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%option noyywrap nounput noinput yylineno
%{
#include "lexer.h"
#include <stdbool.h>
#include <stdio.h>
static bool failed = false;
static char character = '\0';
static char unescape(char escaped)
{
switch (escaped)
{
case 'n': return '\n';
case 't': return '\t';
case '0': return '\0';
default: return escaped;
}
}
// complains, remembers, and hands back TOK_END so the scan stops where it went wrong
static int fail(const char* message)
{
(void)fprintf(stderr, "line %d: %s\n", yylineno, message);
failed = true;
return TOK_END;
}
%}
%%
"::" return TOK_COLONCOLON;
"emit" return TOK_EMIT;
"commit" return TOK_COMMIT;
"decltype" return TOK_DECLTYPE;
"difference" return TOK_DIFFERENCE;
[<>(),;] return yytext[0];
'\\.' character = unescape(yytext[2]); return TOK_CHAR;
'.' character = yytext[1]; return TOK_CHAR;
"//"[^\n]* /* a comment */
[ \t\r\n]+ /* blanks */
[0-9]+ return fail("numeric literals are for the weak, subtract two characters");
[A-Za-z_][A-Za-z0-9_]* return fail("that is not a notion this language recognises");
. return fail("what is this character even");
%%
bool lexer_failed(void)
{
return failed;
}
char lexer_character(void)
{
return character;
}
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