_sre.c

/*
 * Secret Labs' Regular Expression Engine
 *
 * regular expression matching engine
 *
 * partial history:
 * 1999-10-24 fl  created (based on existing template matcher code)
 * 2000-03-06 fl  first alpha, sort of
 * 2000-08-01 fl  fixes for 1.6b1
 * 2000-08-07 fl  use PyOS_CheckStack() if available
 * 2000-09-20 fl  added expand method
 * 2001-03-20 fl  lots of fixes for 2.1b2
 * 2001-04-15 fl  export copyright as Python attribute, not global
 * 2001-04-28 fl  added __copy__ methods (work in progress)
 * 2001-05-14 fl  fixes for 1.5.2 compatibility
 * 2001-07-01 fl  added BIGCHARSET support (from Martin von Loewis)
 * 2001-10-18 fl  fixed group reset issue (from Matthew Mueller)
 * 2001-10-20 fl  added split primitive; reenable unicode for 1.6/2.0/2.1
 * 2001-10-21 fl  added sub/subn primitive
 * 2001-10-24 fl  added finditer primitive (for 2.2 only)
 * 2001-12-07 fl  fixed memory leak in sub/subn (Guido van Rossum)
 * 2002-11-09 fl  fixed empty sub/subn return type
 * 2003-04-18 mvl fully support 4-byte codes
 * 2003-10-17 gn  implemented non recursive scheme
 *
 * Copyright (c) 1997-2001 by Secret Labs AB.  All rights reserved.
 *
 * This version of the SRE library can be redistributed under CNRI's
 * Python 1.6 license.  For any other use, please contact Secret Labs
 * AB (info@pythonware.com).
 *
 * Portions of this engine have been developed in cooperation with
 * CNRI.  Hewlett-Packard provided funding for 1.6 integration and
 * other compatibility work.
 */

#ifndef SRE_RECURSIVE

static char copyright[] =
    " SRE 2.2.2 Copyright (c) 1997-2002 by Secret Labs AB ";

#include "Python.h"
#include "structmember.h" /* offsetof */

#include "sre.h"

#include <ctype.h>

/* name of this module, minus the leading underscore */
#if !defined(SRE_MODULE)
#define SRE_MODULE "sre"
#endif

/* defining this one enables tracing */
#undef VERBOSE

#if PY_VERSION_HEX >= 0x01060000
#if PY_VERSION_HEX  < 0x02020000 || defined(Py_USING_UNICODE)
/* defining this enables unicode support (default under 1.6a1 and later) */
#define HAVE_UNICODE
#endif
#endif

/* -------------------------------------------------------------------- */
/* optional features */

/* enables fast searching */
#define USE_FAST_SEARCH

/* enables aggressive inlining (always on for Visual C) */
#undef USE_INLINE

/* enables copy/deepcopy handling (work in progress) */
#undef USE_BUILTIN_COPY

#if PY_VERSION_HEX < 0x01060000
#define PyObject_DEL(op) PyMem_DEL((op))
#endif

/* -------------------------------------------------------------------- */

#if defined(_MSC_VER)
#pragma optimize("agtw", on) /* doesn't seem to make much difference... */
#pragma warning(disable: 4710) /* who cares if functions are not inlined ;-) */
/* fastest possible local call under MSVC */
#define LOCAL(type) static __inline type __fastcall
#elif defined(USE_INLINE)
#define LOCAL(type) static inline type
#else
#define LOCAL(type) static type
#endif

/* error codes */
#define SRE_ERROR_ILLEGAL -1 /* illegal opcode */
#define SRE_ERROR_STATE -2 /* illegal state */
#define SRE_ERROR_RECURSION_LIMIT -3 /* runaway recursion */
#define SRE_ERROR_MEMORY -9 /* out of memory */

#if defined(VERBOSE)
#define TRACE(v) printf v
#else
#define TRACE(v)
#endif

/* -------------------------------------------------------------------- */
/* search engine state */

/* default character predicates (run sre_chars.py to regenerate tables) */

#define SRE_DIGIT_MASK 1
#define SRE_SPACE_MASK 2
#define SRE_LINEBREAK_MASK 4
#define SRE_ALNUM_MASK 8
#define SRE_WORD_MASK 16

/* FIXME: this assumes ASCII.  create tables in init_sre() instead */

static char sre_char_info[128] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 6, 2,
2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 0, 0, 0, 0, 0, 0, 0, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 0, 0,
0, 0, 16, 0, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 0, 0, 0, 0, 0 };

static char sre_char_lower[128] = { 0, 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, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,
44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60,
61, 62, 63, 64, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,
108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
122, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105,
106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119,
120, 121, 122, 123, 124, 125, 126, 127 };

#define SRE_IS_DIGIT(ch)\
    ((ch) < 128 ? (sre_char_info[(ch)] & SRE_DIGIT_MASK) : 0)
#define SRE_IS_SPACE(ch)\
    ((ch) < 128 ? (sre_char_info[(ch)] & SRE_SPACE_MASK) : 0)
#define SRE_IS_LINEBREAK(ch)\
    ((ch) < 128 ? (sre_char_info[(ch)] & SRE_LINEBREAK_MASK) : 0)
#define SRE_IS_ALNUM(ch)\
    ((ch) < 128 ? (sre_char_info[(ch)] & SRE_ALNUM_MASK) : 0)
#define SRE_IS_WORD(ch)\
    ((ch) < 128 ? (sre_char_info[(ch)] & SRE_WORD_MASK) : 0)

static unsigned int sre_lower(unsigned int ch)
{
    return ((ch) < 128 ? (unsigned int)sre_char_lower[ch] : ch);
}

/* locale-specific character predicates */
/* !(c & ~N) == (c < N+1) for any unsigned c, this avoids
 * warnings when c's type supports only numbers < N+1 */
#define SRE_LOC_IS_DIGIT(ch) (!((ch) & ~255) ? isdigit((ch)) : 0)
#define SRE_LOC_IS_SPACE(ch) (!((ch) & ~255) ? isspace((ch)) : 0)
#define SRE_LOC_IS_LINEBREAK(ch) ((ch) == '\n')
#define SRE_LOC_IS_ALNUM(ch) (!((ch) & ~255) ? isalnum((ch)) : 0)
#define SRE_LOC_IS_WORD(ch) (SRE_LOC_IS_ALNUM((ch)) || (ch) == '_')

static unsigned int sre_lower_locale(unsigned int ch)
{
    return ((ch) < 256 ? (unsigned int)tolower((ch)) : ch);
}

/* unicode-specific character predicates */

#if defined(HAVE_UNICODE)

#define SRE_UNI_IS_DIGIT(ch) Py_UNICODE_ISDIGIT((Py_UNICODE)(ch))
#define SRE_UNI_IS_SPACE(ch) Py_UNICODE_ISSPACE((Py_UNICODE)(ch))
#define SRE_UNI_IS_LINEBREAK(ch) Py_UNICODE_ISLINEBREAK((Py_UNICODE)(ch))
#define SRE_UNI_IS_ALNUM(ch) Py_UNICODE_ISALNUM((Py_UNICODE)(ch))
#define SRE_UNI_IS_WORD(ch) (SRE_UNI_IS_ALNUM((ch)) || (ch) == '_')

static unsigned int sre_lower_unicode(unsigned int ch)
{
    return (unsigned int) Py_UNICODE_TOLOWER((Py_UNICODE)(ch));
}

#endif

LOCAL(int)
sre_category(SRE_CODE category, unsigned int ch)
{
    switch (category) {

    case SRE_CATEGORY_DIGIT:
        return SRE_IS_DIGIT(ch);
    case SRE_CATEGORY_NOT_DIGIT:
        return !SRE_IS_DIGIT(ch);
    case SRE_CATEGORY_SPACE:
        return SRE_IS_SPACE(ch);
    case SRE_CATEGORY_NOT_SPACE:
        return !SRE_IS_SPACE(ch);
    case SRE_CATEGORY_WORD:
        return SRE_IS_WORD(ch);
    case SRE_CATEGORY_NOT_WORD:
        return !SRE_IS_WORD(ch);
    case SRE_CATEGORY_LINEBREAK:
        return SRE_IS_LINEBREAK(ch);
    case SRE_CATEGORY_NOT_LINEBREAK:
        return !SRE_IS_LINEBREAK(ch);

    case SRE_CATEGORY_LOC_WORD:
        return SRE_LOC_IS_WORD(ch);
    case SRE_CATEGORY_LOC_NOT_WORD:
        return !SRE_LOC_IS_WORD(ch);

#if defined(HAVE_UNICODE)
    case SRE_CATEGORY_UNI_DIGIT:
        return SRE_UNI_IS_DIGIT(ch);
    case SRE_CATEGORY_UNI_NOT_DIGIT:
        return !SRE_UNI_IS_DIGIT(ch);
    case SRE_CATEGORY_UNI_SPACE:
        return SRE_UNI_IS_SPACE(ch);
    case SRE_CATEGORY_UNI_NOT_SPACE:
        return !SRE_UNI_IS_SPACE(ch);
    case SRE_CATEGORY_UNI_WORD:
        return SRE_UNI_IS_WORD(ch);
    case SRE_CATEGORY_UNI_NOT_WORD:
        return !SRE_UNI_IS_WORD(ch);
    case SRE_CATEGORY_UNI_LINEBREAK:
        return SRE_UNI_IS_LINEBREAK(ch);
    case SRE_CATEGORY_UNI_NOT_LINEBREAK:
        return !SRE_UNI_IS_LINEBREAK(ch);
#else
    case SRE_CATEGORY_UNI_DIGIT:
        return SRE_IS_DIGIT(ch);
    case SRE_CATEGORY_UNI_NOT_DIGIT:
        return !SRE_IS_DIGIT(ch);
    case SRE_CATEGORY_UNI_SPACE:
        return SRE_IS_SPACE(ch);
    case SRE_CATEGORY_UNI_NOT_SPACE:
        return !SRE_IS_SPACE(ch);
    case SRE_CATEGORY_UNI_WORD:
        return SRE_LOC_IS_WORD(ch);
    case SRE_CATEGORY_UNI_NOT_WORD:
        return !SRE_LOC_IS_WORD(ch);
    case SRE_CATEGORY_UNI_LINEBREAK:
        return SRE_IS_LINEBREAK(ch);
    case SRE_CATEGORY_UNI_NOT_LINEBREAK:
        return !SRE_IS_LINEBREAK(ch);
#endif
    }
    return 0;
}

/* helpers */

static void
data_stack_dealloc(SRE_STATE* state)
{
    if (state->data_stack) {
        free(state->data_stack);
        state->data_stack = NULL;
    }
    state->data_stack_size = state->data_stack_base = 0;
}

static int
data_stack_grow(SRE_STATE* state, int size)
{
    int minsize, cursize;
    minsize = state->data_stack_base+size;
    cursize = state->data_stack_size;
    if (cursize < minsize) {
        void* stack;
        cursize = minsize+minsize/4+1024;
        TRACE(("allocate/grow stack %d\n", cursize));
        stack = realloc(state->data_stack, cursize);
        if (!stack) {
            data_stack_dealloc(state);
            return SRE_ERROR_MEMORY;
        }
        state->data_stack = stack;
        state->data_stack_size = cursize;
    }
    return 0;
}

/* generate 8-bit version */

#define SRE_CHAR unsigned char
#define SRE_AT sre_at
#define SRE_COUNT sre_count
#define SRE_CHARSET sre_charset
#define SRE_INFO sre_info
#define SRE_MATCH sre_match
#define SRE_MATCH_CONTEXT sre_match_context
#define SRE_SEARCH sre_search
#define SRE_LITERAL_TEMPLATE sre_literal_template

#if defined(HAVE_UNICODE)

#define SRE_RECURSIVE
#include "_sre.c"
#undef SRE_RECURSIVE

#undef SRE_LITERAL_TEMPLATE
#undef SRE_SEARCH
#undef SRE_MATCH
#undef SRE_MATCH_CONTEXT
#undef SRE_INFO
#undef SRE_CHARSET
#undef SRE_COUNT
#undef SRE_AT
#undef SRE_CHAR

/* generate 16-bit unicode version */

#define SRE_CHAR Py_UNICODE
#define SRE_AT sre_uat
#define SRE_COUNT sre_ucount
#define SRE_CHARSET sre_ucharset
#define SRE_INFO sre_uinfo
#define SRE_MATCH sre_umatch
#define SRE_MATCH_CONTEXT sre_umatch_context
#define SRE_SEARCH sre_usearch
#define SRE_LITERAL_TEMPLATE sre_uliteral_template
#endif

#endif /* SRE_RECURSIVE */

/* -------------------------------------------------------------------- */
/* String matching engine */

/* the following section is compiled twice, with different character
   settings */

LOCAL(int)
SRE_AT(SRE_STATE* state, SRE_CHAR* ptr, SRE_CODE at)
{
    /* check if pointer is at given position */

    int this, that;

    switch (at) {

    case SRE_AT_BEGINNING:
    case SRE_AT_BEGINNING_STRING:
        return ((void*) ptr == state->beginning);

    case SRE_AT_BEGINNING_LINE:
        return ((void*) ptr == state->beginning ||
                SRE_IS_LINEBREAK((int) ptr[-1]));

    case SRE_AT_END:
        return (((void*) (ptr+1) == state->end &&
                 SRE_IS_LINEBREAK((int) ptr[0])) ||
                ((void*) ptr == state->end));

    case SRE_AT_END_LINE:
        return ((void*) ptr == state->end ||
                SRE_IS_LINEBREAK((int) ptr[0]));

    case SRE_AT_END_STRING:
        return ((void*) ptr == state->end);

    case SRE_AT_BOUNDARY:
        if (state->beginning == state->end)
            return 0;
        that = ((void*) ptr > state->beginning) ?
            SRE_IS_WORD((int) ptr[-1]) : 0;
        this = ((void*) ptr < state->end) ?
            SRE_IS_WORD((int) ptr[0]) : 0;
        return this != that;

    case SRE_AT_NON_BOUNDARY:
        if (state->beginning == state->end)
            return 0;
        that = ((void*) ptr > state->beginning) ?
            SRE_IS_WORD((int) ptr[-1]) : 0;
        this = ((void*) ptr < state->end) ?
            SRE_IS_WORD((int) ptr[0]) : 0;
        return this == that;

    case SRE_AT_LOC_BOUNDARY:
        if (state->beginning == state->end)
            return 0;
        that = ((void*) ptr > state->beginning) ?
            SRE_LOC_IS_WORD((int) ptr[-1]) : 0;
        this = ((void*) ptr < state->end) ?
            SRE_LOC_IS_WORD((int) ptr[0]) : 0;
        return this != that;

    case SRE_AT_LOC_NON_BOUNDARY:
        if (state->beginning == state->end)
            return 0;
        that = ((void*) ptr > state->beginning) ?
            SRE_LOC_IS_WORD((int) ptr[-1]) : 0;
        this = ((void*) ptr < state->end) ?
            SRE_LOC_IS_WORD((int) ptr[0]) : 0;
        return this == that;

#if defined(HAVE_UNICODE)
    case SRE_AT_UNI_BOUNDARY:
        if (state->beginning == state->end)
            return 0;
        that = ((void*) ptr > state->beginning) ?
            SRE_UNI_IS_WORD((int) ptr[-1]) : 0;
        this = ((void*) ptr < state->end) ?
            SRE_UNI_IS_WORD((int) ptr[0]) : 0;
        return this != that;

    case SRE_AT_UNI_NON_BOUNDARY:
        if (state->beginning == state->end)
            return 0;
        that = ((void*) ptr > state->beginning) ?
            SRE_UNI_IS_WORD((int) ptr[-1]) : 0;
        this = ((void*) ptr < state->end) ?
            SRE_UNI_IS_WORD((int) ptr[0]) : 0;
        return this == that;
#endif

    }

    return 0;
}

LOCAL(int)
SRE_CHARSET(SRE_CODE* set, SRE_CODE ch)
{
    /* check if character is a member of the given set */

    int ok = 1;

    for (;;) {
        switch (*set++) {

        case SRE_OP_FAILURE:
            return !ok;

        case SRE_OP_LITERAL:
            /* <LITERAL> <code> */
            if (ch == set[0])
                return ok;
            set++;
            break;

        case SRE_OP_CATEGORY:
            /* <CATEGORY> <code> */
            if (sre_category(set[0], (int) ch))
                return ok;
            set += 1;
            break;

        case SRE_OP_CHARSET:
            if (sizeof(SRE_CODE) == 2) {
                /* <CHARSET> <bitmap> (16 bits per code word) */
                if (ch < 256 && (set[ch >> 4] & (1 << (ch & 15))))
                    return ok;
                set += 16;
            } 
            else {
                /* <CHARSET> <bitmap> (32 bits per code word) */
                if (ch < 256 && (set[ch >> 5] & (1 << (ch & 31))))
                    return ok;
                set += 8;
            }
            break;

        case SRE_OP_RANGE:
            /* <RANGE> <lower> <upper> */
            if (set[0] <= ch && ch <= set[1])
                return ok;
            set += 2;
            break;

        case SRE_OP_NEGATE:
            ok = !ok;
            break;

        case SRE_OP_BIGCHARSET:
            /* <BIGCHARSET> <blockcount> <256 blockindices> <blocks> */
        {
            int count, block;
            count = *(set++);

            if (sizeof(SRE_CODE) == 2) {
                block = ((unsigned char*)set)[ch >> 8];
                set += 128;
                if (set[block*16 + ((ch & 255)>>4)] & (1 << (ch & 15)))
                    return ok;
                set += count*16;
            }
            else {
                /* !(c & ~N) == (c < N+1) for any unsigned c, this avoids
                 * warnings when c's type supports only numbers < N+1 */
                if (!(ch & ~65535))
                    block = ((unsigned char*)set)[ch >> 8];
                else
                    block = -1;
                set += 64;
                if (block >=0 && 
                    (set[block*8 + ((ch & 255)>>5)] & (1 << (ch & 31))))
                    return ok;
                set += count*8;
            }
            break;
        }

        default:
            /* internal error -- there's not much we can do about it
               here, so let's just pretend it didn't match... */
            return 0;
        }
    }
}

LOCAL(int) SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern);

LOCAL(int)
SRE_COUNT(SRE_STATE* state, SRE_CODE* pattern, int maxcount)
{
    SRE_CODE chr;
    SRE_CHAR* ptr = state->ptr;
    SRE_CHAR* end = state->end;
    int i;

    /* adjust end */
    if (maxcount < end - ptr && maxcount != 65535)
        end = ptr + maxcount;

    switch (pattern[0]) {

    case SRE_OP_IN:
        /* repeated set */
        TRACE(("|%p|%p|COUNT IN\n", pattern, ptr));
        while (ptr < end && SRE_CHARSET(pattern + 2, *ptr))
            ptr++;
        break;

    case SRE_OP_ANY:
        /* repeated dot wildcard. */
        TRACE(("|%p|%p|COUNT ANY\n", pattern, ptr));
        while (ptr < end && !SRE_IS_LINEBREAK(*ptr))
            ptr++;
        break;

    case SRE_OP_ANY_ALL:
        /* repeated dot wildcard.  skip to the end of the target
           string, and backtrack from there */
        TRACE(("|%p|%p|COUNT ANY_ALL\n", pattern, ptr));
        ptr = end;
        break;

    case SRE_OP_LITERAL:
        /* repeated literal */
        chr = pattern[1];
        TRACE(("|%p|%p|COUNT LITERAL %d\n", pattern, ptr, chr));
        while (ptr < end && (SRE_CODE) *ptr == chr)
            ptr++;
        break;

    case SRE_OP_LITERAL_IGNORE:
        /* repeated literal */
        chr = pattern[1];
        TRACE(("|%p|%p|COUNT LITERAL_IGNORE %d\n", pattern, ptr, chr));
        while (ptr < end && (SRE_CODE) state->lower(*ptr) == chr)
            ptr++;
        break;

    case SRE_OP_NOT_LITERAL:
        /* repeated non-literal */
        chr = pattern[1];
        TRACE(("|%p|%p|COUNT NOT_LITERAL %d\n", pattern, ptr, chr));
        while (ptr < end && (SRE_CODE) *ptr != chr)
            ptr++;
        break;
                
    case SRE_OP_NOT_LITERAL_IGNORE:
        /* repeated non-literal */
        chr = pattern[1];
        TRACE(("|%p|%p|COUNT NOT_LITERAL_IGNORE %d\n", pattern, ptr, chr));
        while (ptr < end && (SRE_CODE) state->lower(*ptr) != chr)
            ptr++;
        break;

    default:
        /* repeated single character pattern */
        TRACE(("|%p|%p|COUNT SUBPATTERN\n", pattern, ptr));
        while ((SRE_CHAR*) state->ptr < end) {
            i = SRE_MATCH(state, pattern);
            if (i < 0)
                return i;
            if (!i)
                break;
        }
        TRACE(("|%p|%p|COUNT %d\n", pattern, ptr,
               (SRE_CHAR*) state->ptr - ptr));
        return (SRE_CHAR*) state->ptr - ptr;
    }

    TRACE(("|%p|%p|COUNT %d\n", pattern, ptr, ptr - (SRE_CHAR*) state->ptr));
    return ptr - (SRE_CHAR*) state->ptr;
}

#if 0 /* not used in this release */
LOCAL(int)
SRE_INFO(SRE_STATE* state, SRE_CODE* pattern)
{
    /* check if an SRE_OP_INFO block matches at the current position.
       returns the number of SRE_CODE objects to skip if successful, 0
       if no match */

    SRE_CHAR* end = state->end;
    SRE_CHAR* ptr = state->ptr;
    int i;

    /* check minimal length */
    if (pattern[3] && (end - ptr) < pattern[3])
        return 0;

    /* check known prefix */
    if (pattern[2] & SRE_INFO_PREFIX && pattern[5] > 1) {
        /* <length> <skip> <prefix data> <overlap data> */
        for (i = 0; i < pattern[5]; i++)
            if ((SRE_CODE) ptr[i] != pattern[7 + i])
                return 0;
        return pattern[0] + 2 * pattern[6];
    }
    return pattern[0];
}
#endif

/* The macros below should be used to protect recursive SRE_MATCH()
 * calls that *failed* and do *not* return immediately (IOW, those
 * that will backtrack). Explaining:
 *
 * - Recursive SRE_MATCH() returned true: that's usually a success
 *   (besides atypical cases like ASSERT_NOT), therefore there's no
 *   reason to restore lastmark;
 *
 * - Recursive SRE_MATCH() returned false but the current SRE_MATCH()
 *   is returning to the caller: If the current SRE_MATCH() is the
 *   top function of the recursion, returning false will be a matching
 *   failure, and it doesn't matter where lastmark is pointing to.
 *   If it's *not* the top function, it will be a recursive SRE_MATCH()
 *   failure by itself, and the calling SRE_MATCH() will have to deal
 *   with the failure by the same rules explained here (it will restore
 *   lastmark by itself if necessary);
 *
 * - Recursive SRE_MATCH() returned false, and will continue the
 *   outside 'for' loop: must be protected when breaking, since the next
 *   OP could potentially depend on lastmark;
 *   
 * - Recursive SRE_MATCH() returned false, and will be called again
 *   inside a local for/while loop: must be protected between each
 *   loop iteration, since the recursive SRE_MATCH() could do anything,
 *   and could potentially depend on lastmark.
 *
 * For more information, check the discussion at SF patch #712900.
 */
#define LASTMARK_SAVE()     \
    do { \
        ctx->lastmark = state->lastmark; \
        ctx->lastindex = state->lastindex; \
    } while (0)
#define LASTMARK_RESTORE()  \
    do { \
        state->lastmark = ctx->lastmark; \
        state->lastindex = ctx->lastindex; \
    } while (0)

#define RETURN_ERROR(i) do { return i; } while(0)
#define RETURN_FAILURE do { ret = 0; goto exit; } while(0)
#define RETURN_SUCCESS do { ret = 1; goto exit; } while(0)

#define RETURN_ON_ERROR(i) \
    do { if (i < 0) RETURN_ERROR(i); } while (0)
#define RETURN_ON_SUCCESS(i) \
    do { RETURN_ON_ERROR(i); if (i > 0) RETURN_SUCCESS; } while (0)
#define RETURN_ON_FAILURE(i) \
    do { RETURN_ON_ERROR(i); if (i == 0) RETURN_FAILURE; } while (0)

#define SFY(x) #x

#define DATA_STACK_ALLOC(state, type, ptr) \
do { \
    alloc_pos = state->data_stack_base; \
    TRACE(("allocating %s in %d (%d)\n", \
           SFY(type), alloc_pos, sizeof(type))); \
    if (state->data_stack_size < alloc_pos+sizeof(type)) { \
        int j = data_stack_grow(state, sizeof(type)); \
        if (j < 0) return j; \
        if (ctx_pos != -1) \
            DATA_STACK_LOOKUP_AT(state, SRE_MATCH_CONTEXT, ctx, ctx_pos); \
    } \
    ptr = (type*)(state->data_stack+alloc_pos); \
    state->data_stack_base += sizeof(type); \
} while (0)

#define DATA_STACK_LOOKUP_AT(state, type, ptr, pos) \
do { \
    TRACE(("looking up %s at %d\n", SFY(type), pos)); \
    ptr = (type*)(state->data_stack+pos); \
} while (0)

#define DATA_STACK_PUSH(state, data, size) \
do { \
    TRACE(("copy data in %p to %d (%d)\n", \
           data, state->data_stack_base, size)); \
    if (state->data_stack_size < state->data_stack_base+size) { \
        int j = data_stack_grow(state, size); \
        if (j < 0) return j; \
        if (ctx_pos != -1) \
            DATA_STACK_LOOKUP_AT(state, SRE_MATCH_CONTEXT, ctx, ctx_pos); \
    } \
    memcpy(state->data_stack+state->data_stack_base, data, size); \
    state->data_stack_base += size; \
} while (0)

#define DATA_STACK_POP(state, data, size, discard) \
do { \
    TRACE(("copy data to %p from %d (%d)\n", \
           data, state->data_stack_base-size, size)); \
    memcpy(data, state->data_stack+state->data_stack_base-size, size); \
    if (discard) \
        state->data_stack_base -= size; \
} while (0)

#define DATA_STACK_POP_DISCARD(state, size) \
do { \
    TRACE(("discard data from %d (%d)\n", \
           state->data_stack_base-size, size)); \
    state->data_stack_base -= size; \
} while(0)

#define DATA_PUSH(x) \
    DATA_STACK_PUSH(state, (x), sizeof(*(x)))
#define DATA_POP(x) \
    DATA_STACK_POP(state, (x), sizeof(*(x)), 1)
#define DATA_POP_DISCARD(x) \
    DATA_STACK_POP_DISCARD(state, sizeof(*(x)))
#define DATA_ALLOC(t,p) \
    DATA_STACK_ALLOC(state, t, p)
#define DATA_LOOKUP_AT(t,p,pos) \
    DATA_STACK_LOOKUP_AT(state,t,p,pos)

#define MARK_PUSH(lastmark) \
    do if (lastmark > 0) { \
        i = lastmark; /* ctx->lastmark may change if reallocated */ \
        DATA_STACK_PUSH(state, state->mark, (i+1)*sizeof(void*)); \
    } while (0)
#define MARK_POP(lastmark) \
    do if (lastmark > 0) { \
        DATA_STACK_POP(state, state->mark, (lastmark+1)*sizeof(void*), 1); \
    } while (0)
#define MARK_POP_KEEP(lastmark) \
    do if (lastmark > 0) { \
        DATA_STACK_POP(state, state->mark, (lastmark+1)*sizeof(void*), 0); \
    } while (0)
#define MARK_POP_DISCARD(lastmark) \
    do if (lastmark > 0) { \
        DATA_STACK_POP_DISCARD(state, (lastmark+1)*sizeof(void*)); \
    } while (0)

#define JUMP_NONE            0
#define JUMP_MAX_UNTIL_1     1
#define JUMP_MAX_UNTIL_2     2
#define JUMP_MAX_UNTIL_3     3
#define JUMP_MIN_UNTIL_1     4
#define JUMP_MIN_UNTIL_2     5
#define JUMP_MIN_UNTIL_3     6
#define JUMP_REPEAT          7
#define JUMP_REPEAT_ONE_1    8
#define JUMP_REPEAT_ONE_2    9
#define JUMP_MIN_REPEAT_ONE  10
#define JUMP_BRANCH          11
#define JUMP_ASSERT          12
#define JUMP_ASSERT_NOT      13

#define DO_JUMP(jumpvalue, jumplabel, nextpattern) \
    DATA_ALLOC(SRE_MATCH_CONTEXT, nextctx); \
    nextctx->last_ctx_pos = ctx_pos; \
    nextctx->jump = jumpvalue; \
    nextctx->pattern = nextpattern; \
    ctx_pos = alloc_pos; \
    ctx = nextctx; \
    goto entrance; \
    jumplabel: \
    while (0) /* gcc doesn't like labels at end of scopes */ \

typedef struct {
    int last_ctx_pos;
    int jump;
    SRE_CHAR* ptr;
    SRE_CODE* pattern;
    int count;
    int lastmark;
    int lastindex;
    union {
        SRE_CODE chr;
        SRE_REPEAT* rep;
    } u;
} SRE_MATCH_CONTEXT;

/* check if string matches the given pattern.  returns <0 for
   error, 0 for failure, and 1 for success */
LOCAL(int)
SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern)
{
    SRE_CHAR* end = state->end;
    int alloc_pos, ctx_pos = -1;
    int i, ret = 0;
    int jump;

    SRE_MATCH_CONTEXT* ctx;
    SRE_MATCH_CONTEXT* nextctx;

    TRACE(("|%p|%p|ENTER\n", pattern, state->ptr));

    DATA_ALLOC(SRE_MATCH_CONTEXT, ctx);
    ctx->last_ctx_pos = -1;
    ctx->jump = JUMP_NONE;
    ctx->pattern = pattern;
    ctx_pos = alloc_pos;

entrance:

    ctx->ptr = state->ptr;

    if (ctx->pattern[0] == SRE_OP_INFO) {
        /* optimization info block */
        /* <INFO> <1=skip> <2=flags> <3=min> ... */
        if (ctx->pattern[3] && (end - ctx->ptr) < ctx->pattern[3]) {
            TRACE(("reject (got %d chars, need %d)\n",
                   (end - ctx->ptr), ctx->pattern[3]));
            RETURN_FAILURE;
        }
        ctx->pattern += ctx->pattern[1] + 1;
    }

    for (;;) {

        switch (*ctx->pattern++) {

        case SRE_OP_MARK:
            /* set mark */
            /* <MARK> <gid> */
            TRACE(("|%p|%p|MARK %d\n", ctx->pattern,
                   ctx->ptr, ctx->pattern[0]));
            i = ctx->pattern[0];
            if (i & 1)
                state->lastindex = i/2 + 1;
            if (i > state->lastmark) {
                /* state->lastmark is the highest valid index in the
                   state->mark array.  If it is increased by more than 1,
                   the intervening marks must be set to NULL to signal
                   that these marks have not been encountered. */ 
                int j = state->lastmark + 1;
                while (j < i)
                    state->mark[j++] = NULL;
                state->lastmark = i;
            }
            state->mark[i] = ctx->ptr;
            ctx->pattern++;
            break;

        case SRE_OP_LITERAL:
            /* match literal string */
            /* <LITERAL> <code> */
            TRACE(("|%p|%p|LITERAL %d\n", ctx->pattern,
                   ctx->ptr, *ctx->pattern));
            if (ctx->ptr >= end || (SRE_CODE) ctx->ptr[0] != ctx->pattern[0])
                RETURN_FAILURE;
            ctx->pattern++;
            ctx->ptr++;
            break;

        case SRE_OP_NOT_LITERAL:
            /* match anything that is not literal character */
            /* <NOT_LITERAL> <code> */
            TRACE(("|%p|%p|NOT_LITERAL %d\n", ctx->pattern,
                   ctx->ptr, *ctx->pattern));
            if (ctx->ptr >= end || (SRE_CODE) ctx->ptr[0] == ctx->pattern[0])
                RETURN_FAILURE;
            ctx->pattern++;
            ctx->ptr++;
            break;

        case SRE_OP_SUCCESS:
            /* end of pattern */
            TRACE(("|%p|%p|SUCCESS\n", ctx->pattern, ctx->ptr));
            state->ptr = ctx->ptr;
            RETURN_SUCCESS;

        case SRE_OP_AT:
            /* match at given position */
            /* <AT> <code> */
            TRACE(("|%p|%p|AT %d\n", ctx->pattern, ctx->ptr, *ctx->pattern));
            if (!SRE_AT(state, ctx->ptr, *ctx->pattern))
                RETURN_FAILURE;
            ctx->pattern++;
            break;

        case SRE_OP_CATEGORY:
            /* match at given category */
            /* <CATEGORY> <code> */
            TRACE(("|%p|%p|CATEGORY %d\n", ctx->pattern,
                   ctx->ptr, *ctx->pattern));
            if (ctx->ptr >= end || !sre_category(ctx->pattern[0], ctx->ptr[0]))
                RETURN_FAILURE;
            ctx->pattern++;
            ctx->ptr++;
            break;

        case SRE_OP_ANY:
            /* match anything (except a newline) */
            /* <ANY> */
            TRACE(("|%p|%p|ANY\n", ctx->pattern, ctx->ptr));
            if (ctx->ptr >= end || SRE_IS_LINEBREAK(ctx->ptr[0]))
                RETURN_FAILURE;
            ctx->ptr++;
            break;

        case SRE_OP_ANY_ALL:
            /* match anything */
            /* <ANY_ALL> */
            TRACE(("|%p|%p|ANY_ALL\n", ctx->pattern, ctx->ptr));
            if (ctx->ptr >= end)
                RETURN_FAILURE;
            ctx->ptr++;
            break;

        case SRE_OP_IN:
            /* match set member (or non_member) */
            /* <IN> <skip> <set> */
            TRACE(("|%p|%p|IN\n", ctx->pattern, ctx->ptr));
            if (ctx->ptr >= end || !SRE_CHARSET(ctx->pattern + 1, *ctx->ptr))
                RETURN_FAILURE;
            ctx->pattern += ctx->pattern[0];
            ctx->ptr++;
            break;

        case SRE_OP_LITERAL_IGNORE:
            TRACE(("|%p|%p|LITERAL_IGNORE %d\n",
                   ctx->pattern, ctx->ptr, ctx->pattern[0]));
            if (ctx->ptr >= end ||
                state->lower(*ctx->ptr) != state->lower(*ctx->pattern))
                RETURN_FAILURE;
            ctx->pattern++;
            ctx->ptr++;
            break;

        case SRE_OP_NOT_LITERAL_IGNORE:
            TRACE(("|%p|%p|NOT_LITERAL_IGNORE %d\n",
                   ctx->pattern, ctx->ptr, *ctx->pattern));
            if (ctx->ptr >= end ||
                state->lower(*ctx->ptr) == state->lower(*ctx->pattern))
                RETURN_FAILURE;
            ctx->pattern++;
            ctx->ptr++;
            break;

        case SRE_OP_IN_IGNORE:
            TRACE(("|%p|%p|IN_IGNORE\n", ctx->pattern, ctx->ptr));
            if (ctx->ptr >= end
                || !SRE_CHARSET(ctx->pattern+1,
                                (SRE_CODE)state->lower(*ctx->ptr)))
                RETURN_FAILURE;
            ctx->pattern += ctx->pattern[0];
            ctx->ptr++;
            break;

        case SRE_OP_JUMP:
        case SRE_OP_INFO:
            /* jump forward */
            /* <JUMP> <offset> */
            TRACE(("|%p|%p|JUMP %d\n", ctx->pattern,
                   ctx->ptr, ctx->pattern[0]));
            ctx->pattern += ctx->pattern[0];
            break;

        case SRE_OP_BRANCH:
            /* alternation */
            /* <BRANCH> <0=skip> code <JUMP> ... <NULL> */
            TRACE(("|%p|%p|BRANCH\n", ctx->pattern, ctx->ptr));
            LASTMARK_SAVE();
            ctx->u.rep = state->repeat;
            if (ctx->u.rep)
                MARK_PUSH(ctx->lastmark);
            for (; ctx->pattern[0]; ctx->pattern += ctx->pattern[0]) {
                if (ctx->pattern[1] == SRE_OP_LITERAL &&
                    (ctx->ptr >= end ||
                     (SRE_CODE) *ctx->ptr != ctx->pattern[2]))
                    continue;
                if (ctx->pattern[1] == SRE_OP_IN &&
                    (ctx->ptr >= end ||
                     !SRE_CHARSET(ctx->pattern + 3, (SRE_CODE) *ctx->ptr)))
                    continue;
                state->ptr = ctx->ptr;
                DO_JUMP(JUMP_BRANCH, jump_branch, ctx->pattern+1);
                if (ret) {
                    if (ctx->u.rep)
                        MARK_POP_DISCARD(ctx->lastmark);
                    RETURN_ON_ERROR(ret);
                    RETURN_SUCCESS;
                }