regc_lex.c

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/*
 * lexical analyzer
 * This file is #included by regcomp.c.
 *
 * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
 * 
 * Development of this software was funded, in part, by Cray Research Inc.,
 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
 * Corporation, none of whom are responsible for the results.  The author
 * thanks all of them. 
 * 
 * Redistribution and use in source and binary forms -- with or without
 * modification -- are permitted for any purpose, provided that
 * redistributions in source form retain this entire copyright notice and
 * indicate the origin and nature of any modifications.
 * 
 * I'd appreciate being given credit for this package in the documentation
 * of software which uses it, but that is not a requirement.
 * 
 * THIS SOFTWARE IS PROVIDED ``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
 * HENRY SPENCER 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.
 *
 */

/* scanning macros (know about v) */
#define	ATEOS()		(v->now >= v->stop)
#define	HAVE(n)		(v->stop - v->now >= (n))
#define	NEXT1(c)	(!ATEOS() && *v->now == CHR(c))
#define	NEXT2(a,b)	(HAVE(2) && *v->now == CHR(a) && *(v->now+1) == CHR(b))
#define	NEXT3(a,b,c)	(HAVE(3) && *v->now == CHR(a) && \
						*(v->now+1) == CHR(b) && \
						*(v->now+2) == CHR(c))
#define	SET(c)		(v->nexttype = (c))
#define	SETV(c, n)	(v->nexttype = (c), v->nextvalue = (n))
#define	RET(c)		return (SET(c), 1)
#define	RETV(c, n)	return (SETV(c, n), 1)
#define	FAILW(e)	return (ERR(e), 0)	/* ERR does SET(EOS) */
#define	LASTTYPE(t)	(v->lasttype == (t))

/* lexical contexts */
#define	L_ERE	1	/* mainline ERE/ARE */
#define	L_BRE	2	/* mainline BRE */
#define	L_Q	3	/* REG_QUOTE */
#define	L_EBND	4	/* ERE/ARE bound */
#define	L_BBND	5	/* BRE bound */
#define	L_BRACK	6	/* brackets */
#define	L_CEL	7	/* collating element */
#define	L_ECL	8	/* equivalence class */
#define	L_CCL	9	/* character class */
#define	INTOCON(c)	(v->lexcon = (c))
#define	INCON(con)	(v->lexcon == (con))

/* construct pointer past end of chr array */
#define	ENDOF(array)	((array) + sizeof(array)/sizeof(chr))

/*
 - lexstart - set up lexical stuff, scan leading options
 ^ static VOID lexstart(struct vars *);
 */
static VOID
lexstart(v)
struct vars *v;
{
	prefixes(v);			/* may turn on new type bits etc. */
	NOERR();

	if (v->cflags&REG_QUOTE) {
		assert(!(v->cflags&(REG_ADVANCED|REG_EXPANDED|REG_NEWLINE)));
		INTOCON(L_Q);
	} else if (v->cflags&REG_EXTENDED) {
		assert(!(v->cflags&REG_QUOTE));
		INTOCON(L_ERE);
	} else {
		assert(!(v->cflags&(REG_QUOTE|REG_ADVF)));
		INTOCON(L_BRE);
	}

	v->nexttype = EMPTY;		/* remember we were at the start */
	next(v);			/* set up the first token */
}

/*
 - prefixes - implement various special prefixes
 ^ static VOID prefixes(struct vars *);
 */
static VOID
prefixes(v)
struct vars *v;
{
	/* literal string doesn't get any of this stuff */
	if (v->cflags&REG_QUOTE)
		return;

	/* initial "***" gets special things */	
	if (HAVE(4) && NEXT3('*', '*', '*'))
		switch (*(v->now + 3)) {
		case CHR('?'):		/* "***?" error, msg shows version */
			ERR(REG_BADPAT);
			return;		/* proceed no further */
			break;
		case CHR('='):		/* "***=" shifts to literal string */
			NOTE(REG_UNONPOSIX);
			v->cflags |= REG_QUOTE;
			v->cflags &= ~(REG_ADVANCED|REG_EXPANDED|REG_NEWLINE);
			v->now += 4;
			return;		/* and there can be no more prefixes */
			break;
		case CHR(':'):		/* "***:" shifts to AREs */
			NOTE(REG_UNONPOSIX);
			v->cflags |= REG_ADVANCED;
			v->now += 4;
			break;
		default:		/* otherwise *** is just an error */
			ERR(REG_BADRPT);
			return;
			break;
		}

	/* BREs and EREs don't get embedded options */
	if ((v->cflags&REG_ADVANCED) != REG_ADVANCED)
		return;

	/* embedded options (AREs only) */
	if (HAVE(3) && NEXT2('(', '?') && iscalpha(*(v->now + 2))) {
		NOTE(REG_UNONPOSIX);
		v->now += 2;
		for (; !ATEOS() && iscalpha(*v->now); v->now++)
			switch (*v->now) {
			case CHR('b'):		/* BREs (but why???) */
				v->cflags &= ~(REG_ADVANCED|REG_QUOTE);
				break;
			case CHR('c'):		/* case sensitive */
				v->cflags &= ~REG_ICASE;
				break;
			case CHR('e'):		/* plain EREs */
				v->cflags |= REG_EXTENDED;
				v->cflags &= ~(REG_ADVF|REG_QUOTE);
				break;
			case CHR('i'):		/* case insensitive */
				v->cflags |= REG_ICASE;
				break;
			case CHR('m'):		/* Perloid synonym for n */
			case CHR('n'):		/* \n affects ^ $ . [^ */
				v->cflags |= REG_NEWLINE;
				break;
			case CHR('p'):		/* ~Perl, \n affects . [^ */
				v->cflags |= REG_NLSTOP;
				v->cflags &= ~REG_NLANCH;
				break;
			case CHR('q'):		/* literal string */
				v->cflags |= REG_QUOTE;
				v->cflags &= ~REG_ADVANCED;
				break;
			case CHR('s'):		/* single line, \n ordinary */
				v->cflags &= ~REG_NEWLINE;
				break;
			case CHR('t'):		/* tight syntax */
				v->cflags &= ~REG_EXPANDED;
				break;
			case CHR('w'):		/* weird, \n affects ^ $ only */
				v->cflags &= ~REG_NLSTOP;
				v->cflags |= REG_NLANCH;
				break;
			case CHR('x'):		/* expanded syntax */
				v->cflags |= REG_EXPANDED;
				break;
			default:
				ERR(REG_BADOPT);
				return;
			}
		if (!NEXT1(')')) {
			ERR(REG_BADOPT);
			return;
		}
		v->now++;
		if (v->cflags&REG_QUOTE)
			v->cflags &= ~(REG_EXPANDED|REG_NEWLINE);
	}
}

/*
 - lexnest - "call a subroutine", interpolating string at the lexical level
 * Note, this is not a very general facility.  There are a number of
 * implicit assumptions about what sorts of strings can be subroutines.
 ^ static VOID lexnest(struct vars *, chr *, chr *);
 */
static VOID
lexnest(v, beginp, endp)
struct vars *v;
chr *beginp;				/* start of interpolation */
chr *endp;				/* one past end of interpolation */
{
	assert(v->savenow == NULL);	/* only one level of nesting */
	v->savenow = v->now;
	v->savestop = v->stop;
	v->now = beginp;
	v->stop = endp;
}

/*
 * string constants to interpolate as expansions of things like \d
 */
static chr backd[] = {		/* \d */
	CHR('['), CHR('['), CHR(':'),
	CHR('d'), CHR('i'), CHR('g'), CHR('i'), CHR('t'),
	CHR(':'), CHR(']'), CHR(']')
};
static chr backD[] = {		/* \D */
	CHR('['), CHR('^'), CHR('['), CHR(':'),
	CHR('d'), CHR('i'), CHR('g'), CHR('i'), CHR('t'),
	CHR(':'), CHR(']'), CHR(']')
};
static chr brbackd[] = {	/* \d within brackets */
	CHR('['), CHR(':'),
	CHR('d'), CHR('i'), CHR('g'), CHR('i'), CHR('t'),
	CHR(':'), CHR(']')
};
static chr backs[] = {		/* \s */
	CHR('['), CHR('['), CHR(':'),
	CHR('s'), CHR('p'), CHR('a'), CHR('c'), CHR('e'),
	CHR(':'), CHR(']'), CHR(']')
};
static chr backS[] = {		/* \S */
	CHR('['), CHR('^'), CHR('['), CHR(':'),
	CHR('s'), CHR('p'), CHR('a'), CHR('c'), CHR('e'),
	CHR(':'), CHR(']'), CHR(']')
};
static chr brbacks[] = {	/* \s within brackets */
	CHR('['), CHR(':'),
	CHR('s'), CHR('p'), CHR('a'), CHR('c'), CHR('e'),
	CHR(':'), CHR(']')
};
static chr backw[] = {		/* \w */
	CHR('['), CHR('['), CHR(':'),
	CHR('a'), CHR('l'), CHR('n'), CHR('u'), CHR('m'),
	CHR(':'), CHR(']'), CHR('_'), CHR(']')
};
static chr backW[] = {		/* \W */
	CHR('['), CHR('^'), CHR('['), CHR(':'),
	CHR('a'), CHR('l'), CHR('n'), CHR('u'), CHR('m'),
	CHR(':'), CHR(']'), CHR('_'), CHR(']')
};
static chr brbackw[] = {	/* \w within brackets */
	CHR('['), CHR(':'),
	CHR('a'), CHR('l'), CHR('n'), CHR('u'), CHR('m'),
	CHR(':'), CHR(']'), CHR('_')
};

/*
 - lexword - interpolate a bracket expression for word characters
 * Possibly ought to inquire whether there is a "word" character class.
 ^ static VOID lexword(struct vars *);
 */
static VOID
lexword(v)
struct vars *v;
{
	lexnest(v, backw, ENDOF(backw));
}

/*
 - next - get next token
 ^ static int next(struct vars *);
 */
static int			/* 1 normal, 0 failure */
next(v)
struct vars *v;
{
	chr c;

	/* errors yield an infinite sequence of failures */
	if (ISERR())
		return 0;	/* the error has set nexttype to EOS */

	/* remember flavor of last token */
	v->lasttype = v->nexttype;

	/* REG_BOSONLY */
	if (v->nexttype == EMPTY && (v->cflags&REG_BOSONLY)) {
		/* at start of a REG_BOSONLY RE */
		RETV(SBEGIN, 0);		/* same as \A */
	}

	/* if we're nested and we've hit end, return to outer level */
	if (v->savenow != NULL && ATEOS()) {
		v->now = v->savenow;
		v->stop = v->savestop;
		v->savenow = v->savestop = NULL;
	}

	/* skip white space etc. if appropriate (not in literal or []) */
	if (v->cflags&REG_EXPANDED)
		switch (v->lexcon) {
		case L_ERE:
		case L_BRE:
		case L_EBND:
		case L_BBND:
			skip(v);
			break;
		}

	/* handle EOS, depending on context */
	if (ATEOS()) {
		switch (v->lexcon) {
		case L_ERE:
		case L_BRE:
		case L_Q:
			RET(EOS);
			break;
		case L_EBND:
		case L_BBND:
			FAILW(REG_EBRACE);
			break;
		case L_BRACK:
		case L_CEL:
		case L_ECL:
		case L_CCL:
			FAILW(REG_EBRACK);
			break;
		}
		assert(NOTREACHED);
	}

	/* okay, time to actually get a character */
	c = *v->now++;

	/* deal with the easy contexts, punt EREs to code below */
	switch (v->lexcon) {
	case L_BRE:			/* punt BREs to separate function */
		return brenext(v, c);
		break;
	case L_ERE:			/* see below */
		break;
	case L_Q:			/* literal strings are easy */
		RETV(PLAIN, c);
		break;
	case L_BBND:			/* bounds are fairly simple */
	case L_EBND:
		switch (c) {
		case CHR('0'): case CHR('1'): case CHR('2'): case CHR('3'):
		case CHR('4'): case CHR('5'): case CHR('6'): case CHR('7'):
		case CHR('8'): case CHR('9'):
			RETV(DIGIT, (chr)DIGITVAL(c));
			break;
		case CHR(','):
			RET(',');
			break;
		case CHR('}'):		/* ERE bound ends with } */
			if (INCON(L_EBND)) {
				INTOCON(L_ERE);
				if ((v->cflags&REG_ADVF) && NEXT1('?')) {
					v->now++;
					NOTE(REG_UNONPOSIX);
					RETV('}', 0);
				}
				RETV('}', 1);
			} else
				FAILW(REG_BADBR);
			break;
		case CHR('\\'):		/* BRE bound ends with \} */
			if (INCON(L_BBND) && NEXT1('}')) {
				v->now++;
				INTOCON(L_BRE);
				RET('}');
			} else
				FAILW(REG_BADBR);
			break;
		default:
			FAILW(REG_BADBR);
			break;
		}
		assert(NOTREACHED);
		break;
	case L_BRACK:			/* brackets are not too hard */
		switch (c) {
		case CHR(']'):
			if (LASTTYPE('['))
				RETV(PLAIN, c);
			else {
				INTOCON((v->cflags&REG_EXTENDED) ?
							L_ERE : L_BRE);
				RET(']');
			}
			break;
		case CHR('\\'):
			NOTE(REG_UBBS);
			if (!(v->cflags&REG_ADVF))
				RETV(PLAIN, c);
			NOTE(REG_UNONPOSIX);
			if (ATEOS())
				FAILW(REG_EESCAPE);
			(DISCARD)lexescape(v);
			switch (v->nexttype) {	/* not all escapes okay here */
			case PLAIN:
				return 1;
				break;
			case CCLASS:
				switch (v->nextvalue) {
				case 'd':
					lexnest(v, brbackd, ENDOF(brbackd));
					break;
				case 's':
					lexnest(v, brbacks, ENDOF(brbacks));
					break;
				case 'w':
					lexnest(v, brbackw, ENDOF(brbackw));
					break;
				default:
					FAILW(REG_EESCAPE);
					break;
				}
				/* lexnest done, back up and try again */
				v->nexttype = v->lasttype;
				return next(v);
				break;
			}
			/* not one of the acceptable escapes */
			FAILW(REG_EESCAPE);
			break;
		case CHR('-'):
			if (LASTTYPE('[') || NEXT1(']'))
				RETV(PLAIN, c);
			else
				RETV(RANGE, c);
			break;
		case CHR('['):
			if (ATEOS())
				FAILW(REG_EBRACK);
			switch (*v->now++) {
			case CHR('.'):
				INTOCON(L_CEL);
				/* might or might not be locale-specific */
				RET(COLLEL);
				break;
			case CHR('='):
				INTOCON(L_ECL);
				NOTE(REG_ULOCALE);
				RET(ECLASS);
				break;
			case CHR(':'):
				INTOCON(L_CCL);
				NOTE(REG_ULOCALE);
				RET(CCLASS);
				break;
			default:			/* oops */
				v->now--;
				RETV(PLAIN, c);
				break;
			}
			assert(NOTREACHED);
			break;
		default:
			RETV(PLAIN, c);
			break;
		}
		assert(NOTREACHED);
		break;
	case L_CEL:			/* collating elements are easy */
		if (c == CHR('.') && NEXT1(']')) {
			v->now++;
			INTOCON(L_BRACK);
			RETV(END, '.');
		} else
			RETV(PLAIN, c);
		break;
	case L_ECL:			/* ditto equivalence classes */
		if (c == CHR('=') && NEXT1(']')) {
			v->now++;
			INTOCON(L_BRACK);
			RETV(END, '=');
		} else
			RETV(PLAIN, c);
		break;
	case L_CCL:			/* ditto character classes */
		if (c == CHR(':') && NEXT1(']')) {
			v->now++;
			INTOCON(L_BRACK);
			RETV(END, ':');
		} else
			RETV(PLAIN, c);
		break;
	default:
		assert(NOTREACHED);
		break;
	}

	/* that got rid of everything except EREs and AREs */
	assert(INCON(L_ERE));

	/* deal with EREs and AREs, except for backslashes */
	switch (c) {
	case CHR('|'):
		RET('|');
		break;
	case CHR('*'):
		if ((v->cflags&REG_ADVF) && NEXT1('?')) {
			v->now++;
			NOTE(REG_UNONPOSIX);
			RETV('*', 0);
		}
		RETV('*', 1);
		break;
	case CHR('+'):
		if ((v->cflags&REG_ADVF) && NEXT1('?')) {
			v->now++;
			NOTE(REG_UNONPOSIX);
			RETV('+', 0);
		}
		RETV('+', 1);
		break;
	case CHR('?'):
		if ((v->cflags&REG_ADVF) && NEXT1('?')) {
			v->now++;
			NOTE(REG_UNONPOSIX);
			RETV('?', 0);
		}
		RETV('?', 1);
		break;
	case CHR('{'):		/* bounds start or plain character */
		if (v->cflags&REG_EXPANDED)
			skip(v);
		if (ATEOS() || !iscdigit(*v->now)) {
			NOTE(REG_UBRACES);