code/trunk/pcre_compile.c

/*************************************************
*      Perl-Compatible Regular Expressions       *
*************************************************/

/* PCRE is a library of functions to support regular expressions whose syntax
and semantics are as close as possible to those of the Perl 5 language.

                       Written by Philip Hazel
           Copyright (c) 1997-2007 University of Cambridge

-----------------------------------------------------------------------------
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.

    * Neither the name of the University of Cambridge nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-----------------------------------------------------------------------------
*/


/* This module contains the external function pcre_compile(), along with
supporting internal functions that are not used by other modules. */


#ifdef HAVE_CONFIG_H                         
#include <config.h>
#endif                                                               

#define NLBLOCK cd             /* Block containing newline information */
#define PSSTART start_pattern  /* Field containing processed string start */
#define PSEND   end_pattern    /* Field containing processed string end */

#include "pcre_internal.h"


/* When DEBUG is defined, we need the pcre_printint() function, which is also
used by pcretest. DEBUG is not defined when building a production library. */

#ifdef DEBUG
#include "pcre_printint.src"
#endif


/* Macro for setting individual bits in class bitmaps. */

#define SETBIT(a,b) a[b/8] |= (1 << (b%8))


/*************************************************
*      Code parameters and static tables         *
*************************************************/

/* This value specifies the size of stack workspace that is used during the
first pre-compile phase that determines how much memory is required. The regex
is partly compiled into this space, but the compiled parts are discarded as
soon as they can be, so that hopefully there will never be an overrun. The code
does, however, check for an overrun. The largest amount I've seen used is 218,
so this number is very generous.

The same workspace is used during the second, actual compile phase for
remembering forward references to groups so that they can be filled in at the
end. Each entry in this list occupies LINK_SIZE bytes, so even when LINK_SIZE
is 4 there is plenty of room. */

#define COMPILE_WORK_SIZE (4096)


/* Table for handling escaped characters in the range '0'-'z'. Positive returns
are simple data values; negative values are for special things like \d and so
on. Zero means further processing is needed (for things like \x), or the escape
is invalid. */

#ifndef EBCDIC  /* This is the "normal" table for ASCII systems */
static const short int escapes[] = {
     0,      0,      0,      0,      0,      0,      0,      0,   /* 0 - 7 */
     0,      0,    ':',    ';',    '<',    '=',    '>',    '?',   /* 8 - ? */
   '@', -ESC_A, -ESC_B, -ESC_C, -ESC_D, -ESC_E,      0, -ESC_G,   /* @ - G */
-ESC_H,      0,      0, -ESC_K,      0,      0,      0,      0,   /* H - O */
-ESC_P, -ESC_Q, -ESC_R, -ESC_S,      0,      0, -ESC_V, -ESC_W,   /* P - W */
-ESC_X,      0, -ESC_Z,    '[',   '\\',    ']',    '^',    '_',   /* X - _ */
   '`',      7, -ESC_b,      0, -ESC_d,  ESC_e,  ESC_f,      0,   /* ` - g */
-ESC_h,      0,      0, -ESC_k,      0,      0,  ESC_n,      0,   /* h - o */
-ESC_p,      0,  ESC_r, -ESC_s,  ESC_tee,    0, -ESC_v, -ESC_w,   /* p - w */
     0,      0, -ESC_z                                            /* x - z */
};

#else           /* This is the "abnormal" table for EBCDIC systems */
static const short int escapes[] = {
/*  48 */     0,     0,      0,     '.',    '<',   '(',    '+',    '|',
/*  50 */   '&',     0,      0,       0,      0,     0,      0,      0,
/*  58 */     0,     0,    '!',     '$',    '*',   ')',    ';',    '~',
/*  60 */   '-',   '/',      0,       0,      0,     0,      0,      0,
/*  68 */     0,     0,    '|',     ',',    '%',   '_',    '>',    '?',
/*  70 */     0,     0,      0,       0,      0,     0,      0,      0,
/*  78 */     0,   '`',    ':',     '#',    '@',  '\'',    '=',    '"',
/*  80 */     0,     7, -ESC_b,       0, -ESC_d, ESC_e,  ESC_f,      0,
/*  88 */-ESC_h,     0,      0,     '{',      0,     0,      0,      0,
/*  90 */     0,     0, -ESC_k,     'l',      0, ESC_n,      0, -ESC_p,
/*  98 */     0, ESC_r,      0,     '}',      0,     0,      0,      0,
/*  A0 */     0,   '~', -ESC_s, ESC_tee,      0,-ESC_v, -ESC_w,      0,
/*  A8 */     0,-ESC_z,      0,       0,      0,   '[',      0,      0,
/*  B0 */     0,     0,      0,       0,      0,     0,      0,      0,
/*  B8 */     0,     0,      0,       0,      0,   ']',    '=',    '-',
/*  C0 */   '{',-ESC_A, -ESC_B,  -ESC_C, -ESC_D,-ESC_E,      0, -ESC_G,
/*  C8 */-ESC_H,     0,      0,       0,      0,     0,      0,      0,
/*  D0 */   '}',     0, -ESC_K,       0,      0,     0,      0, -ESC_P,
/*  D8 */-ESC_Q,-ESC_R,      0,       0,      0,     0,      0,      0,
/*  E0 */  '\\',     0, -ESC_S,       0,      0,-ESC_V, -ESC_W, -ESC_X,
/*  E8 */     0,-ESC_Z,      0,       0,      0,     0,      0,      0,
/*  F0 */     0,     0,      0,       0,      0,     0,      0,      0,
/*  F8 */     0,     0,      0,       0,      0,     0,      0,      0
};
#endif


/* Tables of names of POSIX character classes and their lengths. The list is
terminated by a zero length entry. The first three must be alpha, lower, upper,
as this is assumed for handling case independence. */

static const char *const posix_names[] = {
  "alpha", "lower", "upper",
  "alnum", "ascii", "blank", "cntrl", "digit", "graph",
  "print", "punct", "space", "word",  "xdigit" };

static const uschar posix_name_lengths[] = {
  5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 6, 0 };

/* Table of class bit maps for each POSIX class. Each class is formed from a
base map, with an optional addition or removal of another map. Then, for some
classes, there is some additional tweaking: for [:blank:] the vertical space
characters are removed, and for [:alpha:] and [:alnum:] the underscore
character is removed. The triples in the table consist of the base map offset,
second map offset or -1 if no second map, and a non-negative value for map
addition or a negative value for map subtraction (if there are two maps). The
absolute value of the third field has these meanings: 0 => no tweaking, 1 =>
remove vertical space characters, 2 => remove underscore. */

static const int posix_class_maps[] = {
  cbit_word,  cbit_digit, -2,             /* alpha */
  cbit_lower, -1,          0,             /* lower */
  cbit_upper, -1,          0,             /* upper */
  cbit_word,  -1,          2,             /* alnum - word without underscore */
  cbit_print, cbit_cntrl,  0,             /* ascii */
  cbit_space, -1,          1,             /* blank - a GNU extension */
  cbit_cntrl, -1,          0,             /* cntrl */
  cbit_digit, -1,          0,             /* digit */
  cbit_graph, -1,          0,             /* graph */
  cbit_print, -1,          0,             /* print */
  cbit_punct, -1,          0,             /* punct */
  cbit_space, -1,          0,             /* space */
  cbit_word,  -1,          0,             /* word - a Perl extension */
  cbit_xdigit,-1,          0              /* xdigit */
};


#define STRING(a)  # a
#define XSTRING(s) STRING(s)

/* The texts of compile-time error messages. These are "char *" because they
are passed to the outside world. Do not ever re-use any error number, because
they are documented. Always add a new error instead. Messages marked DEAD below
are no longer used. */

static const char *error_texts[] = {
  "no error",
  "\\ at end of pattern",
  "\\c at end of pattern",
  "unrecognized character follows \\",
  "numbers out of order in {} quantifier",
  /* 5 */
  "number too big in {} quantifier",
  "missing terminating ] for character class",
  "invalid escape sequence in character class",
  "range out of order in character class",
  "nothing to repeat",
  /* 10 */
  "operand of unlimited repeat could match the empty string",  /** DEAD **/
  "internal error: unexpected repeat",
  "unrecognized character after (?",
  "POSIX named classes are supported only within a class",
  "missing )",
  /* 15 */
  "reference to non-existent subpattern",
  "erroffset passed as NULL",
  "unknown option bit(s) set",
  "missing ) after comment",
  "parentheses nested too deeply",  /** DEAD **/
  /* 20 */
  "regular expression too large",
  "failed to get memory",
  "unmatched parentheses",
  "internal error: code overflow",
  "unrecognized character after (?<",
  /* 25 */
  "lookbehind assertion is not fixed length",
  "malformed number or name after (?(",
  "conditional group contains more than two branches",
  "assertion expected after (?(",
  "(?R or (?[+-]digits must be followed by )",
  /* 30 */
  "unknown POSIX class name",
  "POSIX collating elements are not supported",
  "this version of PCRE is not compiled with PCRE_UTF8 support",
  "spare error",  /** DEAD **/
  "character value in \\x{...} sequence is too large",
  /* 35 */
  "invalid condition (?(0)",
  "\\C not allowed in lookbehind assertion",
  "PCRE does not support \\L, \\l, \\N, \\U, or \\u",
  "number after (?C is > 255",
  "closing ) for (?C expected",
  /* 40 */
  "recursive call could loop indefinitely",
  "unrecognized character after (?P",
  "syntax error in subpattern name (missing terminator)",
  "two named subpatterns have the same name",
  "invalid UTF-8 string",
  /* 45 */
  "support for \\P, \\p, and \\X has not been compiled",
  "malformed \\P or \\p sequence",
  "unknown property name after \\P or \\p",
  "subpattern name is too long (maximum " XSTRING(MAX_NAME_SIZE) " characters)",
  "too many named subpatterns (maximum " XSTRING(MAX_NAME_COUNT) ")",
  /* 50 */
  "repeated subpattern is too long",
  "octal value is greater than \\377 (not in UTF-8 mode)",
  "internal error: overran compiling workspace",
  "internal error: previously-checked referenced subpattern not found",
  "DEFINE group contains more than one branch",
  /* 55 */
  "repeating a DEFINE group is not allowed",
  "inconsistent NEWLINE options",
  "\\g is not followed by a braced name or an optionally braced non-zero number",
  "(?+ or (?- or (?(+ or (?(- must be followed by a non-zero number"
};


/* Table to identify digits and hex digits. This is used when compiling
patterns. Note that the tables in chartables are dependent on the locale, and
may mark arbitrary characters as digits - but the PCRE compiling code expects
to handle only 0-9, a-z, and A-Z as digits when compiling. That is why we have
a private table here. It costs 256 bytes, but it is a lot faster than doing
character value tests (at least in some simple cases I timed), and in some
applications one wants PCRE to compile efficiently as well as match
efficiently.

For convenience, we use the same bit definitions as in chartables:

  0x04   decimal digit
  0x08   hexadecimal digit

Then we can use ctype_digit and ctype_xdigit in the code. */

#ifndef EBCDIC  /* This is the "normal" case, for ASCII systems */
static const unsigned char digitab[] =
  {
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   0-  7 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   8- 15 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  16- 23 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  24- 31 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*    - '  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  ( - /  */
  0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c, /*  0 - 7  */
  0x0c,0x0c,0x00,0x00,0x00,0x00,0x00,0x00, /*  8 - ?  */
  0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /*  @ - G  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  H - O  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  P - W  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  X - _  */
  0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /*  ` - g  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  h - o  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  p - w  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  x -127 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 128-135 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 136-143 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 144-151 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 152-159 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 160-167 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 168-175 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 176-183 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 184-191 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 192-199 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 200-207 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 208-215 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 216-223 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 224-231 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 232-239 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 240-247 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};/* 248-255 */

#else           /* This is the "abnormal" case, for EBCDIC systems */
static const unsigned char digitab[] =
  {
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   0-  7  0 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   8- 15    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  16- 23 10 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  24- 31    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  32- 39 20 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  40- 47    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  48- 55 30 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  56- 63    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*    - 71 40 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  72- |     */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  & - 87 50 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  88- 95    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  - -103 60 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 104- ?     */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 112-119 70 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 120- "     */
  0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /* 128- g  80 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  h -143    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 144- p  90 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  q -159    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 160- x  A0 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  y -175    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  ^ -183 B0 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 184-191    */
  0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /*  { - G  C0 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  H -207    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  } - P  D0 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  Q -223    */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  \ - X  E0 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  Y -239    */
  0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c, /*  0 - 7  F0 */
  0x0c,0x0c,0x00,0x00,0x00,0x00,0x00,0x00};/*  8 -255    */

static const unsigned char ebcdic_chartab[] = { /* chartable partial dup */
  0x80,0x00,0x00,0x00,0x00,0x01,0x00,0x00, /*   0-  7 */
  0x00,0x00,0x00,0x00,0x01,0x01,0x00,0x00, /*   8- 15 */
  0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00, /*  16- 23 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  24- 31 */
  0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00, /*  32- 39 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  40- 47 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  48- 55 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  56- 63 */
  0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*    - 71 */
  0x00,0x00,0x00,0x80,0x00,0x80,0x80,0x80, /*  72- |  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  & - 87 */
  0x00,0x00,0x00,0x80,0x80,0x80,0x00,0x00, /*  88- 95 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  - -103 */
  0x00,0x00,0x00,0x00,0x00,0x10,0x00,0x80, /* 104- ?  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 112-119 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 120- "  */
  0x00,0x1a,0x1a,0x1a,0x1a,0x1a,0x1a,0x12, /* 128- g  */
  0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /*  h -143 */
  0x00,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /* 144- p  */
  0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /*  q -159 */
  0x00,0x00,0x12,0x12,0x12,0x12,0x12,0x12, /* 160- x  */
  0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /*  y -175 */
  0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  ^ -183 */
  0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00, /* 184-191 */
  0x80,0x1a,0x1a,0x1a,0x1a,0x1a,0x1a,0x12, /*  { - G  */
  0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /*  H -207 */
  0x00,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /*  } - P  */
  0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /*  Q -223 */
  0x00,0x00,0x12,0x12,0x12,0x12,0x12,0x12, /*  \ - X  */
  0x12,0x12,0x00,0x00,0x00,0x00,0x00,0x00, /*  Y -239 */
  0x1c,0x1c,0x1c,0x1c,0x1c,0x1c,0x1c,0x1c, /*  0 - 7  */
  0x1c,0x1c,0x00,0x00,0x00,0x00,0x00,0x00};/*  8 -255 */
#endif


/* Definition to allow mutual recursion */

static BOOL
  compile_regex(int, int, uschar **, const uschar **, int *, BOOL, BOOL, int,
    int *, int *, branch_chain *, compile_data *, int *);


/*************************************************
*            Handle escapes                      *
*************************************************/

/* This function is called when a \ has been encountered. It either returns a
positive value for a simple escape such as \n, or a negative value which
encodes one of the more complicated things such as \d. A backreference to group
n is returned as -(ESC_REF + n); ESC_REF is the highest ESC_xxx macro. When
UTF-8 is enabled, a positive value greater than 255 may be returned. On entry,
ptr is pointing at the \. On exit, it is on the final character of the escape
sequence.

Arguments:
  ptrptr         points to the pattern position pointer
  errorcodeptr   points to the errorcode variable
  bracount       number of previous extracting brackets
  options        the options bits
  isclass        TRUE if inside a character class

Returns:         zero or positive => a data character
                 negative => a special escape sequence
                 on error, errorptr is set
*/

static int
check_escape(const uschar **ptrptr, int *errorcodeptr, int bracount,
  int options, BOOL isclass)
{
BOOL utf8 = (options & PCRE_UTF8) != 0;
const uschar *ptr = *ptrptr + 1;
int c, i;

GETCHARINCTEST(c, ptr);           /* Get character value, increment pointer */
ptr--;                            /* Set pointer back to the last byte */

/* If backslash is at the end of the pattern, it's an error. */

if (c == 0) *errorcodeptr = ERR1;

/* Non-alphamerics are literals. For digits or letters, do an initial lookup in
a table. A non-zero result is something that can be returned immediately.
Otherwise further processing may be required. */

#ifndef EBCDIC  /* ASCII coding */
else if (c < '0' || c > 'z') {}                           /* Not alphameric */
else if ((i = escapes[c - '0']) != 0) c = i;

#else           /* EBCDIC coding */
else if (c < 'a' || (ebcdic_chartab[c] & 0x0E) == 0) {}   /* Not alphameric */
else if ((i = escapes[c - 0x48]) != 0)  c = i;
#endif

/* Escapes that need further processing, or are illegal. */

else
  {
  const uschar *oldptr;
  BOOL braced, negated;

  switch (c)
    {
    /* A number of Perl escapes are not handled by PCRE. We give an explicit
    error. */

    case 'l':
    case 'L':
    case 'N':
    case 'u':
    case 'U':
    *errorcodeptr = ERR37;
    break;

    /* \g must be followed by a number, either plain or braced. If positive, it
    is an absolute backreference. If negative, it is a relative backreference.
    This is a Perl 5.10 feature. Perl 5.10 also supports \g{name} as a
    reference to a named group. This is part of Perl's movement towards a
    unified syntax for back references. As this is synonymous with \k{name}, we
    fudge it up by pretending it really was \k. */

    case 'g':
    if (ptr[1] == '{')
      {
      const uschar *p;
      for (p = ptr+2; *p != 0 && *p != '}'; p++)
        if (*p != '-' && (digitab[*p] & ctype_digit) == 0) break;
      if (*p != 0 && *p != '}')
        {
        c = -ESC_k;
        break;
        }
      braced = TRUE;
      ptr++;
      }
    else braced = FALSE;

    if (ptr[1] == '-')
      {
      negated = TRUE;
      ptr++;
      }
    else negated = FALSE;

    c = 0;
    while ((digitab[ptr[1]] & ctype_digit) != 0)
      c = c * 10 + *(++ptr) - '0';

    if (c == 0 || (braced && *(++ptr) != '}'))
      {
      *errorcodeptr = ERR57;
      return 0;
      }

    if (negated)
      {
      if (c > bracount)
        {
        *errorcodeptr = ERR15;
        return 0;
        }
      c = bracount - (c - 1);
      }

    c = -(ESC_REF + c);
    break;

    /* The handling of escape sequences consisting of a string of digits
    starting with one that is not zero is not straightforward. By experiment,
    the way Perl works seems to be as follows:

    Outside a character class, the digits are read as a decimal number. If the
    number is less than 10, or if there are that many previous extracting
    left brackets, then it is a back reference. Otherwise, up to three octal
    digits are read to form an escaped byte. Thus \123 is likely to be octal
    123 (cf \0123, which is octal 012 followed by the literal 3). If the octal
    value is greater than 377, the least significant 8 bits are taken. Inside a
    character class, \ followed by a digit is always an octal number. */

    case '1': case '2': case '3': case '4': case '5':
    case '6': case '7': case '8': case '9':

    if (!isclass)
      {
      oldptr = ptr;
      c -= '0';
      while ((digitab[ptr[1]] & ctype_digit) != 0)
        c = c * 10 + *(++ptr) - '0';
      if (c < 10 || c <= bracount)
        {
        c = -(ESC_REF + c);
        break;
        }
      ptr = oldptr;      /* Put the pointer back and fall through */
      }

    /* Handle an octal number following \. If the first digit is 8 or 9, Perl
    generates a binary zero byte and treats the digit as a following literal.
    Thus we have to pull back the pointer by one. */

    if ((c = *ptr) >= '8')
      {
      ptr--;
      c = 0;
      break;
      }

    /* \0 always starts an octal number, but we may drop through to here with a
    larger first octal digit. The original code used just to take the least
    significant 8 bits of octal numbers (I think this is what early Perls used
    to do). Nowadays we allow for larger numbers in UTF-8 mode, but no more
    than 3 octal digits. */

    case '0':
    c -= '0';
    while(i++ < 2 && ptr[1] >= '0' && ptr[1] <= '7')
        c = c * 8 + *(++ptr) - '0';
    if (!utf8 && c > 255) *errorcodeptr = ERR51;
    break;

    /* \x is complicated. \x{ddd} is a character number which can be greater
    than 0xff in utf8 mode, but only if the ddd are hex digits. If not, { is
    treated as a data character. */

    case 'x':
    if (ptr[1] == '{')
      {
      const uschar *pt = ptr + 2;
      int count = 0;

      c = 0;
      while ((digitab[*pt] & ctype_xdigit) != 0)
        {
        register int cc = *pt++;
        if (c == 0 && cc == '0') continue;     /* Leading zeroes */
        count++;

#ifndef EBCDIC  /* ASCII coding */
        if (cc >= 'a') cc -= 32;               /* Convert to upper case */
        c = (c << 4) + cc - ((cc < 'A')? '0' : ('A' - 10));
#else           /* EBCDIC coding */
        if (cc >= 'a' && cc <= 'z') cc += 64;  /* Convert to upper case */
        c = (c << 4) + cc - ((cc >= '0')? '0' : ('A' - 10));
#endif
        }

      if (*pt == '}')
        {
        if (c < 0 || count > (utf8? 8 : 2)) *errorcodeptr = ERR34;
        ptr = pt;
        break;
        }

      /* If the sequence of hex digits does not end with '}', then we don't
      recognize this construct; fall through to the normal \x handling. */
      }

    /* Read just a single-byte hex-defined char */

    c = 0;
    while (i++ < 2 && (digitab[ptr[1]] & ctype_xdigit) != 0)
      {
      int cc;                               /* Some compilers don't like ++ */
      cc = *(++ptr);                        /* in initializers */
#ifndef EBCDIC  /* ASCII coding */
      if (cc >= 'a') cc -= 32;              /* Convert to upper case */
      c = c * 16 + cc - ((cc < 'A')? '0' : ('A' - 10));
#else           /* EBCDIC coding */
      if (cc <= 'z') cc += 64;              /* Convert to upper case */
      c = c * 16 + cc - ((cc >= '0')? '0' : ('A' - 10));
#endif
      }
    break;

    /* For \c, a following letter is upper-cased; then the 0x40 bit is flipped.
    This coding is ASCII-specific, but then the whole concept of \cx is
    ASCII-specific. (However, an EBCDIC equivalent has now been added.) */

    case 'c':
    c = *(++ptr);
    if (c == 0)
      {
      *errorcodeptr = ERR2;
      return 0;
      }

#ifndef EBCDIC  /* ASCII coding */
    if (c >= 'a' && c <= 'z') c -= 32;
    c ^= 0x40;
#else           /* EBCDIC coding */
    if (c >= 'a' && c <= 'z') c += 64;
    c ^= 0xC0;
#endif
    break;

    /* PCRE_EXTRA enables extensions to Perl in the matter of escapes. Any
    other alphameric following \ is an error if PCRE_EXTRA was set; otherwise,
    for Perl compatibility, it is a literal. This code looks a bit odd, but
    there used to be some cases other than the default, and there may be again
    in future, so I haven't "optimized" it. */

    default:
    if ((options & PCRE_EXTRA) != 0) switch(c)
      {
      default:
      *errorcodeptr = ERR3;
      break;
      }
    break;
    }
  }

*ptrptr = ptr;
return c;
}


#ifdef SUPPORT_UCP
/*************************************************
*               Handle \P and \p                 *
*************************************************/

/* This function is called after \P or \p has been encountered, provided that
PCRE is compiled with support for Unicode properties. On entry, ptrptr is
pointing at the P or p. On exit, it is pointing at the final character of the
escape sequence.

Argument:
  ptrptr         points to the pattern position pointer
  negptr         points to a boolean that is set TRUE for negation else FALSE
  dptr           points to an int that is set to the detailed property value
  errorcodeptr   points to the error code variable

Returns:         type value from ucp_type_table, or -1 for an invalid type
*/

static int
get_ucp(const uschar **ptrptr, BOOL *negptr, int *dptr, int *errorcodeptr)
{
int c, i, bot, top;
const uschar *ptr = *ptrptr;
char name[32];

c = *(++ptr);
if (c == 0) goto ERROR_RETURN;

*negptr = FALSE;

/* \P or \p can be followed by a name in {}, optionally preceded by ^ for
negation. */

if (c == '{')
  {
  if (ptr[1] == '^')
    {
    *negptr = TRUE;
    ptr++;
    }
  for (i = 0; i < (int)sizeof(name) - 1; i++)
    {
    c = *(++ptr);
    if (c == 0) goto ERROR_RETURN;
    if (c == '}') break;
    name[i] = c;
    }
  if (c !='}') goto ERROR_RETURN;
  name[i] = 0;
  }

/* Otherwise there is just one following character */

else
  {
  name[0] = c;
  name[1] = 0;
  }

*ptrptr = ptr;

/* Search for a recognized property name using binary chop */

bot = 0;
top = _pcre_utt_size;

while (bot < top)
  {
  i = (bot + top) >> 1;
  c = strcmp(name, _pcre_utt[i].name);
  if (c == 0)
    {
    *dptr = _pcre_utt[i].value;
    return _pcre_utt[i].type;
    }
  if (c > 0) bot = i + 1; else top = i;
  }

*errorcodeptr = ERR47;
*ptrptr = ptr;
return -1;

ERROR_RETURN:
*errorcodeptr = ERR46;
*ptrptr = ptr;
return -1;
}
#endif


/*************************************************
*            Check for counted repeat            *
*************************************************/

/* This function is called when a '{' is encountered in a place where it might
start a quantifier. It looks ahead to see if it really is a quantifier or not.
It is only a quantifier if it is one of the forms {ddd} {ddd,} or {ddd,ddd}
where the ddds are digits.

Arguments:
  p         pointer to the first char after '{'

Returns:    TRUE or FALSE
*/

static BOOL
is_counted_repeat(const uschar *p)
{
if ((digitab[*p++] & ctype_digit) == 0) return FALSE;
while ((digitab[*p] & ctype_digit) != 0) p++;
if (*p == '}') return TRUE;

if (*p++ != ',') return FALSE;
if (*p == '}') return TRUE;

if ((digitab[*p++] & ctype_digit) == 0) return FALSE;
while ((digitab[*p] & ctype_digit) != 0) p++;

return (*p == '}');
}


/*************************************************
*         Read repeat counts                     *
*************************************************/

/* Read an item of the form {n,m} and return the values. This is called only
after is_counted_repeat() has confirmed that a repeat-count quantifier exists,
so the syntax is guaranteed to be correct, but we need to check the values.

Arguments:
  p              pointer to first char after '{'
  minp           pointer to int for min
  maxp           pointer to int for max
                 returned as -1 if no max
  errorcodeptr   points to error code variable

Returns:         pointer to '}' on success;
                 current ptr on error, with errorcodeptr set non-zero
*/

static const uschar *
read_repeat_counts(const uschar *p, int *minp, int *maxp, int *errorcodeptr)
{
int min = 0;
int max = -1;

/* Read the minimum value and do a paranoid check: a negative value indicates
an integer overflow. */

while ((digitab[*p] & ctype_digit) != 0) min = min * 10 + *p++ - '0';
if (min < 0 || min > 65535)
  {
  *errorcodeptr = ERR5;
  return p;
  }

/* Read the maximum value if there is one, and again do a paranoid on its size.
Also, max must not be less than min. */

if (*p == '}') max = min; else
  {
  if (*(++p) != '}')
    {
    max = 0;
    while((digitab[*p] & ctype_digit) != 0) max = max * 10 + *p++ - '0';
    if (max < 0 || max > 65535)
      {
      *errorcodeptr = ERR5;
      return p;
      }
    if (max < min)
      {
      *errorcodeptr = ERR4;
      return p;
      }
    }
  }

/* Fill in the required variables, and pass back the pointer to the terminating
'}'. */

*minp = min;
*maxp = max;
return p;
}


/*************************************************
*       Find forward referenced subpattern       *
*************************************************/

/* This function scans along a pattern's text looking for capturing
subpatterns, and counting them. If it finds a named pattern that matches the
name it is given, it returns its number. Alternatively, if the name is NULL, it
returns when it reaches a given numbered subpattern. This is used for forward
references to subpatterns. We know that if (?P< is encountered, the name will
be terminated by '>' because that is checked in the first pass.

Arguments:
  ptr          current position in the pattern
  count        current count of capturing parens so far encountered
  name         name to seek, or NULL if seeking a numbered subpattern
  lorn         name length, or subpattern number if name is NULL
  xmode        TRUE if we are in /x mode

Returns:       the number of the named subpattern, or -1 if not found
*/

static int
find_parens(const uschar *ptr, int count, const uschar *name, int lorn,
  BOOL xmode)
{
const uschar *thisname;

for (; *ptr != 0; ptr++)
  {
  int term;

  /* Skip over backslashed characters and also entire \Q...\E */

  if (*ptr == '\\')
    {
    if (*(++ptr) == 0) return -1;
    if (*ptr == 'Q') for (;;)
      {
      while (*(++ptr) != 0 && *ptr != '\\');
      if (*ptr == 0) return -1;
      if (*(++ptr) == 'E') break;
      }
    continue;
    }

  /* Skip over character classes */

  if (*ptr == '[')
    {
    while (*(++ptr) != ']')
      {
      if (*ptr == '\\')
        {
        if (*(++ptr) == 0) return -1;
        if (*ptr == 'Q') for (;;)
          {
          while (*(++ptr) != 0 && *ptr != '\\');
          if (*ptr == 0) return -1;
          if (*(++ptr) == 'E') break;
          }
        continue;
        }
      }
    continue;
    }

  /* Skip comments in /x mode */

  if (xmode && *ptr == '#')
    {
    while (*(++ptr) != 0 && *ptr != '\n');
    if (*ptr == 0) return -1;
    continue;
    }

  /* An opening parens must now be a real metacharacter */

  if (*ptr != '(') continue;
  if (ptr[1] != '?')
    {
    count++;
    if (name == NULL && count == lorn) return count;
    continue;
    }

  ptr += 2;
  if (*ptr == 'P') ptr++;                      /* Allow optional P */

  /* We have to disambiguate (?<! and (?<= from (?<name> */

  if ((*ptr != '<' || ptr[1] == '!' || ptr[1] == '=') &&
       *ptr != '\'')
    continue;

  count++;

  if (name == NULL && count == lorn) return count;
  term = *ptr++;
  if (term == '<') term = '>';
  thisname = ptr;
  while (*ptr != term) ptr++;
  if (name != NULL && lorn == ptr - thisname &&
      strncmp((const char *)name, (const char *)thisname, lorn) == 0)
    return count;
  }

return -1;
}


/*************************************************
*      Find first significant op code            *
*************************************************/

/* This is called by several functions that scan a compiled expression looking
for a fixed first character, or an anchoring op code etc. It skips over things
that do not influence this. For some calls, a change of option is important.
For some calls, it makes sense to skip negative forward and all backward
assertions, and also the \b assertion; for others it does not.

Arguments:
  code         pointer to the start of the group
  options      pointer to external options
  optbit       the option bit whose changing is significant, or
                 zero if none are
  skipassert   TRUE if certain assertions are to be skipped

Returns:       pointer to the first significant opcode
*/

static const uschar*
first_significant_code(const uschar *code, int *options, int optbit,
  BOOL skipassert)
{
for (;;)
  {
  switch ((int)*code)
    {
    case OP_OPT:
    if (optbit > 0 && ((int)code[1] & optbit) != (*options & optbit))
      *options = (int)code[1];
    code += 2;
    break;

    case OP_ASSERT_NOT:
    case OP_ASSERTBACK:
    case OP_ASSERTBACK_NOT:
    if (!skipassert) return code;
    do code += GET(code, 1); while (*code == OP_ALT);
    code += _pcre_OP_lengths[*code];
    break;

    case OP_WORD_BOUNDARY:
    case OP_NOT_WORD_BOUNDARY:
    if (!skipassert) return code;
    /* Fall through */

    case OP_CALLOUT:
    case OP_CREF:
    case OP_RREF:
    case OP_DEF:
    code += _pcre_OP_lengths[*code];
    break;

    default:
    return code;
    }
  }
/* Control never reaches here */
}


/*************************************************
*        Find the fixed length of a pattern      *
*************************************************/

/* Scan a pattern and compute the fixed length of subject that will match it,
if the length is fixed. This is needed for dealing with backward assertions.
In UTF8 mode, the result is in characters rather than bytes.

Arguments:
  code     points to the start of the pattern (the bracket)
  options  the compiling options

Returns:   the fixed length, or -1 if there is no fixed length,
             or -2 if \C was encountered
*/

static int
find_fixedlength(uschar *code, int options)
{
int length = -1;

register int branchlength = 0;
register uschar *cc = code + 1 + LINK_SIZE;

/* Scan along the opcodes for this branch. If we get to the end of the
branch, check the length against that of the other branches. */

for (;;)
  {
  int d;
  register int op = *cc;

  switch (op)
    {
    case OP_CBRA:
    case OP_BRA:
    case OP_ONCE:
    case OP_COND:
    d = find_fixedlength(cc + ((op == OP_CBRA)? 2:0), options);
    if (d < 0) return d;
    branchlength += d;
    do cc += GET(cc, 1); while (*cc == OP_ALT);
    cc += 1 + LINK_SIZE;
    break;

    /* Reached end of a branch; if it's a ket it is the end of a nested
    call. If it's ALT it is an alternation in a nested call. If it is
    END it's the end of the outer call. All can be handled by the same code. */

    case OP_ALT:
    case OP_KET:
    case OP_KETRMAX:
    case OP_KETRMIN:
    case OP_END:
    if (length < 0) length = branchlength;
      else if (length != branchlength) return -1;
    if (*cc != OP_ALT) return length;
    cc += 1 + LINK_SIZE;
    branchlength = 0;
    break;

    /* Skip over assertive subpatterns */

    case OP_ASSERT:
    case OP_ASSERT_NOT:
    case OP_ASSERTBACK:
    case OP_ASSERTBACK_NOT:
    do cc += GET(cc, 1); while (*cc == OP_ALT);
    /* Fall through */

    /* Skip over things that don't match chars */

    case OP_REVERSE:
    case OP_CREF:
    case OP_RREF:
    case OP_DEF:
    case OP_OPT:
    case OP_CALLOUT:
    case OP_SOD:
    case OP_SOM:
    case OP_EOD:
    case OP_EODN:
    case OP_CIRC:
    case OP_DOLL:
    case OP_NOT_WORD_BOUNDARY:
    case OP_WORD_BOUNDARY:
    cc += _pcre_OP_lengths[*cc];
    break;

    /* Handle literal characters */

    case OP_CHAR:
    case OP_CHARNC:
    case OP_NOT:
    branchlength++;
    cc += 2;
#ifdef SUPPORT_UTF8
    if ((options & PCRE_UTF8) != 0)
      {
      while ((*cc & 0xc0) == 0x80) cc++;
      }
#endif
    break;

    /* Handle exact repetitions. The count is already in characters, but we
    need to skip over a multibyte character in UTF8 mode.  */

    case OP_EXACT:
    branchlength += GET2(cc,1);
    cc += 4;
#ifdef SUPPORT_UTF8
    if ((options & PCRE_UTF8) != 0)
      {
      while((*cc & 0x80) == 0x80) cc++;
      }
#endif
    break;

    case OP_TYPEEXACT:
    branchlength += GET2(cc,1);
    cc += 4;
    break;

    /* Handle single-char matchers */

    case OP_PROP:
    case OP_NOTPROP:
    cc += 2;
    /* Fall through */

    case OP_NOT_DIGIT:
    case OP_DIGIT:
    case OP_NOT_WHITESPACE:
    case OP_WHITESPACE:
    case OP_NOT_WORDCHAR:
    case OP_WORDCHAR:
    case OP_ANY:
    branchlength++;
    cc++;
    break;

    /* The single-byte matcher isn't allowed */

    case OP_ANYBYTE:
    return -2;

    /* Check a class for variable quantification */

#ifdef SUPPORT_UTF8
    case OP_XCLASS:
    cc += GET(cc, 1) - 33;
    /* Fall through */
#endif

    case OP_CLASS:
    case OP_NCLASS:
    cc += 33;

    switch (*cc)
      {
      case OP_CRSTAR:
      case OP_CRMINSTAR:
      case OP_CRQUERY:
      case OP_CRMINQUERY:
      return -1;

      case OP_CRRANGE:
      case OP_CRMINRANGE:
      if (GET2(cc,1) != GET2(cc,3)) return -1;
      branchlength += GET2(cc,1);
      cc += 5;
      break;

      default:
      branchlength++;
      }
    break;

    /* Anything else is variable length */

    default:
    return -1;
    }
  }
/* Control never gets here */
}


/*************************************************
*    Scan compiled regex for numbered bracket    *
*************************************************/

/* This little function scans through a compiled pattern until it finds a
capturing bracket with the given number.

Arguments:
  code        points to start of expression
  utf8        TRUE in UTF-8 mode
  number      the required bracket number

Returns:      pointer to the opcode for the bracket, or NULL if not found
*/

static const uschar *
find_bracket(const uschar *code, BOOL utf8, int number)
{
for (;;)
  {
  register int c = *code;
  if (c == OP_END) return NULL;

  /* XCLASS is used for classes that cannot be represented just by a bit
  map. This includes negated single high-valued characters. The length in
  the table is zero; the actual length is stored in the compiled code. */

  if (c == OP_XCLASS) code += GET(code, 1);

  /* Handle capturing bracket */

  else if (c == OP_CBRA)
    {
    int n = GET2(code, 1+LINK_SIZE);
    if (n == number) return (uschar *)code;
    code += _pcre_OP_lengths[c];
    }

  /* In UTF-8 mode, opcodes that are followed by a character may be followed by
  a multi-byte character. The length in the table is a minimum, so we have to
  arrange to skip the extra bytes. */

  else
    {
    code += _pcre_OP_lengths[c];
#ifdef SUPPORT_UTF8
    if (utf8) switch(c)
      {
      case OP_CHAR:
      case OP_CHARNC:
      case OP_EXACT:
      case OP_UPTO:
      case OP_MINUPTO:
      case OP_POSUPTO:
      case OP_STAR:
      case OP_MINSTAR:
      case OP_POSSTAR:
      case OP_PLUS:
      case OP_MINPLUS:
      case OP_POSPLUS:
      case OP_QUERY:
      case OP_MINQUERY:
      case OP_POSQUERY:
      if (code[-1] >= 0xc0) code += _pcre_utf8_table4[code[-1] & 0x3f];
      break;
      }
#endif
    }
  }
}


/*************************************************
*   Scan compiled regex for recursion reference  *
*************************************************/

/* This little function scans through a compiled pattern until it finds an
instance of OP_RECURSE.

Arguments:
  code        points to start of expression
  utf8        TRUE in UTF-8 mode

Returns:      pointer to the opcode for OP_RECURSE, or NULL if not found
*/

static const uschar *
find_recurse(const uschar *code, BOOL utf8)
{
for (;;)
  {
  register int c = *code;
  if (c == OP_END) return NULL;
  if (c == OP_RECURSE) return code;

  /* XCLASS is used for classes that cannot be represented just by a bit
  map. This includes negated single high-valued characters. The length in
  the table is zero; the actual length is stored in the compiled code. */

  if (c == OP_XCLASS) code += GET(code, 1);

  /* Otherwise, we get the item's length from the table. In UTF-8 mode, opcodes
  that are followed by a character may be followed by a multi-byte character.
  The length in the table is a minimum, so we have to arrange to skip the extra
  bytes. */

  else
    {
    code += _pcre_OP_lengths[c];
#ifdef SUPPORT_UTF8
    if (utf8) switch(c)
      {
      case OP_CHAR:
      case OP_CHARNC:
      case OP_EXACT:
      case OP_UPTO:
      case OP_MINUPTO:
      case OP_POSUPTO:
      case OP_STAR:
      case OP_MINSTAR:
      case OP_POSSTAR:
      case OP_PLUS:
      case OP_MINPLUS:
      case OP_POSPLUS:
      case OP_QUERY:
      case OP_MINQUERY:
      case OP_POSQUERY:
      if (code[-1] >= 0xc0) code += _pcre_utf8_table4[code[-1] & 0x3f];
      break;
      }
#endif
    }
  }
}


/*************************************************
*    Scan compiled branch for non-emptiness      *
*************************************************/

/* This function scans through a branch of a compiled pattern to see whether it
can match the empty string or not. It is called from could_be_empty()
below and from compile_branch() when checking for an unlimited repeat of a
group that can match nothing. Note that first_significant_code() skips over
assertions. If we hit an unclosed bracket, we return "empty" - this means we've
struck an inner bracket whose current branch will already have been scanned.

Arguments:
  code        points to start of search
  endcode     points to where to stop
  utf8        TRUE if in UTF8 mode

Returns:      TRUE if what is matched could be empty
*/

static BOOL
could_be_empty_branch(const uschar *code, const uschar *endcode, BOOL utf8)
{
register int c;
for (code = first_significant_code(code + _pcre_OP_lengths[*code], NULL, 0, TRUE);
     code < endcode;
     code = first_significant_code(code + _pcre_OP_lengths[c], NULL, 0, TRUE))
  {
  const uschar *ccode;

  c = *code;

  /* Groups with zero repeats can of course be empty; skip them. */

  if (c == OP_BRAZERO || c == OP_BRAMINZERO)
    {
    code += _pcre_OP_lengths[c];
    do code += GET(code, 1); while (*code == OP_ALT);
    c = *code;
    continue;
    }

  /* For other groups, scan the branches. */

  if (c == OP_BRA || c == OP_CBRA || c == OP_ONCE)
    {
    BOOL empty_branch;
    if (GET(code, 1) == 0) return TRUE;    /* Hit unclosed bracket */

    /* Scan a closed bracket */

    empty_branch = FALSE;
    do
      {
      if (!empty_branch && could_be_empty_branch(code, endcode, utf8))
        empty_branch = TRUE;
      code += GET(code, 1);
      }
    while (*code == OP_ALT);
    if (!empty_branch) return FALSE;   /* All branches are non-empty */
    c = *code;
    continue;
    }

  /* Handle the other opcodes */

  switch (c)
    {
    /* Check for quantifiers after a class */

#ifdef SUPPORT_UTF8
    case OP_XCLASS:
    ccode = code + GET(code, 1);
    goto CHECK_CLASS_REPEAT;
#endif

    case OP_CLASS:
    case OP_NCLASS:
    ccode = code + 33;

#ifdef SUPPORT_UTF8
    CHECK_CLASS_REPEAT:
#endif

    switch (*ccode)
      {
      case OP_CRSTAR:            /* These could be empty; continue */
      case OP_CRMINSTAR:
      case OP_CRQUERY:
      case OP_CRMINQUERY:
      break;

      default:                   /* Non-repeat => class must match */
      case OP_CRPLUS:            /* These repeats aren't empty */
      case OP_CRMINPLUS:
      return FALSE;

      case OP_CRRANGE:
      case OP_CRMINRANGE:
      if (GET2(ccode, 1) > 0) return FALSE;  /* Minimum > 0 */
      break;
      }
    break;

    /* Opcodes that must match a character */

    case OP_PROP:
    case OP_NOTPROP:
    case OP_EXTUNI:
    case OP_NOT_DIGIT:
    case OP_DIGIT:
    case OP_NOT_WHITESPACE:
    case OP_WHITESPACE:
    case OP_NOT_WORDCHAR:
    case OP_WORDCHAR:
    case OP_ANY:
    case OP_ANYBYTE:
    case OP_CHAR:
    case OP_CHARNC:
    case OP_NOT:
    case OP_PLUS:
    case OP_MINPLUS:
    case OP_POSPLUS:
    case OP_EXACT:
    case OP_NOTPLUS:
    case OP_NOTMINPLUS:
    case OP_NOTPOSPLUS:
    case OP_NOTEXACT:
    case OP_TYPEPLUS:
    case OP_TYPEMINPLUS:
    case OP_TYPEPOSPLUS:
    case OP_TYPEEXACT:
    return FALSE;

    /* End of branch */

    case OP_KET:
    case OP_KETRMAX:
    case OP_KETRMIN:
    case OP_ALT:
    return TRUE;

    /* In UTF-8 mode, STAR, MINSTAR, POSSTAR, QUERY, MINQUERY, POSQUERY, UPTO,
    MINUPTO, and POSUPTO may be followed by a multibyte character */

#ifdef SUPPORT_UTF8
    case OP_STAR:
    case OP_MINSTAR:
    case OP_POSSTAR:
    case OP_QUERY:
    case OP_MINQUERY:
    case OP_POSQUERY:
    case OP_UPTO:
    case OP_MINUPTO:
    case OP_POSUPTO:
    if (utf8) while ((code[2] & 0xc0) == 0x80) code++;
    break;
#endif
    }
  }

return TRUE;
}


/*************************************************
*    Scan compiled regex for non-emptiness       *
*************************************************/

/* This function is called to check for left recursive calls. We want to check
the current branch of the current pattern to see if it could match the empty
string. If it could, we must look outwards for branches at other levels,
stopping when we pass beyond the bracket which is the subject of the recursion.

Arguments:
  code        points to start of the recursion
  endcode     points to where to stop (current RECURSE item)
  bcptr       points to the chain of current (unclosed) branch starts
  utf8        TRUE if in UTF-8 mode

Returns:      TRUE if what is matched could be empty
*/

static BOOL
could_be_empty(const uschar *code, const uschar *endcode, branch_chain *bcptr,
  BOOL utf8)
{
while (bcptr != NULL && bcptr->current >= code)
  {
  if (!could_be_empty_branch(bcptr->current, endcode, utf8)) return FALSE;
  bcptr = bcptr->outer;
  }
return TRUE;
}


/*************************************************
*           Check for POSIX class syntax         *
*************************************************/

/* This function is called when the sequence "[:" or "[." or "[=" is
encountered in a character class. It checks whether this is followed by an
optional ^ and then a sequence of letters, terminated by a matching ":]" or
".]" or "=]".

Argument:
  ptr      pointer to the initial [
  endptr   where to return the end pointer
  cd       pointer to compile data

Returns:   TRUE or FALSE
*/

static BOOL
check_posix_syntax(const uschar *ptr, const uschar **endptr, compile_data *cd)
{
int terminator;          /* Don't combine these lines; the Solaris cc */
terminator = *(++ptr);   /* compiler warns about "non-constant" initializer. */
if (*(++ptr) == '^') ptr++;
while ((cd->ctypes[*ptr] & ctype_letter) != 0) ptr++;
if (*ptr == terminator && ptr[1] == ']')
  {
  *endptr = ptr;
  return TRUE;
  }
return FALSE;
}


/*************************************************
*          Check POSIX class name                *
*************************************************/

/* This function is called to check the name given in a POSIX-style class entry
such as [:alnum:].

Arguments:
  ptr        points to the first letter
  len        the length of the name

Returns:     a value representing the name, or -1 if unknown
*/

static int
check_posix_name(const uschar *ptr, int len)
{
register int yield = 0;
while (posix_name_lengths[yield] != 0)
  {
  if (len == posix_name_lengths[yield] &&
    strncmp((const char *)ptr, posix_names[yield], len) == 0) return yield;
  yield++;
  }
return -1;
}


/*************************************************
*    Adjust OP_RECURSE items in repeated group   *
*************************************************/

/* OP_RECURSE items contain an offset from the start of the regex to the group
that is referenced. This means that groups can be replicated for fixed
repetition simply by copying (because the recursion is allowed to refer to
earlier groups that are outside the current group). However, when a group is
optional (i.e. the minimum quantifier is zero), OP_BRAZERO is inserted before
it, after it has been compiled. This means that any OP_RECURSE items within it
that refer to the group itself or any contained groups have to have their
offsets adjusted. That one of the jobs of this function. Before it is called,
the partially compiled regex must be temporarily terminated with OP_END.

This function has been extended with the possibility of forward references for
recursions and subroutine calls. It must also check the list of such references
for the group we are dealing with. If it finds that one of the recursions in
the current group is on this list, it adjusts the offset in the list, not the
value in the reference (which is a group number).

Arguments:
  group      points to the start of the group
  adjust     the amount by which the group is to be moved
  utf8       TRUE in UTF-8 mode
  cd         contains pointers to tables etc.
  save_hwm   the hwm forward reference pointer at the start of the group

Returns:     nothing
*/

static void
adjust_recurse(uschar *group, int adjust, BOOL utf8, compile_data *cd,
  uschar *save_hwm)
{
uschar *ptr = group;
while ((ptr = (uschar *)find_recurse(ptr, utf8)) != NULL)
  {
  int offset;
  uschar *hc;

  /* See if this recursion is on the forward reference list. If so, adjust the
  reference. */

  for (hc = save_hwm; hc < cd->hwm; hc += LINK_SIZE)
    {
    offset = GET(hc, 0);
    if (cd->start_code + offset == ptr + 1)
      {
      PUT(hc, 0, offset + adjust);
      break;
      }
    }

  /* Otherwise, adjust the recursion offset if it's after the start of this
  group. */

  if (hc >= cd->hwm)
    {
    offset = GET(ptr, 1);
    if (cd->start_code + offset >= group) PUT(ptr, 1, offset + adjust);
    }

  ptr += 1 + LINK_SIZE;
  }
}


/*************************************************
*        Insert an automatic callout point       *
*************************************************/

/* This function is called when the PCRE_AUTO_CALLOUT option is set, to insert
callout points before each pattern item.

Arguments:
  code           current code pointer
  ptr            current pattern pointer
  cd             pointers to tables etc

Returns:         new code pointer
*/

static uschar *
auto_callout(uschar *code, const uschar *ptr, compile_data *cd)
{
*code++ = OP_CALLOUT;
*code++ = 255;
PUT(code, 0, ptr - cd->start_pattern);  /* Pattern offset */
PUT(code, LINK_SIZE, 0);                /* Default length */
return code + 2*LINK_SIZE;
}


/*************************************************
*         Complete a callout item                *
*************************************************/

/* A callout item contains the length of the next item in the pattern, which
we can't fill in till after we have reached the relevant point. This is used
for both automatic and manual callouts.

Arguments:
  previous_callout   points to previous callout item
  ptr                current pattern pointer
  cd                 pointers to tables etc

Returns:             nothing
*/

static void
complete_callout(uschar *previous_callout, const uschar *ptr, compile_data *cd)
{
int length = ptr - cd->start_pattern - GET(previous_callout, 2);
PUT(previous_callout, 2 + LINK_SIZE, length);
}


#ifdef SUPPORT_UCP
/*************************************************
*           Get othercase range                  *
*************************************************/

/* This function is passed the start and end of a class range, in UTF-8 mode
with UCP support. It searches up the characters, looking for internal ranges of
characters in the "other" case. Each call returns the next one, updating the
start address.

Arguments:
  cptr        points to starting character value; updated
  d           end value
  ocptr       where to put start of othercase range
  odptr       where to put end of othercase range

Yield:        TRUE when range returned; FALSE when no more
*/

static BOOL
get_othercase_range(unsigned int *cptr, unsigned int d, unsigned int *ocptr,
  unsigned int *odptr)
{
unsigned int c, othercase, next;

for (c = *cptr; c <= d; c++)
  { if ((othercase = _pcre_ucp_othercase(c)) != NOTACHAR) break; }

if (c > d) return FALSE;

*ocptr = othercase;
next = othercase + 1;

for (++c; c <= d; c++)
  {
  if (_pcre_ucp_othercase(c) != next) break;
  next++;
  }

*odptr = next - 1;
*cptr = c;

return TRUE;
}
#endif  /* SUPPORT_UCP */


/*************************************************
*     Check if auto-possessifying is possible    *
*************************************************/

/* This function is called for unlimited repeats of certain items, to see
whether the next thing could possibly match the repeated item. If not, it makes
sense to automatically possessify the repeated item.

Arguments:
  op_code       the repeated op code
  this          data for this item, depends on the opcode
  utf8          TRUE in UTF-8 mode
  utf8_char     used for utf8 character bytes, NULL if not relevant
  ptr           next character in pattern
  options       options bits
  cd            contains pointers to tables etc.

Returns:        TRUE if possessifying is wanted
*/

static BOOL
check_auto_possessive(int op_code, int item, BOOL utf8, uschar *utf8_char,
  const uschar *ptr, int options, compile_data *cd)
{
int next;

/* Skip whitespace and comments in extended mode */

if ((options & PCRE_EXTENDED) != 0)
  {
  for (;;)
    {
    while ((cd->ctypes[*ptr] & ctype_space) != 0) ptr++;
    if (*ptr == '#')
      {
      while (*(++ptr) != 0)
        if (IS_NEWLINE(ptr)) { ptr += cd->nllen; break; }
      }
    else break;
    }
  }

/* If the next item is one that we can handle, get its value. A non-negative
value is a character, a negative value is an escape value. */

if (*ptr == '\\')
  {
  int temperrorcode = 0;
  next = check_escape(&ptr, &temperrorcode, cd->bracount, options, FALSE);
  if (temperrorcode != 0) return FALSE;
  ptr++;    /* Point after the escape sequence */
  }

else if ((cd->ctypes[*ptr] & ctype_meta) == 0)
  {
#ifdef SUPPORT_UTF8
  if (utf8) { GETCHARINC(next, ptr); } else
#endif
  next = *ptr++;
  }

else return FALSE;

/* Skip whitespace and comments in extended mode */

if ((options & PCRE_EXTENDED) != 0)
  {
  for (;;)
    {
    while ((cd->ctypes[*ptr] & ctype_space) != 0) ptr++;
    if (*ptr == '#')
      {
      while (*(++ptr) != 0)
        if (IS_NEWLINE(ptr)) { ptr += cd->nllen; break; }
      }
    else break;
    }
  }

/* If the next thing is itself optional, we have to give up. */

if (*ptr == '*' || *ptr == '?' || strncmp((char *)ptr, "{0,", 3) == 0)
  return FALSE;

/* Now compare the next item with the previous opcode. If the previous is a
positive single character match, "item" either contains the character or, if
"item" is greater than 127 in utf8 mode, the character's bytes are in
utf8_char. */


/* Handle cases when the next item is a character. */

if (next >= 0) switch(op_code)
  {
  case OP_CHAR:
#ifdef SUPPORT_UTF8
  if (utf8 && item > 127) { GETCHAR(item, utf8_char); }
#endif
  return item != next;

  /* For CHARNC (caseless character) we must check the other case. If we have
  Unicode property support, we can use it to test the other case of
  high-valued characters. */

  case OP_CHARNC:
#ifdef SUPPORT_UTF8
  if (utf8 && item > 127) { GETCHAR(item, utf8_char); }
#endif
  if (item == next) return FALSE;
#ifdef SUPPORT_UTF8
  if (utf8)
    {
    unsigned int othercase;
    if (next < 128) othercase = cd->fcc[next]; else
#ifdef SUPPORT_UCP
    othercase = _pcre_ucp_othercase((unsigned int)next);
#else
    othercase = NOTACHAR;
#endif
    return (unsigned int)item != othercase;
    }
  else
#endif  /* SUPPORT_UTF8 */
  return (item != cd->fcc[next]);  /* Non-UTF-8 mode */

  /* For OP_NOT, "item" must be a single-byte character. */

  case OP_NOT:
  if (next < 0) return FALSE;  /* Not a character */
  if (item == next) return TRUE;
  if ((options & PCRE_CASELESS) == 0) return FALSE;
#ifdef SUPPORT_UTF8
  if (utf8)
    {
    unsigned int othercase;
    if (next < 128) othercase = cd->fcc[next]; else
#ifdef SUPPORT_UCP
    othercase = _pcre_ucp_othercase(next);
#else
    othercase = NOTACHAR;
#endif
    return (unsigned int)item == othercase;
    }
  else
#endif  /* SUPPORT_UTF8 */
  return (item == cd->fcc[next]);  /* Non-UTF-8 mode */

  case OP_DIGIT:
  return next > 127 || (cd->ctypes[next] & ctype_digit) == 0;

  case OP_NOT_DIGIT:
  return next <= 127 && (cd->ctypes[next] & ctype_digit) != 0;

  case OP_WHITESPACE:
  return next > 127 || (cd->ctypes[next] & ctype_space) == 0;

  case OP_NOT_WHITESPACE:
  return next <= 127 && (cd->ctypes[next] & ctype_space) != 0;

  case OP_WORDCHAR:
  return next > 127 || (cd->ctypes[next] & ctype_word) == 0;

  case OP_NOT_WORDCHAR:
  return next <= 127 && (cd->ctypes[next] & ctype_word) != 0;

  case OP_HSPACE:
  case OP_NOT_HSPACE:
  switch(next)
    {
    case 0x09:
    case 0x20:
    case 0xa0:
    case 0x1680:
    case 0x180e:
    case 0x2000:
    case 0x2001:
    case 0x2002:
    case 0x2003:
    case 0x2004:
    case 0x2005:
    case 0x2006:
    case 0x2007:
    case 0x2008:
    case 0x2009:
    case 0x200A:
    case 0x202f:
    case 0x205f:
    case 0x3000:
    return op_code != OP_HSPACE;
    default:
    return op_code == OP_HSPACE;
    }

  case OP_VSPACE:
  case OP_NOT_VSPACE:
  switch(next)
    {
    case 0x0a:
    case 0x0b:
    case 0x0c:
    case 0x0d:
    case 0x85:
    case 0x2028:
    case 0x2029:
    return op_code != OP_VSPACE;
    default:
    return op_code == OP_VSPACE;
    }

  default:
  return FALSE;
  }


/* Handle the case when the next item is \d, \s, etc. */

switch(op_code)
  {
  case OP_CHAR:
  case OP_CHARNC:
#ifdef SUPPORT_UTF8
  if (utf8 && item > 127) { GETCHAR(item, utf8_char); }
#endif
  switch(-next)
    {
    case ESC_d:
    return item > 127 || (cd->ctypes[item] & ctype_digit) == 0;

    case ESC_D:
    return item <= 127 && (cd->ctypes[item] & ctype_digit) != 0;

    case ESC_s:
    return item > 127 || (cd->ctypes[item] & ctype_space) == 0;

    case ESC_S:
    return item <= 127 && (cd->ctypes[item] & ctype_space) != 0;

    case ESC_w:
    return item > 127 || (cd->ctypes[item] & ctype_word) == 0;

    case ESC_W:
    return item <= 127 && (cd->ctypes[item] & ctype_word) != 0;

    case ESC_h:
    case ESC_H:
    switch(item)
      {
      case 0x09:
      case 0x20:
      case 0xa0:
      case 0x1680:
      case 0x180e:
      case 0x2000:
      case 0x2001:
      case 0x2002:
      case 0x2003:
      case 0x2004:
      case 0x2005:
      case 0x2006:
      case 0x2007:
      case 0x2008:
      case 0x2009:
      case 0x200A:
      case 0x202f:
      case 0x205f:
      case 0x3000:
      return -next != ESC_h;
      default:
      return -next == ESC_h;
      }

    case ESC_v:
    case ESC_V:
    switch(item)
      {
      case 0x0a:
      case 0x0b:
      case 0x0c:
      case 0x0d:
      case 0x85:
      case 0x2028:
      case 0x2029:
      return -next != ESC_v;
      default:
      return -next == ESC_v;
      }

    default:
    return FALSE;
    }

  case OP_DIGIT:
  return next == -ESC_D || next == -ESC_s || next == -ESC_W ||
         next == -ESC_h || next == -ESC_v;

  case OP_NOT_DIGIT:
  return next == -ESC_d;

  case OP_WHITESPACE:
  return next == -ESC_S || next == -ESC_d || next == -ESC_w;

  case OP_NOT_WHITESPACE:
  return next == -ESC_s || next == -ESC_h || next == -ESC_v;

  case OP_HSPACE:
  return next == -ESC_S || next == -ESC_H || next == -ESC_d || next == -ESC_w;

  case OP_NOT_HSPACE:
  return next == -ESC_h;

  /* Can't have \S in here because VT matches \S (Perl anomaly) */
  case OP_VSPACE:
  return next == -ESC_V || next == -ESC_d || next == -ESC_w;

  case OP_NOT_VSPACE:
  return next == -ESC_v;

  case OP_WORDCHAR:
  return next == -ESC_W || next == -ESC_s || next == -ESC_h || next == -ESC_v;

  case OP_NOT_WORDCHAR:
  return next == -ESC_w || next == -ESC_d;

  default:
  return FALSE;
  }

/* Control does not reach here */
}


/*************************************************
*           Compile one branch                   *
*************************************************/

/* Scan the pattern, compiling it into the a vector. If the options are
changed during the branch, the pointer is used to change the external options
bits. This function is used during the pre-compile phase when we are trying
to find out the amount of memory needed, as well as during the real compile
phase. The value of lengthptr distinguishes the two phases.

Arguments:
  optionsptr     pointer to the option bits
  codeptr        points to the pointer to the current code point
  ptrptr         points to the current pattern pointer
  errorcodeptr   points to error code variable
  firstbyteptr   set to initial literal character, or < 0 (REQ_UNSET, REQ_NONE)
  reqbyteptr     set to the last literal character required, else < 0
  bcptr          points to current branch chain
  cd             contains pointers to tables etc.
  lengthptr      NULL during the real compile phase
                 points to length accumulator during pre-compile phase

Returns:         TRUE on success
                 FALSE, with *errorcodeptr set non-zero on error
*/

static BOOL
compile_branch(int *optionsptr, uschar **codeptr, const uschar **ptrptr,
  int *errorcodeptr, int *firstbyteptr, int *reqbyteptr, branch_chain *bcptr,
  compile_data *cd, int *lengthptr)
{
int repeat_type, op_type;
int repeat_min = 0, repeat_max = 0;      /* To please picky compilers */
int bravalue = 0;
int greedy_default, greedy_non_default;
int firstbyte, reqbyte;
int zeroreqbyte, zerofirstbyte;
int req_caseopt, reqvary, tempreqvary;
int options = *optionsptr;
int after_manual_callout = 0;
int length_prevgroup = 0;
register int c;
register uschar *code = *codeptr;
uschar *last_code = code;
uschar *orig_code = code;
uschar *tempcode;
BOOL inescq = FALSE;
BOOL groupsetfirstbyte = FALSE;
const uschar *ptr = *ptrptr;
const uschar *tempptr;
uschar *previous = NULL;
uschar *previous_callout = NULL;
uschar *save_hwm = NULL;
uschar classbits[32];

#ifdef SUPPORT_UTF8
BOOL class_utf8;
BOOL utf8 = (options & PCRE_UTF8) != 0;
uschar *class_utf8data;
uschar utf8_char[6];
#else
BOOL utf8 = FALSE;
uschar *utf8_char = NULL;
#endif

#ifdef DEBUG
if (lengthptr != NULL) DPRINTF((">> start branch\n"));
#endif

/* Set up the default and non-default settings for greediness */

greedy_default = ((options & PCRE_UNGREEDY) != 0);
greedy_non_default = greedy_default ^ 1;

/* Initialize no first byte, no required byte. REQ_UNSET means "no char
matching encountered yet". It gets changed to REQ_NONE if we hit something that
matches a non-fixed char first char; reqbyte just remains unset if we never
find one.

When we hit a repeat whose minimum is zero, we may have to adjust these values
to take the zero repeat into account. This is implemented by setting them to
zerofirstbyte and zeroreqbyte when such a repeat is encountered. The individual
item types that can be repeated set these backoff variables appropriately. */

firstbyte = reqbyte = zerofirstbyte = zeroreqbyte = REQ_UNSET;

/* The variable req_caseopt contains either the REQ_CASELESS value or zero,
according to the current setting of the caseless flag. REQ_CASELESS is a bit
value > 255. It is added into the firstbyte or reqbyte variables to record the
case status of the value. This is used only for ASCII characters. */

req_caseopt = ((options & PCRE_CASELESS) != 0)? REQ_CASELESS : 0;

/* Switch on next character until the end of the branch */

for (;; ptr++)
  {
  BOOL negate_class;
  BOOL possessive_quantifier;
  BOOL is_quantifier;
  BOOL is_recurse;
  BOOL reset_bracount;
  int class_charcount;
  int class_lastchar;
  int newoptions;
  int recno;
  int refsign;
  int skipbytes;
  int subreqbyte;
  int subfirstbyte;
  int terminator;
  int mclength;
  uschar mcbuffer[8];

  /* Get next byte in the pattern */

  c = *ptr;

  /* If we are in the pre-compile phase, accumulate the length used for the
  previous cycle of this loop. */

  if (lengthptr != NULL)
    {
#ifdef DEBUG
    if (code > cd->hwm) cd->hwm = code;                 /* High water info */
#endif
    if (code > cd->start_workspace + COMPILE_WORK_SIZE) /* Check for overrun */
      {
      *errorcodeptr = ERR52;
      goto FAILED;
      }

    /* There is at least one situation where code goes backwards: this is the
    case of a zero quantifier after a class (e.g. [ab]{0}). At compile time,
    the class is simply eliminated. However, it is created first, so we have to
    allow memory for it. Therefore, don't ever reduce the length at this point.
    */

    if (code < last_code) code = last_code;
    *lengthptr += code - last_code;
    DPRINTF(("length=%d added %d c=%c\n", *lengthptr, code - last_code, c));

    /* If "previous" is set and it is not at the start of the work space, move
    it back to there, in order to avoid filling up the work space. Otherwise,
    if "previous" is NULL, reset the current code pointer to the start. */

    if (previous != NULL)
      {
      if (previous > orig_code)
        {
        memmove(orig_code, previous, code - previous);
        code -= previous - orig_code;
        previous = orig_code;
        }
      }
    else code = orig_code;

    /* Remember where this code item starts so we can pick up the length
    next time round. */

    last_code = code;
    }

  /* In the real compile phase, just check the workspace used by the forward
  reference list. */

  else if (cd->hwm > cd->start_workspace + COMPILE_WORK_SIZE)
    {
    *errorcodeptr = ERR52;
    goto FAILED;
    }

  /* If in \Q...\E, check for the end; if not, we have a literal */

  if (inescq && c != 0)
    {
    if (c == '\\' && ptr[1] == 'E')
      {
      inescq = FALSE;
      ptr++;
      continue;
      }
    else
      {
      if (previous_callout != NULL)
        {
        if (lengthptr == NULL)  /* Don't attempt in pre-compile phase */
          complete_callout(previous_callout, ptr, cd);
        previous_callout = NULL;
        }
      if ((options & PCRE_AUTO_CALLOUT) != 0)
        {
        previous_callout = code;
        code = auto_callout(code, ptr, cd);
        }
      goto NORMAL_CHAR;
      }
    }

  /* Fill in length of a previous callout, except when the next thing is
  a quantifier. */

  is_quantifier = c == '*' || c == '+' || c == '?' ||
    (c == '{' && is_counted_repeat(ptr+1));

  if (!is_quantifier && previous_callout != NULL &&
       after_manual_callout-- <= 0)
    {
    if (lengthptr == NULL)      /* Don't attempt in pre-compile phase */
      complete_callout(previous_callout, ptr, cd);
    previous_callout = NULL;
    }

  /* In extended mode, skip white space and comments */

  if ((options & PCRE_EXTENDED) != 0)
    {
    if ((cd->ctypes[c] & ctype_space) != 0) continue;
    if (c == '#')
      {
      while (*(++ptr) != 0)
        {
        if (IS_NEWLINE(ptr)) { ptr += cd->nllen - 1; break; }
        }
      if (*ptr != 0) continue;

      /* Else fall through to handle end of string */
      c = 0;
      }
    }

  /* No auto callout for quantifiers. */

  if ((options & PCRE_AUTO_CALLOUT) != 0 && !is_quantifier)
    {
    previous_callout = code;
    code = auto_callout(code, ptr, cd);
    }

  switch(c)
    {
    /* ===================================================================*/
    case 0:                        /* The branch terminates at string end */
    case '|':                      /* or | or ) */
    case ')':
    *firstbyteptr = firstbyte;
    *reqbyteptr = reqbyte;
    *codeptr = code;
    *ptrptr = ptr;
    if (lengthptr != NULL)
      {
      *lengthptr += code - last_code;   /* To include callout length */
      DPRINTF((">> end branch\n"));
      }
    return TRUE;


    /* ===================================================================*/
    /* Handle single-character metacharacters. In multiline mode, ^ disables
    the setting of any following char as a first character. */

    case '^':
    if ((options & PCRE_MULTILINE) != 0)
      {
      if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
      }
    previous = NULL;
    *code++ = OP_CIRC;
    break;

    case '$':
    previous = NULL;
    *code++ = OP_DOLL;
    break;

    /* There can never be a first char if '.' is first, whatever happens about
    repeats. The value of reqbyte doesn't change either. */

    case '.':
    if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
    zerofirstbyte = firstbyte;
    zeroreqbyte = reqbyte;
    previous = code;
    *code++ = OP_ANY;
    break;


    /* ===================================================================*/
    /* Character classes. If the included characters are all < 256, we build a
    32-byte bitmap of the permitted characters, except in the special case
    where there is only one such character. For negated classes, we build the
    map as usual, then invert it at the end. However, we use a different opcode
    so that data characters > 255 can be handled correctly.

    If the class contains characters outside the 0-255 range, a different
    opcode is compiled. It may optionally have a bit map for characters < 256,
    but those above are are explicitly listed afterwards. A flag byte tells
    whether the bitmap is present, and whether this is a negated class or not.
    */

    case '[':
    previous = code;

    /* PCRE supports POSIX class stuff inside a class. Perl gives an error if
    they are encountered at the top level, so we'll do that too. */

    if ((ptr[1] == ':' || ptr[1] == '.' || ptr[1] == '=') &&
        check_posix_syntax(ptr, &tempptr, cd))
      {
      *errorcodeptr = (ptr[1] == ':')? ERR13 : ERR31;
      goto FAILED;
      }

    /* If the first character is '^', set the negation flag and skip it. */

    if ((c = *(++ptr)) == '^')
      {
      negate_class = TRUE;
      c = *(++ptr);
      }
    else
      {
      negate_class = FALSE;
      }

    /* Keep a count of chars with values < 256 so that we can optimize the case
    of just a single character (as long as it's < 256). However, For higher
    valued UTF-8 characters, we don't yet do any optimization. */

    class_charcount = 0;
    class_lastchar = -1;

    /* Initialize the 32-char bit map to all zeros. We build the map in a
    temporary bit of memory, in case the class contains only 1 character (less
    than 256), because in that case the compiled code doesn't use the bit map.
    */

    memset(classbits, 0, 32 * sizeof(uschar));

#ifdef SUPPORT_UTF8
    class_utf8 = FALSE;                       /* No chars >= 256 */
    class_utf8data = code + LINK_SIZE + 2;    /* For UTF-8 items */
#endif

    /* Process characters until ] is reached. By writing this as a "do" it
    means that an initial ] is taken as a data character. At the start of the
    loop, c contains the first byte of the character. */

    if (c != 0) do
      {
      const uschar *oldptr;

#ifdef SUPPORT_UTF8
      if (utf8 && c > 127)
        {                           /* Braces are required because the */
        GETCHARLEN(c, ptr, ptr);    /* macro generates multiple statements */
        }
#endif

      /* Inside \Q...\E everything is literal except \E */

      if (inescq)
        {
        if (c == '\\' && ptr[1] == 'E')     /* If we are at \E */
          {
          inescq = FALSE;                   /* Reset literal state */
          ptr++;                            /* Skip the 'E' */
          continue;                         /* Carry on with next */
          }
        goto CHECK_RANGE;                   /* Could be range if \E follows */
        }

      /* Handle POSIX class names. Perl allows a negation extension of the
      form [:^name:]. A square bracket that doesn't match the syntax is
      treated as a literal. We also recognize the POSIX constructions
      [.ch.] and [=ch=] ("collating elements") and fault them, as Perl
      5.6 and 5.8 do. */

      if (c == '[' &&
          (ptr[1] == ':' || ptr[1] == '.' || ptr[1] == '=') &&
          check_posix_syntax(ptr, &tempptr, cd))
        {
        BOOL local_negate = FALSE;
        int posix_class, taboffset, tabopt;
        register const uschar *cbits = cd->cbits;
        uschar pbits[32];

        if (ptr[1] != ':')
          {
          *errorcodeptr = ERR31;
          goto FAILED;
          }

        ptr += 2;
        if (*ptr == '^')
          {
          local_negate = TRUE;
          ptr++;
          }

        posix_class = check_posix_name(ptr, tempptr - ptr);
        if (posix_class < 0)
          {
          *errorcodeptr = ERR30;
          goto FAILED;
          }

        /* If matching is caseless, upper and lower are converted to
        alpha. This relies on the fact that the class table starts with
        alpha, lower, upper as the first 3 entries. */

        if ((options & PCRE_CASELESS) != 0 && posix_class <= 2)
          posix_class = 0;

        /* We build the bit map for the POSIX class in a chunk of local store
        because we may be adding and subtracting from it, and we don't want to
        subtract bits that may be in the main map already. At the end we or the
        result into the bit map that is being built. */

        posix_class *= 3;

        /* Copy in the first table (always present) */

        memcpy(pbits, cbits + posix_class_maps[posix_class],
          32 * sizeof(uschar));

        /* If there is a second table, add or remove it as required. */

        taboffset = posix_class_maps[posix_class + 1];
        tabopt = posix_class_maps[posix_class + 2];

        if (taboffset >= 0)
          {
          if (tabopt >= 0)
            for (c = 0; c < 32; c++) pbits[c] |= cbits[c + taboffset];
          else
            for (c = 0; c < 32; c++) pbits[c] &= ~cbits[c + taboffset];
          }

        /* Not see if we need to remove any special characters. An option
        value of 1 removes vertical space and 2 removes underscore. */

        if (tabopt < 0) tabopt = -tabopt;
        if (tabopt == 1) pbits[1] &= ~0x3c;
          else if (tabopt == 2) pbits[11] &= 0x7f;

        /* Add the POSIX table or its complement into the main table that is
        being built and we are done. */

        if (local_negate)
          for (c = 0; c < 32; c++) classbits[c] |= ~pbits[c];
        else
          for (c = 0; c < 32; c++) classbits[c] |= pbits[c];

        ptr = tempptr + 1;
        class_charcount = 10;  /* Set > 1; assumes more than 1 per class */
        continue;    /* End of POSIX syntax handling */
        }

      /* Backslash may introduce a single character, or it may introduce one
      of the specials, which just set a flag. The sequence \b is a special
      case. Inside a class (and only there) it is treated as backspace.
      Elsewhere it marks a word boundary. Other escapes have preset maps ready
      to or into the one we are building. We assume they have more than one
      character in them, so set class_charcount bigger than one. */

      if (c == '\\')
        {
        c = check_escape(&ptr, errorcodeptr, cd->bracount, options, TRUE);
        if (*errorcodeptr != 0) goto FAILED;

        if (-c == ESC_b) c = '\b';       /* \b is backslash in a class */
        else if (-c == ESC_X) c = 'X';   /* \X is literal X in a class */
        else if (-c == ESC_R) c = 'R';   /* \R is literal R in a class */
        else if (-c == ESC_Q)            /* Handle start of quoted string */
          {
          if (ptr[1] == '\\' && ptr[2] == 'E')
            {
            ptr += 2; /* avoid empty string */
            }
          else inescq = TRUE;
          continue;
          }

        if (c < 0)
          {
          register const uschar *cbits = cd->cbits;
          class_charcount += 2;     /* Greater than 1 is what matters */

          /* Save time by not doing this in the pre-compile phase. */

          if (lengthptr == NULL) switch (-c)
            {
            case ESC_d:
            for (c = 0; c < 32; c++) classbits[c] |= cbits[c+cbit_digit];
            continue;

            case ESC_D:
            for (c = 0; c < 32; c++) classbits[c] |= ~cbits[c+cbit_digit];
            continue;

            case ESC_w:
            for (c = 0; c < 32; c++) classbits[c] |= cbits[c+cbit_word];
            continue;

            case ESC_W:
            for (c = 0; c < 32; c++) classbits[c] |= ~cbits[c+cbit_word];
            continue;

            case ESC_s:
            for (c = 0; c < 32; c++) classbits[c] |= cbits[c+cbit_space];
            classbits[1] &= ~0x08;   /* Perl 5.004 onwards omits VT from \s */
            continue;

            case ESC_S:
            for (c = 0; c < 32; c++) classbits[c] |= ~cbits[c+cbit_space];
            classbits[1] |= 0x08;    /* Perl 5.004 onwards omits VT from \s */
            continue;

            case ESC_E: /* Perl ignores an orphan \E */
            continue;

            default:    /* Not recognized; fall through */
            break;      /* Need "default" setting to stop compiler warning. */
            }

          /* In the pre-compile phase, just do the recognition. */

          else if (c == -ESC_d || c == -ESC_D || c == -ESC_w ||
                   c == -ESC_W || c == -ESC_s || c == -ESC_S) continue;

          /* We need to deal with \H, \h, \V, and \v in both phases because
          they use extra memory. */

          if (-c == ESC_h)
            {
            SETBIT(classbits, 0x09); /* VT */
            SETBIT(classbits, 0x20); /* SPACE */
            SETBIT(classbits, 0xa0); /* NSBP */
#ifdef SUPPORT_UTF8
            if (utf8)
              {
              class_utf8 = TRUE;
              *class_utf8data++ = XCL_SINGLE;
              class_utf8data += _pcre_ord2utf8(0x1680, class_utf8data);
              *class_utf8data++ = XCL_SINGLE;
              class_utf8data += _pcre_ord2utf8(0x180e, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x2000, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x200A, class_utf8data);
              *class_utf8data++ = XCL_SINGLE;
              class_utf8data += _pcre_ord2utf8(0x202f, class_utf8data);
              *class_utf8data++ = XCL_SINGLE;
              class_utf8data += _pcre_ord2utf8(0x205f, class_utf8data);
              *class_utf8data++ = XCL_SINGLE;
              class_utf8data += _pcre_ord2utf8(0x3000, class_utf8data);
              }
#endif
            continue;
            }

          if (-c == ESC_H)
            {
            for (c = 0; c < 32; c++)
              {
              int x = 0xff;
              switch (c)
                {
                case 0x09/8: x ^= 1 << (0x09%8); break;
                case 0x20/8: x ^= 1 << (0x20%8); break;
                case 0xa0/8: x ^= 1 << (0xa0%8); break;
                default: break;
                }
              classbits[c] |= x;
              }

#ifdef SUPPORT_UTF8
            if (utf8)
              {
              class_utf8 = TRUE;
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x0100, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x167f, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x1681, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x180d, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x180f, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x1fff, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x200B, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x202e, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x2030, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x205e, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x2060, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x2fff, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x3001, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x7fffffff, class_utf8data);
              }
#endif
            continue;
            }

          if (-c == ESC_v)
            {
            SETBIT(classbits, 0x0a); /* LF */
            SETBIT(classbits, 0x0b); /* VT */
            SETBIT(classbits, 0x0c); /* FF */
            SETBIT(classbits, 0x0d); /* CR */
            SETBIT(classbits, 0x85); /* NEL */
#ifdef SUPPORT_UTF8
            if (utf8)
              {
              class_utf8 = TRUE;
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x2028, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x2029, class_utf8data);
              }
#endif
            continue;
            }

          if (-c == ESC_V)
            {
            for (c = 0; c < 32; c++)
              {
              int x = 0xff;
              switch (c)
                {
                case 0x0a/8: x ^= 1 << (0x0a%8);
                             x ^= 1 << (0x0b%8);
                             x ^= 1 << (0x0c%8);
                             x ^= 1 << (0x0d%8);
                             break;
                case 0x85/8: x ^= 1 << (0x85%8); break;
                default: break;
                }
              classbits[c] |= x;
              }

#ifdef SUPPORT_UTF8
            if (utf8)
              {
              class_utf8 = TRUE;
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x0100, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x2027, class_utf8data);
              *class_utf8data++ = XCL_RANGE;
              class_utf8data += _pcre_ord2utf8(0x2029, class_utf8data);
              class_utf8data += _pcre_ord2utf8(0x7fffffff, class_utf8data);
              }
#endif
            continue;
            }

          /* We need to deal with \P and \p in both phases. */

#ifdef SUPPORT_UCP
          if (-c == ESC_p || -c == ESC_P)
            {
            BOOL negated;
            int pdata;
            int ptype = get_ucp(&ptr, &negated, &pdata, errorcodeptr);
            if (ptype < 0) goto FAILED;
            class_utf8 = TRUE;
            *class_utf8data++ = ((-c == ESC_p) != negated)?
              XCL_PROP : XCL_NOTPROP;
            *class_utf8data++ = ptype;
            *class_utf8data++ = pdata;
            class_charcount -= 2;   /* Not a < 256 character */
            continue;
            }
#endif
          /* Unrecognized escapes are faulted if PCRE is running in its
          strict mode. By default, for compatibility with Perl, they are
          treated as literals. */

          if ((options & PCRE_EXTRA) != 0)
            {
            *errorcodeptr = ERR7;
            goto FAILED;
            }

          class_charcount -= 2;  /* Undo the default count from above */
          c = *ptr;              /* Get the final character and fall through */
          }

        /* Fall through if we have a single character (c >= 0). This may be
        greater than 256 in UTF-8 mode. */

        }   /* End of backslash handling */

      /* A single character may be followed by '-' to form a range. However,
      Perl does not permit ']' to be the end of the range. A '-' character
      at the end is treated as a literal. Perl ignores orphaned \E sequences
      entirely. The code for handling \Q and \E is messy. */

      CHECK_RANGE:
      while (ptr[1] == '\\' && ptr[2] == 'E')
        {
        inescq = FALSE;
        ptr += 2;
        }

      oldptr = ptr;

      if (!inescq && ptr[1] == '-')
        {
        int d;
        ptr += 2;
        while (*ptr == '\\' && ptr[1] == 'E') ptr += 2;

        /* If we hit \Q (not followed by \E) at this point, go into escaped
        mode. */

        while (*ptr == '\\' && ptr[1] == 'Q')
          {
          ptr += 2;
          if (*ptr == '\\' && ptr[1] == 'E') { ptr += 2; continue; }
          inescq = TRUE;
          break;
          }

        if (*ptr == 0 || (!inescq && *ptr == ']'))
          {
          ptr = oldptr;
          goto LONE_SINGLE_CHARACTER;
          }

#ifdef SUPPORT_UTF8
        if (utf8)
          {                           /* Braces are required because the */
          GETCHARLEN(d, ptr, ptr);    /* macro generates multiple statements */
          }
        else
#endif
        d = *ptr;  /* Not UTF-8 mode */

        /* The second part of a range can be a single-character escape, but
        not any of the other escapes. Perl 5.6 treats a hyphen as a literal
        in such circumstances. */

        if (!inescq && d == '\\')
          {
          d = check_escape(&ptr, errorcodeptr, cd->bracount, options, TRUE);
          if (*errorcodeptr != 0) goto FAILED;

          /* \b is backslash; \X is literal X; \R is literal R; any other
          special means the '-' was literal */

          if (d < 0)
            {
            if (d == -ESC_b) d = '\b';
            else if (d == -ESC_X) d = 'X';
            else if (d == -ESC_R) d = 'R'; else
              {
              ptr = oldptr;
              goto LONE_SINGLE_CHARACTER;  /* A few lines below */
              }
            }
          }

        /* Check that the two values are in the correct order. Optimize
        one-character ranges */

        if (d < c)
          {
          *errorcodeptr = ERR8;
          goto FAILED;
          }

        if (d == c) goto LONE_SINGLE_CHARACTER;  /* A few lines below */

        /* In UTF-8 mode, if the upper limit is > 255, or > 127 for caseless
        matching, we have to use an XCLASS with extra data items. Caseless
        matching for characters > 127 is available only if UCP support is
        available. */

#ifdef SUPPORT_UTF8
        if (utf8 && (d > 255 || ((options & PCRE_CASELESS) != 0 && d > 127)))
          {
          class_utf8 = TRUE;

          /* With UCP support, we can find the other case equivalents of
          the relevant characters. There may be several ranges. Optimize how
          they fit with the basic range. */

#ifdef SUPPORT_UCP
          if ((options & PCRE_CASELESS) != 0)
            {
            unsigned int occ, ocd;
            unsigned int cc = c;
            unsigned int origd = d;
            while (get_othercase_range(&cc, origd, &occ, &ocd))
              {
              if (occ >= (unsigned int)c &&
                  ocd <= (unsigned int)d)
                continue;                          /* Skip embedded ranges */

              if (occ < (unsigned int)c  &&
                  ocd >= (unsigned int)c - 1)      /* Extend the basic range */
                {                                  /* if there is overlap,   */
                c = occ;                           /* noting that if occ < c */
                continue;                          /* we can't have ocd > d  */
                }                                  /* because a subrange is  */
              if (ocd > (unsigned int)d &&
                  occ <= (unsigned int)d + 1)      /* always shorter than    */
                {                                  /* the basic range.       */
                d = ocd;
                continue;
                }

              if (occ == ocd)
                {
                *class_utf8data++ = XCL_SINGLE;
                }
              else
                {
                *class_utf8data++ = XCL_RANGE;
                class_utf8data += _pcre_ord2utf8(occ, class_utf8data);
                }
              class_utf8data += _pcre_ord2utf8(ocd, class_utf8data);
              }
            }
#endif  /* SUPPORT_UCP */

          /* Now record the original range, possibly modified for UCP caseless
          overlapping ranges. */

          *class_utf8data++ = XCL_RANGE;
          class_utf8data += _pcre_ord2utf8(c, class_utf8data);
          class_utf8data += _pcre_ord2utf8(d, class_utf8data);

          /* With UCP support, we are done. Without UCP support, there is no
          caseless matching for UTF-8 characters > 127; we can use the bit map
          for the smaller ones. */

#ifdef SUPPORT_UCP
          continue;    /* With next character in the class */
#else
          if ((options & PCRE_CASELESS) == 0 || c > 127) continue;

          /* Adjust upper limit and fall through to set up the map */

          d = 127;

#endif  /* SUPPORT_UCP */
          }
#endif  /* SUPPORT_UTF8 */

        /* We use the bit map for all cases when not in UTF-8 mode; else
        ranges that lie entirely within 0-127 when there is UCP support; else
        for partial ranges without UCP support. */

        class_charcount += d - c + 1;
        class_lastchar = d;

        /* We can save a bit of time by skipping this in the pre-compile. */

        if (lengthptr == NULL) for (; c <= d; c++)
          {
          classbits[c/8] |= (1 << (c&7));
          if ((options & PCRE_CASELESS) != 0)
            {
            int uc = cd->fcc[c];           /* flip case */
            classbits[uc/8] |= (1 << (uc&7));
            }
          }

        continue;   /* Go get the next char in the class */
        }

      /* Handle a lone single character - we can get here for a normal
      non-escape char, or after \ that introduces a single character or for an
      apparent range that isn't. */

      LONE_SINGLE_CHARACTER:

      /* Handle a character that cannot go in the bit map */

#ifdef SUPPORT_UTF8
      if (utf8 && (c > 255 || ((options & PCRE_CASELESS) != 0 && c > 127)))
        {
        class_utf8 = TRUE;
        *class_utf8data++ = XCL_SINGLE;
        class_utf8data += _pcre_ord2utf8(c, class_utf8data);

#ifdef SUPPORT_UCP
        if ((options & PCRE_CASELESS) != 0)
          {
          unsigned int othercase;
          if ((othercase = _pcre_ucp_othercase(c)) != NOTACHAR)
            {
            *class_utf8data++ = XCL_SINGLE;
            class_utf8data += _pcre_ord2utf8(othercase, class_utf8data);
            }
          }
#endif  /* SUPPORT_UCP */

        }
      else
#endif  /* SUPPORT_UTF8 */

      /* Handle a single-byte character */
        {
        classbits[c/8] |= (1 << (c&7));
        if ((options & PCRE_CASELESS) != 0)
          {
          c = cd->fcc[c];   /* flip case */
          classbits[c/8] |= (1 << (c&7));
          }
        class_charcount++;
        class_lastchar = c;
        }
      }

    /* Loop until ']' reached. This "while" is the end of the "do" above. */

    while ((c = *(++ptr)) != 0 && (c != ']' || inescq));

    if (c == 0)                          /* Missing terminating ']' */
      {
      *errorcodeptr = ERR6;
      goto FAILED;
      }

    /* If class_charcount is 1, we saw precisely one character whose value is
    less than 256. In non-UTF-8 mode we can always optimize. In UTF-8 mode, we
    can optimize the negative case only if there were no characters >= 128
    because OP_NOT and the related opcodes like OP_NOTSTAR operate on
    single-bytes only. This is an historical hangover. Maybe one day we can
    tidy these opcodes to handle multi-byte characters.

    The optimization throws away the bit map. We turn the item into a
    1-character OP_CHAR[NC] if it's positive, or OP_NOT if it's negative. Note
    that OP_NOT does not support multibyte characters. In the positive case, it
    can cause firstbyte to be set. Otherwise, there can be no first char if
    this item is first, whatever repeat count may follow. In the case of
    reqbyte, save the previous value for reinstating. */

#ifdef SUPPORT_UTF8
    if (class_charcount == 1 &&
          (!utf8 ||
          (!class_utf8 && (!negate_class || class_lastchar < 128))))

#else
    if (class_charcount == 1)
#endif
      {
      zeroreqbyte = reqbyte;

      /* The OP_NOT opcode works on one-byte characters only. */

      if (negate_class)
        {
        if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
        zerofirstbyte = firstbyte;
        *code++ = OP_NOT;
        *code++ = class_lastchar;
        break;
        }

      /* For a single, positive character, get the value into mcbuffer, and
      then we can handle this with the normal one-character code. */

#ifdef SUPPORT_UTF8
      if (utf8 && class_lastchar > 127)
        mclength = _pcre_ord2utf8(class_lastchar, mcbuffer);
      else
#endif
        {
        mcbuffer[0] = class_lastchar;
        mclength = 1;
        }
      goto ONE_CHAR;
      }       /* End of 1-char optimization */

    /* The general case - not the one-char optimization. If this is the first
    thing in the branch, there can be no first char setting, whatever the
    repeat count. Any reqbyte setting must remain unchanged after any kind of
    repeat. */

    if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
    zerofirstbyte = firstbyte;
    zeroreqbyte = reqbyte;

    /* If there are characters with values > 255, we have to compile an
    extended class, with its own opcode. If there are no characters < 256,
    we can omit the bitmap in the actual compiled code. */

#ifdef SUPPORT_UTF8
    if (class_utf8)
      {
      *class_utf8data++ = XCL_END;    /* Marks the end of extra data */
      *code++ = OP_XCLASS;
      code += LINK_SIZE;
      *code = negate_class? XCL_NOT : 0;

      /* If the map is required, move up the extra data to make room for it;
      otherwise just move the code pointer to the end of the extra data. */

      if (class_charcount > 0)
        {
        *code++ |= XCL_MAP;
        memmove(code + 32, code, class_utf8data - code);
        memcpy(code, classbits, 32);
        code = class_utf8data + 32;
        }
      else code = class_utf8data;

      /* Now fill in the complete length of the item */

      PUT(previous, 1, code - previous);
      break;   /* End of class handling */
      }
#endif

    /* If there are no characters > 255, negate the 32-byte map if necessary,
    and copy it into the code vector. If this is the first thing in the branch,
    there can be no first char setting, whatever the repeat count. Any reqbyte
    setting must remain unchanged after any kind of repeat. */

    if (negate_class)
      {
      *code++ = OP_NCLASS;
      if (lengthptr == NULL)    /* Save time in the pre-compile phase */
        for (c = 0; c < 32; c++) code[c] = ~classbits[c];
      }
    else
      {
      *code++ = OP_CLASS;
      memcpy(code, classbits, 32);
      }
    code += 32;
    break;


    /* ===================================================================*/
    /* Various kinds of repeat; '{' is not necessarily a quantifier, but this
    has been tested above. */

    case '{':
    if (!is_quantifier) goto NORMAL_CHAR;
    ptr = read_repeat_counts(ptr+1, &repeat_min, &repeat_max, errorcodeptr);
    if (*errorcodeptr != 0) goto FAILED;
    goto REPEAT;

    case '*':
    repeat_min = 0;
    repeat_max = -1;
    goto REPEAT;

    case '+':
    repeat_min = 1;
    repeat_max = -1;
    goto REPEAT;

    case '?':
    repeat_min = 0;
    repeat_max = 1;

    REPEAT:
    if (previous == NULL)
      {
      *errorcodeptr = ERR9;
      goto FAILED;
      }

    if (repeat_min == 0)
      {
      firstbyte = zerofirstbyte;    /* Adjust for zero repeat */
      reqbyte = zeroreqbyte;        /* Ditto */
      }

    /* Remember whether this is a variable length repeat */

    reqvary = (repeat_min == repeat_max)? 0 : REQ_VARY;

    op_type = 0;                    /* Default single-char op codes */
    possessive_quantifier = FALSE;  /* Default not possessive quantifier */

    /* Save start of previous item, in case we have to move it up to make space
    for an inserted OP_ONCE for the additional '+' extension. */

    tempcode = previous;

    /* If the next character is '+', we have a possessive quantifier. This
    implies greediness, whatever the setting of the PCRE_UNGREEDY option.
    If the next character is '?' this is a minimizing repeat, by default,
    but if PCRE_UNGREEDY is set, it works the other way round. We change the
    repeat type to the non-default. */

    if (ptr[1] == '+')
      {
      repeat_type = 0;                  /* Force greedy */
      possessive_quantifier = TRUE;
      ptr++;
      }
    else if (ptr[1] == '?')
      {
      repeat_type = greedy_non_default;
      ptr++;
      }
    else repeat_type = greedy_default;

    /* If previous was a character match, abolish the item and generate a
    repeat item instead. If a char item has a minumum of more than one, ensure
    that it is set in reqbyte - it might not be if a sequence such as x{3} is
    the first thing in a branch because the x will have gone into firstbyte
    instead.  */

    if (*previous == OP_CHAR || *previous == OP_CHARNC)
      {
      /* Deal with UTF-8 characters that take up more than one byte. It's
      easier to write this out separately than try to macrify it. Use c to
      hold the length of the character in bytes, plus 0x80 to flag that it's a
      length rather than a small character. */

#ifdef SUPPORT_UTF8
      if (utf8 && (code[-1] & 0x80) != 0)
        {
        uschar *lastchar = code - 1;
        while((*lastchar & 0xc0) == 0x80) lastchar--;
        c = code - lastchar;            /* Length of UTF-8 character */
        memcpy(utf8_char, lastchar, c); /* Save the char */
        c |= 0x80;                      /* Flag c as a length */
        }
      else
#endif

      /* Handle the case of a single byte - either with no UTF8 support, or
      with UTF-8 disabled, or for a UTF-8 character < 128. */

        {
        c = code[-1];
        if (repeat_min > 1) reqbyte = c | req_caseopt | cd->req_varyopt;
        }

      /* If the repetition is unlimited, it pays to see if the next thing on
      the line is something that cannot possibly match this character. If so,
      automatically possessifying this item gains some performance in the case
      where the match fails. */

      if (!possessive_quantifier &&
          repeat_max < 0 &&
          check_auto_possessive(*previous, c, utf8, utf8_char, ptr + 1,
            options, cd))
        {
        repeat_type = 0;    /* Force greedy */
        possessive_quantifier = TRUE;
        }

      goto OUTPUT_SINGLE_REPEAT;   /* Code shared with single character types */
      }

    /* If previous was a single negated character ([^a] or similar), we use
    one of the special opcodes, replacing it. The code is shared with single-
    character repeats by setting opt_type to add a suitable offset into
    repeat_type. We can also test for auto-possessification. OP_NOT is
    currently used only for single-byte chars. */

    else if (*previous == OP_NOT)
      {
      op_type = OP_NOTSTAR - OP_STAR;  /* Use "not" opcodes */
      c = previous[1];
      if (!possessive_quantifier &&
          repeat_max < 0 &&
          check_auto_possessive(OP_NOT, c, utf8, NULL, ptr + 1, options, cd))
        {
        repeat_type = 0;    /* Force greedy */
        possessive_quantifier = TRUE;
        }
      goto OUTPUT_SINGLE_REPEAT;
      }

    /* If previous was a character type match (\d or similar), abolish it and
    create a suitable repeat item. The code is shared with single-character
    repeats by setting op_type to add a suitable offset into repeat_type. Note
    the the Unicode property types will be present only when SUPPORT_UCP is
    defined, but we don't wrap the little bits of code here because it just
    makes it horribly messy. */

    else if (*previous < OP_EODN)
      {
      uschar *oldcode;
      int prop_type, prop_value;
      op_type = OP_TYPESTAR - OP_STAR;  /* Use type opcodes */
      c = *previous;

      if (!possessive_quantifier &&
          repeat_max < 0 &&
          check_auto_possessive(c, 0, utf8, NULL, ptr + 1, options, cd))
        {
        repeat_type = 0;    /* Force greedy */
        possessive_quantifier = TRUE;
        }

      OUTPUT_SINGLE_REPEAT:
      if (*previous == OP_PROP || *previous == OP_NOTPROP)
        {
        prop_type = previous[1];
        prop_value = previous[2];
        }
      else prop_type = prop_value = -1;

      oldcode = code;
      code = previous;                  /* Usually overwrite previous item */

      /* If the maximum is zero then the minimum must also be zero; Perl allows
      this case, so we do too - by simply omitting the item altogether. */

      if (repeat_max == 0) goto END_REPEAT;

      /* All real repeats make it impossible to handle partial matching (maybe
      one day we will be able to remove this restriction). */

      if (repeat_max != 1) cd->nopartial = TRUE;

      /* Combine the op_type with the repeat_type */

      repeat_type += op_type;

      /* A minimum of zero is handled either as the special case * or ?, or as
      an UPTO, with the maximum given. */

      if (repeat_min == 0)
        {
        if (repeat_max == -1) *code++ = OP_STAR + repeat_type;
          else if (repeat_max == 1) *code++ = OP_QUERY + repeat_type;
        else
          {
          *code++ = OP_UPTO + repeat_type;
          PUT2INC(code, 0, repeat_max);
          }
        }

      /* A repeat minimum of 1 is optimized into some special cases. If the
      maximum is unlimited, we use OP_PLUS. Otherwise, the original item is
      left in place and, if the maximum is greater than 1, we use OP_UPTO with
      one less than the maximum. */

      else if (repeat_min == 1)
        {
        if (repeat_max == -1)
          *code++ = OP_PLUS + repeat_type;
        else
          {
          code = oldcode;                 /* leave previous item in place */
          if (repeat_max == 1) goto END_REPEAT;
          *code++ = OP_UPTO + repeat_type;
          PUT2INC(code, 0, repeat_max - 1);
          }
        }

      /* The case {n,n} is just an EXACT, while the general case {n,m} is
      handled as an EXACT followed by an UPTO. */

      else
        {
        *code++ = OP_EXACT + op_type;  /* NB EXACT doesn't have repeat_type */
        PUT2INC(code, 0, repeat_min);

        /* If the maximum is unlimited, insert an OP_STAR. Before doing so,
        we have to insert the character for the previous code. For a repeated
        Unicode property match, there are two extra bytes that define the
        required property. In UTF-8 mode, long characters have their length in
        c, with the 0x80 bit as a flag. */

        if (repeat_max < 0)
          {
#ifdef SUPPORT_UTF8
          if (utf8 && c >= 128)
            {
            memcpy(code, utf8_char, c & 7);
            code += c & 7;
            }
          else
#endif
            {
            *code++ = c;
            if (prop_type >= 0)
              {
              *code++ = prop_type;
              *code++ = prop_value;
              }
            }
          *code++ = OP_STAR + repeat_type;
          }

        /* Else insert an UPTO if the max is greater than the min, again
        preceded by the character, for the previously inserted code. If the
        UPTO is just for 1 instance, we can use QUERY instead. */

        else if (repeat_max != repeat_min)
          {
#ifdef SUPPORT_UTF8
          if (utf8 && c >= 128)
            {
            memcpy(code, utf8_char, c & 7);
            code += c & 7;
            }
          else
#endif
          *code++ = c;
          if (prop_type >= 0)
            {
            *code++ = prop_type;
            *code++ = prop_value;
            }
          repeat_max -= repeat_min;

          if (repeat_max == 1)
            {
            *code++ = OP_QUERY + repeat_type;
            }
          else
            {
            *code++ = OP_UPTO + repeat_type;
            PUT2INC(code, 0, repeat_max);
            }
          }
        }

      /* The character or character type itself comes last in all cases. */

#ifdef SUPPORT_UTF8
      if (utf8 && c >= 128)
        {
        memcpy(code, utf8_char, c & 7);
        code += c & 7;
        }
      else
#endif
      *code++ = c;

      /* For a repeated Unicode property match, there are two extra bytes that
      define the required property. */

#ifdef SUPPORT_UCP
      if (prop_type >= 0)
        {
        *code++ = prop_type;
        *code++ = prop_value;
        }
#endif
      }

    /* If previous was a character class or a back reference, we put the repeat
    stuff after it, but just skip the item if the repeat was {0,0}. */

    else if (*previous == OP_CLASS ||
             *previous == OP_NCLASS ||
#ifdef SUPPORT_UTF8
             *previous == OP_XCLASS ||
#endif
             *previous == OP_REF)
      {
      if (repeat_max == 0)
        {
        code = previous;
        goto END_REPEAT;
        }

      /* All real repeats make it impossible to handle partial matching (maybe
      one day we will be able to remove this restriction). */

      if (repeat_max != 1) cd->nopartial = TRUE;

      if (repeat_min == 0 && repeat_max == -1)
        *code++ = OP_CRSTAR + repeat_type;
      else if (repeat_min == 1 && repeat_max == -1)
        *code++ = OP_CRPLUS + repeat_type;
      else if (repeat_min == 0 && repeat_max == 1)
        *code++ = OP_CRQUERY + repeat_type;
      else
        {
        *code++ = OP_CRRANGE + repeat_type;
        PUT2INC(code, 0, repeat_min);
        if (repeat_max == -1) repeat_max = 0;  /* 2-byte encoding for max */
        PUT2INC(code, 0, repeat_max);
        }
      }

    /* If previous was a bracket group, we may have to replicate it in certain
    cases. */

    else if (*previous == OP_BRA  || *previous == OP_CBRA ||
             *previous == OP_ONCE || *previous == OP_COND)
      {
      register int i;
      int ketoffset = 0;
      int len = code - previous;
      uschar *bralink = NULL;

      /* Repeating a DEFINE group is pointless */

      if (*previous == OP_COND && previous[LINK_SIZE+1] == OP_DEF)
        {
        *errorcodeptr = ERR55;
        goto FAILED;
        }

      /* This is a paranoid check to stop integer overflow later on */

      if (len > MAX_DUPLENGTH)
        {
        *errorcodeptr = ERR50;
        goto FAILED;
        }

      /* If the maximum repeat count is unlimited, find the end of the bracket
      by scanning through from the start, and compute the offset back to it
      from the current code pointer. There may be an OP_OPT setting following
      the final KET, so we can't find the end just by going back from the code
      pointer. */

      if (repeat_max == -1)
        {
        register uschar *ket = previous;
        do ket += GET(ket, 1); while (*ket != OP_KET);
        ketoffset = code - ket;
        }

      /* The case of a zero minimum is special because of the need to stick
      OP_BRAZERO in front of it, and because the group appears once in the
      data, whereas in other cases it appears the minimum number of times. For
      this reason, it is simplest to treat this case separately, as otherwise
      the code gets far too messy. There are several special subcases when the
      minimum is zero. */

      if (repeat_min == 0)
        {
        /* If the maximum is also zero, we just omit the group from the output
        altogether. */

        if (repeat_max == 0)
          {
          code = previous;
          goto END_REPEAT;
          }

        /* If the maximum is 1 or unlimited, we just have to stick in the
        BRAZERO and do no more at this point. However, we do need to adjust
        any OP_RECURSE calls inside the group that refer to the group itself or
        any internal or forward referenced group, because the offset is from
        the start of the whole regex. Temporarily terminate the pattern while
        doing this. */

        if (repeat_max <= 1)
          {
          *code = OP_END;
          adjust_recurse(previous, 1, utf8, cd, save_hwm);
          memmove(previous+1, previous, len);
          code++;
          *previous++ = OP_BRAZERO + repeat_type;
          }

        /* If the maximum is greater than 1 and limited, we have to replicate
        in a nested fashion, sticking OP_BRAZERO before each set of brackets.
        The first one has to be handled carefully because it's the original
        copy, which has to be moved up. The remainder can be handled by code
        that is common with the non-zero minimum case below. We have to
        adjust the value or repeat_max, since one less copy is required. Once
        again, we may have to adjust any OP_RECURSE calls inside the group. */

        else
          {
          int offset;
          *code = OP_END;
          adjust_recurse(previous, 2 + LINK_SIZE, utf8, cd, save_hwm);
          memmove(previous + 2 + LINK_SIZE, previous, len);
          code += 2 + LINK_SIZE;
          *previous++ = OP_BRAZERO + repeat_type;
          *previous++ = OP_BRA;

          /* We chain together the bracket offset fields that have to be
          filled in later when the ends of the brackets are reached. */

          offset = (bralink == NULL)? 0 : previous - bralink;
          bralink = previous;
          PUTINC(previous, 0, offset);
          }

        repeat_max--;
        }

      /* If the minimum is greater than zero, replicate the group as many
      times as necessary, and adjust the maximum to the number of subsequent
      copies that we need. If we set a first char from the group, and didn't
      set a required char, copy the latter from the former. If there are any
      forward reference subroutine calls in the group, there will be entries on
      the workspace list; replicate these with an appropriate increment. */

      else
        {
        if (repeat_min > 1)
          {
          /* In the pre-compile phase, we don't actually do the replication. We
          just adjust the length as if we had. */

          if (lengthptr != NULL)
            *lengthptr += (repeat_min - 1)*length_prevgroup;

          /* This is compiling for real */

          else
            {
            if (groupsetfirstbyte && reqbyte < 0) reqbyte = firstbyte;
            for (i = 1; i < repeat_min; i++)
              {
              uschar *hc;
              uschar *this_hwm = cd->hwm;
              memcpy(code, previous, len);
              for (hc = save_hwm; hc < this_hwm; hc += LINK_SIZE)
                {
                PUT(cd->hwm, 0, GET(hc, 0) + len);
                cd->hwm += LINK_SIZE;
                }
              save_hwm = this_hwm;
              code += len;
              }
            }
          }

        if (repeat_max > 0) repeat_max -= repeat_min;
        }

      /* This code is common to both the zero and non-zero minimum cases. If
      the maximum is limited, it replicates the group in a nested fashion,
      remembering the bracket starts on a stack. In the case of a zero minimum,
      the first one was set up above. In all cases the repeat_max now specifies
      the number of additional copies needed. Again, we must remember to
      replicate entries on the forward reference list. */

      if (repeat_max >= 0)
        {
        /* In the pre-compile phase, we don't actually do the replication. We
        just adjust the length as if we had. For each repetition we must add 1
        to the length for BRAZERO and for all but the last repetition we must
        add 2 + 2*LINKSIZE to allow for the nesting that occurs. */

        if (lengthptr != NULL && repeat_max > 0)
          *lengthptr += repeat_max * (length_prevgroup + 1 + 2 + 2*LINK_SIZE) -
            2 - 2*LINK_SIZE;  /* Last one doesn't nest */

        /* This is compiling for real */

        else for (i = repeat_max - 1; i >= 0; i--)
          {
          uschar *hc;
          uschar *this_hwm = cd->hwm;

          *code++ = OP_BRAZERO + repeat_type;

          /* All but the final copy start a new nesting, maintaining the
          chain of brackets outstanding. */

          if (i != 0)
            {
            int offset;
            *code++ = OP_BRA;
            offset = (bralink == NULL)? 0 : code - bralink;
            bralink = code;
            PUTINC(code, 0, offset);
            }

          memcpy(code, previous, len);
          for (hc = save_hwm; hc < this_hwm; hc += LINK_SIZE)
            {
            PUT(cd->hwm, 0, GET(hc, 0) + len + ((i != 0)? 2+LINK_SIZE : 1));
            cd->hwm += LINK_SIZE;
            }
          save_hwm = this_hwm;
          code += len;
          }

        /* Now chain through the pending brackets, and fill in their length
        fields (which are holding the chain links pro tem). */

        while (bralink != NULL)
          {
          int oldlinkoffset;
          int offset = code - bralink + 1;
          uschar *bra = code - offset;
          oldlinkoffset = GET(bra, 1);
          bralink = (oldlinkoffset == 0)? NULL : bralink - oldlinkoffset;
          *code++ = OP_KET;
          PUTINC(code, 0, offset);
          PUT(bra, 1, offset);
          }
        }

      /* If the maximum is unlimited, set a repeater in the final copy. We
      can't just offset backwards from the current code point, because we
      don't know if there's been an options resetting after the ket. The
      correct offset was computed above.

      Then, when we are doing the actual compile phase, check to see whether
      this group is a non-atomic one that could match an empty string. If so,
      convert the initial operator to the S form (e.g. OP_BRA -> OP_SBRA) so
      that runtime checking can be done. [This check is also applied to
      atomic groups at runtime, but in a different way.] */

      else
        {
        uschar *ketcode = code - ketoffset;
        uschar *bracode = ketcode - GET(ketcode, 1);
        *ketcode = OP_KETRMAX + repeat_type;
        if (lengthptr == NULL && *bracode != OP_ONCE)
          {
          uschar *scode = bracode;
          do
            {
            if (could_be_empty_branch(scode, ketcode, utf8))
              {
              *bracode += OP_SBRA - OP_BRA;
              break;
              }
            scode += GET(scode, 1);
            }
          while (*scode == OP_ALT);
          }
        }
      }

    /* Else there's some kind of shambles */

    else
      {
      *errorcodeptr = ERR11;
      goto FAILED;
      }

    /* If the character following a repeat is '+', or if certain optimization
    tests above succeeded, possessive_quantifier is TRUE. For some of the
    simpler opcodes, there is an special alternative opcode for this. For
    anything else, we wrap the entire repeated item inside OP_ONCE brackets.
    The '+' notation is just syntactic sugar, taken from Sun's Java package,
    but the special opcodes can optimize it a bit. The repeated item starts at
    tempcode, not at previous, which might be the first part of a string whose
    (former) last char we repeated.

    Possessifying an 'exact' quantifier has no effect, so we can ignore it. But
    an 'upto' may follow. We skip over an 'exact' item, and then test the
    length of what remains before proceeding. */

    if (possessive_quantifier)
      {
      int len;
      if (*tempcode == OP_EXACT || *tempcode == OP_TYPEEXACT ||
          *tempcode == OP_NOTEXACT)
        tempcode += _pcre_OP_lengths[*tempcode];
      len = code - tempcode;
      if (len > 0) switch (*tempcode)
        {
        case OP_STAR:  *tempcode = OP_POSSTAR; break;
        case OP_PLUS:  *tempcode = OP_POSPLUS; break;
        case OP_QUERY: *tempcode = OP_POSQUERY; break;
        case OP_UPTO:  *tempcode = OP_POSUPTO; break;

        case OP_TYPESTAR:  *tempcode = OP_TYPEPOSSTAR; break;
        case OP_TYPEPLUS:  *tempcode = OP_TYPEPOSPLUS; break;
        case OP_TYPEQUERY: *tempcode = OP_TYPEPOSQUERY; break;
        case OP_TYPEUPTO:  *tempcode = OP_TYPEPOSUPTO; break;

        case OP_NOTSTAR:  *tempcode = OP_NOTPOSSTAR; break;
        case OP_NOTPLUS:  *tempcode = OP_NOTPOSPLUS; break;
        case OP_NOTQUERY: *tempcode = OP_NOTPOSQUERY; break;
        case OP_NOTUPTO:  *tempcode = OP_NOTPOSUPTO; break;

        default:
        memmove(tempcode + 1+LINK_SIZE, tempcode, len);
        code += 1 + LINK_SIZE;
        len += 1 + LINK_SIZE;
        tempcode[0] = OP_ONCE;
        *code++ = OP_KET;
        PUTINC(code, 0, len);
        PUT(tempcode, 1, len);
        break;
        }
      }

    /* In all case we no longer have a previous item. We also set the
    "follows varying string" flag for subsequently encountered reqbytes if
    it isn't already set and we have just passed a varying length item. */

    END_REPEAT:
    previous = NULL;
    cd->req_varyopt |= reqvary;
    break;


    /* ===================================================================*/
    /* Start of nested parenthesized sub-expression, or comment or lookahead or
    lookbehind or option setting or condition or all the other extended
    parenthesis forms. First deal with the specials; all are introduced by ?,
    and the appearance of any of them means that this is not a capturing
    group. */

    case '(':
    newoptions = options;
    skipbytes = 0;
    bravalue = OP_CBRA;
    save_hwm = cd->hwm;
    reset_bracount = FALSE;

    if (*(++ptr) == '?')
      {
      int i, set, unset, namelen;
      int *optset;
      const uschar *name;
      uschar *slot;

      switch (*(++ptr))
        {
        case '#':                 /* Comment; skip to ket */
        ptr++;
        while (*ptr != 0 && *ptr != ')') ptr++;
        if (*ptr == 0)
          {
          *errorcodeptr = ERR18;
          goto FAILED;
          }
        continue;


        /* ------------------------------------------------------------ */
        case '|':                 /* Reset capture count for each branch */
        reset_bracount = TRUE;
        /* Fall through */

        /* ------------------------------------------------------------ */
        case ':':                 /* Non-capturing bracket */
        bravalue = OP_BRA;
        ptr++;
        break;


        /* ------------------------------------------------------------ */
        case '(':
        bravalue = OP_COND;       /* Conditional group */

        /* A condition can be an assertion, a number (referring to a numbered
        group), a name (referring to a named group), or 'R', referring to
        recursion. R<digits> and R&name are also permitted for recursion tests.

        There are several syntaxes for testing a named group: (?(name)) is used
        by Python; Perl 5.10 onwards uses (?(<name>) or (?('name')).

        There are two unfortunate ambiguities, caused by history. (a) 'R' can
        be the recursive thing or the name 'R' (and similarly for 'R' followed
        by digits), and (b) a number could be a name that consists of digits.
        In both cases, we look for a name first; if not found, we try the other
        cases. */

        /* For conditions that are assertions, check the syntax, and then exit
        the switch. This will take control down to where bracketed groups,
        including assertions, are processed. */

        if (ptr[1] == '?' && (ptr[2] == '=' || ptr[2] == '!' || ptr[2] == '<'))
          break;

        /* Most other conditions use OP_CREF (a couple change to OP_RREF
        below), and all need to skip 3 bytes at the start of the group. */

        code[1+LINK_SIZE] = OP_CREF;
        skipbytes = 3;
        refsign = -1;

        /* Check for a test for recursion in a named group. */

        if (ptr[1] == 'R' && ptr[2] == '&')
          {
          terminator = -1;
          ptr += 2;
          code[1+LINK_SIZE] = OP_RREF;    /* Change the type of test */
          }

        /* Check for a test for a named group's having been set, using the Perl
        syntax (?(<name>) or (?('name') */

        else if (ptr[1] == '<')
          {
          terminator = '>';
          ptr++;
          }
        else if (ptr[1] == '\'')
          {
          terminator = '\'';
          ptr++;
          }
        else
          {
          terminator = 0;
          if (ptr[1] == '-' || ptr[1] == '+') refsign = *(++ptr);
          }

        /* We now expect to read a name; any thing else is an error */

        if ((cd->ctypes[ptr[1]] & ctype_word) == 0)
          {
          ptr += 1;  /* To get the right offset */
          *errorcodeptr = ERR28;
          goto FAILED;
          }

        /* Read the name, but also get it as a number if it's all digits */

        recno = 0;
        name = ++ptr;
        while ((cd->ctypes[*ptr] & ctype_word) != 0)
          {
          if (recno >= 0)
            recno = ((digitab[*ptr] & ctype_digit) != 0)?
              recno * 10 + *ptr - '0' : -1;
          ptr++;
          }
        namelen = ptr - name;

        if ((terminator > 0 && *ptr++ != terminator) || *ptr++ != ')')
          {
          ptr--;      /* Error offset */
          *errorcodeptr = ERR26;
          goto FAILED;
          }

        /* Do no further checking in the pre-compile phase. */

        if (lengthptr != NULL) break;

        /* In the real compile we do the work of looking for the actual
        reference. If the string started with "+" or "-" we require the rest to
        be digits, in which case recno will be set. */

        if (refsign > 0)
          {
          if (recno <= 0)
            {
            *errorcodeptr = ERR58;
            goto FAILED;
            }
          if (refsign == '-')
            {
            recno = cd->bracount - recno + 1;
            if (recno <= 0)
              {
              *errorcodeptr = ERR15;
              goto FAILED;
              }
            }
          else recno += cd->bracount;
          PUT2(code, 2+LINK_SIZE, recno);
          break;
          }

        /* Otherwise (did not start with "+" or "-"), start by looking for the
        name. */

        slot = cd->name_table;
        for (i = 0; i < cd->names_found; i++)
          {
          if (strncmp((char *)name, (char *)slot+2, namelen) == 0) break;
          slot += cd->name_entry_size;
          }

        /* Found a previous named subpattern */

        if (i < cd->names_found)
          {
          recno = GET2(slot, 0);
          PUT2(code, 2+LINK_SIZE, recno);
          }

        /* Search the pattern for a forward reference */

        else if ((i = find_parens(ptr, cd->bracount, name, namelen,
                        (options & PCRE_EXTENDED) != 0)) > 0)
          {
          PUT2(code, 2+LINK_SIZE, i);
          }

        /* If terminator == 0 it means that the name followed directly after
        the opening parenthesis [e.g. (?(abc)...] and in this case there are
        some further alternatives to try. For the cases where terminator != 0
        [things like (?(<name>... or (?('name')... or (?(R&name)... ] we have
        now checked all the possibilities, so give an error. */

        else if (terminator != 0)
          {
          *errorcodeptr = ERR15;
          goto FAILED;
          }

        /* Check for (?(R) for recursion. Allow digits after R to specify a
        specific group number. */

        else if (*name == 'R')
          {
          recno = 0;
          for (i = 1; i < namelen; i++)
            {
            if ((digitab[name[i]] & ctype_digit) == 0)
              {
              *errorcodeptr = ERR15;
              goto FAILED;
              }
            recno = recno * 10 + name[i] - '0';
            }
          if (recno == 0) recno = RREF_ANY;
          code[1+LINK_SIZE] = OP_RREF;      /* Change test type */
          PUT2(code, 2+LINK_SIZE, recno);
          }

        /* Similarly, check for the (?(DEFINE) "condition", which is always
        false. */

        else if (namelen == 6 && strncmp((char *)name, "DEFINE", 6) == 0)
          {
          code[1+LINK_SIZE] = OP_DEF;
          skipbytes = 1;
          }

        /* Check for the "name" actually being a subpattern number. */

        else if (recno > 0)
          {
          PUT2(code, 2+LINK_SIZE, recno);
          }

        /* Either an unidentified subpattern, or a reference to (?(0) */

        else
          {
          *errorcodeptr = (recno == 0)? ERR35: ERR15;
          goto FAILED;
          }
        break;


        /* ------------------------------------------------------------ */
        case '=':                 /* Positive lookahead */
        bravalue = OP_ASSERT;
        ptr++;
        break;


        /* ------------------------------------------------------------ */
        case '!':                 /* Negative lookahead */
        bravalue = OP_ASSERT_NOT;
        ptr++;
        break;


        /* ------------------------------------------------------------ */
        case '<':                 /* Lookbehind or named define */
        switch (ptr[1])
          {
          case '=':               /* Positive lookbehind */
          bravalue = OP_ASSERTBACK;
          ptr += 2;
          break;

          case '!':               /* Negative lookbehind */
          bravalue = OP_ASSERTBACK_NOT;
          ptr += 2;
          break;

          default:                /* Could be name define, else bad */
          if ((cd->ctypes[ptr[1]] & ctype_word) != 0) goto DEFINE_NAME;
          ptr++;                  /* Correct offset for error */
          *errorcodeptr = ERR24;
          goto FAILED;
          }
        break;


        /* ------------------------------------------------------------ */
        case '>':                 /* One-time brackets */
        bravalue = OP_ONCE;
        ptr++;
        break;


        /* ------------------------------------------------------------ */
        case 'C':                 /* Callout - may be followed by digits; */
        previous_callout = code;  /* Save for later completion */
        after_manual_callout = 1; /* Skip one item before completing */
        *code++ = OP_CALLOUT;
          {
          int n = 0;
          while ((digitab[*(++ptr)] & ctype_digit) != 0)
            n = n * 10 + *ptr - '0';