shithub: scc

ref: 1ffd5f6ee169b5d76958348b3376d82a66a75d63
dir: /lex.c/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "cc.h"
#include "symbol.h"
#include "tokens.h"


#define NR_KWD_HASH 32

static struct keyword {
	char *str;
	unsigned char tok;
	struct keyword *next;
} keywords [] = {"auto", AUTO, NULL,
		 "break", BREAK, NULL,
		 "_Bool", CHAR, NULL,
		 "case", CASE, NULL,
		 "char", CHAR, NULL,
		 "const", CONST, NULL,
		 "continue", CONTINUE, NULL,
		 "default", DEFAULT, NULL,
		 "do", DO, NULL,
		 "double", DOUBLE, NULL,
		 "else", ELSE, NULL,
		 "enum", ENUM, NULL,
		 "extern", EXTERN, NULL,
		 "float", FLOAT, NULL,
		 "for", FOR, NULL,
		 "goto", GOTO, NULL,
		 "if", IF, NULL,
		 "int", INT, NULL,
		 "long", LONG, NULL,
		 "register", REGISTER, NULL,
		 "restricted", RESTRICTED, NULL,
		 "return", RETURN, NULL,
		 "short", SHORT, NULL,
		 "signed", SIGNED, NULL,
		 "sizeof", SIZEOF, NULL,
		 "static", STATIC, NULL,
		 "struct", STRUCT, NULL,
		 "switch", SWITCH, NULL,
		 "typedef", TYPEDEF, NULL,
		 "union", UNION, NULL,
		 "unsigned", UNSIGNED, NULL,
		 "void", VOID, NULL,
		 "volatile", VOLATILE, NULL,
		 "while", WHILE, NULL,
		 NULL, 0, NULL
};

static struct keyword *khash[NR_KWD_HASH];
static FILE *yyin;

union yyval yyval;
unsigned char yytoken;
unsigned char yyhash;
char yytext[TOKSIZ_MAX + 1];
unsigned linenum;
unsigned columnum;
const char *filename;


static unsigned char hashfun(register const char *s)
{
	register unsigned char h, ch;

	for (h = 0; ch = *s++; h += ch)
		/* nothing */;
	return h;
}

void init_lex(void)
{
	register struct keyword *bp;
	static unsigned char h;

	for (bp = keywords; bp->str; bp++) {
		register struct keyword *aux, *ant;
		h = hashfun(bp->str) & (NR_KWD_HASH - 1);
		if (!(aux = khash[h]) || strcmp(bp->str, aux->str) < 0) {
			khash[h] = bp;
			bp->next = aux;
			continue;
		}
		for (ant = aux; aux; ant = aux, aux = aux->next) {
			if (strcmp(bp->str, aux->str) < 0)
				break;
		}
		ant->next = bp;
		bp->next = aux;
	}
}

static char number(void)
{
	register char *bp;
	register char ch;

	for (bp = yytext; bp < yytext + TOKSIZ_MAX; *bp++ = ch) {
		if (!isdigit(ch = getc(yyin)))
			break;
	}
	if (bp == yytext + TOKSIZ_MAX)
		error("identifier too long %s", yytext);
	ungetc(ch, yyin);
	*bp = '\0';
	return CONSTANT;
}

static unsigned char keyword(const char *s, unsigned char key)
{
	register struct keyword *kwp;

	key &= NR_KWD_HASH - 1;
	for (kwp = khash[key]; kwp; kwp = kwp->next) {
		if (!strcmp(kwp->str, yytext))
			return kwp->tok;
	}
	return 0;
}

static unsigned char iden(void)
{
	register char ch;
	register char *bp = yytext;

	for (yyhash = 0; bp < yytext + TOKSIZ_MAX; *bp++ = ch) {
		if (!isalnum(ch = getc(yyin)) && ch != '_')
			break;
		yyhash += ch;
	}
	if (bp == yytext + TOKSIZ_MAX)
		error("identifier too long %s", yytext);
	*bp = '\0';
	ungetc(ch, yyin);

	if (ch = keyword(yytext, yyhash))
		return ch;
	return IDEN;;
}

static unsigned char skip(void)
{
	register int c;
	extern char parser_out_home;

	while (isspace(c = getc(yyin))) {
		if (c == '\n')
			++linenum, columnum = 1;
		else
			++columnum;
	}
	if (c == EOF) {
		if (parser_out_home)
			error("Find EOF while parsing");
		return 1;
	}
	ungetc(c, yyin);
	return 0;
}

static unsigned char
follow(unsigned char op, unsigned char eq, unsigned char rep)
{
	register char c;

	if ((c = getc(yyin)) == '=')
		return eq;
	else if (c == op && rep)
		return rep;
	ungetc(c, yyin);
	return op;
}

static unsigned char rel_shift(unsigned char op)
{
	static char tokens[2][3] = {
		{GE, LSHIFT, LSHIFT_EQ},
		{LE, RSHIFT, RSHIFT_EQ}};
	register char c;
	register char *tp = tokens[op == '>'];

	if ((c = getc(yyin)) == '=') {
		return tp[0];
	} else if (c == op) {
		if ((c = getc(yyin)) == '=')
			return tp[2];
		op = tp[1];
	}
	ungetc(c, yyin);
	return c;
}

static unsigned char minus(void)
{
	register int c;

	switch (c = getc(yyin)) {
	case '-': return DEC;
	case '>': return PTR;
	case '=': return SUB_EQ;
	default:
		ungetc(c, yyin);
		return '-';
	}
}

unsigned char next(void)
{
	register unsigned char c;

	if (!skip())
		c = EOFTOK;
	if (isalpha(c = getc(yyin)) || c == '_') {
		ungetc(c, yyin);
		c = iden();
	} else if (isdigit(c)) {
		ungetc(c, yyin);
		c = number();
	} else {
		switch (c) {
		case '=': c = follow('=', EQ, 0); break;
		case '^': c = follow('^', XOR_EQ, 0); break;
		case '*': c = follow('*', MUL_EQ, 0); break;
		case '!': c = follow('!', NE, 0); break;
		case '+': c = follow('+', ADD_EQ, INC); break;
		case '&': c = follow('&', AND_EQ, AND); break;
		case '|': c = follow('|', OR_EQ, OR); break;
		case '<': c = rel_shift('<'); break;
		case '>': c = rel_shift('>'); break;
		case '-': c = minus(); break;
		}
	}
	return yytoken = c;
}

char accept(unsigned char tok)
{
	if (yytoken == tok) {
		next();
		return 1;
	}
	return 0;
}

void expect(unsigned char tok)
{
	if (yytoken != tok)
		error("unexpected %s", yytext);
	next();
}

void open_file(const char *file)
{
	if (yyin != NULL)
		fclose(yyin);
	if (file == NULL) {
		yyin = stdin;
		filename = "(stdin)";
		return;
	}
	if ((yyin = fopen(file, "r")) == NULL)
		die("file '%s' not found", file);
	filename = file;
	columnum = linenum = 1;
}