue
+			default:
+				yystate = 10
+				continue
+			}
+		case 10:
+			{ count += 1; goto loop }
+		}
+	}
+}
+
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, "\000"},
+		{3, "one two three\000"},
+		{-1, "f0ur\000"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/sentinel.re

@@ -0,0 +1,42 @@
+//go:generate re2go $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import "testing"
+
+// expect a null-terminated string
+func lex(str string) int {
+	var cursor int
+	count := 0
+loop:
+	/*!re2c
+	re2c:yyfill:enable = 0;
+	re2c:define:YYCTYPE = byte;
+	re2c:define:YYPEEK = "str[cursor]";
+	re2c:define:YYSKIP = "cursor += 1";
+
+	*      { return -1 }
+	[\x00] { return count }
+	[a-z]+ { count += 1; goto loop }
+	[ ]+   { goto loop }
+	*/
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		res int
+		str string
+	}{
+		{0, "\000"},
+		{3, "one two three\000"},
+		{-1, "f0ur\000"},
+	}
+
+	for _, x := range tests {
+		t.Run(x.str, func(t *testing.T) {
+			res := lex(x.str)
+			if res != x.res {
+				t.Errorf("got %d, want %d", res, x.res)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/storable_state.go

@@ -0,0 +1,389 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go -f $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+// Intentionally small to trigger buffer refill.
+const SIZE int = 16
+
+type Input struct {
+	file     *os.File
+	data     []byte
+	cursor   int
+	marker   int
+	token    int
+	limit    int
+	state    int
+	yyaccept int
+}
+
+const (
+	lexEnd = iota
+	lexReady
+	lexWaitingForInput
+	lexPacketBroken
+	lexPacketTooBig
+	lexCountMismatch
+)
+
+func fill(in *Input) int {
+	if in.token == 0 {
+		// Error: no space can be freed.
+		// In real life can reallocate a larger buffer.
+		return lexPacketTooBig
+	}
+
+	// Discard everything up to the start of the current lexeme,
+	// shift buffer contents and adjust offsets.
+	copy(in.data[0:], in.data[in.token:in.limit])
+	in.cursor -= in.token
+	in.marker -= in.token
+	in.limit -= in.token
+	in.token = 0
+
+	// Read new data (as much as possible to fill the buffer).
+	n, _ := in.file.Read(in.data[in.limit:SIZE])
+	in.limit += n
+	in.data[in.limit] = 0 // append sentinel symbol
+
+	return lexReady
+}
+
+func lex(in *Input, recv *int) int {
+	var yych byte
+loop:
+	
+
+	yystate := in.state
+	for {
+		switch (yystate) {
+		case -1:
+			fallthrough
+		case 0:
+			yych = in.data[in.cursor]
+			switch (yych) {
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				in.cursor += 1
+				yystate = 3
+				continue
+			default:
+				if (in.limit <= in.cursor) {
+					in.state = 10
+					return lexWaitingForInput
+				}
+				in.cursor += 1
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			in.state = 0
+			{ return lexPacketBroken }
+		case 3:
+			in.marker = in.cursor
+			yych = in.data[in.cursor]
+			switch (yych) {
+			case ';':
+				in.cursor += 1
+				yystate = 4
+				continue
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				in.cursor += 1
+				yystate = 6
+				continue
+			default:
+				if (in.limit <= in.cursor) {
+					in.state = 11
+					return lexWaitingForInput
+				}
+				yystate = 2
+				continue
+			}
+		case 4:
+			yystate = 5
+			continue
+		case 5:
+			in.state = 0
+			{ *recv = *recv + 1; in.token = in.cursor; goto loop }
+		case 6:
+			yych = in.data[in.cursor]
+			yystate = 7
+			continue
+		case 7:
+			switch (yych) {
+			case ';':
+				in.cursor += 1
+				yystate = 4
+				continue
+			case 'a':
+				fallthrough
+			case 'b':
+				fallthrough
+			case 'c':
+				fallthrough
+			case 'd':
+				fallthrough
+			case 'e':
+				fallthrough
+			case 'f':
+				fallthrough
+			case 'g':
+				fallthrough
+			case 'h':
+				fallthrough
+			case 'i':
+				fallthrough
+			case 'j':
+				fallthrough
+			case 'k':
+				fallthrough
+			case 'l':
+				fallthrough
+			case 'm':
+				fallthrough
+			case 'n':
+				fallthrough
+			case 'o':
+				fallthrough
+			case 'p':
+				fallthrough
+			case 'q':
+				fallthrough
+			case 'r':
+				fallthrough
+			case 's':
+				fallthrough
+			case 't':
+				fallthrough
+			case 'u':
+				fallthrough
+			case 'v':
+				fallthrough
+			case 'w':
+				fallthrough
+			case 'x':
+				fallthrough
+			case 'y':
+				fallthrough
+			case 'z':
+				in.cursor += 1
+				yystate = 6
+				continue
+			default:
+				if (in.limit <= in.cursor) {
+					in.state = 12
+					return lexWaitingForInput
+				}
+				yystate = 8
+				continue
+			}
+		case 8:
+			in.cursor = in.marker
+			yystate = 2
+			continue
+		case 9:
+			in.state = 0
+			{ return lexEnd }
+		case 10:
+			if (in.limit <= in.cursor) {
+				yystate = 9
+				continue
+			}
+			yystate = 0
+			continue
+		case 11:
+			if (in.limit <= in.cursor) {
+				yystate = 2
+				continue
+			}
+			yystate = 3
+			continue
+		case 12:
+			if (in.limit <= in.cursor) {
+				yystate = 8
+				continue
+			}
+			yystate = 6
+			continue
+		}
+	}
+
+}
+
+func test(packets []string) int {
+	fname := "pipe"
+	fw, _ := os.Create(fname);
+	fr, _ := os.Open(fname);
+
+	in := &Input{
+		file:   fr,
+		data:   make([]byte, SIZE+1),
+		cursor: SIZE,
+		marker: SIZE,
+		token:  SIZE,
+		limit:  SIZE,
+		state:  -1,
+	}
+	// data is zero-initialized, no need to write sentinel
+
+	var status int
+	send := 0
+	recv := 0
+loop:
+	for {
+		status = lex(in, &recv)
+		if status == lexEnd {
+			if send != recv {
+				status = lexCountMismatch
+			}
+			break loop
+		} else if status == lexWaitingForInput {
+			if send < len(packets) {
+				fw.WriteString(packets[send])
+				send += 1
+			}
+			status = fill(in)
+			if status != lexReady {
+				break loop
+			}
+		} else if status == lexPacketBroken {
+			break loop
+		} else {
+			panic("unexpected status")
+		}
+	}
+
+	fr.Close()
+	fw.Close()
+	os.Remove(fname)
+
+	return status
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		status  int
+		packets []string
+	}{
+		{lexEnd, []string{}},
+		{lexEnd, []string{"zero;", "one;", "two;", "three;", "four;"}},
+		{lexPacketBroken, []string{"??;"}},
+		{lexPacketTooBig, []string{"looooooooooooong;"}},
+	}
+
+	for i, x := range tests {
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			status := test(x.packets)
+			if status != x.status {
+				t.Errorf("got %d, want %d", status, x.status)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/storable_state.re

@@ -0,0 +1,147 @@
+//go:generate re2go -f $INPUT -o $OUTPUT --loop-switch -i
+package main
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+// Intentionally small to trigger buffer refill.
+const SIZE int = 16
+
+type Input struct {
+	file     *os.File
+	data     []byte
+	cursor   int
+	marker   int
+	token    int
+	limit    int
+	state    int
+	yyaccept int
+}
+
+const (
+	lexEnd = iota
+	lexReady
+	lexWaitingForInput
+	lexPacketBroken
+	lexPacketTooBig
+	lexCountMismatch
+)
+
+func fill(in *Input) int {
+	if in.token == 0 {
+		// Error: no space can be freed.
+		// In real life can reallocate a larger buffer.
+		return lexPacketTooBig
+	}
+
+	// Discard everything up to the start of the current lexeme,
+	// shift buffer contents and adjust offsets.
+	copy(in.data[0:], in.data[in.token:in.limit])
+	in.cursor -= in.token
+	in.marker -= in.token
+	in.limit -= in.token
+	in.token = 0
+
+	// Read new data (as much as possible to fill the buffer).
+	n, _ := in.file.Read(in.data[in.limit:SIZE])
+	in.limit += n
+	in.data[in.limit] = 0 // append sentinel symbol
+
+	return lexReady
+}
+
+func lex(in *Input, recv *int) int {
+	var yych byte
+loop:
+	/*!re2c
+	re2c:eof = 0;
+	re2c:define:YYPEEK     = "in.data[in.cursor]";
+	re2c:define:YYSKIP     = "in.cursor += 1";
+	re2c:define:YYBACKUP   = "in.marker = in.cursor";
+	re2c:define:YYRESTORE  = "in.cursor = in.marker";
+	re2c:define:YYLESSTHAN = "in.limit <= in.cursor";
+	re2c:define:YYFILL     = "return lexWaitingForInput";
+	re2c:define:YYGETSTATE = "in.state";
+	re2c:define:YYSETSTATE = "in.state = @@{state}";
+
+	packet = [a-z]+[;];
+
+	*      { return lexPacketBroken }
+	$      { return lexEnd }
+	packet { *recv = *recv + 1; in.token = in.cursor; goto loop }
+	*/
+}
+
+func test(packets []string) int {
+	fname := "pipe"
+	fw, _ := os.Create(fname);
+	fr, _ := os.Open(fname);
+
+	in := &Input{
+		file:   fr,
+		data:   make([]byte, SIZE+1),
+		cursor: SIZE,
+		marker: SIZE,
+		token:  SIZE,
+		limit:  SIZE,
+		state:  -1,
+	}
+	// data is zero-initialized, no need to write sentinel
+
+	var status int
+	send := 0
+	recv := 0
+loop:
+	for {
+		status = lex(in, &recv)
+		if status == lexEnd {
+			if send != recv {
+				status = lexCountMismatch
+			}
+			break loop
+		} else if status == lexWaitingForInput {
+			if send < len(packets) {
+				fw.WriteString(packets[send])
+				send += 1
+			}
+			status = fill(in)
+			if status != lexReady {
+				break loop
+			}
+		} else if status == lexPacketBroken {
+			break loop
+		} else {
+			panic("unexpected status")
+		}
+	}
+
+	fr.Close()
+	fw.Close()
+	os.Remove(fname)
+
+	return status
+}
+
+func TestLex(t *testing.T) {
+	var tests = []struct {
+		status  int
+		packets []string
+	}{
+		{lexEnd, []string{}},
+		{lexEnd, []string{"zero;", "one;", "two;", "three;", "four;"}},
+		{lexPacketBroken, []string{"??;"}},
+		{lexPacketTooBig, []string{"looooooooooooong;"}},
+	}
+
+	for i, x := range tests {
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			status := test(x.packets)
+			if status != x.status {
+				t.Errorf("got %d, want %d", status, x.status)
+			}
+		})
+	}
+}

test/codegen/loop_switch/go/storable_state_error_getstate.go

@@ -0,0 +1 @@
+codegen/loop_switch/go/storable_state_error_getstate.re:3:16: error: `getstate:re2c` is incompatible with the --loop-switch option, as it requires cross-block transitions that are unsupported without the `goto` statement

test/codegen/loop_switch/go/storable_state_error_getstate.re

@@ -0,0 +1,3 @@
+//go:generate re2go -f $INPUT -o $OUTPUT --loop-switch -i
+
+/*!getstate:re2c*/

test/codegen/loop_switch/go/storable_state_two_blocks.go

@@ -0,0 +1,92 @@
+// Code generated by re2c, DO NOT EDIT.
+//go:generate re2go -f $INPUT -o $OUTPUT --loop-switch -i
+
+
+
+	yystate := YYGETSTATE
+	for {
+		switch (yystate) {
+		case -1:
+			fallthrough
+		case 0:
+			YYSETSTATE
+			if (YYLESSTHAN) {
+				YYFILL
+			}
+			yych = YYPEEK
+			YYSKIP
+			switch (yych) {
+			case 'a':
+				yystate = 3
+				continue
+			default:
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			YYSETSTATE
+			{ * }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			YYSETSTATE
+			{ a }
+		case 5:
+			yystate = 0
+			continue
+		}
+	}
+
+
+
+
+	yystate := YYGETSTATE
+	for {
+		switch (yystate) {
+		case -1:
+			fallthrough
+		case 0:
+			yych = YYPEEK
+			switch (yych) {
+			case 'b':
+				YYSKIP
+				yystate = 3
+				continue
+			default:
+				if (YYLESSTHAN) {
+					YYSETSTATE
+					YYFILL
+				}
+				YYSKIP
+				yystate = 1
+				continue
+			}
+		case 1:
+			yystate = 2
+			continue
+		case 2:
+			YYSETSTATE
+			{ * }
+		case 3:
+			yystate = 4
+			continue
+		case 4:
+			YYSETSTATE
+			{ b }
+		case 5:
+			YYSETSTATE
+			{ $ }
+		case 6:
+			if (YYLESSTHAN) {
+				yystate = 5
+				continue
+			}
+			yystate = 0
+			continue
+		}
+	}
+

test/codegen/loop_switch/go/storable_state_two_blocks.re

@@ -0,0 +1,13 @@
+//go:generate re2go -f $INPUT -o $OUTPUT --loop-switch -i
+
+/*!re2c
+    [a] { a }
+    *   { * }
+*/
+
+/*!re2c
+    re2c:eof = 0;
+    [b] { b }
+    $   { $ }
+    *   { * }
+*/

test/conditions/cond_enum_01.re

@@ -1,7 +0,0 @@
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_01.h
-/*!header:re2c:on */
-/*!types:re2c */
-/*!header:re2c:off */
-/*!re2c
-    <a> * {}
-*/

test/conditions/cond_enum_02.c

@@ -1,27 +0,0 @@
-/* Generated by re2c */
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_02.h
-enum YYCONDTYPE {
-	yyca,
-};
-
-
-
-{
-	YYCTYPE yych;
-	switch (YYGETCONDITION()) {
-	case yyca:
-		goto yyc_a;
-	}
-/* *********************************** */
-yyc_a:
-	if (YYLIMIT <= YYCURSOR) YYFILL(1);
-	yych = *YYCURSOR++;
-	{}
-}
-
-/* Generated by re2c */
-
-enum YYCONDTYPE {
-	yyca,
-};
-

test/conditions/cond_enum_02.re

@@ -1,8 +0,0 @@
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_02.h
-/*!types:re2c */
-/*!header:re2c:on */
-/*!types:re2c */
-/*!header:re2c:off */
-/*!re2c
-    <a> * {}
-*/

test/conditions/cond_enum_03.c

@@ -1,31 +0,0 @@
-/* Generated by re2c */
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_03.h
-enum YYCONDTYPE {
-	yyca,
-};
-
-
-
-{
-	YYCTYPE yych;
-	switch (YYGETCONDITION()) {
-	case yyca:
-		goto yyc_a;
-	}
-/* *********************************** */
-yyc_a:
-	if (YYLIMIT <= YYCURSOR) YYFILL(1);
-	yych = *YYCURSOR++;
-	{}
-}
-
-/* Generated by re2c */
-
-enum YYCONDTYPE {
-	yyca,
-};
-
-enum YYCONDTYPE {
-	yyca,
-};
-

test/conditions/cond_enum_03.re

@@ -1,9 +0,0 @@
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_03.h
-/*!types:re2c */
-/*!header:re2c:on */
-/*!types:re2c */
-/*!types:re2c */
-/*!header:re2c:off */
-/*!re2c
-    <a> * {}
-*/

test/conditions/cond_enum_04.c

@@ -1,27 +0,0 @@
-/* Generated by re2c */
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_04.h
-
-
-{
-	YYCTYPE yych;
-	switch (YYGETCONDITION()) {
-	case yyca:
-		goto yyc_a;
-	}
-/* *********************************** */
-yyc_a:
-	if (YYLIMIT <= YYCURSOR) YYFILL(1);
-	yych = *YYCURSOR++;
-	{}
-}
-
-/* Generated by re2c */
-
-enum YYCONDTYPE {
-	yyca,
-};
-
-enum YYCONDTYPE {
-	yyca,
-};
-

test/conditions/cond_enum_04.re

@@ -1,8 +0,0 @@
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_04.h
-/*!header:re2c:on */
-/*!types:re2c */
-/*!types:re2c */
-/*!header:re2c:off */
-/*!re2c
-    <a> * {}
-*/

test/conditions/cond_enum_05.c

@@ -1,25 +0,0 @@
-/* Generated by re2c */
-// re2c $INPUT -o $OUTPUT -ci --type-header cond_enum_05.h
-enum YYCONDTYPE {
-	yyca,
-};
-
-
-{
-	YYCTYPE yych;
-	switch (YYGETCONDITION()) {
-	case yyca:
-		goto yyc_a;
-	}
-/* *********************************** */
-yyc_a:
-	if (YYLIMIT <= YYCURSOR) YYFILL(1);
-	yych = *YYCURSOR++;
-	{}
-}
-
-/* Generated by re2c */
-
-enum YYCONDTYPE {
-	yyca,
-};