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/* Project : tcLex examples
* File : pascal.l
* Language : C, with Flex
* Version : 0.1
* Dates : 10/11/1998
* Source : flex man page
*
* "scanner for a toy Pascal-like langauge"
*
* To pre-process, compile and run this program:
* flex -i -opascal.lex.yy.c pascal.l generates scanner
* gcc -o pascal pascal.lex.yy.c -lfl compiles scanner
* ./pascal textfile runs scanner
*/
%{
/* need this for the call to atof() below */
#include <math.h>
%}
DIGIT [0-9]
ID [a-z][a-z0-9]*
%%
{DIGIT}+ {
printf( "An integer: %s (%d)\n", yytext,
atoi( yytext ) );
}
{DIGIT}+"."{DIGIT}* {
printf( "A float: %s (%g)\n", yytext,
atof( yytext ) );
}
if|then|begin|end|procedure|function {
printf( "A keyword: %s\n", yytext );
}
{ID} printf( "An identifier: %s\n", yytext );
"+"|"-"|"*"|"/" printf( "An operator: %s\n", yytext );
"{"[^}\n]*"}" /* eat up one-line comments */
[ \t\n]+ /* eat up whitespace */
. printf( "Unrecognized character: %s\n", yytext );
%%
main( argc, argv )
int argc;
char **argv;
{
++argv, --argc; /* skip over program name */
if ( argc > 0 )
yyin = fopen( argv[0], "r" );
else
yyin = stdin;
yylex();
}
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