Usenet 1994 January/usenetsourcesnewsgroupsinfomagicjanuary1994.iso/sources/misc/volume25/tcl/part18

Text File | 1991-11-15 | 30.7 KB | 1,288 lines

Newsgroups: comp.sources.misc
From: [e-mail] (Karl Lehenbauer)
Subject:  v25i086:  tcl - tool command language, version 6.1, Part18/33
Message-ID: <[e-mail]>
X-Md4-Signature: 20b946d85ebcce76f62a10f231defea4
Date: Fri, 15 Nov 1991 22:48:47 GMT
Approved: [e-mail]

Submitted-by: [e-mail] (Karl Lehenbauer)
Posting-number: Volume 25, Issue 86
Archive-name: tcl/part18
Environment: UNIX

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#        "End of archive 18 (of 33)."
# Contents:  tcl6.1/regexp.c
# Wrapped by karl@one on Tue Nov 12 19:44:26 1991
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'tcl6.1/regexp.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'tcl6.1/regexp.c'\"
else
echo shar: Extracting \"'tcl6.1/regexp.c'\" \(28040 characters\)
sed "s/^X//" >'tcl6.1/regexp.c' <<'END_OF_FILE'
X/*
X * regcomp and regexec -- regsub and regerror are elsewhere
X *
X *    Copyright (c) 1986 by University of Toronto.
X *    Written by Henry Spencer.  Not derived from licensed software.
X *
X *    Permission is granted to anyone to use this software for any
X *    purpose on any computer system, and to redistribute it freely,
X *    subject to the following restrictions:
X *
X *    1. The author is not responsible for the consequences of use of
X *        this software, no matter how awful, even if they arise
X *        from defects in it.
X *
X *    2. The origin of this software must not be misrepresented, either
X *        by explicit claim or by omission.
X *
X *    3. Altered versions must be plainly marked as such, and must not
X *        be misrepresented as being the original software.
X *
X * Beware that some of this code is subtly aware of the way operator
X * precedence is structured in regular expressions.  Serious changes in
X * regular-expression syntax might require a total rethink.
X *
X * *** NOTE: this code has been altered slightly for use in Tcl. ***
X * *** The only change is to use ckalloc and ckfree instead of   ***
X * *** malloc and free.                         ***
X */
X#include "tclInt.h"
X
X/*
X * The "internal use only" fields in regexp.h are present to pass info from
X * compile to execute that permits the execute phase to run lots faster on
X * simple cases.  They are:
X *
X * regstart    char that must begin a match; '\0' if none obvious
X * reganch    is the match anchored (at beginning-of-line only)?
X * regmust    string (pointer into program) that match must include, or NULL
X * regmlen    length of regmust string
X *
X * Regstart and reganch permit very fast decisions on suitable starting points
X * for a match, cutting down the work a lot.  Regmust permits fast rejection
X * of lines that cannot possibly match.  The regmust tests are costly enough
X * that regcomp() supplies a regmust only if the r.e. contains something
X * potentially expensive (at present, the only such thing detected is * or +
X * at the start of the r.e., which can involve a lot of backup).  Regmlen is
X * supplied because the test in regexec() needs it and regcomp() is computing
X * it anyway.
X */
X
X/*
X * Structure for regexp "program".  This is essentially a linear encoding
X * of a nondeterministic finite-state machine (aka syntax charts or
X * "railroad normal form" in parsing technology).  Each node is an opcode
X * plus a "next" pointer, possibly plus an operand.  "Next" pointers of
X * all nodes except BRANCH implement concatenation; a "next" pointer with
X * a BRANCH on both ends of it is connecting two alternatives.  (Here we
X * have one of the subtle syntax dependencies:  an individual BRANCH (as
X * opposed to a collection of them) is never concatenated with anything
X * because of operator precedence.)  The operand of some types of node is
X * a literal string; for others, it is a node leading into a sub-FSM.  In
X * particular, the operand of a BRANCH node is the first node of the branch.
X * (NB this is *not* a tree structure:  the tail of the branch connects
X * to the thing following the set of BRANCHes.)  The opcodes are:
X */
X
X/* definition    number    opnd?    meaning */
X#define    END    0    /* no    End of program. */
X#define    BOL    1    /* no    Match "" at beginning of line. */
X#define    EOL    2    /* no    Match "" at end of line. */
X#define    ANY    3    /* no    Match any one character. */
X#define    ANYOF    4    /* str    Match any character in this string. */
X#define    ANYBUT    5    /* str    Match any character not in this string. */
X#define    BRANCH    6    /* node    Match this alternative, or the next... */
X#define    BACK    7    /* no    Match "", "next" ptr points backward. */
X#define    EXACTLY    8    /* str    Match this string. */
X#define    NOTHING    9    /* no    Match empty string. */
X#define    STAR    10    /* node    Match this (simple) thing 0 or more times. */
X#define    PLUS    11    /* node    Match this (simple) thing 1 or more times. */
X#define    OPEN    20    /* no    Mark this point in input as start of #n. */
X            /*    OPEN+1 is number 1, etc. */
X#define    CLOSE    30    /* no    Analogous to OPEN. */
X
X/*
X * Opcode notes:
X *
X * BRANCH    The set of branches constituting a single choice are hooked
X *        together with their "next" pointers, since precedence prevents
X *        anything being concatenated to any individual branch.  The
X *        "next" pointer of the last BRANCH in a choice points to the
X *        thing following the whole choice.  This is also where the
X *        final "next" pointer of each individual branch points; each
X *        branch starts with the operand node of a BRANCH node.
X *
X * BACK        Normal "next" pointers all implicitly point forward; BACK
X *        exists to make loop structures possible.
X *
X * STAR,PLUS    '?', and complex '*' and '+', are implemented as circular
X *        BRANCH structures using BACK.  Simple cases (one character
X *        per match) are implemented with STAR and PLUS for speed
X *        and to minimize recursive plunges.
X *
X * OPEN,CLOSE    ...are numbered at compile time.
X */
X
X/*
X * A node is one char of opcode followed by two chars of "next" pointer.
X * "Next" pointers are stored as two 8-bit pieces, high order first.  The
X * value is a positive offset from the opcode of the node containing it.
X * An operand, if any, simply follows the node.  (Note that much of the
X * code generation knows about this implicit relationship.)
X *
X * Using two bytes for the "next" pointer is vast overkill for most things,
X * but allows patterns to get big without disasters.
X */
X#define    OP(p)    (*(p))
X#define    NEXT(p)    (((*((p)+1)&0377)<<8) + (*((p)+2)&0377))
X#define    OPERAND(p)    ((p) + 3)
X
X/*
X * See regmagic.h for one further detail of program structure.
X */
X
X
X/*
X * Utility definitions.
X */
X#ifndef CHARBITS
X#define    UCHARAT(p)    ((int)*(unsigned char *)(p))
X#else
X#define    UCHARAT(p)    ((int)*(p)&CHARBITS)
X#endif
X
X#define    FAIL(m)    { regerror(m); return(NULL); }
X#define    ISMULT(c)    ((c) == '*' || (c) == '+' || (c) == '?')
X#define    META    "^$.[()|?+*\\"
X
X/*
X * Flags to be passed up and down.
X */
X#define    HASWIDTH    01    /* Known never to match null string. */
X#define    SIMPLE        02    /* Simple enough to be STAR/PLUS operand. */
X#define    SPSTART        04    /* Starts with * or +. */
X#define    WORST        0    /* Worst case. */
X
X/*
X * Global work variables for regcomp().
X */
Xstatic char *regparse;        /* Input-scan pointer. */
Xstatic int regnpar;        /* () count. */
Xstatic char regdummy;
Xstatic char *regcode;        /* Code-emit pointer; ®dummy = don't. */
Xstatic long regsize;        /* Code size. */
X
X/*
X * The first byte of the regexp internal "program" is actually this magic
X * number; the start node begins in the second byte.
X */
X#define    MAGIC    0234
X
X
X/*
X * Forward declarations for regcomp()'s friends.
X */
X#ifndef STATIC
X#define    STATIC    static
X#endif
XSTATIC char *reg();
XSTATIC char *regbranch();
XSTATIC char *regpiece();
XSTATIC char *regatom();
XSTATIC char *regnode();
XSTATIC char *regnext();
XSTATIC void regc();
XSTATIC void reginsert();
XSTATIC void regtail();
XSTATIC void regoptail();
X#ifdef STRCSPN
XSTATIC int strcspn();
X#endif
X
X/*
X - regcomp - compile a regular expression into internal code
X *
X * We can't allocate space until we know how big the compiled form will be,
X * but we can't compile it (and thus know how big it is) until we've got a
X * place to put the code.  So we cheat:  we compile it twice, once with code
X * generation turned off and size counting turned on, and once "for real".
X * This also means that we don't allocate space until we are sure that the
X * thing really will compile successfully, and we never have to move the
X * code and thus invalidate pointers into it.  (Note that it has to be in
X * one piece because free() must be able to free it all.)
X *
X * Beware that the optimization-preparation code in here knows about some
X * of the structure of the compiled regexp.
X */
Xregexp *
Xregcomp(exp)
Xchar *exp;
X{
X    register regexp *r;
X    register char *scan;
X    register char *longest;
X    register int len;
X    int flags;
X
X    if (exp == NULL)
X        FAIL("NULL argument");
X
X    /* First pass: determine size, legality. */
X    regparse = exp;
X    regnpar = 1;
X    regsize = 0L;
X    regcode = ®dummy;
X    regc(MAGIC);
X    if (reg(0, &flags) == NULL)
X        return(NULL);
X
X    /* Small enough for pointer-storage convention? */
X    if (regsize >= 32767L)        /* Probably could be 65535L. */
X        FAIL("regexp too big");
X
X    /* Allocate space. */
X    r = (regexp *)ckalloc(sizeof(regexp) + (unsigned)regsize);
X    if (r == NULL)
X        FAIL("out of space");
X
X    /* Second pass: emit code. */
X    regparse = exp;
X    regnpar = 1;
X    regcode = r->program;
X    regc(MAGIC);
X    if (reg(0, &flags) == NULL)
X        return(NULL);
X
X    /* Dig out information for optimizations. */
X    r->regstart = '\0';    /* Worst-case defaults. */
X    r->reganch = 0;
X    r->regmust = NULL;
X    r->regmlen = 0;
X    scan = r->program+1;            /* First BRANCH. */
X    if (OP(regnext(scan)) == END) {        /* Only one top-level choice. */
X        scan = OPERAND(scan);
X
X        /* Starting-point info. */
X        if (OP(scan) == EXACTLY)
X            r->regstart = *OPERAND(scan);
X        else if (OP(scan) == BOL)
X            r->reganch++;
X
X        /*
X         * If there's something expensive in the r.e., find the
X         * longest literal string that must appear and make it the
X         * regmust.  Resolve ties in favor of later strings, since
X         * the regstart check works with the beginning of the r.e.
X         * and avoiding duplication strengthens checking.  Not a
X         * strong reason, but sufficient in the absence of others.
X         */
X        if (flags&SPSTART) {
X            longest = NULL;
X            len = 0;
X            for (; scan != NULL; scan = regnext(scan))
X                if (OP(scan) == EXACTLY && strlen(OPERAND(scan)) >= len) {
X                    longest = OPERAND(scan);
X                    len = strlen(OPERAND(scan));
X                }
X            r->regmust = longest;
X            r->regmlen = len;
X        }
X    }
X
X    return(r);
X}
X
X/*
X - reg - regular expression, i.e. main body or parenthesized thing
X *
X * Caller must absorb opening parenthesis.
X *
X * Combining parenthesis handling with the base level of regular expression
X * is a trifle forced, but the need to tie the tails of the branches to what
X * follows makes it hard to avoid.
X */
Xstatic char *
Xreg(paren, flagp)
Xint paren;            /* Parenthesized? */
Xint *flagp;
X{
X    register char *ret;
X    register char *br;
X    register char *ender;
X    register int parno = 0;
X    int flags;
X
X    *flagp = HASWIDTH;    /* Tentatively. */
X
X    /* Make an OPEN node, if parenthesized. */
X    if (paren) {
X        if (regnpar >= NSUBEXP)
X            FAIL("too many ()");
X        parno = regnpar;
X        regnpar++;
X        ret = regnode(OPEN+parno);
X    } else
X        ret = NULL;
X
X    /* Pick up the branches, linking them together. */
X    br = regbranch(&flags);
X    if (br == NULL)
X        return(NULL);
X    if (ret != NULL)
X        regtail(ret, br);    /* OPEN -> first. */
X    else
X        ret = br;
X    if (!(flags&HASWIDTH))
X        *flagp &= ~HASWIDTH;
X    *flagp |= flags&SPSTART;
X    while (*regparse == '|') {
X        regparse++;
X        br = regbranch(&flags);
X        if (br == NULL)
X            return(NULL);
X        regtail(ret, br);    /* BRANCH -> BRANCH. */
X        if (!(flags&HASWIDTH))
X            *flagp &= ~HASWIDTH;
X        *flagp |= flags&SPSTART;
X    }
X
X    /* Make a closing node, and hook it on the end. */
X    ender = regnode((paren) ? CLOSE+parno : END);
X    regtail(ret, ender);
X
X    /* Hook the tails of the branches to the closing node. */
X    for (br = ret; br != NULL; br = regnext(br))
X        regoptail(br, ender);
X
X    /* Check for proper termination. */
X    if (paren && *regparse++ != ')') {
X        FAIL("unmatched ()");
X    } else if (!paren && *regparse != '\0') {
X        if (*regparse == ')') {
X            FAIL("unmatched ()");
X        } else
X            FAIL("junk on end");    /* "Can't happen". */
X        /* NOTREACHED */
X    }
X
X    return(ret);
X}
X
X/*
X - regbranch - one alternative of an | operator
X *
X * Implements the concatenation operator.
X */
Xstatic char *
Xregbranch(flagp)
Xint *flagp;
X{
X    register char *ret;
X    register char *chain;
X    register char *latest;
X    int flags;
X
X    *flagp = WORST;        /* Tentatively. */
X
X    ret = regnode(BRANCH);
X    chain = NULL;
X    while (*regparse != '\0' && *regparse != '|' && *regparse != ')') {
X        latest = regpiece(&flags);
X        if (latest == NULL)
X            return(NULL);
X        *flagp |= flags&HASWIDTH;
X        if (chain == NULL)    /* First piece. */
X            *flagp |= flags&SPSTART;
X        else
X            regtail(chain, latest);
X        chain = latest;
X    }
X    if (chain == NULL)    /* Loop ran zero times. */
X        (void) regnode(NOTHING);
X
X    return(ret);
X}
X
X/*
X - regpiece - something followed by possible [*+?]
X *
X * Note that the branching code sequences used for ? and the general cases
X * of * and + are somewhat optimized:  they use the same NOTHING node as
X * both the endmarker for their branch list and the body of the last branch.
X * It might seem that this node could be dispensed with entirely, but the
X * endmarker role is not redundant.
X */
Xstatic char *
Xregpiece(flagp)
Xint *flagp;
X{
X    register char *ret;
X    register char op;
X    register char *next;
X    int flags;
X
X    ret = regatom(&flags);
X    if (ret == NULL)
X        return(NULL);
X
X    op = *regparse;
X    if (!ISMULT(op)) {
X        *flagp = flags;
X        return(ret);
X    }
X
X    if (!(flags&HASWIDTH) && op != '?')
X        FAIL("*+ operand could be empty");
X    *flagp = (op != '+') ? (WORST|SPSTART) : (WORST|HASWIDTH);
X
X    if (op == '*' && (flags&SIMPLE))
X        reginsert(STAR, ret);
X    else if (op == '*') {
X        /* Emit x* as (x&|), where & means "self". */
X        reginsert(BRANCH, ret);            /* Either x */
X        regoptail(ret, regnode(BACK));        /* and loop */
X        regoptail(ret, ret);            /* back */
X        regtail(ret, regnode(BRANCH));        /* or */
X        regtail(ret, regnode(NOTHING));        /* null. */
X    } else if (op == '+' && (flags&SIMPLE))
X        reginsert(PLUS, ret);
X    else if (op == '+') {
X        /* Emit x+ as x(&|), where & means "self". */
X        next = regnode(BRANCH);            /* Either */
X        regtail(ret, next);
X        regtail(regnode(BACK), ret);        /* loop back */
X        regtail(next, regnode(BRANCH));        /* or */
X        regtail(ret, regnode(NOTHING));        /* null. */
X    } else if (op == '?') {
X        /* Emit x? as (x|) */
X        reginsert(BRANCH, ret);            /* Either x */
X        regtail(ret, regnode(BRANCH));        /* or */
X        next = regnode(NOTHING);        /* null. */
X        regtail(ret, next);
X        regoptail(ret, next);
X    }
X    regparse++;
X    if (ISMULT(*regparse))
X        FAIL("nested *?+");
X
X    return(ret);
X}
X
X/*
X - regatom - the lowest level
X *
X * Optimization:  gobbles an entire sequence of ordinary characters so that
X * it can turn them into a single node, which is smaller to store and
X * faster to run.  Backslashed characters are exceptions, each becoming a
X * separate node; the code is simpler that way and it's not worth fixing.
X */
Xstatic char *
Xregatom(flagp)
Xint *flagp;
X{
X    register char *ret;
X    int flags;
X
X    *flagp = WORST;        /* Tentatively. */
X
X    switch (*regparse++) {
X    case '^':
X        ret = regnode(BOL);
X        break;
X    case '$':
X        ret = regnode(EOL);
X        break;
X    case '.':
X        ret = regnode(ANY);
X        *flagp |= HASWIDTH|SIMPLE;
X        break;
X    case '[': {
X            register int clss;
X            register int classend;
X
X            if (*regparse == '^') {    /* Complement of range. */
X                ret = regnode(ANYBUT);
X                regparse++;
X            } else
X                ret = regnode(ANYOF);
X            if (*regparse == ']' || *regparse == '-')
X                regc(*regparse++);
X            while (*regparse != '\0' && *regparse != ']') {
X                if (*regparse == '-') {
X                    regparse++;
X                    if (*regparse == ']' || *regparse == '\0')
X                        regc('-');
X                    else {
X                        clss = UCHARAT(regparse-2)+1;
X                        classend = UCHARAT(regparse);
X                        if (clss > classend+1)
X                            FAIL("invalid [] range");
X                        for (; clss <= classend; clss++)
X                            regc(clss);
X                        regparse++;
X                    }
X                } else
X                    regc(*regparse++);
X            }
X            regc('\0');
X            if (*regparse != ']')
X                FAIL("unmatched []");
X            regparse++;
X            *flagp |= HASWIDTH|SIMPLE;
X        }
X        break;
X    case '(':
X        ret = reg(1, &flags);
X        if (ret == NULL)
X            return(NULL);
X        *flagp |= flags&(HASWIDTH|SPSTART);
X        break;
X    case '\0':
X    case '|':
X    case ')':
X        FAIL("internal urp");    /* Supposed to be caught earlier. */
X        /* NOTREACHED */
X        break;
X    case '?':
X    case '+':
X    case '*':
X        FAIL("?+* follows nothing");
X        /* NOTREACHED */
X        break;
X    case '\\':
X        if (*regparse == '\0')
X            FAIL("trailing \\");
X        ret = regnode(EXACTLY);
X        regc(*regparse++);
X        regc('\0');
X        *flagp |= HASWIDTH|SIMPLE;
X        break;
X    default: {
X            register int len;
X            register char ender;
X
X            regparse--;
X            len = strcspn(regparse, META);
X            if (len <= 0)
X                FAIL("internal disaster");
X            ender = *(regparse+len);
X            if (len > 1 && ISMULT(ender))
X                len--;        /* Back off clear of ?+* operand. */
X            *flagp |= HASWIDTH;
X            if (len == 1)
X                *flagp |= SIMPLE;
X            ret = regnode(EXACTLY);
X            while (len > 0) {
X                regc(*regparse++);
X                len--;
X            }
X            regc('\0');
X        }
X        break;
X    }
X
X    return(ret);
X}
X
X/*
X - regnode - emit a node
X */
Xstatic char *            /* Location. */
Xregnode(op)
Xchar op;
X{
X    register char *ret;
X    register char *ptr;
X
X    ret = regcode;
X    if (ret == ®dummy) {
X        regsize += 3;
X        return(ret);
X    }
X
X    ptr = ret;
X    *ptr++ = op;
X    *ptr++ = '\0';        /* Null "next" pointer. */
X    *ptr++ = '\0';
X    regcode = ptr;
X
X    return(ret);
X}
X
X/*
X - regc - emit (if appropriate) a byte of code
X */
Xstatic void
Xregc(b)
Xchar b;
X{
X    if (regcode != ®dummy)
X        *regcode++ = b;
X    else
X        regsize++;
X}
X
X/*
X - reginsert - insert an operator in front of already-emitted operand
X *
X * Means relocating the operand.
X */
Xstatic void
Xreginsert(op, opnd)
Xchar op;
Xchar *opnd;
X{
X    register char *src;
X    register char *dst;
X    register char *place;
X
X    if (regcode == ®dummy) {
X        regsize += 3;
X        return;
X    }
X
X    src = regcode;
X    regcode += 3;
X    dst = regcode;
X    while (src > opnd)
X        *--dst = *--src;
X
X    place = opnd;        /* Op node, where operand used to be. */
X    *place++ = op;
X    *place++ = '\0';
X    *place++ = '\0';
X}
X
X/*
X - regtail - set the next-pointer at the end of a node chain
X */
Xstatic void
Xregtail(p, val)
Xchar *p;
Xchar *val;
X{
X    register char *scan;
X    register char *temp;
X    register int offset;
X
X    if (p == ®dummy)
X        return;
X
X    /* Find last node. */
X    scan = p;
X    for (;;) {
X        temp = regnext(scan);
X        if (temp == NULL)
X            break;
X        scan = temp;
X    }
X
X    if (OP(scan) == BACK)
X        offset = scan - val;
X    else
X        offset = val - scan;
X    *(scan+1) = (offset>>8)&0377;
X    *(scan+2) = offset&0377;
X}
X
X/*
X - regoptail - regtail on operand of first argument; nop if operandless
X */
Xstatic void
Xregoptail(p, val)
Xchar *p;
Xchar *val;
X{
X    /* "Operandless" and "op != BRANCH" are synonymous in practice. */
X    if (p == NULL || p == ®dummy || OP(p) != BRANCH)
X        return;
X    regtail(OPERAND(p), val);
X}
X
X/*
X * regexec and friends
X */
X
X/*
X * Global work variables for regexec().
X */
Xstatic char *reginput;        /* String-input pointer. */
Xstatic char *regbol;        /* Beginning of input, for ^ check. */
Xstatic char **regstartp;    /* Pointer to startp array. */
Xstatic char **regendp;        /* Ditto for endp. */
X
X/*
X * Forwards.
X */
XSTATIC int regtry();
XSTATIC int regmatch();
XSTATIC int regrepeat();
X
X#ifdef DEBUG
Xint regnarrate = 0;
Xvoid regdump();
XSTATIC char *regprop();
X#endif
X
X/*
X - regexec - match a regexp against a string
X */
Xint
Xregexec(prog, string)
Xregister regexp *prog;
Xregister char *string;
X{
X    register char *s;
X    extern char *strchr();
X
X    /* Be paranoid... */
X    if (prog == NULL || string == NULL) {
X        regerror("NULL parameter");
X        return(0);
X    }
X
X    /* Check validity of program. */
X    if (UCHARAT(prog->program) != MAGIC) {
X        regerror("corrupted program");
X        return(0);
X    }
X
X    /* If there is a "must appear" string, look for it. */
X    if (prog->regmust != NULL) {
X        s = string;
X        while ((s = strchr(s, prog->regmust[0])) != NULL) {
X            if (strncmp(s, prog->regmust, prog->regmlen) == 0)
X                break;    /* Found it. */
X            s++;
X        }
X        if (s == NULL)    /* Not present. */
X            return(0);
X    }
X
X    /* Mark beginning of line for ^ . */
X    regbol = string;
X
X    /* Simplest case:  anchored match need be tried only once. */
X    if (prog->reganch)
X        return(regtry(prog, string));
X
X    /* Messy cases:  unanchored match. */
X    s = string;
X    if (prog->regstart != '\0')
X        /* We know what char it must start with. */
X        while ((s = strchr(s, prog->regstart)) != NULL) {
X            if (regtry(prog, s))
X                return(1);
X            s++;
X        }
X    else
X        /* We don't -- general case. */
X        do {
X            if (regtry(prog, s))
X                return(1);
X        } while (*s++ != '\0');
X
X    /* Failure. */
X    return(0);
X}
X
X/*
X - regtry - try match at specific point
X */
Xstatic int            /* 0 failure, 1 success */
Xregtry(prog, string)
Xregexp *prog;
Xchar *string;
X{
X    register int i;
X    register char **sp;
X    register char **ep;
X
X    reginput = string;
X    regstartp = prog->startp;
X    regendp = prog->endp;
X
X    sp = prog->startp;
X    ep = prog->endp;
X    for (i = NSUBEXP; i > 0; i--) {
X        *sp++ = NULL;
X        *ep++ = NULL;
X    }
X    if (regmatch(prog->program + 1)) {
X        prog->startp[0] = string;
X        prog->endp[0] = reginput;
X        return(1);
X    } else
X        return(0);
X}
X
X/*
X - regmatch - main matching routine
X *
X * Conceptually the strategy is simple:  check to see whether the current
X * node matches, call self recursively to see whether the rest matches,
X * and then act accordingly.  In practice we make some effort to avoid
X * recursion, in particular by going through "ordinary" nodes (that don't
X * need to know whether the rest of the match failed) by a loop instead of
X * by recursion.
X */
Xstatic int            /* 0 failure, 1 success */
Xregmatch(prog)
Xchar *prog;
X{
X    register char *scan;    /* Current node. */
X    char *next;        /* Next node. */
X    extern char *strchr();
X
X    scan = prog;
X#ifdef DEBUG
X    if (scan != NULL && regnarrate)
X        fprintf(stderr, "%s(\n", regprop(scan));
X#endif
X    while (scan != NULL) {
X#ifdef DEBUG
X        if (regnarrate)
X            fprintf(stderr, "%s...\n", regprop(scan));
X#endif
X        next = regnext(scan);
X
X        switch (OP(scan)) {
X        case BOL:
X            if (reginput != regbol)
X                return(0);
X            break;
X        case EOL:
X            if (*reginput != '\0')
X                return(0);
X            break;
X        case ANY:
X            if (*reginput == '\0')
X                return(0);
X            reginput++;
X            break;
X        case EXACTLY: {
X                register int len;
X                register char *opnd;
X
X                opnd = OPERAND(scan);
X                /* Inline the first character, for speed. */
X                if (*opnd != *reginput)
X                    return(0);
X                len = strlen(opnd);
X                if (len > 1 && strncmp(opnd, reginput, len) != 0)
X                    return(0);
X                reginput += len;
X            }
X            break;
X        case ANYOF:
X             if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == NULL)
X                return(0);
X            reginput++;
X            break;
X        case ANYBUT:
X             if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != NULL)
X                return(0);
X            reginput++;
X            break;
X        case NOTHING:
X            break;
X        case BACK:
X            break;
X        case OPEN+1:
X        case OPEN+2:
X        case OPEN+3:
X        case OPEN+4:
X        case OPEN+5:
X        case OPEN+6:
X        case OPEN+7:
X        case OPEN+8:
X        case OPEN+9: {
X                register int no;
X                register char *save;
X
X                no = OP(scan) - OPEN;
X                save = reginput;
X
X                if (regmatch(next)) {
X                    /*
X                     * Don't set startp if some later
X                     * invocation of the same parentheses
X                     * already has.
X                     */
X                    if (regstartp[no] == NULL)
X                        regstartp[no] = save;
X                    return(1);
X                } else
X                    return(0);
X            }
X            /* NOTREACHED */
X            break;
X        case CLOSE+1:
X        case CLOSE+2:
X        case CLOSE+3:
X        case CLOSE+4:
X        case CLOSE+5:
X        case CLOSE+6:
X        case CLOSE+7:
X        case CLOSE+8:
X        case CLOSE+9: {
X                register int no;
X                register char *save;
X
X                no = OP(scan) - CLOSE;
X                save = reginput;
X
X                if (regmatch(next)) {
X                    /*
X                     * Don't set endp if some later
X                     * invocation of the same parentheses
X                     * already has.
X                     */
X                    if (regendp[no] == NULL)
X                        regendp[no] = save;
X                    return(1);
X                } else
X                    return(0);
X            }
X            /* NOTREACHED */
X            break;
X        case BRANCH: {
X                register char *save;
X
X                if (OP(next) != BRANCH)        /* No choice. */
X                    next = OPERAND(scan);    /* Avoid recursion. */
X                else {
X                    do {
X                        save = reginput;
X                        if (regmatch(OPERAND(scan)))
X                            return(1);
X                        reginput = save;
X                        scan = regnext(scan);
X                    } while (scan != NULL && OP(scan) == BRANCH);
X                    return(0);
X                    /* NOTREACHED */
X                }
X            }
X            /* NOTREACHED */
X            break;
X        case STAR:
X        case PLUS: {
X                register char nextch;
X                register int no;
X                register char *save;
X                register int min;
X
X                /*
X                 * Lookahead to avoid useless match attempts
X                 * when we know what character comes next.
X                 */
X                nextch = '\0';
X                if (OP(next) == EXACTLY)
X                    nextch = *OPERAND(next);
X                min = (OP(scan) == STAR) ? 0 : 1;
X                save = reginput;
X                no = regrepeat(OPERAND(scan));
X                while (no >= min) {
X                    /* If it could work, try it. */
X                    if (nextch == '\0' || *reginput == nextch)
X                        if (regmatch(next))
X                            return(1);
X                    /* Couldn't or didn't -- back up. */
X                    no--;
X                    reginput = save + no;
X                }
X                return(0);
X            }
X            /* NOTREACHED */
X            break;
X        case END:
X            return(1);    /* Success! */
X            /* NOTREACHED */
X            break;
X        default:
X            regerror("memory corruption");
X            return(0);
X            /* NOTREACHED */
X            break;
X        }
X
X        scan = next;
X    }
X
X    /*
X     * We get here only if there's trouble -- normally "case END" is
X     * the terminating point.
X     */
X    regerror("corrupted pointers");
X    return(0);
X}
X
X/*
X - regrepeat - repeatedly match something simple, report how many
X */
Xstatic int
Xregrepeat(p)
Xchar *p;
X{
X    register int count = 0;
X    register char *scan;
X    register char *opnd;
X
X    scan = reginput;
X    opnd = OPERAND(p);
X    switch (OP(p)) {
X    case ANY:
X        count = strlen(scan);
X        scan += count;
X        break;
X    case EXACTLY:
X        while (*opnd == *scan) {
X            count++;
X            scan++;
X        }
X        break;
X    case ANYOF:
X        while (*scan != '\0' && strchr(opnd, *scan) != NULL) {
X            count++;
X            scan++;
X        }
X        break;
X    case ANYBUT:
X        while (*scan != '\0' && strchr(opnd, *scan) == NULL) {
X            count++;
X            scan++;
X        }
X        break;
X    default:        /* Oh dear.  Called inappropriately. */
X        regerror("internal foulup");
X        count = 0;    /* Best compromise. */
X        break;
X    }
X    reginput = scan;
X
X    return(count);
X}
X
X/*
X - regnext - dig the "next" pointer out of a node
X */
Xstatic char *
Xregnext(p)
Xregister char *p;
X{
X    register int offset;
X
X    if (p == ®dummy)
X        return(NULL);
X
X    offset = NEXT(p);
X    if (offset == 0)
X        return(NULL);
X
X    if (OP(p) == BACK)
X        return(p-offset);
X    else
X        return(p+offset);
X}
X
X#ifdef DEBUG
X
XSTATIC char *regprop();
X
X/*
X - regdump - dump a regexp onto stdout in vaguely comprehensible form
X */
Xvoid
Xregdump(r)
Xregexp *r;
X{
X    register char *s;
X    register char op = EXACTLY;    /* Arbitrary non-END op. */
X    register char *next;
X    extern char *strchr();
X
X
X    s = r->program + 1;
X    while (op != END) {    /* While that wasn't END last time... */
X        op = OP(s);
X        printf("%2d%s", s-r->program, regprop(s));    /* Where, what. */
X        next = regnext(s);
X        if (next == NULL)        /* Next ptr. */
X            printf("(0)");
X        else
X            printf("(%d)", (s-r->program)+(next-s));
X        s += 3;
X        if (op == ANYOF || op == ANYBUT || op == EXACTLY) {
X            /* Literal string, where present. */
X            while (*s != '\0') {
X                putchar(*s);
X                s++;
X            }
X            s++;
X        }
X        putchar('\n');
X    }
X
X    /* Header fields of interest. */
X    if (r->regstart != '\0')
X        printf("start `%c' ", r->regstart);
X    if (r->reganch)
X        printf("anchored ");
X    if (r->regmust != NULL)
X        printf("must have \"%s\"", r->regmust);
X    printf("\n");
X}
X
X/*
X - regprop - printable representation of opcode
X */
Xstatic char *
Xregprop(op)
Xchar *op;
X{
X    register char *p;
X    static char buf[50];
X
X    (void) strcpy(buf, ":");
X
X    switch (OP(op)) {
X    case BOL:
X        p = "BOL";
X        break;
X    case EOL:
X        p = "EOL";
X        break;
X    case ANY:
X        p = "ANY";
X        break;
X    case ANYOF:
X        p = "ANYOF";
X        break;
X    case ANYBUT:
X        p = "ANYBUT";
X        break;
X    case BRANCH:
X        p = "BRANCH";
X        break;
X    case EXACTLY:
X        p = "EXACTLY";
X        break;
X    case NOTHING:
X        p = "NOTHING";
X        break;
X    case BACK:
X        p = "BACK";
X        break;
X    case END:
X        p = "END";
X        break;
X    case OPEN+1:
X    case OPEN+2:
X    case OPEN+3:
X    case OPEN+4:
X    case OPEN+5:
X    case OPEN+6:
X    case OPEN+7:
X    case OPEN+8:
X    case OPEN+9:
X        sprintf(buf+strlen(buf), "OPEN%d", OP(op)-OPEN);
X        p = NULL;
X        break;
X    case CLOSE+1:
X    case CLOSE+2:
X    case CLOSE+3:
X    case CLOSE+4:
X    case CLOSE+5:
X    case CLOSE+6:
X    case CLOSE+7:
X    case CLOSE+8:
X    case CLOSE+9:
X        sprintf(buf+strlen(buf), "CLOSE%d", OP(op)-CLOSE);
X        p = NULL;
X        break;
X    case STAR:
X        p = "STAR";
X        break;
X    case PLUS:
X        p = "PLUS";
X        break;
X    default:
X        regerror("corrupted opcode");
X        break;
X    }
X    if (p != NULL)
X        (void) strcat(buf, p);
X    return(buf);
X}
X#endif
X
X/*
X * The following is provided for those people who do not have strcspn() in
X * their C libraries.  They should get off their butts and do something
X * about it; at least one public-domain implementation of those (highly
X * useful) string routines has been published on Usenet.
X */
X#ifdef STRCSPN
X/*
X * strcspn - find length of initial segment of s1 consisting entirely
X * of characters not from s2
X */
X
Xstatic int
Xstrcspn(s1, s2)
Xchar *s1;
Xchar *s2;
X{
X    register char *scan1;
X    register char *scan2;
X    register int count;
X
X    count = 0;
X    for (scan1 = s1; *scan1 != '\0'; scan1++) {
X        for (scan2 = s2; *scan2 != '\0';)    /* ++ moved down. */
X            if (*scan1 == *scan2++)
X                return(count);
X        count++;
X    }
X    return(count);
X}
X#endif
END_OF_FILE
if test 28040 -ne `wc -c <'tcl6.1/regexp.c'`; then
    echo shar: \"'tcl6.1/regexp.c'\" unpacked with wrong size!
fi
# end of 'tcl6.1/regexp.c'
fi
echo shar: End of archive 18 \(of 33\).
cp /dev/null ark18isdone
MISSING=""
for I in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 ; do
    if test ! -f ark${I}isdone ; then
    MISSING="${MISSING} ${I}"
    fi
done
if test "${MISSING}" = "" ; then
    echo You have unpacked all 33 archives.
    rm -f ark[1-9]isdone ark[1-9][0-9]isdone
else
    echo You still need to unpack the following archives:
    echo "        " ${MISSING}
fi
##  End of shell archive.
exit 0

exit 0 # Just in case...
--
Kent Landfield                   INTERNET: [e-mail]
Sterling Software, IMD           UUCP:     uunet!sparky!kent
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