Re: %destructor support for lalr1.cc

[Alexandre Duret-Lutz]

After some testing with error recovery in my grammar, I've found
that one of my error_start_ assignments was misplaced.  This new
patch corrects this (basically error_start_ assignments appear
in lalr1.cc where yylerrsp increments occur in yacc.c).

2003-12-30  Alexandre Duret-Lutz  <address@hidden>

        %destructor support and merge of error locations in lalr1.cc.

        * data/lalr1.cc (b4_cxx_destruct_def): New macro.
        (Parser::stos_): Define unconditionally.
        (Parser::destruct_): New method.  Generate its body with
        b4_yydestruct_generate.
        (Parser::error_start_): New attribute.
        (Parser::parse) <yyerrlab, yyerrlab1>: Call destruct_ on erroneous
        token which are discarded.
        (Parser::parse) <yyerrlab, yyerrorlab, yyerrlab1>: Update
        error_start_ when erroneous token are discarded.
        (Parser::parse) <yyerrlab1>: Compute the location of the error
        token so that it covers all the discarded tokens.
        * tests/actions.at (_AT_CHECK_PRINTER_AND_DESTRUCTOR): Adjust so
        it can be called with `%skeleton "lalr1.cc"', and do that.

Index: data/lalr1.cc
===================================================================
RCS file: /cvsroot/bison/bison/data/lalr1.cc,v
retrieving revision 1.42
diff -u -r1.42 lalr1.cc
--- data/lalr1.cc       27 Aug 2003 07:00:10 -0000      1.42
+++ data/lalr1.cc       30 Dec 2003 19:14:23 -0000
@@ -114,6 +114,14 @@
 m4_define([b4_cc_var_decl],
          [    $1;])
 
+# b4_cxx_destruct_def(IGNORED-ARGUMENTS)
+# --------------------------------------
+# Declare the destruct_ method.
+m4_define([b4_cxx_destruct_def],
+[void
+yy::b4_parser_class_name::destruct_ (int yytype, SemanticType *yyvaluep, 
LocationType *yylocationp)[]dnl
+])
+
 # We do want M4 expansion after # for CPP macros.
 m4_changecom()
 m4_divert(0)dnl
@@ -250,6 +258,7 @@
     static const ]b4_int_type_for([b4_table])[ table_[];
     static const ]b4_int_type(b4_table_ninf, b4_table_ninf)[ table_ninf_;
     static const ]b4_int_type_for([b4_check])[ check_[];
+    static const ]b4_int_type_for([b4_stos])[ stos_[];
     static const ]b4_int_type_for([b4_r1])[ r1_[];
     static const ]b4_int_type_for([b4_r2])[ r2_[];
 
@@ -262,7 +271,6 @@
     static const RhsNumberType rhs_[];
     static const ]b4_int_type_for([b4_prhs])[ prhs_[];
     static const ]b4_int_type_for([b4_rline])[ rline_[];
-    static const ]b4_int_type_for([b4_stos])[ stos_[];
     static const ]b4_int_type_for([b4_toknum])[ token_number_[];
     virtual void reduce_print_ (int yyrule);
     virtual void stack_print_ ();
@@ -270,6 +278,8 @@
 
     /* Even more tables.  */
     static inline TokenNumberType translate_ (int token);
+    static inline void destruct_ (int yytype, SemanticType *yyvaluep,
+                                 LocationType *yylocationp);
 
     /* Constants.  */
     static const int eof_;
@@ -307,6 +317,8 @@
     /* Semantic value and location of lookahead token.  */
     SemanticType value;
     LocationType location;
+    /* Beginning of the last erroneous token popped off.  */
+    Position error_start_;
 
     /* @@$ and $$.  */
     SemanticType yyval;
@@ -349,6 +361,7 @@
 #define YYABORT                goto yyabortlab
 #define YYERROR                goto yyerrorlab
 
+]b4_yydestruct_generate([b4_cxx_destruct_def])[
 
 int
 yy::]b4_parser_class_name[::parse ()
@@ -530,6 +543,7 @@
   /* If not already recovering from an error, report this error.  */
   report_syntax_error_ ();
 
+  error_start_ = location.begin;
   if (errstatus_ == 3)
     {
       /* If just tried and failed to reuse lookahead token after an
@@ -543,23 +557,26 @@
          if (looka_ == eof_)
             for (;;)
               {
+                 error_start_ = location_stack_[0].begin;
                  state_stack_.pop ();
                  semantic_stack_.pop ();
                  location_stack_.pop ();
                 if (state_stack_.height () == 1)
                   YYABORT;
 //              YYDSYMPRINTF ("Error: popping", yystos[*yyssp], yyvsp, yylsp);
-// FIXME: yydestruct (yystos[*yyssp], yyvsp]b4_location_if([, yylsp])[);
+                 destruct_ (stos_[state_stack_[0]],
+                            &semantic_stack_[0],
+                            &location_stack_[0]);
               }
         }
       else
         {
 #if YYDEBUG
-           YYCDEBUG << "Discarding token " << looka_
-                   << " (" << name_[ilooka_] << ")." << std::endl;
-//       yydestruct (yytoken, &yylval]b4_location_if([, &yylloc])[);
+          YYCDEBUG << "Discarding token " << looka_
+                  << " (" << name_[ilooka_] << ")." << std::endl;
 #endif
-           looka_ = empty_;
+          destruct_ (ilooka_, &value, &location);
+          looka_ = empty_;
         }
     }
 
@@ -582,6 +599,7 @@
 
   state_stack_.pop (len_);
   semantic_stack_.pop (len_);
+  error_start_ = location_stack_[len_ - 1].begin;
   location_stack_.pop (len_);
   state_ = state_stack_[0];
   goto yyerrlab1;
@@ -631,6 +649,8 @@
            }
        }
 #endif
+      destruct_ (stos_[state_], &semantic_stack_[0], &location_stack_[0]);
+      error_start_ = location_stack_[0].begin;
 
       state_stack_.pop ();
       semantic_stack_.pop ();
@@ -644,8 +664,13 @@
 
   YYCDEBUG << "Shifting error token, ";
 
-  semantic_stack_.push (value);
-  location_stack_.push (location);
+  {
+    Location errloc;
+    errloc.begin = error_start_;
+    errloc.end = location.end;
+    semantic_stack_.push (value);
+    location_stack_.push (errloc);
+  }
 
   state_ = n_;
   goto yynewstate;
Index: tests/actions.at
===================================================================
RCS file: /cvsroot/bison/bison/tests/actions.at,v
retrieving revision 1.27
diff -u -r1.27 actions.at
--- tests/actions.at    28 Dec 2002 08:38:14 -0000      1.27
+++ tests/actions.at    30 Dec 2003 19:14:23 -0000
@@ -1,5 +1,5 @@
 # Executing Actions.                               -*- Autotest -*-
-# Copyright (C) 2001, 2002 Free Software Foundation, Inc.
+# Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
 
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -314,15 +314,16 @@
 
 # Make sure complex $n work.
 
+AT_BISON_OPTION_PUSHDEFS([$5])
 AT_DATA_GRAMMAR([[input.y]],
 [[$5
 %{
 #include <stdio.h>
 #include <stdlib.h>
-#define RANGE(Location) (Location).first_line, (Location).last_line
-static int yylex (void);
-static void yyerror (const char *msg);
-%}
+]AT_LALR1_CC_IF(
+  [#define RANGE(Location) (Location).begin.line, (Location).end.line],
+  [#define RANGE(Location) (Location).first_line, (Location).last_line])
+[%}
 %error-verbose
 %debug
 %verbose
@@ -331,6 +332,13 @@
 {
   int ival;
 }
+
+%{
+]AT_LALR1_CC_IF([typedef yy::Location YYLTYPE;])
+[static int yylex (]AT_LEX_FORMALS[);
+static void yyerror (const char *msg);
+%}
+
 %type <ival> 'x' ';' thing line input
 
 %printer { fprintf (yyoutput, "address@hidden", $$, RANGE (@$)); }
@@ -406,7 +414,7 @@
 ;
 %%
 static int
-yylex (void)
+yylex (]AT_LEX_FORMALS[)
 {
   static const unsigned int input[] =
     {
@@ -424,13 +432,23 @@
 
   if (counter < (sizeof(input) / sizeof (input[0])))
     {
-       yylval.ival = counter;
+]AT_LALR1_CC_IF(
+[       yylval->ival = counter;
+       /* As in BASIC, line numbers go from 10 to 10.  */
+       yylloc->begin.line = yylloc->begin.column = 10 * counter;
+       yylloc->end.line = yylloc->end.column = yylloc->begin.line + 9;
+       printf ("sending: '%c' (address@hidden)\n",
+               input[[counter]], yylval->ival, RANGE (*yylloc));
+       return (int) input[[counter++]];
+],
+[       yylval.ival = counter;
        /* As in BASIC, line numbers go from 10 to 10.  */
        yylloc.first_line = yylloc.first_column = 10 * counter;
        yylloc.last_line = yylloc.last_column = yylloc.first_line + 9;
        printf ("sending: '%c' (address@hidden)\n",
-               input[counter], yylval.ival, RANGE (yylloc));
-       return (int) input[counter++];
+               input[[counter]], yylval.ival, RANGE (yylloc));
+       return (int) input[[counter++]];
+])[
     }
   else
     {
@@ -439,11 +457,34 @@
     }
 }
 
-static void
+]AT_LALR1_CC_IF(
+[/* Currently, print_ is required in C++. */
+void
+yy::Parser::print_ ()
+{
+  std::cerr << location;
+}
+
+/* A C++ error reporting function. */
+void
+yy::Parser::error_ ()
+{
+  printf ("%d-%d: %s\n", RANGE (location), message.c_str());
+}
+
+static bool yydebug;
+int
+yyparse ()
+{
+  yy::Parser parser (yydebug, yy::Location::Location ());
+  return parser.parse ();
+}
+],
+[static void
 yyerror (const char *msg)
 {
   printf ("%d-%d: %s\n", RANGE (yylloc), msg);
-}
+}])[
 
 int
 main (void)
@@ -460,7 +501,8 @@
 ]])
 
 AT_CHECK([bison -o input.c input.y])
-AT_COMPILE([input])
+AT_LALR1_CC_IF([AT_COMPILE_CXX([input])],
+               [AT_COMPILE([input])])
 AT_PARSER_CHECK([./input], 1,
 [[sending: 'x' (address@hidden)
 thing (address@hidden): 'x' (address@hidden)
@@ -512,6 +554,7 @@
 
 
 AT_CHECK_PRINTER_AND_DESTRUCTOR()
+AT_CHECK_PRINTER_AND_DESTRUCTOR([%locations %defines %skeleton "lalr1.cc"])
 
 # FIXME.  This test case fails.
 #AT_CHECK_PRINTER_AND_DESTRUCTOR([%glr-parser])

-- 
Alexandre Duret-Lutz