/* icalc.l - a lex specification file for generating a lexical analyzer
 *  for a simple integer calculator 
 *
 * The lexical analyzer generated by this lex specification will recognize 
 * simple operators, parenthesis, and integer constants as tokens and return 
 * them to the syntax analyzer generated by the corresponding icalc.y file.
 */

%{

/* place C preprocessor and global/local variable declarations here */

#include <stdio.h>
#include "icalc.h"

/* yylval is a global variable that lex uses to pass values to yacc */
extern int yylval;

%}

%%

"+"	  { return PLUS; }
"-"	  { return MINUS; }
"*"	  { return MULT; }
"/"	  { return DIV; }
"("	  { return LPAREN; }
")"	  { return RPAREN; }

[0-9]+    { /* match a numeric string and convert to a binary int */
            yylval = atoi(yytext); 
 	    return NUM; 
           }

[ \t\f\v]+	  { /* ignore all white space */ }

[^0-9+\-*/()]  { /* any other lexeme NOT one of the above is an error */
	            return yytext[0];
	        }