compilers/cw/C.flex

D			[0-9]
L			[a-zA-Z_]
H			[a-fA-F0-9]
E			[Ee][+-]?{D}+
FS			(f|F|l|L)
IS			(u|U|l|L)*

%{
#include <stdio.h>
#include "C.tab.h"
#include <string.h>
#include <stdlib.h>
#include "token.h"
TOKEN* make_string(char*);
extern TOKEN* lookup_token(char*);
TOKEN* make_int(char*);
TOKEN* lasttok;

void count(void);
void comment(void);
%}

%%
"/*"			{ comment(); }

"auto"			{ count(); return(AUTO); }
"break"			{ count(); return(BREAK); }
"continue"		{ count(); return(CONTINUE); }
"else"			{ count(); return(ELSE); }
"extern"		{ count(); return(EXTERN); }
"if"			{ count(); return(IF); }
"int"			{ count(); return(INT); }
"function"		{ count(); return(FUNCTION); }
"return"		{ count(); return(RETURN); }
"void"			{ count(); return(VOID); }
"while"			{ count(); return(WHILE); }

{L}({L}|{D})*		{ count(); lasttok = lookup_token(yytext);
                          return(IDENTIFIER); }

{D}+{IS}?		{ count(); lasttok = make_int(yytext);return(CONSTANT); }
L?'(\\.|[^\\'])+'	{ count(); lasttok = make_int(yytext);return(CONSTANT); }

L?\"(\\.|[^\\"])*\"	{ count(); lasttok = make_string(yytext);
                          return(STRING_LITERAL); }

"<="			{ count(); return(LE_OP); }
">="			{ count(); return(GE_OP); }
"=="			{ count(); return(EQ_OP); }
"!="			{ count(); return(NE_OP); }
";"			{ count(); return(';'); }
"{"     		{ count(); return('{'); }
"}"     		{ count(); return('}'); }
","			{ count(); return(','); }
":"			{ count(); return(':'); }
"="			{ count(); return('='); }
"("			{ count(); return('('); }
")"			{ count(); return(')'); }
"!"			{ count(); return('!'); }
"-"			{ count(); return('-'); }
"+"			{ count(); return('+'); }
"*"			{ count(); return('*'); }
"/"			{ count(); return('/'); }
"%"			{ count(); return('%'); }
"<"			{ count(); return('<'); }
">"			{ count(); return('>'); }

[ \t\v\n\f]		{ count(); }
.			{ /* ignore bad characters */ }

%%

int yywrap(void)
{
	return(1);
}


void comment(void)
{
	char c, c1;

loop:
	while ((c = input()) != '*' && c != 0)
		putchar(c);

	if ((c1 = input()) != '/' && c != 0)
	{
		unput(c1);
		goto loop;
	}

	if (c != 0)
		putchar(c1);
}


int column = 0;

void count()
{
	int i;

	for (i = 0; yytext[i] != '\0'; i++)
		if (yytext[i] == '\n')
			column = 0;
		else if (yytext[i] == '\t')
			column += 8 - (column % 8);
		else
			column++;

	ECHO;
}


TOKEN *new_token(int type)
{
    TOKEN *ans = (TOKEN*)malloc(sizeof(TOKEN));
    ans->type = type;
    return ans;
}

TOKEN *make_string(char *s)
{
    TOKEN *ans = new_token(STRING_LITERAL);
    int len = strlen(s);
    ans->lexeme = (char*)calloc(1, len-1);
    strncpy(ans->lexeme, s+1, len-2);
    return ans;
}

TOKEN *make_int(char *s)
{
    int n = *s!='\'' ? atoi(s) : *(s+1);
    TOKEN *ans = new_token(CONSTANT);
    ans->value = n;
    return ans;
}