/* file: token_recognizer.l */
%{
#include <stdio.h>
%}
 
DIGIT   [0-9]
ID      [A-Za-z_][A-Za-z0-9_]*
WS      [ \t]+
 
%%
"if"            { printf("<KEYWORD, %s>\n", yytext); }
"else"          { printf("<KEYWORD, %s>\n", yytext); }
{ID}            { printf("<IDENT, %s>\n", yytext); }
{DIGIT}+        { printf("<NUMBER, %s>\n", yytext); }
"+"|"-"|"*"|"/"  { printf("<OP, %s>\n", yytext); }
";"             { printf("<SEMICOLON>\n"); }
{WS}            { /* ignore whitespace */ }
\n              { /* treat newline separately if needed */ }
.               { printf("<UNKNOWN, %s>\n", yytext); }
%%
 
int main(void){
  yylex();
  return 0;
}
 

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