/* scanner for a toy Pascal-like language */

%option noyywrap

DIGIT    [0-9]
ID       [a-z][a-z0-9]*

%%
{DIGIT}+    printf( "An integer: %s\n", yytext );

{DIGIT}+"."{DIGIT}*  printf( "A float: %s\n", 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( int argc, char **argv ) 
{
  ++argv, --argc;  /* skip over program name */
  if ( argc > 0 )
    yyin = fopen( argv[0], "r" );
  else
    yyin = stdin;

  yylex(); 
}