Re: Language with comments

[Kelly Leahy]

Stefano,

You should recognize the entire comment in one lexical pass, and should NOT 
return the '#' token.  In other words, treat the '#' begun comment as 
whitespace - do the same for it that you do for whitespace.  Write a regular 
expression for single-line comments that matches everything to the end of the 
line (\n char).

Kelly

----- Original Message ----
From: Stefano Simonucci <address@hidden>
To: address@hidden
Sent: Tuesday, May 8, 2007 11:30:08 AM
Subject: Language with comments


Hi! 
I try to make a syntactic recognizer. In the language can be included
also comments of the type " # <comment> ".
I have made two files: prova.lex and prova.y for flex and bison.
A comment consists of a list (also empty) of identifier.
But I get always syntax errors.
We enclose the files prova.lex, prova.y, a file for the compilation
(compila) and an input file (prova.E) 
Thank you.
  Stefano


-- 
Stefano Simonucci

GNU/Linux User: #81790  http://counter.li.org
%{

#include <string.h>

%}

delim [ \t\n]

ws {delim}+

letter  [A-Za-z]

digit [0-9]

id {letter}({letter}|{digit})*

num {digit}+|{digit}+\.{digit}*|{digit}+\.{digit}*{digit}*e\-{digit}+

%%

{ws} { printf("\n"); return '\n'; }

{id}  { strcpy(yylval.lexeme, yytext);
        printf("%s ",yytext);

        return ID;

      }

{num} { strcpy(yylval.lexeme, yytext);

        return NUM;

      }

"+"   return '+';

"-"   return '-';

"*"   return '*';

"/"   return '/';

"("   return '(';

")"   return ')';

","   return ',';

"="   return '=';

"#"   { printf("#"); return '#'; }
%{

#include <stdio.h>

%}

%union

{ char lexeme[100+1]; }

%token <lexeme> ID

%token <lexeme> NUM

%left '+' '-'

%left '*' '/'

%right UNIMINUS UNIPLUS '#'

%start init

%type <lexeme> term


%%
init : /* empty */

     | init line 
     
     ;

line : '\n' 

     | '#' comment '\n' 

     ;

comment : /* empty line */

        | comment term 

term  :  ID {sprintf($$,"%s",$1); }   

      |  NUM   {sprintf($$,"%s",$1); }   

      ;

%%

#include "lex.yy.c"

int main()

{

  return yyparse();

}
reticolo=set(vecX,vecY);
typefunction fespace(reticolo Q)
{
   double A(Q.Nx,Q.Ny); symbol R=Q;
}
reticolo Q;
VQ=fespace(Q);
_______________________________________________
address@hidden http://lists.gnu.org/mailman/listinfo/help-bison