Merge commit '98acd3f494b28ddd8c345a2bb9311e41e2d56ddd' as 'tcl8.6'

1 files changed, 1195 insertions, 0 deletions

diff --git a/tcl8.6/generic/regc_lex.c b/tcl8.6/generic/regc_lex.c
new file mode 100644
index 0000000..affcb48
--- /dev/null
+++ b/tcl8.6/generic/regc_lex.c
@@ -0,0 +1,1195 @@
+/*
+ * 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(
+    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(
+    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 *, const chr *, const chr *);
+ */
+static void
+lexnest(
+    struct vars *v,
+    const chr *beginp,		/* start of interpolation */
+    const 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 const chr backd[] = {	/* \d */
+    CHR('['), CHR('['), CHR(':'),
+    CHR('d'), CHR('i'), CHR('g'), CHR('i'), CHR('t'),
+    CHR(':'), CHR(']'), CHR(']')
+};
+static const chr backD[] = {	/* \D */
+    CHR('['), CHR('^'), CHR('['), CHR(':'),
+    CHR('d'), CHR('i'), CHR('g'), CHR('i'), CHR('t'),
+    CHR(':'), CHR(']'), CHR(']')
+};
+static const chr brbackd[] = {	/* \d within brackets */
+    CHR('['), CHR(':'),
+    CHR('d'), CHR('i'), CHR('g'), CHR('i'), CHR('t'),
+    CHR(':'), CHR(']')
+};
+static const chr backs[] = {	/* \s */
+    CHR('['), CHR('['), CHR(':'),
+    CHR('s'), CHR('p'), CHR('a'), CHR('c'), CHR('e'),
+    CHR(':'), CHR(']'), CHR(']')
+};
+static const chr backS[] = {	/* \S */
+    CHR('['), CHR('^'), CHR('['), CHR(':'),
+    CHR('s'), CHR('p'), CHR('a'), CHR('c'), CHR('e'),
+    CHR(':'), CHR(']'), CHR(']')
+};
+static const chr brbacks[] = {	/* \s within brackets */
+    CHR('['), CHR(':'),
+    CHR('s'), CHR('p'), CHR('a'), CHR('c'), CHR('e'),
+    CHR(':'), CHR(']')
+};
+
+#define PUNCT_CONN \
+	CHR('_'), \
+	0x203f /* UNDERTIE */, \
+	0x2040 /* CHARACTER TIE */,\
+	0x2054 /* INVERTED UNDERTIE */,\
+	0xfe33 /* PRESENTATION FORM FOR VERTICAL LOW LINE */, \
+	0xfe34 /* PRESENTATION FORM FOR VERTICAL WAVY LOW LINE */, \
+	0xfe4d /* DASHED LOW LINE */, \
+	0xfe4e /* CENTRELINE LOW LINE */, \
+	0xfe4f /* WAVY LOW LINE */, \
+	0xff3f /* FULLWIDTH LOW LINE */
+
+static const chr backw[] = {	/* \w */
+    CHR('['), CHR('['), CHR(':'),
+    CHR('a'), CHR('l'), CHR('n'), CHR('u'), CHR('m'),
+    CHR(':'), CHR(']'), PUNCT_CONN, CHR(']')
+};
+static const chr backW[] = {	/* \W */
+    CHR('['), CHR('^'), CHR('['), CHR(':'),
+    CHR('a'), CHR('l'), CHR('n'), CHR('u'), CHR('m'),
+    CHR(':'), CHR(']'), PUNCT_CONN, CHR(']')
+};
+static const chr brbackw[] = {	/* \w within brackets */
+    CHR('['), CHR(':'),
+    CHR('a'), CHR('l'), CHR('n'), CHR('u'), CHR('m'),
+    CHR(':'), CHR(']'), PUNCT_CONN
+};
+
+/*
+ - 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(
+    struct vars *v)
+{
+    lexnest(v, backw, ENDOF(backw));
+}
+
+/*
+ - next - get next token
+ ^ static int next(struct vars *);
+ */
+static int			/* 1 normal, 0 failure */
+next(
+    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);
+	    NOTE(REG_UUNSPEC);
+	    RETV(PLAIN, c);
+	} else {
+	    NOTE(REG_UBOUNDS);
+	    INTOCON(L_EBND);
+	    RET('{');
+	}
+	assert(NOTREACHED);
+	break;
+    case CHR('('):		/* parenthesis, or advanced extension */
+	if ((v->cflags&REG_ADVF) && NEXT1('?')) {
+	    NOTE(REG_UNONPOSIX);
+	    v->now++;
+	    switch (*v->now++) {
+	    case CHR(':'):	/* non-capturing paren */
+		RETV('(', 0);
+		break;
+	    case CHR('#'):	/* comment */
+		while (!ATEOS() && *v->now != CHR(')')) {
+		    v->now++;
+		}
+		if (!ATEOS()) {
+		    v->now++;
+		}
+		assert(v->nexttype == v->lasttype);
+		return next(v);
+		break;
+	    case CHR('='):	/* positive lookahead */
+		NOTE(REG_ULOOKAHEAD);
+		RETV(LACON, 1);
+		break;
+	    case CHR('!'):	/* negative lookahead */
+		NOTE(REG_ULOOKAHEAD);
+		RETV(LACON, 0);
+		break;
+	    default:
+		FAILW(REG_BADRPT);
+		break;
+	    }
+	    assert(NOTREACHED);
+	}
+	if (v->cflags&REG_NOSUB) {
+	    RETV('(', 0);	/* all parens non-capturing */
+	} else {
+	    RETV('(', 1);
+	}
+	break;
+    case CHR(')'):
+	if (LASTTYPE('(')) {
+	    NOTE(REG_UUNSPEC);
+	}
+	RETV(')', c);
+	break;
+    case CHR('['):		/* easy except for [[:<:]] and [[:>:]] */
+	if (HAVE(6) &&	*(v->now+0) == CHR('[') &&
+		*(v->now+1) == CHR(':') &&
+		(*(v->now+2) == CHR('<') || *(v->now+2) == CHR('>')) &&
+		*(v->now+3) == CHR(':') &&
+		*(v->now+4) == CHR(']') &&
+		*(v->now+5) == CHR(']')) {
+	    c = *(v->now+2);
+	    v->now += 6;
+	    NOTE(REG_UNONPOSIX);
+	    RET((c == CHR('<')) ? '<' : '>');
+	}
+	INTOCON(L_BRACK);
+	if (NEXT1('^')) {
+	    v->now++;
+	    RETV('[', 0);
+	}
+	RETV('[', 1);
+	break;
+    case CHR('.'):
+	RET('.');
+	break;
+    case CHR('^'):
+	RET('^');
+	break;
+    case CHR('$'):
+	RET('$');
+	break;
+    case CHR('\\'):		/* mostly punt backslashes to code below */
+	if (ATEOS()) {
+	    FAILW(REG_EESCAPE);
+	}
+	break;
+    default:		/* ordinary character */
+	RETV(PLAIN, c);
+	break;
+    }
+
+    /*
+     * ERE/ARE backslash handling; backslash already eaten.
+     */
+
+    assert(!ATEOS());
+    if (!(v->cflags&REG_ADVF)) {/* only AREs have non-trivial escapes */
+	if (iscalnum(*v->now)) {
+	    NOTE(REG_UBSALNUM);
+	    NOTE(REG_UUNSPEC);
+	}
+	RETV(PLAIN, *v->now++);
+    }
+    (DISCARD)lexescape(v);
+    if (ISERR()) {
+	FAILW(REG_EESCAPE);
+    }
+    if (v->nexttype == CCLASS) {/* fudge at lexical level */
+	switch (v->nextvalue) {
+	case 'd':	lexnest(v, backd, ENDOF(backd)); break;
+	case 'D':	lexnest(v, backD, ENDOF(backD)); break;
+	case 's':	lexnest(v, backs, ENDOF(backs)); break;
+	case 'S':	lexnest(v, backS, ENDOF(backS)); break;
+	case 'w':	lexnest(v, backw, ENDOF(backw)); break;
+	case 'W':	lexnest(v, backW, ENDOF(backW)); break;
+	default:
+	    assert(NOTREACHED);
+	    FAILW(REG_ASSERT);
+	    break;
+	}
+	/* lexnest done, back up and try again */
+	v->nexttype = v->lasttype;
+	return next(v);
+    }
+
+    /*
+     * Otherwise, lexescape has already done the work.
+     */
+
+    return !ISERR();
+}
+
+/*
+ - lexescape - parse an ARE backslash escape (backslash already eaten)
+ * Note slightly nonstandard use of the CCLASS type code.
+ ^ static int lexescape(struct vars *);
+ */
+static int			/* not actually used, but convenient for RETV */
+lexescape(
+    struct vars *v)
+{
+    chr c;
+    int i;
+    static const chr alert[] = {
+	CHR('a'), CHR('l'), CHR('e'), CHR('r'), CHR('t')
+    };
+    static const chr esc[] = {
+	CHR('E'), CHR('S'), CHR('C')
+    };
+    const chr *save;
+
+    assert(v->cflags&REG_ADVF);
+
+    assert(!ATEOS());
+    c = *v->now++;
+    if (!iscalnum(c)) {
+	RETV(PLAIN, c);
+    }
+
+    NOTE(REG_UNONPOSIX);
+    switch (c) {
+    case CHR('a'):
+	RETV(PLAIN, chrnamed(v, alert, ENDOF(alert), CHR('\007')));
+	break;
+    case CHR('A'):
+	RETV(SBEGIN, 0);
+	break;
+    case CHR('b'):
+	RETV(PLAIN, CHR('\b'));
+	break;
+    case CHR('B'):
+	RETV(PLAIN, CHR('\\'));
+	break;
+    case CHR('c'):
+	NOTE(REG_UUNPORT);
+	if (ATEOS()) {
+	    FAILW(REG_EESCAPE);
+	}
+	RETV(PLAIN, (chr)(*v->now++ & 037));
+	break;
+    case CHR('d'):
+	NOTE(REG_ULOCALE);
+	RETV(CCLASS, 'd');
+	break;
+    case CHR('D'):
+	NOTE(REG_ULOCALE);
+	RETV(CCLASS, 'D');
+	break;
+    case CHR('e'):
+	NOTE(REG_UUNPORT);
+	RETV(PLAIN, chrnamed(v, esc, ENDOF(esc), CHR('\033')));
+	break;
+    case CHR('f'):
+	RETV(PLAIN, CHR('\f'));
+	break;
+    case CHR('m'):
+	RET('<');
+	break;
+    case CHR('M'):
+	RET('>');
+	break;
+    case CHR('n'):
+	RETV(PLAIN, CHR('\n'));
+	break;
+    case CHR('r'):
+	RETV(PLAIN, CHR('\r'));
+	break;
+    case CHR('s'):
+	NOTE(REG_ULOCALE);
+	RETV(CCLASS, 's');
+	break;
+    case CHR('S'):
+	NOTE(REG_ULOCALE);
+	RETV(CCLASS, 'S');
+	break;
+    case CHR('t'):
+	RETV(PLAIN, CHR('\t'));
+	break;
+    case CHR('u'):
+	c = (uchr) lexdigits(v, 16, 1, 4);
+	if (ISERR()) {
+	    FAILW(REG_EESCAPE);
+	}
+	RETV(PLAIN, c);
+	break;
+    case CHR('U'):
+	i = lexdigits(v, 16, 1, 8);
+	if (ISERR()) {
+	    FAILW(REG_EESCAPE);
+	}
+	if (i > 0xFFFF) {
+	    /* TODO: output a Surrogate pair
+	     */
+	    i = 0xFFFD;
+	}
+	RETV(PLAIN, (uchr) i);
+	break;
+    case CHR('v'):
+	RETV(PLAIN, CHR('\v'));
+	break;
+    case CHR('w'):
+	NOTE(REG_ULOCALE);
+	RETV(CCLASS, 'w');
+	break;
+    case CHR('W'):
+	NOTE(REG_ULOCALE);
+	RETV(CCLASS, 'W');
+	break;
+    case CHR('x'):
+	NOTE(REG_UUNPORT);
+	c = (uchr) lexdigits(v, 16, 1, 2);
+	if (ISERR()) {
+	    FAILW(REG_EESCAPE);
+	}
+	RETV(PLAIN, c);
+	break;
+    case CHR('y'):
+	NOTE(REG_ULOCALE);
+	RETV(WBDRY, 0);
+	break;
+    case CHR('Y'):
+	NOTE(REG_ULOCALE);
+	RETV(NWBDRY, 0);
+	break;
+    case CHR('Z'):
+	RETV(SEND, 0);
+	break;
+    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'):
+	save = v->now;
+	v->now--;		/* put first digit back */
+	c = (uchr) lexdigits(v, 10, 1, 255);	/* REs >255 long outside spec */
+	if (ISERR()) {
+	    FAILW(REG_EESCAPE);
+	}
+
+	/*
+	 * Ugly heuristic (first test is "exactly 1 digit?")
+	 */
+
+	if (v->now - save == 0 || ((int) c > 0 && (int)c <= v->nsubexp)) {
+	    NOTE(REG_UBACKREF);
+	    RETV(BACKREF, (chr)c);
+	}
+
+	/*
+	 * Oops, doesn't look like it's a backref after all...
+	 */
+
+	v->now = save;
+
+	/*
+	 * And fall through into octal number.
+	 */
+
+    case CHR('0'):
+	NOTE(REG_UUNPORT);
+	v->now--;		/* put first digit back */
+	c = (uchr) lexdigits(v, 8, 1, 3);
+	if (ISERR()) {
+	    FAILW(REG_EESCAPE);
+	}
+	if (c > 0xff) {
+	    /* out of range, so we handled one digit too much */
+	    v->now--;
+	    c >>= 3;
+	}
+	RETV(PLAIN, c);
+	break;
+    default:
+	assert(iscalpha(c));
+	FAILW(REG_EESCAPE);	/* unknown alphabetic escape */
+	break;
+    }
+    assert(NOTREACHED);
+}
+
+/*
+ - lexdigits - slurp up digits and return chr value
+ ^ static int lexdigits(struct vars *, int, int, int);
+ */
+static int			/* chr value; errors signalled via ERR */
+lexdigits(
+    struct vars *v,
+    int base,
+    int minlen,
+    int maxlen)
+{
+    int n;
+    int len;
+    chr c;
+    int d;
+    const uchr ub = (uchr) base;
+
+    n = 0;
+    for (len = 0; len < maxlen && !ATEOS(); len++) {
+	if (n > 0x10fff) {
+	    /* Stop when continuing would otherwise overflow */
+	    break;
+	}
+	c = *v->now++;
+	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'):
+	    d = DIGITVAL(c);
+	    break;
+	case CHR('a'): case CHR('A'): d = 10; break;
+	case CHR('b'): case CHR('B'): d = 11; break;
+	case CHR('c'): case CHR('C'): d = 12; break;
+	case CHR('d'): case CHR('D'): d = 13; break;
+	case CHR('e'): case CHR('E'): d = 14; break;
+	case CHR('f'): case CHR('F'): d = 15; break;
+	default:
+	    v->now--;		/* oops, not a digit at all */
+	    d = -1;
+	    break;
+	}
+
+	if (d >= base) {	/* not a plausible digit */
+	    v->now--;
+	    d = -1;
+	}
+	if (d < 0) {
+	    break;		/* NOTE BREAK OUT */
+	}
+	n = n*ub + (uchr)d;
+    }
+    if (len < minlen) {
+	ERR(REG_EESCAPE);
+    }
+
+    return n;
+}
+
+/*
+ - brenext - get next BRE token
+ * This is much like EREs except for all the stupid backslashes and the
+ * context-dependency of some things.
+ ^ static int brenext(struct vars *, pchr);
+ */
+static int			/* 1 normal, 0 failure */
+brenext(
+    struct vars *v,
+    pchr pc)
+{
+    chr c = (chr)pc;
+
+    switch (c) {
+    case CHR('*'):
+	if (LASTTYPE(EMPTY) || LASTTYPE('(') || LASTTYPE('^')) {
+	    RETV(PLAIN, c);
+	}
+	RET('*');
+	break;
+    case CHR('['):
+	if (HAVE(6) &&	*(v->now+0) == CHR('[') &&
+		*(v->now+1) == CHR(':') &&
+		(*(v->now+2) == CHR('<') || *(v->now+2) == CHR('>')) &&
+		*(v->now+3) == CHR(':') &&
+		*(v->now+4) == CHR(']') &&
+		*(v->now+5) == CHR(']')) {
+	    c = *(v->now+2);
+	    v->now += 6;
+	    NOTE(REG_UNONPOSIX);
+	    RET((c == CHR('<')) ? '<' : '>');
+	}
+	INTOCON(L_BRACK);
+	if (NEXT1('^')) {
+	    v->now++;
+	    RETV('[', 0);
+	}
+	RETV('[', 1);
+	break;
+    case CHR('.'):
+	RET('.');
+	break;
+    case CHR('^'):
+	if (LASTTYPE(EMPTY)) {
+	    RET('^');
+	}
+	if (LASTTYPE('(')) {
+	    NOTE(REG_UUNSPEC);
+	    RET('^');
+	}
+	RETV(PLAIN, c);
+	break;
+    case CHR('$'):
+	if (v->cflags&REG_EXPANDED) {
+	    skip(v);
+	}
+	if (ATEOS()) {
+	    RET('$');
+	}
+	if (NEXT2('\\', ')')) {
+	    NOTE(REG_UUNSPEC);
+	    RET('$');
+	}
+	RETV(PLAIN, c);
+	break;
+    case CHR('\\'):
+	break;			/* see below */
+    default:
+	RETV(PLAIN, c);
+	break;
+    }
+
+    assert(c == CHR('\\'));
+
+    if (ATEOS()) {
+	FAILW(REG_EESCAPE);
+    }
+
+    c = *v->now++;
+    switch (c) {
+    case CHR('{'):
+	INTOCON(L_BBND);
+	NOTE(REG_UBOUNDS);
+	RET('{');
+	break;
+    case CHR('('):
+	RETV('(', 1);
+	break;
+    case CHR(')'):
+	RETV(')', c);
+	break;
+    case CHR('<'):
+	NOTE(REG_UNONPOSIX);
+	RET('<');
+	break;
+    case CHR('>'):
+	NOTE(REG_UNONPOSIX);
+	RET('>');
+	break;
+    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'):
+	NOTE(REG_UBACKREF);
+	RETV(BACKREF, (chr)DIGITVAL(c));
+	break;
+    default:
+	if (iscalnum(c)) {
+	    NOTE(REG_UBSALNUM);
+	    NOTE(REG_UUNSPEC);
+	}
+	RETV(PLAIN, c);
+	break;
+    }
+
+    assert(NOTREACHED);
+}
+
+/*
+ - skip - skip white space and comments in expanded form
+ ^ static void skip(struct vars *);
+ */
+static void
+skip(
+    struct vars *v)
+{
+    const chr *start = v->now;
+
+    assert(v->cflags&REG_EXPANDED);
+
+    for (;;) {
+	while (!ATEOS() && iscspace(*v->now)) {
+	    v->now++;
+	}
+	if (ATEOS() || *v->now != CHR('#')) {
+	    break;		/* NOTE BREAK OUT */
+	}
+	assert(NEXT1('#'));
+	while (!ATEOS() && *v->now != CHR('\n')) {
+	    v->now++;
+	}
+
+	/*
+	 * Leave the newline to be picked up by the iscspace loop.
+	 */
+    }
+
+    if (v->now != start) {
+	NOTE(REG_UNONPOSIX);
+    }
+}
+
+/*
+ - newline - return the chr for a newline
+ * This helps confine use of CHR to this source file.
+ ^ static chr newline(NOPARMS);
+ */
+static chr
+newline(void)
+{
+    return CHR('\n');
+}
+
+/*
+ - chrnamed - return the chr known by a given (chr string) name
+ * The code is a bit clumsy, but this routine gets only such specialized
+ * use that it hardly matters.
+ ^ static chr chrnamed(struct vars *, const chr *, const chr *, pchr);
+ */
+static chr
+chrnamed(
+    struct vars *v,
+    const chr *startp,		/* start of name */
+    const chr *endp,		/* just past end of name */
+    pchr lastresort)		/* what to return if name lookup fails */
+{
+    celt c;
+    int errsave;
+    int e;
+    struct cvec *cv;
+
+    errsave = v->err;
+    v->err = 0;
+    c = element(v, startp, endp);
+    e = v->err;
+    v->err = errsave;
+
+    if (e != 0) {
+	return (chr)lastresort;
+    }
+
+    cv = range(v, c, c, 0);
+    if (cv->nchrs == 0) {
+	return (chr)lastresort;
+    }
+    return cv->chrs[0];
+}
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */