lalr1.cc: check (and fix) %initial-action exception safety

[bison.git] / data / lalr1.cc

diff --git a/data/lalr1.cc b/data/lalr1.cc
index 5e83ee32998b0364d8ae52d0f5cab74cb8377131..2ec1d0d702f6277d8885809279472c520bd037f5 100644 (file)
--- a/data/lalr1.cc
+++ b/data/lalr1.cc
@@ -298,25 +298,8 @@ m4_if(b4_prefix, [yy], [],
 # endif
 #endif
 
-/* YYLLOC_DEFAULT -- Set CURRENT to span from RHS[1] to RHS[N].
-   If N is 0, then set CURRENT to the empty location which ends
-   the previous symbol: RHS[0] (always defined).  */
-
 #define YYRHSLOC(Rhs, K) ((Rhs)[K])
-#ifndef YYLLOC_DEFAULT
-# define YYLLOC_DEFAULT(Current, Rhs, N)                               \
- do                                                                    \
-   if (N)                                                              \
-     {                                                                 \
-       (Current).begin = YYRHSLOC (Rhs, 1).begin;                      \
-       (Current).end   = YYRHSLOC (Rhs, N).end;                        \
-     }                                                                 \
-   else                                                                \
-     {                                                                 \
-       (Current).begin = (Current).end = YYRHSLOC (Rhs, 0).end;        \
-     }                                                                 \
- while (false)
-#endif
+]b4_yylloc_default_define[
 
 /* Suppress unused-variable warnings by "using" E.  */
 #define YYUSE(e) ((void) (e))
@@ -352,9 +335,9 @@ do {                                        \
 #else /* !]b4_api_PREFIX[DEBUG */
 
 # define YYCDEBUG if (false) std::cerr
-# define YY_SYMBOL_PRINT(Title, Type, Value, Location)
-# define YY_REDUCE_PRINT(Rule)
-# define YY_STACK_PRINT()
+# define YY_SYMBOL_PRINT(Title, Type, Value, Location) YYUSE(Type)
+# define YY_REDUCE_PRINT(Rule)        static_cast<void>(0)
+# define YY_STACK_PRINT()             static_cast<void>(0)
 
 #endif /* !]b4_api_PREFIX[DEBUG */
 
@@ -550,15 +533,17 @@ do {                                      \
 
     int yyresult;
 
+    // FIXME: This shoud be completely indented.  It is not yet to
+    // avoid gratuitous conflicts when merging into the master branch.
+    try
+      {
     YYCDEBUG << "Starting parse" << std::endl;
 
 ]m4_ifdef([b4_initial_action], [
-m4_pushdef([b4_at_dollar],     [yylloc])dnl
-m4_pushdef([b4_dollar_dollar], [yylval])dnl
-    /* User initialization code.  */
-    b4_user_initial_action
-m4_popdef([b4_dollar_dollar])dnl
-m4_popdef([b4_at_dollar])])dnl
+b4_dollar_pushdef([yylval], [], [yylloc])dnl
+/* User initialization code.  */
+b4_user_initial_action
+b4_dollar_popdef])[]dnl
 
   [  /* Initialize the stacks.  The initial state will be pushed in
        yynewstate, since the latter expects the semantical and the
@@ -592,14 +577,13 @@ m4_popdef([b4_at_dollar])])dnl
     /* Read a lookahead token.  */
     if (yychar == yyempty_)
       {
-       YYCDEBUG << "Reading a token: ";
-       yychar = ]b4_c_function_call([yylex], [int],
-                                    [b4_api_PREFIX[STYPE*], [&yylval]][]dnl
+        YYCDEBUG << "Reading a token: ";
+        yychar = ]b4_c_function_call([yylex], [int],
+                                     [b4_api_PREFIX[STYPE*], [&yylval]][]dnl
 b4_locations_if([, [[location*], [&yylloc]]])dnl
 m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
       }
 
-
     /* Convert token to internal form.  */
     if (yychar <= yyeof_)
       {
@@ -670,17 +654,21 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
     else
       yyval = yysemantic_stack_[0];
 
+    // Compute the default @@$.
     {
       slice<location_type, location_stack_type> slice (yylocation_stack_, yylen);
       YYLLOC_DEFAULT (yyloc, slice, yylen);
     }
+
+    // Perform the reduction.
     YY_REDUCE_PRINT (yyn);
     switch (yyn)
       {
-       ]b4_user_actions[
-       default:
-          break;
+        ]b4_user_actions[
+      default:
+        break;
       }
+
     /* User semantic actions sometimes alter yychar, and that requires
        that yytoken be updated with the new translation.  We take the
        approach of translating immediately before every use of yytoken.
@@ -731,20 +719,19 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
     yyerror_range[1] = yylloc;
     if (yyerrstatus_ == 3)
       {
-       /* If just tried and failed to reuse lookahead token after an
-        error, discard it.  */
-
-       if (yychar <= yyeof_)
-         {
-         /* Return failure if at end of input.  */
-         if (yychar == yyeof_)
-           YYABORT;
-         }
-       else
-         {
-           yydestruct_ ("Error: discarding", yytoken, &yylval, &yylloc);
-           yychar = yyempty_;
-         }
+        /* If just tried and failed to reuse lookahead token after an
+           error, discard it.  */
+        if (yychar <= yyeof_)
+          {
+            /* Return failure if at end of input.  */
+            if (yychar == yyeof_)
+              YYABORT;
+          }
+        else
+          {
+            yydestruct_ ("Error: discarding", yytoken, &yylval, &yylloc);
+            yychar = yyempty_;
+          }
       }
 
     /* Else will try to reuse lookahead token after shifting the error
@@ -793,7 +780,7 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
 
        /* Pop the current state because it cannot handle the error token.  */
        if (yystate_stack_.height () == 1)
-       YYABORT;
+         YYABORT;
 
        yyerror_range[1] = yylocation_stack_[0];
        yydestruct_ ("Error: popping",
@@ -841,16 +828,40 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
     /* Do not reclaim the symbols of the rule which action triggered
        this YYABORT or YYACCEPT.  */
     yypop_ (yylen);
-    while (yystate_stack_.height () != 1)
+    while (1 < yystate_stack_.height ())
       {
-       yydestruct_ ("Cleanup: popping",
-                  yystos_[yystate_stack_[0]],
-                  &yysemantic_stack_[0],
-                  &yylocation_stack_[0]);
-       yypop_ ();
+        yydestruct_ ("Cleanup: popping",
+                     yystos_[yystate_stack_[0]],
+                     &yysemantic_stack_[0],
+                     &yylocation_stack_[0]);
+        yypop_ ();
       }
 
     return yyresult;
+    }
+    catch (...)
+      {
+        YYCDEBUG << "Exception caught" << std::endl;
+        if (yychar != yyempty_)
+          {
+            /* Make sure we have latest lookahead translation.  See
+               comments at user semantic actions for why this is
+               necessary.  */
+            yytoken = yytranslate_ (yychar);
+            yydestruct_ ("Cleanup: discarding lookahead", yytoken, &yylval,
+                         &yylloc);
+          }
+
+        while (1 < yystate_stack_.height ())
+          {
+            yydestruct_ ("Cleanup: popping",
+                         yystos_[yystate_stack_[0]],
+                         &yysemantic_stack_[0],
+                         &yylocation_stack_[0]);
+            yypop_ ();
+          }
+        throw;
+      }
   }
 
   // Generate an error message.
@@ -1123,5 +1134,5 @@ b4_error_verbose_if([int yystate, int yytoken],
   const ]b4_parser_class_name[::token_number_type ]b4_parser_class_name[::yyundef_token_ = ]b4_undef_token_number[;
 
 ]b4_namespace_close[
-]b4_epilogue
+]b4_epilogue[]dnl
 m4_divert_pop(0)