common/regex/regsubexec.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped

/*
 * posix regex ed(1) style substitute execute
 */

#include "reglib.h"

#define NEED(p,b,n,r)   \
    do \
    { \
        if (((b)->re_end - (b)->re_cur) < (n)) \
        { \
            size_t  o = (b)->re_cur - (b)->re_buf; \
            size_t  a = ((b)->re_end - (b)->re_buf); \
            if (a < n) \
                a = roundof(n, 128); \
            a *= 2; \
            if (!((b)->re_buf = alloc(p->env->disc, (b)->re_buf, a))) \
            { \
                (b)->re_buf = (b)->re_cur = (b)->re_end = 0; \
                c = REG_ESPACE; \
                r; \
            } \
            (b)->re_cur = (b)->re_buf + o; \
            (b)->re_end = (b)->re_buf + a; \
        } \
    } while (0)

#define PUTC(p,b,x,r)   \
    do \
    { \
        NEED(p, b, 1, r); \
        *(b)->re_cur++ = (x); \
    } while (0)

#define PUTS(p,b,x,z,r) \
    do if (z) \
    { \
        NEED(p, b, z, r); \
        memcpy((b)->re_cur, x, z); \
        (b)->re_cur += (z); \
    } while (0)

/*
 * do a single substitution
 */

static int
sub(const regex_t* p, register regsub_t* b, const char* ss, register regsubop_t* op, size_t nmatch, register regmatch_t* match)
{
    register char*  s;
    register char*  e;
    register int    c;

    for (;; op++)
    {
        switch (op->len)
        {
        case -1:
            break;
        case 0:
            if (op->off >= nmatch)
                return REG_ESUBREG;
            if ((c = match[op->off].rm_so) < 0)
                continue;
            s = (char*)ss + c;
            if ((c = match[op->off].rm_eo) < 0)
                continue;
            e = (char*)ss + c;
            NEED(p, b, e - s, return c);
            switch (op->op)
            {
            case REG_SUB_UPPER:
                while (s < e)
                {
                    c = *s++;
                    if (islower(c))
                        c = toupper(c);
                    *b->re_cur++ = c;
                }
                break;
            case REG_SUB_LOWER:
                while (s < e)
                {
                    c = *s++;
                    if (isupper(c))
                        c = tolower(c);
                    *b->re_cur++ = c;
                }
                break;
            case REG_SUB_UPPER|REG_SUB_LOWER:
                while (s < e)
                {
                    c = *s++;
                    if (isupper(c))
                        c = tolower(c);
                    else if (islower(c))
                        c = toupper(c);
                    *b->re_cur++ = c;
                }
                break;
            default:
                while (s < e)
                    *b->re_cur++ = *s++;
                break;
            }
            continue;
        default:
            NEED(p, b, op->len, return c);
            s = b->re_rhs + op->off;
            e = s + op->len;
            while (s < e)
                *b->re_cur++ = *s++;
            continue;
        }
        break;
    }
    return 0;
}

/*
 * ed(1) style substitute using matches from last regexec()
 */

int
regsubexec(const regex_t* p, const char* s, size_t nmatch, regmatch_t* match)
{
    register int        c;
    register regsub_t*  b;
    const char*     e;
    int         m;

    if (!p->env->sub || (p->env->flags & REG_NOSUB) || !nmatch)
        return fatal(p->env->disc, REG_BADPAT, NiL);
    b = p->re_sub;
    m = b->re_min;
    b->re_cur = b->re_buf;
    e = (const char*)p->env->end;
    c = 0;
    for (;;)
    {
        if (--m > 0)
            PUTS(p, b, s, match->rm_eo, return fatal(p->env->disc, c, NiL));
        else
        {
            PUTS(p, b, s, match->rm_so, return fatal(p->env->disc, c, NiL));
            if (!c && (c = sub(p, b, s, b->re_ops, nmatch, match)))
                return fatal(p->env->disc, c, NiL);
        }
        s += match->rm_eo;
        if (m <= 0 && !(b->re_flags & REG_SUB_ALL) || !*s)
            break;
        if (c = regnexec(p, s, e - s, nmatch, match, p->env->flags|(match->rm_so == match->rm_eo ? REG_ADVANCE : 0)))
        {
            if (c != REG_NOMATCH)
                return fatal(p->env->disc, c, NiL);
            break;
        }
        if (!match->rm_so && !match->rm_eo && *s && m <= 1)
        {
            match->rm_so = match->rm_eo = 1;
            c = 1;
        }
    }
    while (s < e)
    {
        c = *s++;
        PUTC(p, b, c, return fatal(p->env->disc, c, NiL));
    }
    NEED(p, b, 1, return fatal(p->env->disc, c, NiL));
    *b->re_cur = 0;
    b->re_len = b->re_cur - b->re_buf;
    return 0;
}