2020-01-05 release

1 files changed, 2541 insertions, 0 deletions

diff --git a/libregexp.c b/libregexp.c
new file mode 100644
index 0000000..4425ce5
--- /dev/null
+++ b/libregexp.c
@@ -0,0 +1,2541 @@
+/*
+ * Regular Expression Engine
+ * 
+ * Copyright (c) 2017-2018 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <inttypes.h>
+#include <string.h>
+#include <assert.h>
+
+#include "cutils.h"
+#include "libregexp.h"
+
+/*
+  TODO:
+
+  - Add full unicode canonicalize rules for character ranges (not
+    really useful but needed for exact "ignorecase" compatibility).
+
+  - Add a lock step execution mode (=linear time execution guaranteed)
+    when the regular expression is "simple" i.e. no backreference nor
+    complicated lookahead. The opcodes are designed for this execution
+    model.
+*/
+
+#if defined(TEST)
+#define DUMP_REOP
+#endif
+
+typedef enum {
+#define DEF(id, size) REOP_ ## id,
+#include "libregexp-opcode.h"
+#undef DEF
+    REOP_COUNT,
+} REOPCodeEnum;
+
+#define CAPTURE_COUNT_MAX 255
+#define STACK_SIZE_MAX 255
+
+/* unicode code points */
+#define CP_LS   0x2028
+#define CP_PS   0x2029
+
+#define TMP_BUF_SIZE 128
+
+typedef struct {
+    DynBuf byte_code;
+    const uint8_t *buf_ptr;
+    const uint8_t *buf_end;
+    const uint8_t *buf_start;
+    int re_flags;
+    BOOL is_utf16;
+    BOOL ignore_case;
+    BOOL dotall;
+    int capture_count;
+    int total_capture_count; /* -1 = not computed yet */
+    int has_named_captures; /* -1 = don't know, 0 = no, 1 = yes */
+    void *mem_opaque;
+    DynBuf group_names;
+    union {
+        char error_msg[TMP_BUF_SIZE];
+        char tmp_buf[TMP_BUF_SIZE];
+    } u;
+} REParseState;
+
+typedef struct {
+#ifdef DUMP_REOP
+    const char *name;
+#endif
+    uint8_t size;
+} REOpCode;
+
+static const REOpCode reopcode_info[REOP_COUNT] = {
+#ifdef DUMP_REOP
+#define DEF(id, size) { #id, size },
+#else
+#define DEF(id, size) { size },
+#endif
+#include "libregexp-opcode.h"
+#undef DEF
+};
+
+#define RE_HEADER_FLAGS         0
+#define RE_HEADER_CAPTURE_COUNT 1
+#define RE_HEADER_STACK_SIZE    2
+
+#define RE_HEADER_LEN 7
+
+static inline int is_digit(int c) {
+    return c >= '0' && c <= '9';
+}
+
+/* insert 'len' bytes at position 'pos' */
+static void dbuf_insert(DynBuf *s, int pos, int len)
+{
+    dbuf_realloc(s, s->size + len);
+    memmove(s->buf + pos + len, s->buf + pos, s->size - pos);
+    s->size += len;
+}
+
+/* canonicalize with the specific JS regexp rules */
+static uint32_t lre_canonicalize(uint32_t c, BOOL is_utf16)
+{
+    uint32_t res[LRE_CC_RES_LEN_MAX];
+    int len;
+    if (is_utf16) {
+        if (likely(c < 128)) {
+            if (c >= 'A' && c <= 'Z')
+                c = c - 'A' + 'a';
+        } else {
+            lre_case_conv(res, c, 2);
+            c = res[0];
+        }
+    } else {
+        if (likely(c < 128)) {
+            if (c >= 'a' && c <= 'z')
+                c = c - 'a' + 'A';
+        } else {
+            /* legacy regexp: to upper case if single char >= 128 */
+            len = lre_case_conv(res, c, FALSE);
+            if (len == 1 && res[0] >= 128)
+                c = res[0];
+        }
+    }
+    return c;
+}
+
+static const uint16_t char_range_d[] = {
+    1,
+    0x0030, 0x0039 + 1,
+};
+
+/* code point ranges for Zs,Zl or Zp property */
+static const uint16_t char_range_s[] = {
+    10,
+    0x0009, 0x000D + 1,
+    0x0020, 0x0020 + 1,
+    0x00A0, 0x00A0 + 1,
+    0x1680, 0x1680 + 1,
+    0x2000, 0x200A + 1,
+    /* 2028;LINE SEPARATOR;Zl;0;WS;;;;;N;;;;; */
+    /* 2029;PARAGRAPH SEPARATOR;Zp;0;B;;;;;N;;;;; */
+    0x2028, 0x2029 + 1,
+    0x202F, 0x202F + 1,
+    0x205F, 0x205F + 1,
+    0x3000, 0x3000 + 1,
+    /* FEFF;ZERO WIDTH NO-BREAK SPACE;Cf;0;BN;;;;;N;BYTE ORDER MARK;;;; */
+    0xFEFF, 0xFEFF + 1,
+};
+
+BOOL lre_is_space(int c)
+{
+    int i, n, low, high;
+    n = (countof(char_range_s) - 1) / 2;
+    for(i = 0; i < n; i++) {
+        low = char_range_s[2 * i + 1];
+        if (c < low)
+            return FALSE;
+        high = char_range_s[2 * i + 2];
+        if (c < high)
+            return TRUE;
+    }
+    return FALSE;
+}
+
+uint32_t const lre_id_start_table_ascii[4] = {
+    /* $ A-Z _ a-z */
+    0x00000000, 0x00000010, 0x87FFFFFE, 0x07FFFFFE
+};
+
+uint32_t const lre_id_continue_table_ascii[4] = {
+    /* $ 0-9 A-Z _ a-z */
+    0x00000000, 0x03FF0010, 0x87FFFFFE, 0x07FFFFFE
+};
+
+
+static const uint16_t char_range_w[] = {
+    4,
+    0x0030, 0x0039 + 1,
+    0x0041, 0x005A + 1,
+    0x005F, 0x005F + 1,
+    0x0061, 0x007A + 1,
+};
+
+#define CLASS_RANGE_BASE 0x40000000
+
+typedef enum {
+    CHAR_RANGE_d,
+    CHAR_RANGE_D,
+    CHAR_RANGE_s,
+    CHAR_RANGE_S,
+    CHAR_RANGE_w,
+    CHAR_RANGE_W,
+} CharRangeEnum;
+
+static const uint16_t *char_range_table[] = {
+    char_range_d,
+    char_range_s,
+    char_range_w,
+};
+
+static int cr_init_char_range(REParseState *s, CharRange *cr, uint32_t c)
+{
+    BOOL invert;
+    const uint16_t *c_pt;
+    int len, i;
+    
+    invert = c & 1;
+    c_pt = char_range_table[c >> 1];
+    len = *c_pt++;
+    cr_init(cr, s->mem_opaque, lre_realloc);
+    for(i = 0; i < len * 2; i++) {
+        if (cr_add_point(cr, c_pt[i]))
+            goto fail;
+    }
+    if (invert) {
+        if (cr_invert(cr))
+            goto fail;
+    }
+    return 0;
+ fail:
+    cr_free(cr);
+    return -1;
+}
+
+static int cr_canonicalize(CharRange *cr)
+{
+    CharRange a;
+    uint32_t pt[2];
+    int i, ret;
+
+    cr_init(&a, cr->mem_opaque, lre_realloc);
+    pt[0] = 'a';
+    pt[1] = 'z' + 1;
+    ret = cr_op(&a, cr->points, cr->len, pt, 2, CR_OP_INTER);
+    if (ret)
+        goto fail;
+    /* convert to upper case */
+    /* XXX: the generic unicode case would be much more complicated
+       and not really useful */
+    for(i = 0; i < a.len; i++) {
+        a.points[i] += 'A' - 'a';
+    }
+    /* Note: for simplicity we keep the lower case ranges */
+    ret = cr_union1(cr, a.points, a.len);
+ fail:
+    cr_free(&a);
+    return ret;
+}
+
+#ifdef DUMP_REOP
+static __maybe_unused void lre_dump_bytecode(const uint8_t *buf,
+                                                     int buf_len)
+{
+    int pos, len, opcode, bc_len, re_flags, i;
+    uint32_t val;
+    
+    assert(buf_len >= RE_HEADER_LEN);
+
+    re_flags=  buf[0];
+    bc_len = get_u32(buf + 3);
+    assert(bc_len + RE_HEADER_LEN <= buf_len);
+    printf("flags: 0x%x capture_count=%d stack_size=%d\n",
+           re_flags, buf[1], buf[2]);
+    if (re_flags & LRE_FLAG_NAMED_GROUPS) {
+        const char *p;
+        p = (char *)buf + RE_HEADER_LEN + bc_len;
+        printf("named groups: ");
+        for(i = 1; i < buf[1]; i++) {
+            if (i != 1)
+                printf(",");
+            printf("<%s>", p);
+            p += strlen(p) + 1;
+        }
+        printf("\n");
+        assert(p == (char *)(buf + buf_len));
+    }
+    printf("bytecode_len=%d\n", bc_len);
+
+    buf += RE_HEADER_LEN;
+    pos = 0;
+    while (pos < bc_len) {
+        printf("%5u: ", pos);
+        opcode = buf[pos];
+        len = reopcode_info[opcode].size;
+        if (opcode >= REOP_COUNT) {
+            printf(" invalid opcode=0x%02x\n", opcode);
+            break;
+        }
+        if ((pos + len) > bc_len) {
+            printf(" buffer overflow (opcode=0x%02x)\n", opcode);
+            break;
+        }
+        printf("%s", reopcode_info[opcode].name);
+        switch(opcode) {
+        case REOP_char:
+            val = get_u16(buf + pos + 1);
+            if (val >= ' ' && val <= 126)
+                printf(" '%c'", val);
+            else
+                printf(" 0x%04x", val);
+            break;
+        case REOP_char32:
+            val = get_u32(buf + pos + 1);
+            if (val >= ' ' && val <= 126)
+                printf(" '%c'", val);
+            else
+                printf(" 0x%08x", val);
+            break;
+        case REOP_goto:
+        case REOP_split_goto_first:
+        case REOP_split_next_first:
+        case REOP_loop:
+        case REOP_lookahead:
+        case REOP_negative_lookahead:
+        case REOP_bne_char_pos:
+            val = get_u32(buf + pos + 1);
+            val += (pos + 5);
+            printf(" %u", val);
+            break;
+        case REOP_simple_greedy_quant:
+            printf(" %u %u %u %u",
+                   get_u32(buf + pos + 1) + (pos + 17),
+                   get_u32(buf + pos + 1 + 4),
+                   get_u32(buf + pos + 1 + 8),
+                   get_u32(buf + pos + 1 + 12));
+            break;
+        case REOP_save_start:
+        case REOP_save_end:
+        case REOP_back_reference:
+        case REOP_backward_back_reference:
+            printf(" %u", buf[pos + 1]);
+            break;
+        case REOP_save_reset:
+            printf(" %u %u", buf[pos + 1], buf[pos + 2]);
+            break;
+        case REOP_push_i32:
+            val = get_u32(buf + pos + 1);
+            printf(" %d", val);
+            break;
+        case REOP_range:
+            {
+                int n, i;
+                n = get_u16(buf + pos + 1);
+                len += n * 4;
+                for(i = 0; i < n * 2; i++) {
+                    val = get_u16(buf + pos + 3 + i * 2);
+                    printf(" 0x%04x", val);
+                }
+            }
+            break;
+        case REOP_range32:
+            {
+                int n, i;
+                n = get_u16(buf + pos + 1);
+                len += n * 8;
+                for(i = 0; i < n * 2; i++) {
+                    val = get_u32(buf + pos + 3 + i * 4);
+                    printf(" 0x%08x", val);
+                }
+            }
+            break;
+        default:
+            break;
+        }
+        printf("\n");
+        pos += len;
+    }
+}
+#endif
+
+static void re_emit_op(REParseState *s, int op)
+{
+    dbuf_putc(&s->byte_code, op);
+}
+
+/* return the offset of the u32 value */
+static int re_emit_op_u32(REParseState *s, int op, uint32_t val)
+{
+    int pos;
+    dbuf_putc(&s->byte_code, op);
+    pos = s->byte_code.size;
+    dbuf_put_u32(&s->byte_code, val);
+    return pos;
+}
+
+static int re_emit_goto(REParseState *s, int op, uint32_t val)
+{
+    int pos;
+    dbuf_putc(&s->byte_code, op);
+    pos = s->byte_code.size;
+    dbuf_put_u32(&s->byte_code, val - (pos + 4));
+    return pos;
+}
+
+static void re_emit_op_u8(REParseState *s, int op, uint32_t val)
+{
+    dbuf_putc(&s->byte_code, op);
+    dbuf_putc(&s->byte_code, val);
+}
+
+static void re_emit_op_u16(REParseState *s, int op, uint32_t val)
+{
+    dbuf_putc(&s->byte_code, op);
+    dbuf_put_u16(&s->byte_code, val);
+}
+
+static int __attribute__((format(printf, 2, 3))) re_parse_error(REParseState *s, const char *fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+    vsnprintf(s->u.error_msg, sizeof(s->u.error_msg), fmt, ap);
+    va_end(ap);
+    return -1;
+}
+
+/* Return -1 in case of overflow */
+static int parse_digits(const uint8_t **pp)
+{
+    const uint8_t *p;
+    uint64_t v;
+    int c;
+    
+    p = *pp;
+    v = 0;
+    for(;;) {
+        c = *p;
+        if (c < '0' || c > '9')
+            break;
+        v = v * 10 + c - '0';
+        if (v >= INT32_MAX)
+            return -1;
+        p++;
+    }
+    *pp = p;
+    return v;
+}
+
+static int re_parse_expect(REParseState *s, const uint8_t **pp, int c)
+{
+    const uint8_t *p;
+    p = *pp;
+    if (*p != c)
+        return re_parse_error(s, "expecting '%c'", c);
+    p++;
+    *pp = p;
+    return 0;
+}
+
+/* Parse an escape sequence, *pp points after the '\':
+   allow_utf16 value:
+   0 : no UTF-16 escapes allowed
+   1 : UTF-16 escapes allowed
+   2 : UTF-16 escapes allowed and escapes of surrogate pairs are
+   converted to a unicode character (unicode regexp case).
+
+   Return the unicode char and update *pp if recognized,
+   return -1 if malformed escape,
+   return -2 otherwise. */
+int lre_parse_escape(const uint8_t **pp, int allow_utf16)
+{
+    const uint8_t *p;
+    uint32_t c;
+
+    p = *pp;
+    c = *p++;
+    switch(c) {
+    case 'b':
+        c = '\b';
+        break;
+    case 'f':
+        c = '\f';
+        break;
+    case 'n':
+        c = '\n';
+        break;
+    case 'r':
+        c = '\r';
+        break;
+    case 't':
+        c = '\t';
+        break;
+    case 'v':
+        c = '\v';
+        break;
+    case 'x':
+    case 'u':
+        {
+            int h, n, i;
+            uint32_t c1;
+            
+            if (*p == '{' && allow_utf16) {
+                p++;
+                c = 0;
+                for(;;) {
+                    h = from_hex(*p++);
+                    if (h < 0)
+                        return -1;
+                    c = (c << 4) | h;
+                    if (c > 0x10FFFF)
+                        return -1;
+                    if (*p == '}')
+                        break;
+                }
+                p++;
+            } else {
+                if (c == 'x') {
+                    n = 2;
+                } else {
+                    n = 4;
+                }
+
+                c = 0;
+                for(i = 0; i < n; i++) {
+                    h = from_hex(*p++);
+                    if (h < 0) {
+                        return -1;
+                    }
+                    c = (c << 4) | h;
+                }
+                if (c >= 0xd800 && c < 0xdc00 &&
+                    allow_utf16 == 2 && p[0] == '\\' && p[1] == 'u') {
+                    /* convert an escaped surrogate pair into a
+                       unicode char */
+                    c1 = 0;
+                    for(i = 0; i < 4; i++) {
+                        h = from_hex(p[2 + i]);
+                        if (h < 0)
+                            break;
+                        c1 = (c1 << 4) | h;
+                    }
+                    if (i == 4 && c1 >= 0xdc00 && c1 < 0xe000) {
+                        p += 6;
+                        c = (((c & 0x3ff) << 10) | (c1 & 0x3ff)) + 0x10000;
+                    }
+                }
+            }
+        }
+        break;
+    case '0' ... '7':
+        c -= '0';
+        if (allow_utf16 == 2) {
+            /* only accept \0 not followed by digit */
+            if (c != 0 || is_digit(*p))
+                return -1;
+        } else {
+            /* parse a legacy octal sequence */
+            uint32_t v;
+            v = *p - '0';
+            if (v > 7)
+                break;
+            c = (c << 3) | v;
+            p++;
+            if (c >= 32)
+                break;
+            v = *p - '0';
+            if (v > 7)
+                break;
+            c = (c << 3) | v;
+            p++;
+        }
+        break;
+    default:
+        return -2;
+    }
+    *pp = p;
+    return c;
+}
+
+#ifdef CONFIG_ALL_UNICODE
+/* XXX: we use the same chars for name and value */
+static BOOL is_unicode_char(int c)
+{
+    return ((c >= '0' && c <= '9') ||
+            (c >= 'A' && c <= 'Z') ||
+            (c >= 'a' && c <= 'z') ||
+            (c == '_'));
+}
+
+static int parse_unicode_property(REParseState *s, CharRange *cr,
+                                  const uint8_t **pp, BOOL is_inv)
+{
+    const uint8_t *p;
+    char name[64], value[64];
+    char *q;
+    BOOL script_ext;
+    int ret;
+
+    p = *pp;
+    if (*p != '{')
+        return re_parse_error(s, "expecting '{' after \\p");
+    p++;
+    q = name;
+    while (is_unicode_char(*p)) {
+        if ((q - name) > sizeof(name) - 1)
+            goto unknown_property_name;
+        *q++ = *p++;
+    }
+    *q = '\0';
+    q = value;
+    if (*p == '=') {
+        p++;
+        while (is_unicode_char(*p)) {
+            if ((q - value) > sizeof(value) - 1)
+                return re_parse_error(s, "unknown unicode property value");
+            *q++ = *p++;
+        }
+    }
+    *q = '\0';
+    if (*p != '}')
+        return re_parse_error(s, "expecting '}'");
+    p++;
+    //    printf("name=%s value=%s\n", name, value);
+
+    if (!strcmp(name, "Script") || !strcmp(name, "sc")) {
+        script_ext = FALSE;
+        goto do_script;
+    } else if (!strcmp(name, "Script_Extensions") || !strcmp(name, "scx")) {
+        script_ext = TRUE;
+    do_script:
+        cr_init(cr, s->mem_opaque, lre_realloc);
+        ret = unicode_script(cr, value, script_ext);
+        if (ret) {
+            cr_free(cr);
+            if (ret == -2)
+                return re_parse_error(s, "unknown unicode script");
+            else
+                goto out_of_memory;
+        }
+    } else if (!strcmp(name, "General_Category") || !strcmp(name, "gc")) {
+        cr_init(cr, s->mem_opaque, lre_realloc);
+        ret = unicode_general_category(cr, value);
+        if (ret) {
+            cr_free(cr);
+            if (ret == -2)
+                return re_parse_error(s, "unknown unicode general category");
+            else
+                goto out_of_memory;
+        }
+    } else if (value[0] == '\0') {
+        cr_init(cr, s->mem_opaque, lre_realloc);
+        ret = unicode_general_category(cr, name);
+        if (ret == -1) {
+            cr_free(cr);
+            goto out_of_memory;
+        }
+        if (ret < 0) {
+            ret = unicode_prop(cr, name);
+            if (ret) {
+                cr_free(cr);
+                if (ret == -2)
+                    goto unknown_property_name;
+                else
+                    goto out_of_memory;
+            }
+        }
+    } else {
+    unknown_property_name:
+        return re_parse_error(s, "unknown unicode property name");
+    }
+
+    if (is_inv) {
+        if (cr_invert(cr)) {
+            cr_free(cr);
+            return -1;
+        }
+    }
+    *pp = p;
+    return 0;
+ out_of_memory:
+    return re_parse_error(s, "out of memory");
+}
+#endif /* CONFIG_ALL_UNICODE */
+
+/* return -1 if error otherwise the character or a class range
+   (CLASS_RANGE_BASE). In case of class range, 'cr' is
+   initialized. Otherwise, it is ignored. */
+static int get_class_atom(REParseState *s, CharRange *cr,
+                          const uint8_t **pp, BOOL inclass)
+{
+    const uint8_t *p;
+    uint32_t c;
+    int ret;
+    
+    p = *pp;
+
+    c = *p;
+    switch(c) {
+    case '\\':
+        p++;
+        if (p >= s->buf_end)
+            goto unexpected_end;
+        c = *p++;
+        switch(c) {
+        case 'd':
+            c = CHAR_RANGE_d;
+            goto class_range;
+        case 'D':
+            c = CHAR_RANGE_D;
+            goto class_range;
+        case 's':
+            c = CHAR_RANGE_s;
+            goto class_range;
+        case 'S':
+            c = CHAR_RANGE_S;
+            goto class_range;
+        case 'w':
+            c = CHAR_RANGE_w;
+            goto class_range;
+        case 'W':
+            c = CHAR_RANGE_W;
+        class_range:
+            if (cr_init_char_range(s, cr, c))
+                return -1;
+            c = CLASS_RANGE_BASE;
+            break;
+        case 'c':
+            c = *p;
+            if ((c >= 'a' && c <= 'z') ||
+                (c >= 'A' && c <= 'Z') ||
+                (((c >= '0' && c <= '9') || c == '_') &&
+                 inclass && !s->is_utf16)) {   /* Annex B.1.4 */
+                c &= 0x1f;
+                p++;
+            } else if (s->is_utf16) {
+                goto invalid_escape;
+            } else {
+                /* otherwise return '\' and 'c' */
+                p--;
+                c = '\\';
+            }
+            break;
+#ifdef CONFIG_ALL_UNICODE
+        case 'p':
+        case 'P':
+            if (s->is_utf16) {
+                if (parse_unicode_property(s, cr, &p, (c == 'P')))
+                    return -1;
+                c = CLASS_RANGE_BASE;
+                break;
+            }
+            /* fall thru */
+#endif
+        default:
+            p--;
+            ret = lre_parse_escape(&p, s->is_utf16 * 2);
+            if (ret >= 0) {
+                c = ret;
+            } else {
+                if (ret == -2 && *p != '\0' && strchr("^$\\.*+?()[]{}|/", *p)) {
+                    /* always valid to escape these characters */
+                    goto normal_char;
+                } else if (s->is_utf16) {
+                invalid_escape:
+                    return re_parse_error(s, "invalid escape sequence in regular expression");
+                } else {
+                    /* just ignore the '\' */
+                    goto normal_char;
+                }
+            }
+            break;
+        }
+        break;
+    case '\0':
+        if (p >= s->buf_end) {
+        unexpected_end:
+            return re_parse_error(s, "unexpected end");
+        }
+        /* fall thru */
+    default:
+    normal_char:
+        /* normal char */
+        if (c >= 128) {
+            c = unicode_from_utf8(p, UTF8_CHAR_LEN_MAX, &p);
+            if ((unsigned)c > 0xffff && !s->is_utf16) {
+                /* XXX: should handle non BMP-1 code points */
+                return re_parse_error(s, "malformed unicode char");
+            }
+        } else {
+            p++;
+        }
+        break;
+    }
+    *pp = p;
+    return c;
+}
+
+static int re_emit_range(REParseState *s, const CharRange *cr)
+{
+    int len, i;
+    uint32_t high;
+    
+    len = (unsigned)cr->len / 2;
+    if (len >= 65535)
+        return re_parse_error(s, "too many ranges");
+    if (len == 0) {
+        /* not sure it can really happen. Emit a match that is always
+           false */
+        re_emit_op_u32(s, REOP_char32, -1);
+    } else {
+        high = cr->points[cr->len - 1];
+        if (high == UINT32_MAX)
+            high = cr->points[cr->len - 2];
+        if (high <= 0xffff) {
+            /* can use 16 bit ranges with the conversion that 0xffff =
+               infinity */
+            re_emit_op_u16(s, REOP_range, len);
+            for(i = 0; i < cr->len; i += 2) {
+                dbuf_put_u16(&s->byte_code, cr->points[i]);
+                high = cr->points[i + 1] - 1;
+                if (high == UINT32_MAX - 1)
+                    high = 0xffff;
+                dbuf_put_u16(&s->byte_code, high);
+            }
+        } else {
+            re_emit_op_u16(s, REOP_range32, len);
+            for(i = 0; i < cr->len; i += 2) {
+                dbuf_put_u32(&s->byte_code, cr->points[i]);
+                dbuf_put_u32(&s->byte_code, cr->points[i + 1] - 1);
+            }
+        }
+    }
+    return 0;
+}
+
+static int re_parse_char_class(REParseState *s, const uint8_t **pp)
+{
+    const uint8_t *p;
+    uint32_t c1, c2;
+    CharRange cr_s, *cr = &cr_s;
+    CharRange cr1_s, *cr1 = &cr1_s;
+    BOOL invert;
+    
+    cr_init(cr, s->mem_opaque, lre_realloc);
+    p = *pp;
+    p++;    /* skip '[' */
+    invert = FALSE;
+    if (*p == '^') {
+        p++;
+        invert = TRUE;
+    }
+    for(;;) {
+        if (*p == ']')
+            break;
+        c1 = get_class_atom(s, cr1, &p, TRUE);
+        if ((int)c1 < 0)
+            goto fail;
+        if (*p == '-' && p[1] != ']') {
+            const uint8_t *p0 = p + 1;
+            if (c1 >= CLASS_RANGE_BASE) {
+                if (s->is_utf16) {
+                    cr_free(cr1);
+                    goto invalid_class_range;
+                }
+                /* Annex B: match '-' character */
+                goto class_atom;
+            }
+            c2 = get_class_atom(s, cr1, &p0, TRUE);
+            if ((int)c2 < 0)
+                goto fail;
+            if (c2 >= CLASS_RANGE_BASE) {
+                cr_free(cr1);
+                if (s->is_utf16) {
+                    goto invalid_class_range;
+                }
+                /* Annex B: match '-' character */
+                goto class_atom;
+            }
+            p = p0;
+            if (c2 < c1) {
+            invalid_class_range:
+                re_parse_error(s, "invalid class range");
+                goto fail;
+            }
+            if (cr_union_interval(cr, c1, c2))
+                goto memory_error;
+        } else {
+        class_atom:
+            if (c1 >= CLASS_RANGE_BASE) {
+                int ret;
+                ret = cr_union1(cr, cr1->points, cr1->len);
+                cr_free(cr1);
+                if (ret)
+                    goto memory_error;
+            } else {
+                if (cr_union_interval(cr, c1, c1))
+                    goto memory_error;
+            }
+        }
+    }
+    if (s->ignore_case) {
+        if (cr_canonicalize(cr))
+            goto memory_error;
+    }
+    if (invert) {
+        if (cr_invert(cr))
+            goto memory_error;
+    }
+    if (re_emit_range(s, cr))
+        goto fail;
+    cr_free(cr);
+    p++;    /* skip ']' */
+    *pp = p;
+    return 0;
+ memory_error:
+    re_parse_error(s, "out of memory");
+ fail:
+    cr_free(cr);
+    return -1;
+}
+
+/* Return:
+   1 if the opcodes in bc_buf[] always advance the character pointer.
+   0 if the character pointer may not be advanced.
+   -1 if the code may depend on side effects of its previous execution (backreference)
+*/
+static int re_check_advance(const uint8_t *bc_buf, int bc_buf_len)
+{
+    int pos, opcode, ret, len, i;
+    uint32_t val, last;
+    BOOL has_back_reference;
+    uint8_t capture_bitmap[CAPTURE_COUNT_MAX];
+    
+    ret = -2; /* not known yet */
+    pos = 0;
+    has_back_reference = FALSE;
+    memset(capture_bitmap, 0, sizeof(capture_bitmap));
+    
+    while (pos < bc_buf_len) {
+        opcode = bc_buf[pos];
+        len = reopcode_info[opcode].size;
+        switch(opcode) {
+        case REOP_range:
+            val = get_u16(bc_buf + pos + 1);
+            len += val * 4;
+            goto simple_char;
+        case REOP_range32:
+            val = get_u16(bc_buf + pos + 1);
+            len += val * 8;
+            goto simple_char;
+        case REOP_char:
+        case REOP_char32:
+        case REOP_dot:
+        case REOP_any:
+        simple_char:
+            if (ret == -2)
+                ret = 1;
+            break;
+        case REOP_line_start:
+        case REOP_line_end:
+        case REOP_push_i32:
+        case REOP_push_char_pos:
+        case REOP_drop:
+        case REOP_word_boundary:
+        case REOP_not_word_boundary:
+        case REOP_prev:
+            /* no effect */
+            break;
+        case REOP_save_start:
+        case REOP_save_end:
+            val = bc_buf[pos + 1];
+            capture_bitmap[val] |= 1;
+            break;
+        case REOP_save_reset:
+            {
+                val = bc_buf[pos + 1];
+                last = bc_buf[pos + 2];
+                while (val < last)
+                    capture_bitmap[val++] |= 1;
+            }
+            break;
+        case REOP_back_reference:
+        case REOP_backward_back_reference:
+            val = bc_buf[pos + 1];
+            capture_bitmap[val] |= 2;
+            has_back_reference = TRUE;
+            break;
+        default:
+            /* safe behvior: we cannot predict the outcome */
+            if (ret == -2)
+                ret = 0;
+            break;
+        }
+        pos += len;
+    }
+    if (has_back_reference) {
+        /* check if there is back reference which references a capture
+           made in the some code */
+        for(i = 0; i < CAPTURE_COUNT_MAX; i++) {
+            if (capture_bitmap[i] == 3)
+                return -1;
+        }
+    }
+    if (ret == -2)
+        ret = 0;
+    return ret;
+}
+
+/* return -1 if a simple quantifier cannot be used. Otherwise return
+   the number of characters in the atom. */
+static int re_is_simple_quantifier(const uint8_t *bc_buf, int bc_buf_len)
+{
+    int pos, opcode, len, count;
+    uint32_t val;
+    
+    count = 0;
+    pos = 0;
+    while (pos < bc_buf_len) {
+        opcode = bc_buf[pos];
+        len = reopcode_info[opcode].size;
+        switch(opcode) {
+        case REOP_range:
+            val = get_u16(bc_buf + pos + 1);
+            len += val * 4;
+            goto simple_char;
+        case REOP_range32:
+            val = get_u16(bc_buf + pos + 1);
+            len += val * 8;
+            goto simple_char;
+        case REOP_char:
+        case REOP_char32:
+        case REOP_dot:
+        case REOP_any:
+        simple_char:
+            count++;
+            break;
+        case REOP_line_start:
+        case REOP_line_end:
+        case REOP_word_boundary:
+        case REOP_not_word_boundary:
+            break;
+        default:
+            return -1;
+        }
+        pos += len;
+    }
+    return count;
+}
+
+/* '*pp' is the first char after '<' */
+static int re_parse_group_name(char *buf, int buf_size,
+                               const uint8_t **pp, BOOL is_utf16)
+{
+    const uint8_t *p;
+    uint32_t c;
+    char *q;
+
+    p = *pp;
+    q = buf;
+    for(;;) {
+        c = *p;
+        if (c == '\\') {
+            p++;
+            if (*p != 'u')
+                return -1;
+            c = lre_parse_escape(&p, is_utf16 * 2);
+        } else if (c == '>') {
+            break;
+        } else if (c >= 128) {
+            c = unicode_from_utf8(p, UTF8_CHAR_LEN_MAX, &p);
+        } else {
+            p++;
+        }
+        if (c > 0x10FFFF)
+            return -1;
+        if (q == buf) {
+            if (!lre_js_is_ident_first(c))
+                return -1;
+        } else {
+            if (!lre_js_is_ident_next(c))
+                return -1;
+        }
+        if ((q - buf + UTF8_CHAR_LEN_MAX + 1) > buf_size)
+            return -1;
+        if (c < 128) {
+            *q++ = c;
+        } else {
+            q += unicode_to_utf8((uint8_t*)q, c);
+        }
+    }
+    if (q == buf)
+        return -1;
+    *q = '\0';
+    p++;
+    *pp = p;
+    return 0;
+}
+
+/* if capture_name = NULL: return the number of captures + 1.
+   Otherwise, return the capture index corresponding to capture_name
+   or -1 if none */
+static int re_parse_captures(REParseState *s, int *phas_named_captures,
+                             const char *capture_name)
+{
+    const uint8_t *p;
+    int capture_index;
+    char name[TMP_BUF_SIZE];
+
+    capture_index = 1;
+    *phas_named_captures = 0;
+    for (p = s->buf_start; p < s->buf_end; p++) {
+        switch (*p) {
+        case '(':
+            if (p[1] == '?') {
+                if (p[2] == '<' && p[3] != '=' && p[3] != '!') {
+                    *phas_named_captures = 1;
+                    /* potential named capture */
+                    if (capture_name) {
+                        p += 3;
+                        if (re_parse_group_name(name, sizeof(name), &p,
+                                                s->is_utf16) == 0) {
+                            if (!strcmp(name, capture_name))
+                                return capture_index;
+                        }
+                    }
+                    capture_index++;
+                }
+            } else {
+                capture_index++;
+            }
+            break;
+        case '\\':
+            p++;
+            break;
+        case '[':
+            for (p += 1 + (*p == ']'); p < s->buf_end && *p != ']'; p++) {
+                if (*p == '\\')
+                    p++;
+            }
+            break;
+        }
+    }
+    if (capture_name)
+        return -1;
+    else
+        return capture_index;
+}
+
+static int re_count_captures(REParseState *s)
+{
+    if (s->total_capture_count < 0) {
+        s->total_capture_count = re_parse_captures(s, &s->has_named_captures,
+                                                   NULL);
+    }
+    return s->total_capture_count;
+}
+
+static BOOL re_has_named_captures(REParseState *s)
+{
+    if (s->has_named_captures < 0)
+        re_count_captures(s);
+    return s->has_named_captures;
+}
+
+static int find_group_name(REParseState *s, const char *name)
+{
+    const char *p, *buf_end;
+    size_t len, name_len;
+    int capture_index;
+    
+    name_len = strlen(name);
+    p = (char *)s->group_names.buf;
+    buf_end = (char *)s->group_names.buf + s->group_names.size;
+    capture_index = 1;
+    while (p < buf_end) {
+        len = strlen(p);
+        if (len == name_len && memcmp(name, p, name_len) == 0)
+            return capture_index;
+        p += len + 1;
+        capture_index++;
+    }
+    return -1;
+}
+
+static int re_parse_disjunction(REParseState *s, BOOL is_backward_dir);
+
+static int re_parse_term(REParseState *s, BOOL is_backward_dir)
+{
+    const uint8_t *p;
+    int c, last_atom_start, quant_min, quant_max, last_capture_count;
+    BOOL greedy, add_zero_advance_check, is_neg, is_backward_lookahead;
+    CharRange cr_s, *cr = &cr_s;
+    
+    last_atom_start = -1;
+    last_capture_count = 0;
+    p = s->buf_ptr;
+    c = *p;
+    switch(c) {
+    case '^':
+        p++;
+        re_emit_op(s, REOP_line_start);
+        break;
+    case '$':
+        p++;
+        re_emit_op(s, REOP_line_end);
+        break;
+    case '.':
+        p++;
+        last_atom_start = s->byte_code.size;
+        last_capture_count = s->capture_count;
+        if (is_backward_dir)
+            re_emit_op(s, REOP_prev);
+        re_emit_op(s, s->dotall ? REOP_any : REOP_dot);
+        if (is_backward_dir)
+            re_emit_op(s, REOP_prev);
+        break;
+    case '{':
+        /* As an extension (see ES6 annex B), we accept '{' not
+           followed by digits as a normal atom */
+        if (!is_digit(p[1])) {
+            if (s->is_utf16)
+                goto invalid_quant_count;
+            goto parse_class_atom;
+        }
+        /* fall tru */
+    case '*':
+    case '+':
+    case '?':
+        return re_parse_error(s, "nothing to repeat");
+    case '(':
+        if (p[1] == '?') {
+            if (p[2] == ':') {
+                p += 3;
+                last_atom_start = s->byte_code.size;
+                last_capture_count = s->capture_count;
+                s->buf_ptr = p;
+                if (re_parse_disjunction(s, is_backward_dir))
+                    return -1;
+                p = s->buf_ptr;
+                if (re_parse_expect(s, &p, ')'))
+                    return -1;
+            } else if ((p[2] == '=' || p[2] == '!')) {
+                is_neg = (p[2] == '!');
+                is_backward_lookahead = FALSE;
+                p += 3;
+                goto lookahead;
+            } else if (p[2] == '<' &&
+                       (p[3] == '=' || p[3] == '!')) {
+                int pos;
+                is_neg = (p[3] == '!');
+                is_backward_lookahead = TRUE;
+                p += 4;
+                /* lookahead */
+            lookahead:
+                /* Annex B allows lookahead to be used as an atom for
+                   the quantifiers */
+                if (!s->is_utf16 && !is_backward_lookahead)  {
+                    last_atom_start = s->byte_code.size;
+                    last_capture_count = s->capture_count;
+                }
+                pos = re_emit_op_u32(s, REOP_lookahead + is_neg, 0);
+                s->buf_ptr = p;
+                if (re_parse_disjunction(s, is_backward_lookahead))
+                    return -1;
+                p = s->buf_ptr;
+                if (re_parse_expect(s, &p, ')'))
+                    return -1;
+                re_emit_op(s, REOP_match);
+                /* jump after the 'match' after the lookahead is successful */
+                put_u32(s->byte_code.buf + pos, s->byte_code.size - (pos + 4));
+            } else if (p[2] == '<') {
+                p += 3;
+                if (re_parse_group_name(s->u.tmp_buf, sizeof(s->u.tmp_buf),
+                                        &p, s->is_utf16)) {
+                    return re_parse_error(s, "invalid group name");
+                }
+                if (find_group_name(s, s->u.tmp_buf) > 0) {
+                    return re_parse_error(s, "duplicate group name");
+                }
+                /* group name with a trailing zero */
+                dbuf_put(&s->group_names, (uint8_t *)s->u.tmp_buf,
+                         strlen(s->u.tmp_buf) + 1);
+                s->has_named_captures = 1;
+                goto parse_capture;
+            } else {
+                return re_parse_error(s, "invalid group");
+            }
+        } else {
+            int capture_index;
+            p++;
+            /* capture without group name */
+            dbuf_putc(&s->group_names, 0);
+        parse_capture:
+            if (s->capture_count >= CAPTURE_COUNT_MAX)
+                return re_parse_error(s, "too many captures");
+            last_atom_start = s->byte_code.size;
+            last_capture_count = s->capture_count;
+            capture_index = s->capture_count++;
+            re_emit_op_u8(s, REOP_save_start + is_backward_dir,
+                          capture_index);
+            
+            s->buf_ptr = p;
+            if (re_parse_disjunction(s, is_backward_dir))
+                return -1;
+            p = s->buf_ptr;
+            
+            re_emit_op_u8(s, REOP_save_start + 1 - is_backward_dir,
+                          capture_index);
+            
+            if (re_parse_expect(s, &p, ')'))
+                return -1;
+        }
+        break;
+    case '\\':
+        switch(p[1]) {
+        case 'b':
+        case 'B':
+            re_emit_op(s, REOP_word_boundary + (p[1] != 'b'));
+            p += 2;
+            break;
+        case 'k':
+            {
+                const uint8_t *p1;
+                int dummy_res;
+                
+                p1 = p;
+                if (p1[2] != '<') {
+                    /* annex B: we tolerate invalid group names in non
+                       unicode mode if there is no named capture
+                       definition */
+                    if (s->is_utf16 || re_has_named_captures(s))
+                        return re_parse_error(s, "expecting group name");
+                    else
+                        goto parse_class_atom;
+                }
+                p1 += 3;
+                if (re_parse_group_name(s->u.tmp_buf, sizeof(s->u.tmp_buf),
+                                        &p1, s->is_utf16)) {
+                    if (s->is_utf16 || re_has_named_captures(s))
+                        return re_parse_error(s, "invalid group name");
+                    else
+                        goto parse_class_atom;
+                }
+                c = find_group_name(s, s->u.tmp_buf);
+                if (c < 0) {
+                    /* no capture name parsed before, try to look
+                       after (inefficient, but hopefully not common */
+                    c = re_parse_captures(s, &dummy_res, s->u.tmp_buf);
+                    if (c < 0) {
+                        if (s->is_utf16 || re_has_named_captures(s))
+                            return re_parse_error(s, "group name not defined");
+                        else
+                            goto parse_class_atom;
+                    }
+                }
+                p = p1;
+            }
+            goto emit_back_reference;
+        case '0':
+            p += 2;
+            c = 0;
+            if (s->is_utf16) {
+                if (is_digit(*p)) {
+                    return re_parse_error(s, "invalid decimal escape in regular expression");
+                }
+            } else {
+                /* Annex B.1.4: accept legacy octal */
+                if (*p >= '0' && *p <= '7') {
+                    c = *p++ - '0';
+                    if (*p >= '0' && *p <= '7') {
+                        c = (c << 3) + *p++ - '0';
+                    }
+                }
+            }
+            goto normal_char;
+        case '1' ... '9':
+            {
+                const uint8_t *q = ++p;
+                
+                c = parse_digits(&p);
+                if (c < 0 || (c >= s->capture_count && c >= re_count_captures(s))) {
+                    if (!s->is_utf16) {
+                        /* Annex B.1.4: accept legacy octal */
+                        p = q;
+                        if (*p <= '7') {
+                            c = 0;
+                            if (*p <= '3')
+                                c = *p++ - '0';
+                            if (*p >= '0' && *p <= '7') {
+                                c = (c << 3) + *p++ - '0';
+                                if (*p >= '0' && *p <= '7') {
+                                    c = (c << 3) + *p++ - '0';
+                                }
+                            }
+                        } else {
+                            c = *p++;
+                        }
+                        goto normal_char;
+                    }
+                    return re_parse_error(s, "back reference out of range in reguar expression");
+                }
+            emit_back_reference:
+                last_atom_start = s->byte_code.size;
+                last_capture_count = s->capture_count;
+                re_emit_op_u8(s, REOP_back_reference + is_backward_dir, c);
+            }
+            break;
+        default:
+            goto parse_class_atom;
+        }
+        break;
+    case '[':
+        last_atom_start = s->byte_code.size;
+        last_capture_count = s->capture_count;
+        if (is_backward_dir)
+            re_emit_op(s, REOP_prev);
+        if (re_parse_char_class(s, &p))
+            return -1;
+        if (is_backward_dir)
+            re_emit_op(s, REOP_prev);
+        break;
+    case ']':
+    case '}':
+        if (s->is_utf16)
+            return re_parse_error(s, "syntax error");
+        goto parse_class_atom;
+    default:
+    parse_class_atom:
+        c = get_class_atom(s, cr, &p, FALSE);
+        if ((int)c < 0)
+            return -1;
+    normal_char:
+        last_atom_start = s->byte_code.size;
+        last_capture_count = s->capture_count;
+        if (is_backward_dir)
+            re_emit_op(s, REOP_prev);
+        if (c >= CLASS_RANGE_BASE) {
+            int ret;
+            /* Note: canonicalization is not needed */
+            ret = re_emit_range(s, cr);
+            cr_free(cr);
+            if (ret)
+                return -1;
+        } else {
+            if (s->ignore_case)
+                c = lre_canonicalize(c, s->is_utf16);
+            if (c <= 0xffff)
+                re_emit_op_u16(s, REOP_char, c);
+            else
+                re_emit_op_u32(s, REOP_char32, c);
+        }
+        if (is_backward_dir)
+            re_emit_op(s, REOP_prev);
+        break;
+    }
+
+    /* quantifier */
+    if (last_atom_start >= 0) {
+        c = *p;
+        switch(c) {
+        case '*':
+            p++;
+            quant_min = 0;
+            quant_max = INT32_MAX;
+            goto quantifier;
+        case '+':
+            p++;
+            quant_min = 1;
+            quant_max = INT32_MAX;
+            goto quantifier;
+        case '?':
+            p++;
+            quant_min = 0;
+            quant_max = 1;
+            goto quantifier;
+        case '{':
+            /* As an extension (see ES6 annex B), we accept '{' not
+               followed by digits as a normal atom */
+            if (!is_digit(p[1])) {
+                if (s->is_utf16)
+                    goto invalid_quant_count;
+                break;
+            }
+            p++;
+            quant_min = parse_digits(&p);
+            if (quant_min < 0) {
+            invalid_quant_count:
+                return re_parse_error(s, "invalid repetition count");
+            }
+            quant_max = quant_min;
+            if (*p == ',') {
+                p++;
+                if (is_digit(*p)) {
+                    quant_max = parse_digits(&p);
+                    if (quant_max < 0 || quant_max < quant_min)
+                        goto invalid_quant_count;
+                } else {
+                    quant_max = INT32_MAX; /* infinity */
+                }
+            }
+            if (re_parse_expect(s, &p, '}'))
+                return -1;
+        quantifier:
+            greedy = TRUE;
+            if (*p == '?') {
+                p++;
+                greedy = FALSE;
+            }
+            if (last_atom_start < 0) {
+                return re_parse_error(s, "nothing to repeat");
+            }
+            if (greedy) {
+                int len, pos;
+                
+                if (quant_max > 0) {
+                    /* specific optimization for simple quantifiers */
+                    len = re_is_simple_quantifier(s->byte_code.buf + last_atom_start,
+                                                 s->byte_code.size - last_atom_start);
+                    if (len > 0) {
+                        re_emit_op(s, REOP_match);
+                        
+                        dbuf_insert(&s->byte_code, last_atom_start, 17);
+                        pos = last_atom_start;
+                        s->byte_code.buf[pos++] = REOP_simple_greedy_quant;
+                        put_u32(&s->byte_code.buf[pos],
+                                s->byte_code.size - last_atom_start - 17);
+                        pos += 4;
+                        put_u32(&s->byte_code.buf[pos], quant_min);
+                        pos += 4;
+                        put_u32(&s->byte_code.buf[pos], quant_max);
+                        pos += 4;
+                        put_u32(&s->byte_code.buf[pos], len);
+                        pos += 4;
+                        goto done;
+                    }
+                }
+                
+                add_zero_advance_check = (re_check_advance(s->byte_code.buf + last_atom_start,
+                                                           s->byte_code.size - last_atom_start) == 0);
+            } else {
+                add_zero_advance_check = FALSE;
+            }
+            
+            {
+                int len, pos;
+                len = s->byte_code.size - last_atom_start;
+                if (quant_min == 0) {
+                    /* need to reset the capture in case the atom is
+                       not executed */
+                    if (last_capture_count != s->capture_count) {
+                        dbuf_insert(&s->byte_code, last_atom_start, 3);
+                        s->byte_code.buf[last_atom_start++] = REOP_save_reset;
+                        s->byte_code.buf[last_atom_start++] = last_capture_count;
+                        s->byte_code.buf[last_atom_start++] = s->capture_count - 1;
+                    }
+                    if (quant_max == 0) {
+                        s->byte_code.size = last_atom_start;
+                    } else if (quant_max == 1) {
+                        dbuf_insert(&s->byte_code, last_atom_start, 5);
+                        s->byte_code.buf[last_atom_start] = REOP_split_goto_first +
+                            greedy;
+                        put_u32(s->byte_code.buf + last_atom_start + 1, len);
+                    } else if (quant_max == INT32_MAX) {
+                        dbuf_insert(&s->byte_code, last_atom_start, 5 + add_zero_advance_check);
+                        s->byte_code.buf[last_atom_start] = REOP_split_goto_first +
+                            greedy;
+                        put_u32(s->byte_code.buf + last_atom_start + 1,
+                                len + 5 + add_zero_advance_check);
+                        if (add_zero_advance_check) {
+                            /* avoid infinite loop by stoping the
+                               recursion if no advance was made in the
+                               atom (only works if the atom has no
+                               side effect) */
+                            s->byte_code.buf[last_atom_start + 1 + 4] = REOP_push_char_pos;
+                            re_emit_goto(s, REOP_bne_char_pos, last_atom_start); 
+                        } else {
+                            re_emit_goto(s, REOP_goto, last_atom_start);
+                        }
+                    } else {
+                        dbuf_insert(&s->byte_code, last_atom_start, 10);
+                        pos = last_atom_start;
+                        s->byte_code.buf[pos++] = REOP_push_i32;
+                        put_u32(s->byte_code.buf + pos, quant_max);
+                        pos += 4;
+                        s->byte_code.buf[pos++] = REOP_split_goto_first + greedy;
+                        put_u32(s->byte_code.buf + pos, len + 5);
+                        re_emit_goto(s, REOP_loop, last_atom_start + 5);
+                        re_emit_op(s, REOP_drop);
+                    }
+                } else if (quant_min == 1 && quant_max == INT32_MAX &&
+                           !add_zero_advance_check) {
+                    re_emit_goto(s, REOP_split_next_first - greedy,
+                                 last_atom_start);
+                } else {
+                    if (quant_min == 1) {
+                        /* nothing to add */
+                    } else {
+                        dbuf_insert(&s->byte_code, last_atom_start, 5);
+                        s->byte_code.buf[last_atom_start] = REOP_push_i32;
+                        put_u32(s->byte_code.buf + last_atom_start + 1,
+                                quant_min);
+                        last_atom_start += 5;
+                        re_emit_goto(s, REOP_loop, last_atom_start);
+                        re_emit_op(s, REOP_drop);
+                    }
+                    if (quant_max == INT32_MAX) {
+                        pos = s->byte_code.size;
+                        re_emit_op_u32(s, REOP_split_goto_first + greedy,
+                                       len + 5 + add_zero_advance_check);
+                        if (add_zero_advance_check)
+                            re_emit_op(s, REOP_push_char_pos);
+                        /* copy the atom */
+                        dbuf_put_self(&s->byte_code, last_atom_start, len);
+                        if (add_zero_advance_check)
+                            re_emit_goto(s, REOP_bne_char_pos, pos);
+                        else
+                            re_emit_goto(s, REOP_goto, pos);
+                    } else if (quant_max > quant_min) {
+                        re_emit_op_u32(s, REOP_push_i32, quant_max - quant_min);
+                        pos = s->byte_code.size;
+                        re_emit_op_u32(s, REOP_split_goto_first + greedy, len + 5);
+                        /* copy the atom */
+                        dbuf_put_self(&s->byte_code, last_atom_start, len);
+                        
+                        re_emit_goto(s, REOP_loop, pos);
+                        re_emit_op(s, REOP_drop);
+                    }
+                }
+                last_atom_start = -1;
+            }
+            break;
+        default:
+            break;
+        }
+    }
+ done:
+    s->buf_ptr = p;
+    return 0;
+}
+
+static int re_parse_alternative(REParseState *s, BOOL is_backward_dir)
+{
+    const uint8_t *p;
+    int ret;
+    size_t start, term_start, end, term_size;
+
+    start = s->byte_code.size;
+    for(;;) {
+        p = s->buf_ptr;
+        if (p >= s->buf_end)
+            break;
+        if (*p == '|' || *p == ')')
+            break;
+        term_start = s->byte_code.size;
+        ret = re_parse_term(s, is_backward_dir);
+        if (ret)
+            return ret;
+        if (is_backward_dir) {
+            /* reverse the order of the terms (XXX: inefficient, but
+               speed is not really critical here) */
+            end = s->byte_code.size;
+            term_size = end - term_start;
+            if (dbuf_realloc(&s->byte_code, end + term_size))
+                return -1;
+            memmove(s->byte_code.buf + start + term_size,
+                    s->byte_code.buf + start,
+                    end - start);
+            memcpy(s->byte_code.buf + start, s->byte_code.buf + end,
+                   term_size);
+        }
+    }
+    return 0;
+}
+    
+static int re_parse_disjunction(REParseState *s, BOOL is_backward_dir)
+{
+    int start, len, pos;
+
+    start = s->byte_code.size;
+    if (re_parse_alternative(s, is_backward_dir))
+        return -1;
+    while (*s->buf_ptr == '|') {
+        s->buf_ptr++;
+
+        len = s->byte_code.size - start;
+
+        /* insert a split before the first alternative */
+        dbuf_insert(&s->byte_code, start, 5);
+        s->byte_code.buf[start] = REOP_split_next_first;
+        put_u32(s->byte_code.buf + start + 1, len + 5);
+
+        pos = re_emit_op_u32(s, REOP_goto, 0);
+
+        if (re_parse_alternative(s, is_backward_dir))
+            return -1;
+        
+        /* patch the goto */
+        len = s->byte_code.size - (pos + 4);
+        put_u32(s->byte_code.buf + pos, len);
+    }
+    return 0;
+}
+
+/* the control flow is recursive so the analysis can be linear */
+static int compute_stack_size(const uint8_t *bc_buf, int bc_buf_len)
+{
+    int stack_size, stack_size_max, pos, opcode, len;
+    uint32_t val;
+    
+    stack_size = 0;
+    stack_size_max = 0;
+    bc_buf += RE_HEADER_LEN;
+    bc_buf_len -= RE_HEADER_LEN;
+    pos = 0;
+    while (pos < bc_buf_len) {
+        opcode = bc_buf[pos];
+        len = reopcode_info[opcode].size;
+        assert(opcode < REOP_COUNT);
+        assert((pos + len) <= bc_buf_len);
+        switch(opcode) {
+        case REOP_push_i32:
+        case REOP_push_char_pos:
+            stack_size++;
+            if (stack_size > stack_size_max) {
+                if (stack_size > STACK_SIZE_MAX)
+                    return -1;
+                stack_size_max = stack_size;
+            }
+            break;
+        case REOP_drop:
+        case REOP_bne_char_pos:
+            assert(stack_size > 0);
+            stack_size--;
+            break;
+        case REOP_range:
+            val = get_u16(bc_buf + pos + 1);
+            len += val * 4;
+            break;
+        case REOP_range32:
+            val = get_u16(bc_buf + pos + 1);
+            len += val * 8;
+            break;
+        }
+        pos += len;
+    }
+    return stack_size_max;
+}
+
+/* 'buf' must be a zero terminated UTF-8 string of length buf_len.
+   Return NULL if error and allocate an error message in *perror_msg,
+   otherwise the compiled bytecode and its length in plen.
+*/
+uint8_t *lre_compile(int *plen, char *error_msg, int error_msg_size,
+                     const char *buf, size_t buf_len, int re_flags,
+                     void *opaque)
+{
+    REParseState s_s, *s = &s_s;
+    int stack_size;
+    BOOL is_sticky;
+    
+    memset(s, 0, sizeof(*s));
+    s->mem_opaque = opaque;
+    s->buf_ptr = (const uint8_t *)buf;
+    s->buf_end = s->buf_ptr + buf_len;
+    s->buf_start = s->buf_ptr;
+    s->re_flags = re_flags;
+    s->is_utf16 = ((re_flags & LRE_FLAG_UTF16) != 0);
+    is_sticky = ((re_flags & LRE_FLAG_STICKY) != 0);
+    s->ignore_case = ((re_flags & LRE_FLAG_IGNORECASE) != 0);
+    s->dotall = ((re_flags & LRE_FLAG_DOTALL) != 0);
+    s->capture_count = 1;
+    s->total_capture_count = -1;
+    s->has_named_captures = -1;
+    
+    dbuf_init2(&s->byte_code, opaque, lre_realloc);
+    dbuf_init2(&s->group_names, opaque, lre_realloc);
+
+    dbuf_putc(&s->byte_code, re_flags); /* first element is the flags */
+    dbuf_putc(&s->byte_code, 0); /* second element is the number of captures */
+    dbuf_putc(&s->byte_code, 0); /* stack size */
+    dbuf_put_u32(&s->byte_code, 0); /* bytecode length */
+    
+    if (!is_sticky) {
+        /* iterate thru all positions (about the same as .*?( ... ) )
+           .  We do it without an explicit loop so that lock step
+           thread execution will be possible in an optimized
+           implementation */
+        re_emit_op_u32(s, REOP_split_goto_first, 1 + 5);
+        re_emit_op(s, REOP_any);
+        re_emit_op_u32(s, REOP_goto, -(5 + 1 + 5));
+    }
+    re_emit_op_u8(s, REOP_save_start, 0);
+
+    if (re_parse_disjunction(s, FALSE)) {
+    error:
+        dbuf_free(&s->byte_code);
+        dbuf_free(&s->group_names);
+        pstrcpy(error_msg, error_msg_size, s->u.error_msg);
+        *plen = 0;
+        return NULL;
+    }
+
+    re_emit_op_u8(s, REOP_save_end, 0);
+    
+    re_emit_op(s, REOP_match);
+
+    if (*s->buf_ptr != '\0') {
+        re_parse_error(s, "extraneous characters at the end");
+        goto error;
+    }
+
+    if (dbuf_error(&s->byte_code)) {
+        re_parse_error(s, "out of memory");
+        goto error;
+    }
+    
+    stack_size = compute_stack_size(s->byte_code.buf, s->byte_code.size);
+    if (stack_size < 0) {
+        re_parse_error(s, "too many imbricated quantifiers");
+        goto error;
+    }
+    
+    s->byte_code.buf[RE_HEADER_CAPTURE_COUNT] = s->capture_count;
+    s->byte_code.buf[RE_HEADER_STACK_SIZE] = stack_size;
+    put_u32(s->byte_code.buf + 3, s->byte_code.size - RE_HEADER_LEN);
+
+    /* add the named groups if needed */
+    if (s->group_names.size > (s->capture_count - 1)) {
+        dbuf_put(&s->byte_code, s->group_names.buf, s->group_names.size);
+        s->byte_code.buf[RE_HEADER_FLAGS] |= LRE_FLAG_NAMED_GROUPS;
+    }
+    dbuf_free(&s->group_names);
+    
+#ifdef DUMP_REOP
+    lre_dump_bytecode(s->byte_code.buf, s->byte_code.size);
+#endif
+    
+    error_msg[0] = '\0';
+    *plen = s->byte_code.size;
+    return s->byte_code.buf;
+}
+
+static BOOL is_line_terminator(uint32_t c)
+{
+    return (c == '\n' || c == '\r' || c == CP_LS || c == CP_PS);
+}
+
+static BOOL is_word_char(uint32_t c)
+{
+    return ((c >= '0' && c <= '9') ||
+            (c >= 'a' && c <= 'z') ||
+            (c >= 'A' && c <= 'Z') ||
+            (c == '_'));
+}
+
+#define GET_CHAR(c, cptr, cbuf_end)                                     \
+    do {                                                                \
+        if (cbuf_type == 0) {                                           \
+            c = *cptr++;                                                \
+        } else {                                                        \
+            uint32_t __c1;                                              \
+            c = *(uint16_t *)cptr;                                      \
+            cptr += 2;                                                  \
+            if (c >= 0xd800 && c < 0xdc00 &&                            \
+                cbuf_type == 2 && cptr < cbuf_end) {                    \
+                __c1 = *(uint16_t *)cptr;                               \
+                if (__c1 >= 0xdc00 && __c1 < 0xe000) {                  \
+                    c = (((c & 0x3ff) << 10) | (__c1 & 0x3ff)) + 0x10000; \
+                    cptr += 2;                                          \
+                }                                                       \
+            }                                                           \
+        }                                                               \
+    } while (0)
+
+#define PEEK_CHAR(c, cptr, cbuf_end)             \
+    do {                                         \
+        if (cbuf_type == 0) {                    \
+            c = cptr[0];                         \
+        } else {                                 \
+            uint32_t __c1;                                              \
+            c = ((uint16_t *)cptr)[0];                                  \
+            if (c >= 0xd800 && c < 0xdc00 &&                            \
+                cbuf_type == 2 && (cptr + 2) < cbuf_end) {              \
+                __c1 = ((uint16_t *)cptr)[1];                           \
+                if (__c1 >= 0xdc00 && __c1 < 0xe000) {                  \
+                    c = (((c & 0x3ff) << 10) | (__c1 & 0x3ff)) + 0x10000; \
+                }                                                       \
+            }                                                           \
+        }                                        \
+    } while (0)
+
+#define PEEK_PREV_CHAR(c, cptr, cbuf_start)                 \
+    do {                                         \
+        if (cbuf_type == 0) {                    \
+            c = cptr[-1];                        \
+        } else {                                 \
+            uint32_t __c1;                                              \
+            c = ((uint16_t *)cptr)[-1];                                 \
+            if (c >= 0xdc00 && c < 0xe000 &&                            \
+                cbuf_type == 2 && (cptr - 4) >= cbuf_start) {              \
+                __c1 = ((uint16_t *)cptr)[-2];                          \
+                if (__c1 >= 0xd800 && __c1 < 0xdc00 ) {                 \
+                    c = (((__c1 & 0x3ff) << 10) | (c & 0x3ff)) + 0x10000; \
+                }                                                       \
+            }                                                           \
+        }                                                               \
+    } while (0)
+
+#define GET_PREV_CHAR(c, cptr, cbuf_start)       \
+    do {                                         \
+        if (cbuf_type == 0) {                    \
+            cptr--;                              \
+            c = cptr[0];                         \
+        } else {                                 \
+            uint32_t __c1;                                              \
+            cptr -= 2;                                                  \
+            c = ((uint16_t *)cptr)[0];                                 \
+            if (c >= 0xdc00 && c < 0xe000 &&                            \
+                cbuf_type == 2 && cptr > cbuf_start) {                  \
+                __c1 = ((uint16_t *)cptr)[-1];                          \
+                if (__c1 >= 0xd800 && __c1 < 0xdc00 ) {                 \
+                    cptr -= 2;                                          \
+                    c = (((__c1 & 0x3ff) << 10) | (c & 0x3ff)) + 0x10000; \
+                }                                                       \
+            }                                                           \
+        }                                                               \
+    } while (0)
+
+#define PREV_CHAR(cptr, cbuf_start)       \
+    do {                                  \
+        if (cbuf_type == 0) {             \
+            cptr--;                       \
+        } else {                          \
+            cptr -= 2;                          \
+            if (cbuf_type == 2) {                                       \
+                c = ((uint16_t *)cptr)[0];                              \
+                if (c >= 0xdc00 && c < 0xe000 && cptr > cbuf_start) {   \
+                    c = ((uint16_t *)cptr)[-1];                         \
+                    if (c >= 0xd800 && c < 0xdc00)                      \
+                        cptr -= 2;                                      \
+                }                                                       \
+            }                                                           \
+        }                                                               \
+    } while (0)
+
+typedef uintptr_t StackInt;
+
+typedef enum {
+    RE_EXEC_STATE_SPLIT,
+    RE_EXEC_STATE_LOOKAHEAD,
+    RE_EXEC_STATE_NEGATIVE_LOOKAHEAD,
+    RE_EXEC_STATE_GREEDY_QUANT,
+} REExecStateEnum;
+
+typedef struct REExecState {
+    REExecStateEnum type : 8;
+    uint8_t stack_len;
+    size_t count; /* only used for RE_EXEC_STATE_GREEDY_QUANT */
+    const uint8_t *cptr;
+    const uint8_t *pc;
+    void *buf[0];
+} REExecState;
+
+typedef struct {
+    const uint8_t *cbuf;
+    const uint8_t *cbuf_end;
+    /* 0 = 8 bit chars, 1 = 16 bit chars, 2 = 16 bit chars, UTF-16 */
+    int cbuf_type; 
+    int capture_count;
+    int stack_size_max;
+    BOOL multi_line;
+    BOOL ignore_case;
+    BOOL is_utf16;
+    void *opaque; /* used for stack overflow check */
+
+    size_t state_size;
+    uint8_t *state_stack;
+    size_t state_stack_size;
+    size_t state_stack_len;
+} REExecContext;
+
+static int push_state(REExecContext *s,
+                      uint8_t **capture,
+                      StackInt *stack, size_t stack_len,
+                      const uint8_t *pc, const uint8_t *cptr,
+                      REExecStateEnum type, size_t count)
+{
+    REExecState *rs;
+    uint8_t *new_stack;
+    size_t new_size, i, n;
+    StackInt *stack_buf;
+
+    if (unlikely((s->state_stack_len + 1) > s->state_stack_size)) {
+        /* reallocate the stack */
+        new_size = s->state_stack_size * 3 / 2;
+        if (new_size < 8)
+            new_size = 8;
+        new_stack = lre_realloc(s->opaque, s->state_stack, new_size * s->state_size);
+        if (!new_stack)
+            return -1;
+        s->state_stack_size = new_size;
+        s->state_stack = new_stack;
+    }
+    rs = (REExecState *)(s->state_stack + s->state_stack_len * s->state_size);
+    s->state_stack_len++;
+    rs->type = type;
+    rs->count = count;
+    rs->stack_len = stack_len;
+    rs->cptr = cptr;
+    rs->pc = pc;
+    n = 2 * s->capture_count;
+    for(i = 0; i < n; i++)
+        rs->buf[i] = capture[i];
+    stack_buf = (StackInt *)(rs->buf + n);
+    for(i = 0; i < stack_len; i++)
+        stack_buf[i] = stack[i];
+    return 0;
+}
+
+/* return 1 if match, 0 if not match or -1 if error. */
+static intptr_t lre_exec_backtrack(REExecContext *s, uint8_t **capture,
+                                   StackInt *stack, int stack_len,
+                                   const uint8_t *pc, const uint8_t *cptr,
+                                   BOOL no_recurse)
+{
+    int opcode, ret;
+    int cbuf_type;
+    uint32_t val, c;
+    const uint8_t *cbuf_end;
+    
+    cbuf_type = s->cbuf_type;
+    cbuf_end = s->cbuf_end;
+
+    for(;;) {
+        //        printf("top=%p: pc=%d\n", th_list.top, (int)(pc - (bc_buf + RE_HEADER_LEN)));
+        opcode = *pc++;
+        switch(opcode) {
+        case REOP_match:
+            {
+                REExecState *rs;
+                if (no_recurse)
+                    return (intptr_t)cptr;
+                ret = 1;
+                goto recurse;
+            no_match:
+                if (no_recurse)
+                    return 0;
+                ret = 0;
+            recurse:
+                for(;;) {
+                    if (s->state_stack_len == 0)
+                        return ret;
+                    rs = (REExecState *)(s->state_stack +
+                                         (s->state_stack_len - 1) * s->state_size);
+                    if (rs->type == RE_EXEC_STATE_SPLIT) {
+                        if (!ret) {
+                        pop_state:
+                            memcpy(capture, rs->buf,
+                                   sizeof(capture[0]) * 2 * s->capture_count);
+                        pop_state1:
+                            pc = rs->pc;
+                            cptr = rs->cptr;
+                            stack_len = rs->stack_len;
+                            memcpy(stack, rs->buf + 2 * s->capture_count,
+                                   stack_len * sizeof(stack[0]));
+                            s->state_stack_len--;
+                            break;
+                        }
+                    } else if (rs->type == RE_EXEC_STATE_GREEDY_QUANT) {
+                        if (!ret) {
+                            uint32_t char_count, i;
+                            memcpy(capture, rs->buf,
+                                   sizeof(capture[0]) * 2 * s->capture_count);
+                            stack_len = rs->stack_len;
+                            memcpy(stack, rs->buf + 2 * s->capture_count,
+                                   stack_len * sizeof(stack[0]));
+                            pc = rs->pc;
+                            cptr = rs->cptr;
+                            /* go backward */
+                            char_count = get_u32(pc + 12);
+                            for(i = 0; i < char_count; i++) {
+                                PREV_CHAR(cptr, s->cbuf);
+                            }
+                            pc = (pc + 16) + (int)get_u32(pc);
+                            rs->cptr = cptr;
+                            rs->count--;
+                            if (rs->count == 0) {
+                                s->state_stack_len--;
+                            }
+                            break;
+                        }
+                    } else {
+                        ret = ((rs->type == RE_EXEC_STATE_LOOKAHEAD && ret) ||
+                               (rs->type == RE_EXEC_STATE_NEGATIVE_LOOKAHEAD && !ret));
+                        if (ret) {
+                            /* keep the capture in case of positive lookahead */
+                            if (rs->type == RE_EXEC_STATE_LOOKAHEAD)
+                                goto pop_state1;
+                            else
+                                goto pop_state;
+                        }
+                    }
+                    s->state_stack_len--;
+                }
+            }
+            break;
+        case REOP_char32:
+            val = get_u32(pc);
+            pc += 4;
+            goto test_char;
+        case REOP_char:
+            val = get_u16(pc);
+            pc += 2;
+        test_char:
+            if (cptr >= cbuf_end)
+                goto no_match;
+            GET_CHAR(c, cptr, cbuf_end);
+            if (s->ignore_case) {
+                c = lre_canonicalize(c, s->is_utf16);
+            }
+            if (val != c)
+                goto no_match;
+            break;
+        case REOP_split_goto_first:
+        case REOP_split_next_first:
+            {
+                const uint8_t *pc1;
+                
+                val = get_u32(pc);
+                pc += 4;
+                if (opcode == REOP_split_next_first) {
+                    pc1 = pc + (int)val;
+                } else {
+                    pc1 = pc;
+                    pc = pc + (int)val;
+                }
+                ret = push_state(s, capture, stack, stack_len,
+                                 pc1, cptr, RE_EXEC_STATE_SPLIT, 0);
+                if (ret < 0)
+                    return -1;
+                break;
+            }
+        case REOP_lookahead:
+        case REOP_negative_lookahead:
+            val = get_u32(pc);
+            pc += 4;
+            ret = push_state(s, capture, stack, stack_len,
+                             pc + (int)val, cptr,
+                             RE_EXEC_STATE_LOOKAHEAD + opcode - REOP_lookahead,
+                             0);
+            if (ret < 0)
+                return -1;
+            break;
+            
+        case REOP_goto:
+            val = get_u32(pc);
+            pc += 4 + (int)val;
+            break;
+        case REOP_line_start:
+            if (cptr == s->cbuf)
+                break;
+            if (!s->multi_line)
+                goto no_match;
+            PEEK_PREV_CHAR(c, cptr, s->cbuf);
+            if (!is_line_terminator(c))
+                goto no_match;
+            break;
+        case REOP_line_end:
+            if (cptr == cbuf_end)
+                break;
+            if (!s->multi_line)
+                goto no_match;
+            PEEK_CHAR(c, cptr, cbuf_end);
+            if (!is_line_terminator(c))
+                goto no_match;
+            break;
+        case REOP_dot:
+            if (cptr == cbuf_end)
+                goto no_match;
+            GET_CHAR(c, cptr, cbuf_end);
+            if (is_line_terminator(c))
+                goto no_match;
+            break;
+        case REOP_any:
+            if (cptr == cbuf_end)
+                goto no_match;
+            GET_CHAR(c, cptr, cbuf_end);
+            break;
+        case REOP_save_start:
+        case REOP_save_end:
+            val = *pc++;
+            assert(val < s->capture_count);
+            capture[2 * val + opcode - REOP_save_start] = (uint8_t *)cptr;
+            break;
+        case REOP_save_reset:
+            {
+                uint32_t val2;
+                val = pc[0];
+                val2 = pc[1];
+                pc += 2;
+                assert(val2 < s->capture_count);
+                while (val <= val2) {
+                    capture[2 * val] = NULL;
+                    capture[2 * val + 1] = NULL;
+                    val++;
+                }
+            }
+            break;
+        case REOP_push_i32:
+            val = get_u32(pc);
+            pc += 4;
+            stack[stack_len++] = val;
+            break;
+        case REOP_drop:
+            stack_len--;
+            break;
+        case REOP_loop:
+            val = get_u32(pc);
+            pc += 4;
+            if (--stack[stack_len - 1] != 0) {
+                pc += (int)val;
+            }
+            break;
+        case REOP_push_char_pos:
+            stack[stack_len++] = (uintptr_t)cptr;
+            break;
+        case REOP_bne_char_pos:
+            val = get_u32(pc);
+            pc += 4;
+            if (stack[--stack_len] != (uintptr_t)cptr)
+                pc += (int)val;
+            break;
+        case REOP_word_boundary:
+        case REOP_not_word_boundary:
+            {
+                BOOL v1, v2;
+                /* char before */
+                if (cptr == s->cbuf) {
+                    v1 = FALSE;
+                } else {
+                    PEEK_PREV_CHAR(c, cptr, s->cbuf);
+                    v1 = is_word_char(c);
+                }
+                /* current char */
+                if (cptr >= cbuf_end) {
+                    v2 = FALSE;
+                } else {
+                    PEEK_CHAR(c, cptr, cbuf_end);
+                    v2 = is_word_char(c);
+                }
+                if (v1 ^ v2 ^ (REOP_not_word_boundary - opcode))
+                    goto no_match;
+            }
+            break;
+        case REOP_back_reference:
+        case REOP_backward_back_reference:
+            {
+                const uint8_t *cptr1, *cptr1_end, *cptr1_start;
+                uint32_t c1, c2;
+                
+                val = *pc++;
+                if (val >= s->capture_count)
+                    goto no_match;
+                cptr1_start = capture[2 * val];
+                cptr1_end = capture[2 * val + 1];
+                if (!cptr1_start || !cptr1_end)
+                    break;
+                if (opcode == REOP_back_reference) {
+                    cptr1 = cptr1_start;
+                    while (cptr1 < cptr1_end) {
+                        if (cptr >= cbuf_end)
+                            goto no_match;
+                        GET_CHAR(c1, cptr1, cptr1_end);
+                        GET_CHAR(c2, cptr, cbuf_end);
+                        if (s->ignore_case) {
+                            c1 = lre_canonicalize(c1, s->is_utf16);
+                            c2 = lre_canonicalize(c2, s->is_utf16);
+                        }
+                        if (c1 != c2)
+                            goto no_match;
+                    }
+                } else {
+                    cptr1 = cptr1_end;
+                    while (cptr1 > cptr1_start) {
+                        if (cptr == s->cbuf)
+                            goto no_match;
+                        GET_PREV_CHAR(c1, cptr1, cptr1_start);
+                        GET_PREV_CHAR(c2, cptr, s->cbuf);
+                        if (s->ignore_case) {
+                            c1 = lre_canonicalize(c1, s->is_utf16);
+                            c2 = lre_canonicalize(c2, s->is_utf16);
+                        }
+                        if (c1 != c2)
+                            goto no_match;
+                    }
+                }
+            }
+            break;
+        case REOP_range:
+            {
+                int n;
+                uint32_t low, high, idx_min, idx_max, idx;
+                
+                n = get_u16(pc); /* n must be >= 1 */
+                pc += 2;
+                if (cptr >= cbuf_end)
+                    goto no_match;
+                GET_CHAR(c, cptr, cbuf_end);
+                if (s->ignore_case) {
+                    c = lre_canonicalize(c, s->is_utf16);
+                }
+                idx_min = 0;
+                low = get_u16(pc + 0 * 4);
+                if (c < low)
+                    goto no_match;
+                idx_max = n - 1;
+                high = get_u16(pc + idx_max * 4 + 2);
+                /* 0xffff in for last value means +infinity */
+                if (unlikely(c >= 0xffff) && high == 0xffff)
+                    goto range_match;
+                if (c > high)
+                    goto no_match;
+                while (idx_min <= idx_max) {
+                    idx = (idx_min + idx_max) / 2;
+                    low = get_u16(pc + idx * 4);
+                    high = get_u16(pc + idx * 4 + 2);
+                    if (c < low)
+                        idx_max = idx - 1;
+                    else if (c > high)
+                        idx_min = idx + 1;
+                    else
+                        goto range_match;
+                }
+                goto no_match;
+            range_match:
+                pc += 4 * n;
+            }
+            break;
+        case REOP_range32:
+            {
+                int n;
+                uint32_t low, high, idx_min, idx_max, idx;
+                
+                n = get_u16(pc); /* n must be >= 1 */
+                pc += 2;
+                if (cptr >= cbuf_end)
+                    goto no_match;
+                GET_CHAR(c, cptr, cbuf_end);
+                if (s->ignore_case) {
+                    c = lre_canonicalize(c, s->is_utf16);
+                }
+                idx_min = 0;
+                low = get_u32(pc + 0 * 8);
+                if (c < low)
+                    goto no_match;
+                idx_max = n - 1;
+                high = get_u32(pc + idx_max * 8 + 4);
+                if (c > high)
+                    goto no_match;
+                while (idx_min <= idx_max) {
+                    idx = (idx_min + idx_max) / 2;
+                    low = get_u32(pc + idx * 8);
+                    high = get_u32(pc + idx * 8 + 4);
+                    if (c < low)
+                        idx_max = idx - 1;
+                    else if (c > high)
+                        idx_min = idx + 1;
+                    else
+                        goto range32_match;
+                }
+                goto no_match;
+            range32_match:
+                pc += 8 * n;
+            }
+            break;
+        case REOP_prev:
+            /* go to the previous char */
+            if (cptr == s->cbuf)
+                goto no_match;
+            PREV_CHAR(cptr, s->cbuf);
+            break;
+        case REOP_simple_greedy_quant:
+            {
+                uint32_t next_pos, quant_min, quant_max;
+                size_t q;
+                intptr_t res;
+                const uint8_t *pc1;
+                
+                next_pos = get_u32(pc);
+                quant_min = get_u32(pc + 4);
+                quant_max = get_u32(pc + 8);
+                pc += 16;
+                pc1 = pc;
+                pc += (int)next_pos;
+                
+                q = 0;
+                for(;;) {
+                    res = lre_exec_backtrack(s, capture, stack, stack_len,
+                                             pc1, cptr, TRUE);
+                    if (res == -1)
+                        return res;
+                    if (!res)
+                        break;
+                    cptr = (uint8_t *)res;
+                    q++;
+                    if (q >= quant_max && quant_max != INT32_MAX)
+                        break;
+                }
+                if (q < quant_min)
+                    goto no_match;
+                if (q > quant_min) {
+                    /* will examine all matches down to quant_min */
+                    ret = push_state(s, capture, stack, stack_len,
+                                     pc1 - 16, cptr,
+                                     RE_EXEC_STATE_GREEDY_QUANT,
+                                     q - quant_min);
+                    if (ret < 0)
+                        return -1;
+                }
+            }
+            break;
+        default:
+            abort();
+        }
+    }
+}
+
+/* Return 1 if match, 0 if not match or -1 if error. cindex is the
+   starting position of the match and must be such as 0 <= cindex <=
+   clen. */
+int lre_exec(uint8_t **capture,
+             const uint8_t *bc_buf, const uint8_t *cbuf, int cindex, int clen,
+             int cbuf_type, void *opaque)
+{
+    REExecContext s_s, *s = &s_s;
+    int re_flags, i, alloca_size, ret;
+    StackInt *stack_buf;
+    
+    re_flags = bc_buf[RE_HEADER_FLAGS];
+    s->multi_line = (re_flags & LRE_FLAG_MULTILINE) != 0;
+    s->ignore_case = (re_flags & LRE_FLAG_IGNORECASE) != 0;
+    s->is_utf16 = (re_flags & LRE_FLAG_UTF16) != 0;
+    s->capture_count = bc_buf[RE_HEADER_CAPTURE_COUNT];
+    s->stack_size_max = bc_buf[RE_HEADER_STACK_SIZE];
+    s->cbuf = cbuf;
+    s->cbuf_end = cbuf + (clen << cbuf_type);
+    s->cbuf_type = cbuf_type;
+    if (s->cbuf_type == 1 && s->is_utf16)
+        s->cbuf_type = 2;
+    s->opaque = opaque;
+
+    s->state_size = sizeof(REExecState) +
+        s->capture_count * sizeof(capture[0]) * 2 +
+        s->stack_size_max * sizeof(stack_buf[0]);
+    s->state_stack = NULL;
+    s->state_stack_len = 0;
+    s->state_stack_size = 0;
+    
+    for(i = 0; i < s->capture_count * 2; i++)
+        capture[i] = NULL;
+    alloca_size = s->stack_size_max * sizeof(stack_buf[0]);
+    stack_buf = alloca(alloca_size);
+    ret = lre_exec_backtrack(s, capture, stack_buf, 0, bc_buf + RE_HEADER_LEN,
+                             cbuf + (cindex << cbuf_type), FALSE);
+    lre_realloc(s->opaque, s->state_stack, 0);
+    return ret;
+}
+
+int lre_get_capture_count(const uint8_t *bc_buf)
+{
+    return bc_buf[RE_HEADER_CAPTURE_COUNT];
+}
+
+int lre_get_flags(const uint8_t *bc_buf)
+{
+    return bc_buf[RE_HEADER_FLAGS];
+}
+
+#ifdef TEST
+
+BOOL lre_check_stack_overflow(void *opaque, size_t alloca_size)
+{
+    return FALSE;
+}
+
+void *lre_realloc(void *opaque, void *ptr, size_t size)
+{
+    return realloc(ptr, size);
+}
+
+int main(int argc, char **argv)
+{
+    int len, ret, i;
+    uint8_t *bc;
+    char error_msg[64];
+    uint8_t *capture[CAPTURE_COUNT_MAX * 2];
+    const char *input;
+    int input_len, capture_count;
+    
+    if (argc < 3) {
+        printf("usage: %s regexp input\n", argv[0]);
+        exit(1);
+    }
+    bc = lre_compile(&len, error_msg, sizeof(error_msg), argv[1],
+                     strlen(argv[1]), 0, NULL);
+    if (!bc) {
+        fprintf(stderr, "error: %s\n", error_msg);
+        exit(1);
+    }
+
+    input = argv[2];
+    input_len = strlen(input);
+    
+    ret = lre_exec(capture, bc, (uint8_t *)input, 0, input_len, 0, NULL);
+    printf("ret=%d\n", ret);
+    if (ret == 1) {
+        capture_count = lre_get_capture_count(bc);
+        for(i = 0; i < 2 * capture_count; i++) {
+            uint8_t *ptr;
+            ptr = capture[i];
+            printf("%d: ", i);
+            if (!ptr)
+                printf("<nil>");
+            else
+                printf("%u", (int)(ptr - (uint8_t *)input));
+            printf("\n");
+        }
+    }
+    return 0;
+}
+#endif