/*	$NetBSD: str.c,v 1.19 2011/09/08 12:00:26 christos Exp $	*/

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)str.c	8.2 (Berkeley) 4/28/95";
#endif
__RCSID("$NetBSD: str.c,v 1.19 2011/09/08 12:00:26 christos Exp $");
#endif /* not lint */

#include <sys/types.h>

#include <err.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "extern.h"

static int	backslash(STR *);
static int	bracket(STR *);
static int	c_class(const void *, const void *);
static void	genclass(STR *);
static void	genequiv(STR *);
static int	genrange(STR *);
static void	genseq(STR *);

int
next(STR *s)
{
	int ch;

	switch (s->state) {
	case EOS:
		return 0;
	case INFINITE:
		return 1;
	case NORMAL:
		switch (ch = *s->str) {
		case '\0':
			s->state = EOS;
			return 0;
		case '\\':
			s->lastch = backslash(s);
			break;
		case '[':
			if (bracket(s))
				return next(s);
			/* FALLTHROUGH */
		default:
			++s->str;
			s->lastch = ch;
			break;
		}

		/* We can start a range at any time. */
		if (s->str[0] == '-' && genrange(s))
			return next(s);
		return 1;
	case RANGE:
		if (s->cnt-- == 0) {
			s->state = NORMAL;
			return next(s);
		}
		++s->lastch;
		return 1;
	case SEQUENCE:
		if (s->cnt-- == 0) {
			s->state = NORMAL;
			return next(s);
		}
		return 1;
	case SET:
		if ((s->lastch = s->set[s->cnt++]) == OOBCH) {
			s->state = NORMAL;
			return next(s);
		}
		return 1;
	}
	/* NOTREACHED */
	return 0;
}

static int
bracket(STR *s)
{
	char *p;

	switch (s->str[1]) {
	case ':':				/* "[:class:]" */
		if ((p = strstr(s->str + 2, ":]")) == NULL)
			return 0;
		*p = '\0';
		s->str += 2;
		genclass(s);
		s->str = p + 2;
		return 1;
	case '=':				/* "[=equiv=]" */
		if ((p = strstr(s->str + 2, "=]")) == NULL)
			return 0;
		s->str += 2;
		genequiv(s);
		return 1;
	default:				/* "[\###*n]" or "[#*n]" */
		if ((p = strpbrk(s->str + 2, "*]")) == NULL)
			return 0;
		if (p[0] != '*' || strchr(p, ']') == NULL)
			return 0;
		s->str += 1;
		genseq(s);
		return 1;
	}
	/* NOTREACHED */
}

typedef struct {
	const char *name;
	int (*func)(int);
} CLASS;

static const CLASS classes[] = {
	{ "alnum",  isalnum  },
	{ "alpha",  isalpha  },
	{ "blank",  isblank  },
	{ "cntrl",  iscntrl  },
	{ "digit",  isdigit  },
	{ "graph",  isgraph  },
	{ "lower",  islower  },
	{ "print",  isprint  },
	{ "punct",  ispunct  },
	{ "space",  isspace  },
	{ "upper",  isupper  },
	{ "xdigit", isxdigit },
};

static void
genclass(STR *s)
{
	int cnt;
	const CLASS *cp;
	CLASS tmp;
	int *p;

	tmp.name = s->str;
	if ((cp = bsearch(&tmp, classes, sizeof(classes) /
	    sizeof(*cp), sizeof(*cp), c_class)) == NULL)
		errx(1, "unknown class %s", s->str);

	if ((s->set = p = malloc((NCHARS + 1) * sizeof(*p))) == NULL)
		err(1, "malloc");

	for (cnt = 0; cnt < NCHARS; ++cnt)
		if ((*cp->func)(cnt))
			*p++ = cnt;
	*p++ = OOBCH;
	memset(p, 0, NCHARS + 1 - (p - s->set));

	s->cnt = 0;
	s->state = SET;
}

static int
c_class(const void *a, const void *b)
{
	return strcmp(((const CLASS *)a)->name, ((const CLASS *)b)->name);
}

/*
 * English doesn't have any equivalence classes, so for now
 * we just syntax check and grab the character.
 */
static void
genequiv(STR *s)
{
	if (*s->str == '\\') {
		s->equiv[0] = backslash(s);
		if (*s->str != '=')
			errx(1, "misplaced equivalence equals sign");
	} else {
		s->equiv[0] = s->str[0];
		if (s->str[1] != '=')
			errx(1, "misplaced equivalence equals sign");
	}
	s->str += 2;
	s->cnt = 0;
	s->state = SET;
	s->set = s->equiv;
}

static int
genrange(STR *s)
{
	int stopval;
	char *savestart;

	savestart = s->str;
	stopval = *++s->str == '\\' ? backslash(s) : *s->str++;
	if (stopval < (u_char)s->lastch) {
		s->str = savestart;
		return 0;
	}
	s->cnt = stopval - s->lastch + 1;
	s->state = RANGE;
	--s->lastch;
	return 1;
}

static void
genseq(STR *s)
{
	char *ep;

	if (s->which == STRING1)
		errx(1, "sequences only valid in string2");

	if (*s->str == '\\')
		s->lastch = backslash(s);
	else
		s->lastch = *s->str++;
	if (*s->str != '*')
		errx(1, "misplaced sequence asterisk");

	switch (*++s->str) {
	case '\\':
		s->cnt = backslash(s);
		break;
	case ']':
		s->cnt = 0;
		++s->str;
		break;
	default:
		if (isdigit(*s->str)) {
			s->cnt = strtol(s->str, &ep, 0);
			if (*ep == ']') {
				s->str = ep + 1;
				break;
			}
		}
		errx(1, "illegal sequence count");
		/* NOTREACHED */
	}

	s->state = s->cnt ? SEQUENCE : INFINITE;
}

/*
 * Translate \??? into a character.  Up to 3 octal digits, if no digits either
 * an escape code or a literal character.
 */
static int
backslash(STR *s)
{
	int ch, cnt, val;

	for (cnt = val = 0;;) {
		ch = *++s->str;
		if (!isascii(ch) || !isdigit(ch))
			break;
		val = val * 8 + ch - '0';
		if (++cnt == 3) {
			++s->str;
			break;
		}
	}
	if (cnt)
		return val;
	if (ch != '\0')
		++s->str;
	switch (ch) {
	case 'a':			/* escape characters */
		return '\7';
	case 'b':
		return '\b';
	case 'e':
		return '\033';
	case 'f':
		return '\f';
	case 'n':
		return '\n';
	case 'r':
		return '\r';
	case 't':
		return '\t';
	case 'v':
		return '\13';
	case '\0':			/*  \" -> \ */
		s->state = EOS;
		return '\\';
	default:			/* \x" -> x */
		return ch;
	}
}