ParserYy.y

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/* $Id: ParserYy.y,v 1.3 2004/07/14 14:29:59 pfb Exp $ */

%{
#include <stdio.h>
#define YYDEBUG 1
#define YYERROR_VERBOSE

  int yylex();
  FILE *input;

%}

%union {
  double val;
  char   tstr[128];
}

%token LBRACE RBRACE
%token EQUALS
%token <tstr> ALPHA
%token <val>  NUM
/* %type  <tstr> lvalue
%type  <val>  rvalue */

%%

file               :  /* empty */
                   | blocks
                   ;

blocks             : LBRACE blocks RBRACE
                   | LBRACE statements RBRACE
                   ;

statements         : lvalue EQUALS rvalue
                   ;

lvalue             : ALPHA
                       {
                       // printf("lvalue = %s\n", $<tstr>1);
                       }
                   ;

rvalue             : ALPHA
                       {
                       // printf("rvalue = %s\n", $<tstr>1);
                       }
                   | NUM
                       {
                       // printf("rvalue = %f\n", $<val>1);
                       }
                   ;

%%

#include <ctype.h>
#include <stdio.h>

extern FILE *input;

int yylex()
  {
  int c;

  /* skip white space  */
  while ((c = getc(input)) == ' ' ||
          c == '\t' ||
          c == '\n')  
    ;
  
  if (c == '{')
    return LBRACE;
  if (c == '}')
    return RBRACE;
  if (c == '=')
    return EQUALS;

  /* process numbers   */
  if (isdigit(c))                
    {
    ungetc(c, input);
    fscanf(input, "%lf", &yylval.val);
    return NUM;
    }
  
  /* process names */
  if (isalpha(c))
    {
    ungetc(c, input);
    fscanf(input, "%s", &yylval.tstr);
    return ALPHA;
    }

  /* return end-of-file  */
  if (c == EOF)                            
    return 0;
  /* return single chars */
  return c;                                
  }

int yyerror(const char *s)
  {
  printf("%s: %s\n", __FILE__, s);
  }

/*
 * $Log: ParserYy.y,v $
 * Revision 1.3  2004/07/14 14:29:59  pfb
 * Added debug stuff.
 *
 * Revision 1.2  2004/07/14 06:30:10  pfb
 * Took out debut POs.
 *
 * Revision 1.1  2004/07/13 13:49:12  pfb
 * Initial rev.
 *
 *
 */

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