aoc-2022/day_4/lexer.l

%{
#include <stdio.h>
#include <stdlib.h>
#include "parser.h"
%}

%option warn nodefault

/* makes the scanner terminate after reaching <<EOF>> instead of assuming a new input was provided */
%option noyywrap
/* disable some unused functionality, add scanner tracking */
%option nounput noinput batch debug

/* gimme a reentrant parser (overkill but more pure) */
%option reentrant

%option bison-bridge


NL      [\n]
NUM     [0-9]
MINUS   [-]
COMMA   [,]


%%

{NL}        {
                return NEWLINE;
            }
{NUM}+      {
                unsigned long num = strtoul(yytext, NULL, 10);
                yylval->num = num;
                return NUMBER;
            }
{MINUS}     {
                return MINUS;
            }
{COMMA}     {
                return SEP;
            }
<<EOF>>     {
                return END_OF_FILE;
            }
.           {
                printf("[error] Encountered unexpected token %s\n", yytext);
                return 0;
            }

%%