Issue #18685: Extract template part of _sre.c into separated sre_lib.h file.

1 files changed, 1329 insertions, 0 deletions

diff --git a/Modules/sre_lib.h b/Modules/sre_lib.h
new file mode 100644
index 0000000000..214c22af7e
--- /dev/null
+++ b/Modules/sre_lib.h
@@ -0,0 +1,1329 @@
+/*
+ * Secret Labs' Regular Expression Engine
+ *
+ * regular expression matching engine
+ *
+ * Copyright (c) 1997-2001 by Secret Labs AB.  All rights reserved.
+ *
+ * See the _sre.c file for information on usage and redistribution.
+ */
+
+/* String matching engine */
+
+/* This file is included three times, with different character settings */
+
+LOCAL(int)
+SRE(at)(SRE_STATE* state, SRE_CHAR* ptr, SRE_CODE at)
+{
+    /* check if pointer is at given position */
+
+    Py_ssize_t thisp, thatp;
+
+    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;
+        thatp = ((void*) ptr > state->beginning) ?
+            SRE_IS_WORD((int) ptr[-1]) : 0;
+        thisp = ((void*) ptr < state->end) ?
+            SRE_IS_WORD((int) ptr[0]) : 0;
+        return thisp != thatp;
+
+    case SRE_AT_NON_BOUNDARY:
+        if (state->beginning == state->end)
+            return 0;
+        thatp = ((void*) ptr > state->beginning) ?
+            SRE_IS_WORD((int) ptr[-1]) : 0;
+        thisp = ((void*) ptr < state->end) ?
+            SRE_IS_WORD((int) ptr[0]) : 0;
+        return thisp == thatp;
+
+    case SRE_AT_LOC_BOUNDARY:
+        if (state->beginning == state->end)
+            return 0;
+        thatp = ((void*) ptr > state->beginning) ?
+            SRE_LOC_IS_WORD((int) ptr[-1]) : 0;
+        thisp = ((void*) ptr < state->end) ?
+            SRE_LOC_IS_WORD((int) ptr[0]) : 0;
+        return thisp != thatp;
+
+    case SRE_AT_LOC_NON_BOUNDARY:
+        if (state->beginning == state->end)
+            return 0;
+        thatp = ((void*) ptr > state->beginning) ?
+            SRE_LOC_IS_WORD((int) ptr[-1]) : 0;
+        thisp = ((void*) ptr < state->end) ?
+            SRE_LOC_IS_WORD((int) ptr[0]) : 0;
+        return thisp == thatp;
+
+    case SRE_AT_UNI_BOUNDARY:
+        if (state->beginning == state->end)
+            return 0;
+        thatp = ((void*) ptr > state->beginning) ?
+            SRE_UNI_IS_WORD((int) ptr[-1]) : 0;
+        thisp = ((void*) ptr < state->end) ?
+            SRE_UNI_IS_WORD((int) ptr[0]) : 0;
+        return thisp != thatp;
+
+    case SRE_AT_UNI_NON_BOUNDARY:
+        if (state->beginning == state->end)
+            return 0;
+        thatp = ((void*) ptr > state->beginning) ?
+            SRE_UNI_IS_WORD((int) ptr[-1]) : 0;
+        thisp = ((void*) ptr < state->end) ?
+            SRE_UNI_IS_WORD((int) ptr[0]) : 0;
+        return thisp == thatp;
+
+    }
+
+    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++;
+            break;
+
+        case SRE_OP_CHARSET:
+            /* <CHARSET> <bitmap> */
+            if (ch < 256 &&
+                (set[ch/SRE_CODE_BITS] & (1u << (ch & (SRE_CODE_BITS-1)))))
+                return ok;
+            set += 256/SRE_CODE_BITS;
+            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> */
+        {
+            Py_ssize_t count, block;
+            count = *(set++);
+
+            if (ch < 0x10000u)
+                block = ((unsigned char*)set)[ch >> 8];
+            else
+                block = -1;
+            set += 256/sizeof(SRE_CODE);
+            if (block >=0 &&
+                (set[(block * 256 + (ch & 255))/SRE_CODE_BITS] &
+                    (1u << (ch & (SRE_CODE_BITS-1)))))
+                return ok;
+            set += count * (256/SRE_CODE_BITS);
+            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(Py_ssize_t) SRE(match)(SRE_STATE* state, SRE_CODE* pattern);
+
+LOCAL(Py_ssize_t)
+SRE(count)(SRE_STATE* state, SRE_CODE* pattern, Py_ssize_t maxcount)
+{
+    SRE_CODE chr;
+    SRE_CHAR c;
+    SRE_CHAR* ptr = (SRE_CHAR *)state->ptr;
+    SRE_CHAR* end = (SRE_CHAR *)state->end;
+    Py_ssize_t i;
+
+    /* adjust end */
+    if (maxcount < end - ptr && maxcount != SRE_MAXREPEAT)
+        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));
+        c = (SRE_CHAR) chr;
+#if SIZEOF_SRE_CHAR < 4
+        if ((SRE_CODE) c != chr)
+            ; /* literal can't match: doesn't fit in char width */
+        else
+#endif
+        while (ptr < end && *ptr == c)
+            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));
+        c = (SRE_CHAR) chr;
+#if SIZEOF_SRE_CHAR < 4
+        if ((SRE_CODE) c != chr)
+            ptr = end; /* literal can't match: doesn't fit in char width */
+        else
+#endif
+        while (ptr < end && *ptr != c)
+            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 %" PY_FORMAT_SIZE_T "d\n", pattern, ptr,
+               (SRE_CHAR*) state->ptr - ptr));
+        return (SRE_CHAR*) state->ptr - ptr;
+    }
+
+    TRACE(("|%p|%p|COUNT %" PY_FORMAT_SIZE_T "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 = (SRE_CHAR*) state->end;
+    SRE_CHAR* ptr = (SRE_CHAR*) state->ptr;
+    Py_ssize_t 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 %" PY_FORMAT_SIZE_T "d " \
+           "(%" PY_FORMAT_SIZE_T "d)\n", \
+           SFY(type), alloc_pos, sizeof(type))); \
+    if (sizeof(type) > state->data_stack_size - alloc_pos) { \
+        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 %" PY_FORMAT_SIZE_T "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 %" PY_FORMAT_SIZE_T "d " \
+           "(%" PY_FORMAT_SIZE_T "d)\n", \
+           data, state->data_stack_base, size)); \
+    if (size > state->data_stack_size - state->data_stack_base) { \
+        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 %" PY_FORMAT_SIZE_T "d " \
+           "(%" PY_FORMAT_SIZE_T "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 %" PY_FORMAT_SIZE_T "d " \
+           "(%" PY_FORMAT_SIZE_T "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 {
+    Py_ssize_t last_ctx_pos;
+    Py_ssize_t jump;
+    SRE_CHAR* ptr;
+    SRE_CODE* pattern;
+    Py_ssize_t count;
+    Py_ssize_t lastmark;
+    Py_ssize_t 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(Py_ssize_t)
+SRE(match)(SRE_STATE* state, SRE_CODE* pattern)
+{
+    SRE_CHAR* end = (SRE_CHAR *)state->end;
+    Py_ssize_t alloc_pos, ctx_pos = -1;
+    Py_ssize_t i, ret = 0;
+    Py_ssize_t jump;
+    unsigned int sigcount=0;
+
+    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 = (SRE_CHAR *)state->ptr;
+
+    if (ctx->pattern[0] == SRE_OP_INFO) {
+        /* optimization info block */
+        /* <INFO> <1=skip> <2=flags> <3=min> ... */
+        if (ctx->pattern[3] && (Py_uintptr_t)(end - ctx->ptr) < ctx->pattern[3]) {
+            TRACE(("reject (got %" PY_FORMAT_SIZE_T "d chars, "
+                   "need %" PY_FORMAT_SIZE_T "d)\n",
+                   end - ctx->ptr, (Py_ssize_t) ctx->pattern[3]));
+            RETURN_FAILURE;
+        }
+        ctx->pattern += ctx->pattern[1] + 1;
+    }
+
+    for (;;) {
+        ++sigcount;
+        if ((0 == (sigcount & 0xfff)) && PyErr_CheckSignals())
+            RETURN_ERROR(SRE_ERROR_INTERRUPTED);
+
+        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. */
+                Py_ssize_t 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;
+                }
+                if (ctx->u.rep)
+                    MARK_POP_KEEP(ctx->lastmark);
+                LASTMARK_RESTORE();
+            }
+            if (ctx->u.rep)
+                MARK_POP_DISCARD(ctx->lastmark);
+            RETURN_FAILURE;
+
+        case SRE_OP_REPEAT_ONE:
+            /* match repeated sequence (maximizing regexp) */
+
+            /* this operator only works if the repeated item is
+               exactly one character wide, and we're not already
+               collecting backtracking points.  for other cases,
+               use the MAX_REPEAT operator */
+
+            /* <REPEAT_ONE> <skip> <1=min> <2=max> item <SUCCESS> tail */
+
+            TRACE(("|%p|%p|REPEAT_ONE %d %d\n", ctx->pattern, ctx->ptr,
+                   ctx->pattern[1], ctx->pattern[2]));
+
+            if ((Py_ssize_t) ctx->pattern[1] > end - ctx->ptr)
+                RETURN_FAILURE; /* cannot match */
+
+            state->ptr = ctx->ptr;
+
+            ret = SRE(count)(state, ctx->pattern+3, ctx->pattern[2]);
+            RETURN_ON_ERROR(ret);
+            DATA_LOOKUP_AT(SRE(match_context), ctx, ctx_pos);
+            ctx->count = ret;
+            ctx->ptr += ctx->count;
+
+            /* when we arrive here, count contains the number of
+               matches, and ctx->ptr points to the tail of the target
+               string.  check if the rest of the pattern matches,
+               and backtrack if not. */
+
+            if (ctx->count < (Py_ssize_t) ctx->pattern[1])
+                RETURN_FAILURE;
+
+            if (ctx->pattern[ctx->pattern[0]] == SRE_OP_SUCCESS) {
+                /* tail is empty.  we're finished */
+                state->ptr = ctx->ptr;
+                RETURN_SUCCESS;
+            }
+
+            LASTMARK_SAVE();
+
+            if (ctx->pattern[ctx->pattern[0]] == SRE_OP_LITERAL) {
+                /* tail starts with a literal. skip positions where
+                   the rest of the pattern cannot possibly match */
+                ctx->u.chr = ctx->pattern[ctx->pattern[0]+1];
+                for (;;) {
+                    while (ctx->count >= (Py_ssize_t) ctx->pattern[1] &&
+                           (ctx->ptr >= end || *ctx->ptr != ctx->u.chr)) {
+                        ctx->ptr--;
+                        ctx->count--;
+                    }
+                    if (ctx->count < (Py_ssize_t) ctx->pattern[1])
+                        break;
+                    state->ptr = ctx->ptr;
+                    DO_JUMP(JUMP_REPEAT_ONE_1, jump_repeat_one_1,
+                            ctx->pattern+ctx->pattern[0]);
+                    if (ret) {
+                        RETURN_ON_ERROR(ret);
+                        RETURN_SUCCESS;
+                    }
+
+                    LASTMARK_RESTORE();
+
+                    ctx->ptr--;
+                    ctx->count--;
+                }
+
+            } else {
+                /* general case */
+                while (ctx->count >= (Py_ssize_t) ctx->pattern[1]) {
+                    state->ptr = ctx->ptr;
+                    DO_JUMP(JUMP_REPEAT_ONE_2, jump_repeat_one_2,
+                            ctx->pattern+ctx->pattern[0]);
+                    if (ret) {
+                        RETURN_ON_ERROR(ret);
+                        RETURN_SUCCESS;
+                    }
+                    ctx->ptr--;
+                    ctx->count--;
+                    LASTMARK_RESTORE();
+                }
+            }
+            RETURN_FAILURE;
+
+        case SRE_OP_MIN_REPEAT_ONE:
+            /* match repeated sequence (minimizing regexp) */
+
+            /* this operator only works if the repeated item is
+               exactly one character wide, and we're not already
+               collecting backtracking points.  for other cases,
+               use the MIN_REPEAT operator */
+
+            /* <MIN_REPEAT_ONE> <skip> <1=min> <2=max> item <SUCCESS> tail */
+
+            TRACE(("|%p|%p|MIN_REPEAT_ONE %d %d\n", ctx->pattern, ctx->ptr,
+                   ctx->pattern[1], ctx->pattern[2]));
+
+            if ((Py_ssize_t) ctx->pattern[1] > end - ctx->ptr)
+                RETURN_FAILURE; /* cannot match */
+
+            state->ptr = ctx->ptr;
+
+            if (ctx->pattern[1] == 0)
+                ctx->count = 0;
+            else {
+                /* count using pattern min as the maximum */
+                ret = SRE(count)(state, ctx->pattern+3, ctx->pattern[1]);
+                RETURN_ON_ERROR(ret);
+                DATA_LOOKUP_AT(SRE(match_context), ctx, ctx_pos);
+                if (ret < (Py_ssize_t) ctx->pattern[1])
+                    /* didn't match minimum number of times */
+                    RETURN_FAILURE;
+                /* advance past minimum matches of repeat */
+                ctx->count = ret;
+                ctx->ptr += ctx->count;
+            }
+
+            if (ctx->pattern[ctx->pattern[0]] == SRE_OP_SUCCESS) {
+                /* tail is empty.  we're finished */
+                state->ptr = ctx->ptr;
+                RETURN_SUCCESS;
+
+            } else {
+                /* general case */
+                LASTMARK_SAVE();
+                while ((Py_ssize_t)ctx->pattern[2] == SRE_MAXREPEAT
+                       || ctx->count <= (Py_ssize_t)ctx->pattern[2]) {
+                    state->ptr = ctx->ptr;
+                    DO_JUMP(JUMP_MIN_REPEAT_ONE,jump_min_repeat_one,
+                            ctx->pattern+ctx->pattern[0]);
+                    if (ret) {
+                        RETURN_ON_ERROR(ret);
+                        RETURN_SUCCESS;
+                    }
+                    state->ptr = ctx->ptr;
+                    ret = SRE(count)(state, ctx->pattern+3, 1);
+                    RETURN_ON_ERROR(ret);
+                    DATA_LOOKUP_AT(SRE(match_context), ctx, ctx_pos);
+                    if (ret == 0)
+                        break;
+                    assert(ret == 1);
+                    ctx->ptr++;
+                    ctx->count++;
+                    LASTMARK_RESTORE();
+                }
+            }
+            RETURN_FAILURE;
+
+        case SRE_OP_REPEAT:
+            /* create repeat context.  all the hard work is done
+               by the UNTIL operator (MAX_UNTIL, MIN_UNTIL) */
+            /* <REPEAT> <skip> <1=min> <2=max> item <UNTIL> tail */
+            TRACE(("|%p|%p|REPEAT %d %d\n", ctx->pattern, ctx->ptr,
+                   ctx->pattern[1], ctx->pattern[2]));
+
+            /* install new repeat context */
+            ctx->u.rep = (SRE_REPEAT*) PyObject_MALLOC(sizeof(*ctx->u.rep));
+            if (!ctx->u.rep) {
+                PyErr_NoMemory();
+                RETURN_FAILURE;
+            }
+            ctx->u.rep->count = -1;
+            ctx->u.rep->pattern = ctx->pattern;
+            ctx->u.rep->prev = state->repeat;
+            ctx->u.rep->last_ptr = NULL;
+            state->repeat = ctx->u.rep;
+
+            state->ptr = ctx->ptr;
+            DO_JUMP(JUMP_REPEAT, jump_repeat, ctx->pattern+ctx->pattern[0]);
+            state->repeat = ctx->u.rep->prev;
+            PyObject_FREE(ctx->u.rep);
+
+            if (ret) {
+                RETURN_ON_ERROR(ret);
+                RETURN_SUCCESS;
+            }
+            RETURN_FAILURE;
+
+        case SRE_OP_MAX_UNTIL:
+            /* maximizing repeat */
+            /* <REPEAT> <skip> <1=min> <2=max> item <MAX_UNTIL> tail */
+
+            /* FIXME: we probably need to deal with zero-width
+               matches in here... */
+
+            ctx->u.rep = state->repeat;
+            if (!ctx->u.rep)
+                RETURN_ERROR(SRE_ERROR_STATE);
+
+            state->ptr = ctx->ptr;
+
+            ctx->count = ctx->u.rep->count+1;
+
+            TRACE(("|%p|%p|MAX_UNTIL %" PY_FORMAT_SIZE_T "d\n", ctx->pattern,
+                   ctx->ptr, ctx->count));
+
+            if (ctx->count < (Py_ssize_t) ctx->u.rep->pattern[1]) {
+                /* not enough matches */
+                ctx->u.rep->count = ctx->count;
+                DO_JUMP(JUMP_MAX_UNTIL_1, jump_max_until_1,
+                        ctx->u.rep->pattern+3);
+                if (ret) {
+                    RETURN_ON_ERROR(ret);
+                    RETURN_SUCCESS;
+                }
+                ctx->u.rep->count = ctx->count-1;
+                state->ptr = ctx->ptr;
+                RETURN_FAILURE;
+            }
+
+            if ((ctx->count < (Py_ssize_t) ctx->u.rep->pattern[2] ||
+                ctx->u.rep->pattern[2] == SRE_MAXREPEAT) &&
+                state->ptr != ctx->u.rep->last_ptr) {
+                /* we may have enough matches, but if we can
+                   match another item, do so */
+                ctx->u.rep->count = ctx->count;
+                LASTMARK_SAVE();
+                MARK_PUSH(ctx->lastmark);
+                /* zero-width match protection */
+                DATA_PUSH(&ctx->u.rep->last_ptr);
+                ctx->u.rep->last_ptr = state->ptr;
+                DO_JUMP(JUMP_MAX_UNTIL_2, jump_max_until_2,
+                        ctx->u.rep->pattern+3);
+                DATA_POP(&ctx->u.rep->last_ptr);
+                if (ret) {
+                    MARK_POP_DISCARD(ctx->lastmark);
+                    RETURN_ON_ERROR(ret);
+                    RETURN_SUCCESS;
+                }
+                MARK_POP(ctx->lastmark);
+                LASTMARK_RESTORE();
+                ctx->u.rep->count = ctx->count-1;
+                state->ptr = ctx->ptr;
+            }
+
+            /* cannot match more repeated items here.  make sure the
+               tail matches */
+            state->repeat = ctx->u.rep->prev;
+            DO_JUMP(JUMP_MAX_UNTIL_3, jump_max_until_3, ctx->pattern);
+            RETURN_ON_SUCCESS(ret);
+            state->repeat = ctx->u.rep;
+            state->ptr = ctx->ptr;
+            RETURN_FAILURE;
+
+        case SRE_OP_MIN_UNTIL:
+            /* minimizing repeat */
+            /* <REPEAT> <skip> <1=min> <2=max> item <MIN_UNTIL> tail */
+
+            ctx->u.rep = state->repeat;
+            if (!ctx->u.rep)
+                RETURN_ERROR(SRE_ERROR_STATE);
+
+            state->ptr = ctx->ptr;
+
+            ctx->count = ctx->u.rep->count+1;
+
+            TRACE(("|%p|%p|MIN_UNTIL %" PY_FORMAT_SIZE_T "d %p\n", ctx->pattern,
+                   ctx->ptr, ctx->count, ctx->u.rep->pattern));
+
+            if (ctx->count < (Py_ssize_t) ctx->u.rep->pattern[1]) {
+                /* not enough matches */
+                ctx->u.rep->count = ctx->count;
+                DO_JUMP(JUMP_MIN_UNTIL_1, jump_min_until_1,
+                        ctx->u.rep->pattern+3);
+                if (ret) {
+                    RETURN_ON_ERROR(ret);
+                    RETURN_SUCCESS;
+                }
+                ctx->u.rep->count = ctx->count-1;
+                state->ptr = ctx->ptr;
+                RETURN_FAILURE;
+            }
+
+            LASTMARK_SAVE();
+
+            /* see if the tail matches */
+            state->repeat = ctx->u.rep->prev;
+            DO_JUMP(JUMP_MIN_UNTIL_2, jump_min_until_2, ctx->pattern);
+            if (ret) {
+                RETURN_ON_ERROR(ret);
+                RETURN_SUCCESS;
+            }
+
+            state->repeat = ctx->u.rep;
+            state->ptr = ctx->ptr;
+
+            LASTMARK_RESTORE();
+
+            if ((ctx->count >= (Py_ssize_t) ctx->u.rep->pattern[2]
+                && ctx->u.rep->pattern[2] != SRE_MAXREPEAT) ||
+                state->ptr == ctx->u.rep->last_ptr)
+                RETURN_FAILURE;
+
+            ctx->u.rep->count = ctx->count;
+            /* zero-width match protection */
+            DATA_PUSH(&ctx->u.rep->last_ptr);
+            ctx->u.rep->last_ptr = state->ptr;
+            DO_JUMP(JUMP_MIN_UNTIL_3,jump_min_until_3,
+                    ctx->u.rep->pattern+3);
+            DATA_POP(&ctx->u.rep->last_ptr);
+            if (ret) {
+                RETURN_ON_ERROR(ret);
+                RETURN_SUCCESS;
+            }
+            ctx->u.rep->count = ctx->count-1;
+            state->ptr = ctx->ptr;
+            RETURN_FAILURE;
+
+        case SRE_OP_GROUPREF:
+            /* match backreference */
+            TRACE(("|%p|%p|GROUPREF %d\n", ctx->pattern,
+                   ctx->ptr, ctx->pattern[0]));
+            i = ctx->pattern[0];
+            {
+                Py_ssize_t groupref = i+i;
+                if (groupref >= state->lastmark) {
+                    RETURN_FAILURE;
+                } else {
+                    SRE_CHAR* p = (SRE_CHAR*) state->mark[groupref];
+                    SRE_CHAR* e = (SRE_CHAR*) state->mark[groupref+1];
+                    if (!p || !e || e < p)
+                        RETURN_FAILURE;
+                    while (p < e) {
+                        if (ctx->ptr >= end || *ctx->ptr != *p)
+                            RETURN_FAILURE;
+                        p++;
+                        ctx->ptr++;
+                    }
+                }
+            }
+            ctx->pattern++;
+            break;
+
+        case SRE_OP_GROUPREF_IGNORE:
+            /* match backreference */
+            TRACE(("|%p|%p|GROUPREF_IGNORE %d\n", ctx->pattern,
+                   ctx->ptr, ctx->pattern[0]));
+            i = ctx->pattern[0];
+            {
+                Py_ssize_t groupref = i+i;
+                if (groupref >= state->lastmark) {
+                    RETURN_FAILURE;
+                } else {
+                    SRE_CHAR* p = (SRE_CHAR*) state->mark[groupref];
+                    SRE_CHAR* e = (SRE_CHAR*) state->mark[groupref+1];
+                    if (!p || !e || e < p)
+                        RETURN_FAILURE;
+                    while (p < e) {
+                        if (ctx->ptr >= end ||
+                            state->lower(*ctx->ptr) != state->lower(*p))
+                            RETURN_FAILURE;
+                        p++;
+                        ctx->ptr++;
+                    }
+                }
+            }
+            ctx->pattern++;
+            break;
+
+        case SRE_OP_GROUPREF_EXISTS:
+            TRACE(("|%p|%p|GROUPREF_EXISTS %d\n", ctx->pattern,
+                   ctx->ptr, ctx->pattern[0]));
+            /* <GROUPREF_EXISTS> <group> <skip> codeyes <JUMP> codeno ... */
+            i = ctx->pattern[0];
+            {
+                Py_ssize_t groupref = i+i;
+                if (groupref >= state->lastmark) {
+                    ctx->pattern += ctx->pattern[1];
+                    break;
+                } else {
+                    SRE_CHAR* p = (SRE_CHAR*) state->mark[groupref];
+                    SRE_CHAR* e = (SRE_CHAR*) state->mark[groupref+1];
+                    if (!p || !e || e < p) {
+                        ctx->pattern += ctx->pattern[1];
+                        break;
+                    }
+                }
+            }
+            ctx->pattern += 2;
+            break;
+
+        case SRE_OP_ASSERT:
+            /* assert subpattern */
+            /* <ASSERT> <skip> <back> <pattern> */
+            TRACE(("|%p|%p|ASSERT %d\n", ctx->pattern,
+                   ctx->ptr, ctx->pattern[1]));
+            state->ptr = ctx->ptr - ctx->pattern[1];
+            if (state->ptr < state->beginning)
+                RETURN_FAILURE;
+            DO_JUMP(JUMP_ASSERT, jump_assert, ctx->pattern+2);
+            RETURN_ON_FAILURE(ret);
+            ctx->pattern += ctx->pattern[0];
+            break;
+
+        case SRE_OP_ASSERT_NOT:
+            /* assert not subpattern */
+            /* <ASSERT_NOT> <skip> <back> <pattern> */
+            TRACE(("|%p|%p|ASSERT_NOT %d\n", ctx->pattern,
+                   ctx->ptr, ctx->pattern[1]));
+            state->ptr = ctx->ptr - ctx->pattern[1];
+            if (state->ptr >= state->beginning) {
+                DO_JUMP(JUMP_ASSERT_NOT, jump_assert_not, ctx->pattern+2);
+                if (ret) {
+                    RETURN_ON_ERROR(ret);
+                    RETURN_FAILURE;
+                }
+            }
+            ctx->pattern += ctx->pattern[0];
+            break;
+
+        case SRE_OP_FAILURE:
+            /* immediate failure */
+            TRACE(("|%p|%p|FAILURE\n", ctx->pattern, ctx->ptr));
+            RETURN_FAILURE;
+
+        default:
+            TRACE(("|%p|%p|UNKNOWN %d\n", ctx->pattern, ctx->ptr,
+                   ctx->pattern[-1]));
+            RETURN_ERROR(SRE_ERROR_ILLEGAL);
+        }
+    }
+
+exit:
+    ctx_pos = ctx->last_ctx_pos;
+    jump = ctx->jump;
+    DATA_POP_DISCARD(ctx);
+    if (ctx_pos == -1)
+        return ret;
+    DATA_LOOKUP_AT(SRE(match_context), ctx, ctx_pos);
+
+    switch (jump) {
+        case JUMP_MAX_UNTIL_2:
+            TRACE(("|%p|%p|JUMP_MAX_UNTIL_2\n", ctx->pattern, ctx->ptr));
+            goto jump_max_until_2;
+        case JUMP_MAX_UNTIL_3:
+            TRACE(("|%p|%p|JUMP_MAX_UNTIL_3\n", ctx->pattern, ctx->ptr));
+            goto jump_max_until_3;
+        case JUMP_MIN_UNTIL_2:
+            TRACE(("|%p|%p|JUMP_MIN_UNTIL_2\n", ctx->pattern, ctx->ptr));
+            goto jump_min_until_2;
+        case JUMP_MIN_UNTIL_3:
+            TRACE(("|%p|%p|JUMP_MIN_UNTIL_3\n", ctx->pattern, ctx->ptr));
+            goto jump_min_until_3;
+        case JUMP_BRANCH:
+            TRACE(("|%p|%p|JUMP_BRANCH\n", ctx->pattern, ctx->ptr));
+            goto jump_branch;
+        case JUMP_MAX_UNTIL_1:
+            TRACE(("|%p|%p|JUMP_MAX_UNTIL_1\n", ctx->pattern, ctx->ptr));
+            goto jump_max_until_1;
+        case JUMP_MIN_UNTIL_1:
+            TRACE(("|%p|%p|JUMP_MIN_UNTIL_1\n", ctx->pattern, ctx->ptr));
+            goto jump_min_until_1;
+        case JUMP_REPEAT:
+            TRACE(("|%p|%p|JUMP_REPEAT\n", ctx->pattern, ctx->ptr));
+            goto jump_repeat;
+        case JUMP_REPEAT_ONE_1:
+            TRACE(("|%p|%p|JUMP_REPEAT_ONE_1\n", ctx->pattern, ctx->ptr));
+            goto jump_repeat_one_1;
+        case JUMP_REPEAT_ONE_2:
+            TRACE(("|%p|%p|JUMP_REPEAT_ONE_2\n", ctx->pattern, ctx->ptr));
+            goto jump_repeat_one_2;
+        case JUMP_MIN_REPEAT_ONE:
+            TRACE(("|%p|%p|JUMP_MIN_REPEAT_ONE\n", ctx->pattern, ctx->ptr));
+            goto jump_min_repeat_one;
+        case JUMP_ASSERT:
+            TRACE(("|%p|%p|JUMP_ASSERT\n", ctx->pattern, ctx->ptr));
+            goto jump_assert;
+        case JUMP_ASSERT_NOT:
+            TRACE(("|%p|%p|JUMP_ASSERT_NOT\n", ctx->pattern, ctx->ptr));
+            goto jump_assert_not;
+        case JUMP_NONE:
+            TRACE(("|%p|%p|RETURN %" PY_FORMAT_SIZE_T "d\n", ctx->pattern,
+                   ctx->ptr, ret));
+            break;
+    }
+
+    return ret; /* should never get here */
+}
+
+LOCAL(Py_ssize_t)
+SRE(search)(SRE_STATE* state, SRE_CODE* pattern)
+{
+    SRE_CHAR* ptr = (SRE_CHAR *)state->start;
+    SRE_CHAR* end = (SRE_CHAR *)state->end;
+    Py_ssize_t status = 0;
+    Py_ssize_t prefix_len = 0;
+    Py_ssize_t prefix_skip = 0;
+    SRE_CODE* prefix = NULL;
+    SRE_CODE* charset = NULL;
+    SRE_CODE* overlap = NULL;
+    int flags = 0;
+
+    if (pattern[0] == SRE_OP_INFO) {
+        /* optimization info block */
+        /* <INFO> <1=skip> <2=flags> <3=min> <4=max> <5=prefix info>  */
+
+        flags = pattern[2];
+
+        if (pattern[3] > 1) {
+            /* adjust end point (but make sure we leave at least one
+               character in there, so literal search will work) */
+            end -= pattern[3] - 1;
+            if (end <= ptr)
+                end = ptr;
+        }
+
+        if (flags & SRE_INFO_PREFIX) {
+            /* pattern starts with a known prefix */
+            /* <length> <skip> <prefix data> <overlap data> */
+            prefix_len = pattern[5];
+            prefix_skip = pattern[6];
+            prefix = pattern + 7;
+            overlap = prefix + prefix_len - 1;
+        } else if (flags & SRE_INFO_CHARSET)
+            /* pattern starts with a character from a known set */
+            /* <charset> */
+            charset = pattern + 5;
+
+        pattern += 1 + pattern[1];
+    }
+
+    TRACE(("prefix = %p %" PY_FORMAT_SIZE_T "d %" PY_FORMAT_SIZE_T "d\n",
+           prefix, prefix_len, prefix_skip));
+    TRACE(("charset = %p\n", charset));
+
+#if defined(USE_FAST_SEARCH)
+    if (prefix_len > 1) {
+        /* pattern starts with a known prefix.  use the overlap
+           table to skip forward as fast as we possibly can */
+        Py_ssize_t i = 0;
+
+        end = (SRE_CHAR *)state->end;
+        if (prefix_len > end - ptr)
+            return 0;
+#if SIZEOF_SRE_CHAR < 4
+        for (i = 0; i < prefix_len; i++)
+            if ((SRE_CODE)(SRE_CHAR) prefix[i] != prefix[i])
+                return 0; /* literal can't match: doesn't fit in char width */
+#endif
+        while (ptr < end) {
+            SRE_CHAR c = (SRE_CHAR) prefix[0];
+            while (*ptr++ != c) {
+                if (ptr >= end)
+                    return 0;
+            }
+            if (ptr >= end)
+                return 0;
+
+            i = 1;
+            do {
+                if (*ptr == (SRE_CHAR) prefix[i]) {
+                    if (++i != prefix_len) {
+                        if (++ptr >= end)
+                            return 0;
+                        continue;
+                    }
+                    /* found a potential match */
+                    TRACE(("|%p|%p|SEARCH SCAN\n", pattern, ptr));
+                    state->start = ptr - (prefix_len - 1);
+                    state->ptr = ptr - (prefix_len - prefix_skip - 1);
+                    if (flags & SRE_INFO_LITERAL)
+                        return 1; /* we got all of it */
+                    status = SRE(match)(state, pattern + 2*prefix_skip);
+                    if (status != 0)
+                        return status;
+                    /* close but no cigar -- try again */
+                    if (++ptr >= end)
+                        return 0;
+                }
+                i = overlap[i];
+            } while (i != 0);
+        }
+        return 0;
+    }
+#endif
+
+    if (pattern[0] == SRE_OP_LITERAL) {
+        /* pattern starts with a literal character.  this is used
+           for short prefixes, and if fast search is disabled */
+        SRE_CHAR c = (SRE_CHAR) pattern[1];
+#if SIZEOF_SRE_CHAR < 4
+        if ((SRE_CODE) c != pattern[1])
+            return 0; /* literal can't match: doesn't fit in char width */
+#endif
+        end = (SRE_CHAR *)state->end;
+        while (ptr < end) {
+            while (*ptr != c) {
+                if (++ptr >= end)
+                    return 0;
+            }
+            TRACE(("|%p|%p|SEARCH LITERAL\n", pattern, ptr));
+            state->start = ptr;
+            state->ptr = ++ptr;
+            if (flags & SRE_INFO_LITERAL)
+                return 1; /* we got all of it */
+            status = SRE(match)(state, pattern + 2);
+            if (status != 0)
+                break;
+        }
+    } else if (charset) {
+        /* pattern starts with a character from a known set */
+        end = (SRE_CHAR *)state->end;
+        for (;;) {
+            while (ptr < end && !SRE(charset)(charset, *ptr))
+                ptr++;
+            if (ptr >= end)
+                return 0;
+            TRACE(("|%p|%p|SEARCH CHARSET\n", pattern, ptr));
+            state->start = ptr;
+            state->ptr = ptr;
+            status = SRE(match)(state, pattern);
+            if (status != 0)
+                break;
+            ptr++;
+        }
+    } else
+        /* general case */
+        while (ptr <= end) {
+            TRACE(("|%p|%p|SEARCH\n", pattern, ptr));
+            state->start = state->ptr = ptr++;
+            status = SRE(match)(state, pattern);
+            if (status != 0)
+                break;
+        }
+
+    return status;
+}
+
+#undef SRE_CHAR
+#undef SIZEOF_SRE_CHAR
+#undef SRE
+
+/* vim:ts=4:sw=4:et
+*/