[Pcre-svn] [1142] code/trunk: More partial match tweaks.

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Subject: [Pcre-svn] [1142] code/trunk: More partial match tweaks.
Revision: 1142
          http://www.exim.org/viewvc/pcre2?view=rev&revision=1142
Author:   ph10
Date:     2019-07-22 17:30:44 +0100 (Mon, 22 Jul 2019)
Log Message:
-----------
More partial match tweaks.


Modified Paths:
--------------
    code/trunk/ChangeLog
    code/trunk/doc/html/pcre2api.html
    code/trunk/doc/html/pcre2partial.html
    code/trunk/doc/pcre2.txt
    code/trunk/doc/pcre2api.3
    code/trunk/doc/pcre2partial.3
    code/trunk/src/pcre2_dfa_match.c
    code/trunk/src/pcre2_intmodedep.h
    code/trunk/src/pcre2_match.c
    code/trunk/testdata/testinput2
    code/trunk/testdata/testinput6
    code/trunk/testdata/testoutput2
    code/trunk/testdata/testoutput6


Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/ChangeLog    2019-07-22 16:30:44 UTC (rev 1142)
@@ -104,7 +104,11 @@
     is another situation where adding characters to the current subject can
     lead to a full match. Example: /c*+(?<=[bc])/ with subject "ab".


-    (b) An empty string partial hard match can be returned for \z and \Z as it
+    (b) Similarly, if a pattern could match an empty string, an empty partial 
+    match may be given. Example: /(?![ab]).*/ with subject "ab". This case 
+    applies only to PCRE2_PARTIAL_HARD.
+    
+    (c) An empty string partial hard match can be returned for \z and \Z as it
     is documented that they shouldn't match. 




Modified: code/trunk/doc/html/pcre2api.html
===================================================================
--- code/trunk/doc/html/pcre2api.html    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/html/pcre2api.html    2019-07-22 16:30:44 UTC (rev 1142)
@@ -2057,7 +2057,7 @@
   PCRE2_ERROR_BADOPTION      the value of <i>what</i> was invalid
   PCRE2_ERROR_UNSET          the requested field is not set
 </pre>
-The "magic number" is placed at the start of each compiled pattern as an simple
+The "magic number" is placed at the start of each compiled pattern as a simple
 check against passing an arbitrary memory pointer. Here is a typical call of
 <b>pcre2_pattern_info()</b>, to obtain the length of the compiled pattern:
 <pre>
@@ -2114,7 +2114,7 @@
   PCRE2_INFO_BACKREFMAX
 </pre>
 Return the number of the highest backreference in the pattern. The third
-argument should point to an <b>uint32_t</b> variable. Named capture groups
+argument should point to a <b>uint32_t</b> variable. Named capture groups
 acquire numbers as well as names, and these count towards the highest
 backreference. Backreferences such as \4 or \g{12} match the captured
 characters of the given group, but in addition, the check that a capture
@@ -2132,7 +2132,7 @@
 </pre>
 Return the highest capture group number in the pattern. In patterns where (?|
 is not used, this is also the total number of capture groups. The third
-argument should point to an <b>uint32_t</b> variable.
+argument should point to a <b>uint32_t</b> variable.
 <pre>
   PCRE2_INFO_DEPTHLIMIT
 </pre>
@@ -2157,7 +2157,7 @@
   PCRE2_INFO_FIRSTCODETYPE
 </pre>
 Return information about the first code unit of any matched string, for a
-non-anchored pattern. The third argument should point to an <b>uint32_t</b>
+non-anchored pattern. The third argument should point to a <b>uint32_t</b>
 variable. If there is a fixed first value, for example, the letter "c" from a
 pattern such as (cat|cow|coyote), 1 is returned, and the value can be retrieved
 using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed first value, but it is
@@ -2169,7 +2169,7 @@
 </pre>
 Return the value of the first code unit of any matched string for a pattern
 where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0. The third
-argument should point to an <b>uint32_t</b> variable. In the 8-bit library, the
+argument should point to a <b>uint32_t</b> variable. In the 8-bit library, the
 value is always less than 256. In the 16-bit library the value can be up to
 0xffff. In the 32-bit library in UTF-32 mode the value can be up to 0x10ffff,
 and up to 0xffffffff when not using UTF-32 mode.
@@ -2185,12 +2185,12 @@
   PCRE2_INFO_HASBACKSLASHC
 </pre>
 Return 1 if the pattern contains any instances of \C, otherwise 0. The third
-argument should point to an <b>uint32_t</b> variable.
+argument should point to a <b>uint32_t</b> variable.
 <pre>
   PCRE2_INFO_HASCRORLF
 </pre>
 Return 1 if the pattern contains any explicit matches for CR or LF characters,
-otherwise 0. The third argument should point to an <b>uint32_t</b> variable. An
+otherwise 0. The third argument should point to a <b>uint32_t</b> variable. An
 explicit match is either a literal CR or LF character, or \r or \n or one of
 the equivalent hexadecimal or octal escape sequences.
 <pre>
@@ -2206,7 +2206,7 @@
   PCRE2_INFO_JCHANGED
 </pre>
 Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
-0. The third argument should point to an <b>uint32_t</b> variable. (?J) and
+0. The third argument should point to a <b>uint32_t</b> variable. (?J) and
 (?-J) set and unset the local PCRE2_DUPNAMES option, respectively.
 <pre>
   PCRE2_INFO_JITSIZE
@@ -2218,7 +2218,7 @@
   PCRE2_INFO_LASTCODETYPE
 </pre>
 Returns 1 if there is a rightmost literal code unit that must exist in any
-matched string, other than at its start. The third argument should  point to an
+matched string, other than at its start. The third argument should  point to a
 <b>uint32_t</b> variable. If there is no such value, 0 is returned. When 1 is
 returned, the code unit value itself can be retrieved using
 PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal value is
@@ -2231,12 +2231,12 @@
 Return the value of the rightmost literal code unit that must exist in any
 matched string, other than at its start, for a pattern where
 PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argument
-should point to an <b>uint32_t</b> variable.
+should point to a <b>uint32_t</b> variable.
 <pre>
   PCRE2_INFO_MATCHEMPTY
 </pre>
 Return 1 if the pattern might match an empty string, otherwise 0. The third
-argument should point to an <b>uint32_t</b> variable. When a pattern contains
+argument should point to a <b>uint32_t</b> variable. When a pattern contains
 recursive subroutine calls it is not always possible to determine whether or
 not it can match an empty string. PCRE2 takes a cautious approach and returns 1
 in such cases.
@@ -2279,7 +2279,7 @@
 returned. Otherwise the returned value is 0. This value is not computed when
 PCRE2_NO_START_OPTIMIZE is set. The value is a number of characters, which in
 UTF mode may be different from the number of code units. The third argument
-should point to an <b>uint32_t</b> variable. The value is a lower bound to the
+should point to a <b>uint32_t</b> variable. The value is a lower bound to the
 length of any matching string. There may not be any strings of that length that
 do actually match, but every string that does match is at least that long.
 <pre>
@@ -2726,7 +2726,8 @@
 These options turn on the partial matching feature. A partial match occurs if
 the end of the subject string is reached successfully, but there are not enough
 subject characters to complete the match. In addition, either at least one 
-character must have been inspected or the pattern must contain a lookbehind.
+character must have been inspected or the pattern must contain a lookbehind, or 
+the pattern must be one that could match an empty string.
 </P>
 <P>
 If this situation arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD)
@@ -3850,7 +3851,7 @@
 </P>
 <br><a name="SEC42" href="#TOC1">REVISION</a><br>
 <P>
-Last updated: 20 July 2019
+Last updated: 22 July 2019
 <br>
 Copyright &copy; 1997-2019 University of Cambridge.
 <br>


Modified: code/trunk/doc/html/pcre2partial.html
===================================================================
--- code/trunk/doc/html/pcre2partial.html    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/html/pcre2partial.html    2019-07-22 16:30:44 UTC (rev 1142)
@@ -80,16 +80,18 @@
 A partial match occurs during a call to <b>pcre2_match()</b> when the end of the
 subject string is reached successfully, but matching cannot continue because
 more characters are needed, and in addition, either at least one character in
-the subject has been inspected or the pattern contains a lookbehind. An
+the subject has been inspected or the pattern contains a lookbehind, or (when 
+PCRE2_PARTIAL_HARD is set) the pattern could match an empty string. An
 inspected character need not form part of the final matched string; lookbehind
 assertions and the \K escape sequence provide ways of inspecting characters
 before the start of a matched string.
 </P>
 <P>
-The two additional requirements define the cases where adding more characters
-to the existing subject may complete the match. Without these conditions there
-would be a partial match of an empty string at the end of the subject for all 
-unanchored patterns (and also for anchored patterns if the subject itself is 
+The three additional requirements define the cases where adding more characters
+to the existing subject may complete the same match that would occur if they
+had all been present in the first place. Without these conditions there would
+be a partial match of an empty string at the end of the subject for all
+unanchored patterns (and also for anchored patterns if the subject itself is
 empty).
 </P>
 <P>
@@ -449,7 +451,7 @@
 </P>
 <br><a name="SEC10" href="#TOC1">REVISION</a><br>
 <P>
-Last updated: 21 July 2019
+Last updated: 22 July 2019
 <br>
 Copyright &copy; 1997-2019 University of Cambridge.
 <br>


Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/pcre2.txt    2019-07-22 16:30:44 UTC (rev 1142)
@@ -2013,8 +2013,8 @@
          PCRE2_ERROR_BADOPTION      the value of what was invalid
          PCRE2_ERROR_UNSET          the requested field is not set


-       The  "magic  number" is placed at the start of each compiled pattern as
-       an simple check against passing an arbitrary memory pointer. Here is  a
+       The "magic number" is placed at the start of each compiled pattern as a
+       simple check against passing an arbitrary memory  pointer.  Here  is  a
        typical  call of pcre2_pattern_info(), to obtain the length of the com-
        piled pattern:


@@ -2073,7 +2073,7 @@
          PCRE2_INFO_BACKREFMAX


        Return  the  number  of  the  highest backreference in the pattern. The
-       third argument should point to  an  uint32_t  variable.  Named  capture
+       third argument should point  to  a  uint32_t  variable.  Named  capture
        groups  acquire  numbers  as well as names, and these count towards the
        highest backreference. Backreferences such as \4 or  \g{12}  match  the
        captured characters of the given group, but in addition, the check that
@@ -2091,7 +2091,7 @@


        Return the highest capture group number in  the  pattern.  In  patterns
        where (?| is not used, this is also the total number of capture groups.
-       The third argument should point to an uint32_t variable.
+       The third argument should point to a uint32_t variable.


          PCRE2_INFO_DEPTHLIMIT


@@ -2117,7 +2117,7 @@
          PCRE2_INFO_FIRSTCODETYPE


        Return information about the first code unit of any matched string, for
-       a non-anchored pattern. The third argument should point to an  uint32_t
+       a non-anchored pattern. The third argument should point to  a  uint32_t
        variable.  If there is a fixed first value, for example, the letter "c"
        from a pattern such as (cat|cow|coyote), 1 is returned, and  the  value
        can  be  retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
@@ -2129,7 +2129,7 @@


        Return the value of the first code unit of any  matched  string  for  a
        pattern  where  PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
-       The third argument should point to an uint32_t variable. In  the  8-bit
+       The third argument should point to a uint32_t variable.  In  the  8-bit
        library,  the  value is always less than 256. In the 16-bit library the
        value can be up to 0xffff. In the 32-bit library  in  UTF-32  mode  the
        value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
@@ -2147,12 +2147,12 @@
          PCRE2_INFO_HASBACKSLASHC


        Return  1 if the pattern contains any instances of \C, otherwise 0. The
-       third argument should point to an uint32_t variable.
+       third argument should point to a uint32_t variable.


          PCRE2_INFO_HASCRORLF


        Return 1 if the pattern contains any explicit  matches  for  CR  or  LF
-       characters, otherwise 0. The third argument should point to an uint32_t
+       characters,  otherwise 0. The third argument should point to a uint32_t
        variable. An explicit match is either a literal CR or LF character,  or
        \r  or  \n  or  one  of  the equivalent hexadecimal or octal escape se-
        quences.
@@ -2169,7 +2169,7 @@
          PCRE2_INFO_JCHANGED


        Return  1  if  the (?J) or (?-J) option setting is used in the pattern,
-       otherwise 0. The third argument should point to an  uint32_t  variable.
+       otherwise 0. The third argument should point to  a  uint32_t  variable.
        (?J)  and  (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
        tively.


@@ -2183,13 +2183,13 @@

        Returns 1 if there is a rightmost literal code unit that must exist  in
        any  matched string, other than at its start. The third argument should
-       point to an uint32_t variable. If there is no  such  value,  0  is  re-
-       turned. When 1 is returned, the code unit value itself can be retrieved
-       using PCRE2_INFO_LASTCODEUNIT. For anchored patterns,  a  last  literal
-       value  is recorded only if it follows something of variable length. For
-       example, for the pattern /^a\d+z\d+/ the returned value is 1 (with  "z"
-       returned  from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned
-       value is 0.
+       point to a uint32_t variable. If there is no such value, 0 is returned.
+       When  1  is returned, the code unit value itself can be retrieved using
+       PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal value is
+       recorded  only if it follows something of variable length. For example,
+       for the pattern /^a\d+z\d+/ the returned value is 1 (with "z"  returned
+       from  PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned value is
+       0.


          PCRE2_INFO_LASTCODEUNIT


@@ -2196,15 +2196,15 @@
        Return the value of the rightmost literal code unit that must exist  in
        any  matched  string,  other  than  at  its  start, for a pattern where
        PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
-       ment should point to an uint32_t variable.
+       ment should point to a uint32_t variable.


          PCRE2_INFO_MATCHEMPTY


        Return  1  if the pattern might match an empty string, otherwise 0. The
-       third argument should point to an uint32_t  variable.  When  a  pattern
-       contains recursive subroutine calls it is not always possible to deter-
-       mine whether or not it can match an empty string. PCRE2  takes  a  cau-
-       tious approach and returns 1 in such cases.
+       third argument should point to a uint32_t variable. When a pattern con-
+       tains recursive subroutine calls it is not always possible to determine
+       whether or not it can match an empty string. PCRE2 takes a cautious ap-
+       proach and returns 1 in such cases.


          PCRE2_INFO_MATCHLIMIT


@@ -2244,7 +2244,7 @@
        value is returned. Otherwise the returned value is 0. This value is not
        computed  when PCRE2_NO_START_OPTIMIZE is set. The value is a number of
        characters, which in UTF mode may be different from the number of  code
-       units.  The  third  argument  should point to an uint32_t variable. The
+       units.  The  third  argument  should  point to a uint32_t variable. The
        value is a lower bound to the length of any matching string. There  may
        not  be  any  strings  of that length that do actually match, but every
        string that does match is at least that long.
@@ -2663,18 +2663,19 @@
        curs if the end of the subject  string  is  reached  successfully,  but
        there are not enough subject characters to complete the match. In addi-
        tion, either at least one character must have  been  inspected  or  the
-       pattern must contain a lookbehind.
+       pattern  must  contain  a  lookbehind,  or the pattern must be one that
+       could match an empty string.


-       If  this  situation  arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PAR-
+       If this situation arises when PCRE2_PARTIAL_SOFT  (but  not  PCRE2_PAR-
        TIAL_HARD) is set, matching continues by testing any remaining alterna-
-       tives.  Only  if  no complete match can be found is PCRE2_ERROR_PARTIAL
-       returned instead of PCRE2_ERROR_NOMATCH.  In  other  words,  PCRE2_PAR-
-       TIAL_SOFT  specifies  that  the  caller is prepared to handle a partial
+       tives. Only if no complete match can be  found  is  PCRE2_ERROR_PARTIAL
+       returned  instead  of  PCRE2_ERROR_NOMATCH.  In other words, PCRE2_PAR-
+       TIAL_SOFT specifies that the caller is prepared  to  handle  a  partial
        match, but only if no complete match can be found.


-       If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In  this
-       case,  if  a  partial match is found, pcre2_match() immediately returns
-       PCRE2_ERROR_PARTIAL, without considering  any  other  alternatives.  In
+       If  PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
+       case, if a partial match is found,  pcre2_match()  immediately  returns
+       PCRE2_ERROR_PARTIAL,  without  considering  any  other alternatives. In
        other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
        ered to be more important that an alternative complete match.


@@ -2684,38 +2685,38 @@

NEWLINE HANDLING WHEN MATCHING

-       When  PCRE2 is built, a default newline convention is set; this is usu-
-       ally the standard convention for the operating system. The default  can
-       be  overridden  in a compile context by calling pcre2_set_newline(). It
-       can also be overridden by starting a pattern string with, for  example,
-       (*CRLF),  as  described  in  the  section on newline conventions in the
-       pcre2pattern page. During matching, the newline choice affects the  be-
-       haviour  of the dot, circumflex, and dollar metacharacters. It may also
-       alter the way the match starting position is  advanced  after  a  match
+       When PCRE2 is built, a default newline convention is set; this is  usu-
+       ally  the standard convention for the operating system. The default can
+       be overridden in a compile context by calling  pcre2_set_newline().  It
+       can  also be overridden by starting a pattern string with, for example,
+       (*CRLF), as described in the section  on  newline  conventions  in  the
+       pcre2pattern  page. During matching, the newline choice affects the be-
+       haviour of the dot, circumflex, and dollar metacharacters. It may  also
+       alter  the  way  the  match starting position is advanced after a match
        failure for an unanchored pattern.


        When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
-       set as the newline convention, and a match attempt  for  an  unanchored
+       set  as  the  newline convention, and a match attempt for an unanchored
        pattern fails when the current starting position is at a CRLF sequence,
-       and the pattern contains no explicit matches for CR or  LF  characters,
-       the  match  position  is  advanced by two characters instead of one, in
+       and  the  pattern contains no explicit matches for CR or LF characters,
+       the match position is advanced by two characters  instead  of  one,  in
        other words, to after the CRLF.


        The above rule is a compromise that makes the most common cases work as
-       expected.  For example, if the pattern is .+A (and the PCRE2_DOTALL op-
-       tion is not set), it does not match the string "\r\nA"  because,  after
-       failing  at the start, it skips both the CR and the LF before retrying.
-       However, the pattern [\r\n]A does match that string,  because  it  con-
+       expected. For example, if the pattern is .+A (and the PCRE2_DOTALL  op-
+       tion  is  not set), it does not match the string "\r\nA" because, after
+       failing at the start, it skips both the CR and the LF before  retrying.
+       However,  the  pattern  [\r\n]A does match that string, because it con-
        tains an explicit CR or LF reference, and so advances only by one char-
        acter after the first failure.


        An explicit match for CR of LF is either a literal appearance of one of
-       those  characters  in the pattern, or one of the \r or \n or equivalent
+       those characters in the pattern, or one of the \r or \n  or  equivalent
        octal or hexadecimal escape sequences. Implicit matches such as [^X] do
-       not  count, nor does \s, even though it includes CR and LF in the char-
+       not count, nor does \s, even though it includes CR and LF in the  char-
        acters that it matches.


-       Notwithstanding the above, anomalous effects may still occur when  CRLF
+       Notwithstanding  the above, anomalous effects may still occur when CRLF
        is a valid newline sequence and explicit \r or \n escapes appear in the
        pattern.


@@ -2726,82 +2727,82 @@

        PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);


-       In general, a pattern matches a certain portion of the subject, and  in
-       addition,  further  substrings  from  the  subject may be picked out by
-       parenthesized parts of the pattern.  Following  the  usage  in  Jeffrey
-       Friedl's  book,  this  is  called  "capturing" in what follows, and the
-       phrase "capture group" (Perl terminology) is used for a fragment  of  a
-       pattern  that picks out a substring. PCRE2 supports several other kinds
+       In  general, a pattern matches a certain portion of the subject, and in
+       addition, further substrings from the subject  may  be  picked  out  by
+       parenthesized  parts  of  the  pattern.  Following the usage in Jeffrey
+       Friedl's book, this is called "capturing"  in  what  follows,  and  the
+       phrase  "capture  group" (Perl terminology) is used for a fragment of a
+       pattern that picks out a substring. PCRE2 supports several other  kinds
        of parenthesized group that do not cause substrings to be captured. The
-       pcre2_pattern_info()  function can be used to find out how many capture
+       pcre2_pattern_info() function can be used to find out how many  capture
        groups there are in a compiled pattern.


-       You can use auxiliary functions for accessing  captured  substrings  by
+       You  can  use  auxiliary functions for accessing captured substrings by
        number or by name, as described in sections below.


        Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
-       ues, called  the  ovector,  which  contains  the  offsets  of  captured
-       strings.   It   is   part  of  the  match  data  block.   The  function
-       pcre2_get_ovector_pointer() returns the address  of  the  ovector,  and
+       ues,  called  the  ovector,  which  contains  the  offsets  of captured
+       strings.  It  is  part  of  the  match  data   block.    The   function
+       pcre2_get_ovector_pointer()  returns  the  address  of the ovector, and
        pcre2_get_ovector_count() returns the number of pairs of values it con-
        tains.


        Within the ovector, the first in each pair of values is set to the off-
        set of the first code unit of a substring, and the second is set to the
-       offset of the first code unit after the end of a substring. These  val-
-       ues  are always code unit offsets, not character offsets. That is, they
+       offset  of the first code unit after the end of a substring. These val-
+       ues are always code unit offsets, not character offsets. That is,  they
        are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit li-
        brary, and 32-bit offsets in the 32-bit library.


-       After  a  partial  match  (error  return PCRE2_ERROR_PARTIAL), only the
-       first pair of offsets (that is, ovector[0]  and  ovector[1])  are  set.
-       They  identify  the part of the subject that was partially matched. See
+       After a partial match  (error  return  PCRE2_ERROR_PARTIAL),  only  the
+       first  pair  of  offsets  (that is, ovector[0] and ovector[1]) are set.
+       They identify the part of the subject that was partially  matched.  See
        the pcre2partial documentation for details of partial matching.


-       After a fully successful match, the first pair  of  offsets  identifies
-       the  portion  of the subject string that was matched by the entire pat-
-       tern. The next pair is used for the first captured  substring,  and  so
-       on.  The  value  returned by pcre2_match() is one more than the highest
-       numbered pair that has been set. For example, if  two  substrings  have
-       been  captured,  the returned value is 3. If there are no captured sub-
+       After  a  fully  successful match, the first pair of offsets identifies
+       the portion of the subject string that was matched by the  entire  pat-
+       tern.  The  next  pair is used for the first captured substring, and so
+       on. The value returned by pcre2_match() is one more  than  the  highest
+       numbered  pair  that  has been set. For example, if two substrings have
+       been captured, the returned value is 3. If there are no  captured  sub-
        strings, the return value from a successful match is 1, indicating that
        just the first pair of offsets has been set.


-       If  a  pattern uses the \K escape sequence within a positive assertion,
+       If a pattern uses the \K escape sequence within a  positive  assertion,
        the reported start of a successful match can be greater than the end of
-       the  match.   For  example,  if the pattern (?=ab\K) is matched against
+       the match.  For example, if the pattern  (?=ab\K)  is  matched  against
        "ab", the start and end offset values for the match are 2 and 0.


-       If a capture group is matched repeatedly within a single  match  opera-
+       If  a  capture group is matched repeatedly within a single match opera-
        tion, it is the last portion of the subject that it matched that is re-
        turned.


        If the ovector is too small to hold all the captured substring offsets,
-       as  much  as possible is filled in, and the function returns a value of
-       zero. If captured substrings are not of interest, pcre2_match() may  be
+       as much as possible is filled in, and the function returns a  value  of
+       zero.  If captured substrings are not of interest, pcre2_match() may be
        called with a match data block whose ovector is of minimum length (that
        is, one pair).


-       It is possible for capture group number n+1 to match some part  of  the
-       subject  when  group  n  has  not been used at all. For example, if the
+       It  is  possible for capture group number n+1 to match some part of the
+       subject when group n has not been used at  all.  For  example,  if  the
        string "abc" is matched against the pattern (a|(z))(bc) the return from
-       the  function  is 4, and groups 1 and 3 are matched, but 2 is not. When
-       this happens, both values in the offset pairs corresponding  to  unused
+       the function is 4, and groups 1 and 3 are matched, but 2 is  not.  When
+       this  happens,  both values in the offset pairs corresponding to unused
        groups are set to PCRE2_UNSET.


-       Offset  values  that  correspond to unused groups at the end of the ex-
-       pression are also set to PCRE2_UNSET. For example, if the string  "abc"
-       is  matched  against  the pattern (abc)(x(yz)?)? groups 2 and 3 are not
-       matched. The return from the function is 2, because  the  highest  used
-       capture  group  number  is  1. The offsets for for the second and third
-       capture groupss (assuming the vector is large enough,  of  course)  are
+       Offset values that correspond to unused groups at the end  of  the  ex-
+       pression  are also set to PCRE2_UNSET. For example, if the string "abc"
+       is matched against the pattern (abc)(x(yz)?)? groups 2 and  3  are  not
+       matched.  The  return  from the function is 2, because the highest used
+       capture group number is 1. The offsets for for  the  second  and  third
+       capture  groupss  (assuming  the vector is large enough, of course) are
        set to PCRE2_UNSET.


        Elements in the ovector that do not correspond to capturing parentheses
        in the pattern are never changed. That is, if a pattern contains n cap-
        turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
-       pcre2_match(). The other elements retain whatever  values  they  previ-
-       ously  had.  After  a failed match attempt, the contents of the ovector
+       pcre2_match().  The  other  elements retain whatever values they previ-
+       ously had. After a failed match attempt, the contents  of  the  ovector
        are unchanged.



@@ -2811,25 +2812,25 @@

        PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);


-       As well as the offsets in the ovector, other information about a  match
-       is  retained  in the match data block and can be retrieved by the above
-       functions in appropriate circumstances. If they  are  called  at  other
+       As  well as the offsets in the ovector, other information about a match
+       is retained in the match data block and can be retrieved by  the  above
+       functions  in  appropriate  circumstances.  If they are called at other
        times, the result is undefined.


-       After  a  successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
-       failure to match (PCRE2_ERROR_NOMATCH), a mark name may  be  available.
-       The  function pcre2_get_mark() can be called to access this name, which
-       can be specified in the pattern by  any  of  the  backtracking  control
+       After a successful match, a partial match (PCRE2_ERROR_PARTIAL),  or  a
+       failure  to  match (PCRE2_ERROR_NOMATCH), a mark name may be available.
+       The function pcre2_get_mark() can be called to access this name,  which
+       can  be  specified  in  the  pattern by any of the backtracking control
        verbs, not just (*MARK). The same function applies to all the verbs. It
        returns a pointer to the zero-terminated name, which is within the com-
        piled pattern. If no name is available, NULL is returned. The length of
-       the name (excluding the terminating zero) is stored in  the  code  unit
-       that  precedes  the name. You should use this length instead of relying
+       the  name  (excluding  the terminating zero) is stored in the code unit
+       that precedes the name. You should use this length instead  of  relying
        on the terminating zero if the name might contain a binary zero.


-       After a successful match, the name that is returned is  the  last  mark
+       After  a  successful  match, the name that is returned is the last mark
        name encountered on the matching path through the pattern. Instances of
-       backtracking verbs without names do not count. Thus,  for  example,  if
+       backtracking  verbs  without  names do not count. Thus, for example, if
        the matching path contains (*MARK:A)(*PRUNE), the name "A" is returned.
        After a "no match" or a partial match, the last encountered name is re-
        turned. For example, consider this pattern:
@@ -2836,30 +2837,30 @@


          ^(*MARK:A)((*MARK:B)a|b)c


-       When  it  matches "bc", the returned name is A. The B mark is "seen" in
-       the first branch of the group, but it is not on the matching  path.  On
-       the  other  hand,  when  this pattern fails to match "bx", the returned
+       When it matches "bc", the returned name is A. The B mark is  "seen"  in
+       the  first  branch of the group, but it is not on the matching path. On
+       the other hand, when this pattern fails to  match  "bx",  the  returned
        name is B.


-       Warning: By default, certain start-of-match optimizations are  used  to
-       give  a  fast "no match" result in some situations. For example, if the
-       anchoring is removed from the pattern above, there is an initial  check
-       for  the presence of "c" in the subject before running the matching en-
+       Warning:  By  default, certain start-of-match optimizations are used to
+       give a fast "no match" result in some situations. For example,  if  the
+       anchoring  is removed from the pattern above, there is an initial check
+       for the presence of "c" in the subject before running the matching  en-
        gine. This check fails for "bx", causing a match failure without seeing
-       any  marks. You can disable the start-of-match optimizations by setting
-       the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or  by  starting
+       any marks. You can disable the start-of-match optimizations by  setting
+       the  PCRE2_NO_START_OPTIMIZE  option for pcre2_compile() or by starting
        the pattern with (*NO_START_OPT).


-       After  a  successful  match, a partial match, or one of the invalid UTF
-       errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar()  can
+       After a successful match, a partial match, or one of  the  invalid  UTF
+       errors  (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
        be called. After a successful or partial match it returns the code unit
-       offset of the character at which the match started. For  a  non-partial
-       match,  this can be different to the value of ovector[0] if the pattern
-       contains the \K escape sequence. After a partial match,  however,  this
-       value  is  always the same as ovector[0] because \K does not affect the
+       offset  of  the character at which the match started. For a non-partial
+       match, this can be different to the value of ovector[0] if the  pattern
+       contains  the  \K escape sequence. After a partial match, however, this
+       value is always the same as ovector[0] because \K does not  affect  the
        result of a partial match.


-       After a UTF check failure, pcre2_get_startchar() can be used to  obtain
+       After  a UTF check failure, pcre2_get_startchar() can be used to obtain
        the code unit offset of the invalid UTF character. Details are given in
        the pcre2unicode page.


@@ -2866,14 +2867,14 @@

ERROR RETURNS FROM pcre2_match()

-       If pcre2_match() fails, it returns a negative number. This can be  con-
-       verted  to a text string by calling the pcre2_get_error_message() func-
-       tion (see "Obtaining a textual error message" below).   Negative  error
-       codes  are  also  returned  by other functions, and are documented with
-       them. The codes are given names in the header file. If UTF checking  is
+       If  pcre2_match() fails, it returns a negative number. This can be con-
+       verted to a text string by calling the pcre2_get_error_message()  func-
+       tion  (see  "Obtaining a textual error message" below).  Negative error
+       codes are also returned by other functions,  and  are  documented  with
+       them.  The codes are given names in the header file. If UTF checking is
        in force and an invalid UTF subject string is detected, one of a number
-       of UTF-specific negative error codes is returned. Details are given  in
-       the  pcre2unicode  page. The following are the other errors that may be
+       of  UTF-specific negative error codes is returned. Details are given in
+       the pcre2unicode page. The following are the other errors that  may  be
        returned by pcre2_match():


          PCRE2_ERROR_NOMATCH
@@ -2882,20 +2883,20 @@


          PCRE2_ERROR_PARTIAL


-       The subject string did not match, but it did match partially.  See  the
+       The  subject  string did not match, but it did match partially. See the
        pcre2partial documentation for details of partial matching.


          PCRE2_ERROR_BADMAGIC


        PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
-       to catch the case when it is passed a junk pointer. This is  the  error
+       to  catch  the case when it is passed a junk pointer. This is the error
        that is returned when the magic number is not present.


          PCRE2_ERROR_BADMODE


-       This  error is given when a compiled pattern is passed to a function in
-       a library of a different code unit width, for example, a  pattern  com-
-       piled  by  the  8-bit  library  is passed to a 16-bit or 32-bit library
+       This error is given when a compiled pattern is passed to a function  in
+       a  library  of a different code unit width, for example, a pattern com-
+       piled by the 8-bit library is passed to  a  16-bit  or  32-bit  library
        function.


          PCRE2_ERROR_BADOFFSET
@@ -2909,15 +2910,15 @@
          PCRE2_ERROR_BADUTFOFFSET


        The UTF code unit sequence that was passed as a subject was checked and
-       found  to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
-       value of startoffset did not point to the beginning of a UTF  character
+       found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but  the
+       value  of startoffset did not point to the beginning of a UTF character
        or the end of the subject.


          PCRE2_ERROR_CALLOUT


-       This  error  is never generated by pcre2_match() itself. It is provided
-       for use by callout  functions  that  want  to  cause  pcre2_match()  or
-       pcre2_callout_enumerate()  to  return a distinctive error code. See the
+       This error is never generated by pcre2_match() itself. It  is  provided
+       for  use  by  callout  functions  that  want  to cause pcre2_match() or
+       pcre2_callout_enumerate() to return a distinctive error code.  See  the
        pcre2callout documentation for details.


          PCRE2_ERROR_DEPTHLIMIT
@@ -2930,7 +2931,7 @@


          PCRE2_ERROR_INTERNAL


-       An unexpected internal error has occurred. This error could  be  caused
+       An  unexpected  internal error has occurred. This error could be caused
        by a bug in PCRE2 or by overwriting of the compiled pattern.


          PCRE2_ERROR_JIT_STACKLIMIT
@@ -2937,7 +2938,7 @@


        This error is returned when a pattern that was successfully studied us-
        ing JIT is being matched, but the memory available for the just-in-time
-       processing  stack  is  not large enough. See the pcre2jit documentation
+       processing stack is not large enough. See  the  pcre2jit  documentation
        for more details.


          PCRE2_ERROR_MATCHLIMIT
@@ -2946,11 +2947,11 @@


          PCRE2_ERROR_NOMEMORY


-       If a pattern contains many nested backtracking points, heap  memory  is
-       used  to  remember them. This error is given when the memory allocation
-       function (default or  custom)  fails.  Note  that  a  different  error,
-       PCRE2_ERROR_HEAPLIMIT,  is given if the amount of memory needed exceeds
-       the   heap   limit.   PCRE2_ERROR_NOMEMORY   is   also   returned    if
+       If  a  pattern contains many nested backtracking points, heap memory is
+       used to remember them. This error is given when the  memory  allocation
+       function  (default  or  custom)  fails.  Note  that  a different error,
+       PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed  exceeds
+       the    heap   limit.   PCRE2_ERROR_NOMEMORY   is   also   returned   if
        PCRE2_COPY_MATCHED_SUBJECT is set and memory allocation fails.


          PCRE2_ERROR_NULL
@@ -2959,12 +2960,12 @@


          PCRE2_ERROR_RECURSELOOP


-       This  error  is  returned  when  pcre2_match() detects a recursion loop
-       within the pattern. Specifically, it means that either the  whole  pat-
+       This error is returned when  pcre2_match()  detects  a  recursion  loop
+       within  the  pattern. Specifically, it means that either the whole pat-
        tern or a capture group has been called recursively for the second time
-       at the same position in the subject string. Some simple  patterns  that
-       might  do  this are detected and faulted at compile time, but more com-
-       plicated cases, in particular mutual recursions between  two  different
+       at  the  same position in the subject string. Some simple patterns that
+       might do this are detected and faulted at compile time, but  more  com-
+       plicated  cases,  in particular mutual recursions between two different
        groups, cannot be detected until matching is attempted.



@@ -2973,20 +2974,20 @@
        int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
          PCRE2_SIZE bufflen);


-       A  text  message  for  an  error code from any PCRE2 function (compile,
-       match, or auxiliary) can be obtained  by  calling  pcre2_get_error_mes-
-       sage().  The  code  is passed as the first argument, with the remaining
-       two arguments specifying a code unit buffer  and  its  length  in  code
-       units,  into  which the text message is placed. The message is returned
-       in code units of the appropriate width for the library  that  is  being
+       A text message for an error code  from  any  PCRE2  function  (compile,
+       match,  or  auxiliary)  can be obtained by calling pcre2_get_error_mes-
+       sage(). The code is passed as the first argument,  with  the  remaining
+       two  arguments  specifying  a  code  unit buffer and its length in code
+       units, into which the text message is placed. The message  is  returned
+       in  code  units  of the appropriate width for the library that is being
        used.


-       The  returned message is terminated with a trailing zero, and the func-
-       tion returns the number of code  units  used,  excluding  the  trailing
+       The returned message is terminated with a trailing zero, and the  func-
+       tion  returns  the  number  of  code units used, excluding the trailing
        zero. If the error number is unknown, the negative error code PCRE2_ER-
-       ROR_BADDATA is returned. If the buffer is too  small,  the  message  is
+       ROR_BADDATA  is  returned.  If  the buffer is too small, the message is
        truncated (but still with a trailing zero), and the negative error code
-       PCRE2_ERROR_NOMEMORY is returned.  None of the messages are very  long;
+       PCRE2_ERROR_NOMEMORY  is returned.  None of the messages are very long;
        a buffer size of 120 code units is ample.



@@ -3005,39 +3006,39 @@

        void pcre2_substring_free(PCRE2_UCHAR *buffer);


-       Captured  substrings  can  be accessed directly by using the ovector as
+       Captured substrings can be accessed directly by using  the  ovector  as
        described above.  For convenience, auxiliary functions are provided for
-       extracting   captured  substrings  as  new,  separate,  zero-terminated
+       extracting  captured  substrings  as  new,  separate,   zero-terminated
        strings. A substring that contains a binary zero is correctly extracted
-       and  has  a  further  zero  added on the end, but the result is not, of
+       and has a further zero added on the end, but  the  result  is  not,  of
        course, a C string.


        The functions in this section identify substrings by number. The number
        zero refers to the entire matched substring, with higher numbers refer-
-       ring to substrings captured by parenthesized groups.  After  a  partial
-       match,  only  substring  zero  is  available. An attempt to extract any
-       other substring gives the error PCRE2_ERROR_PARTIAL. The  next  section
+       ring  to  substrings  captured by parenthesized groups. After a partial
+       match, only substring zero is available.  An  attempt  to  extract  any
+       other  substring  gives the error PCRE2_ERROR_PARTIAL. The next section
        describes similar functions for extracting captured substrings by name.


-       If  a  pattern uses the \K escape sequence within a positive assertion,
+       If a pattern uses the \K escape sequence within a  positive  assertion,
        the reported start of a successful match can be greater than the end of
-       the  match.   For  example,  if the pattern (?=ab\K) is matched against
-       "ab", the start and end offset values for the match are  2  and  0.  In
-       this  situation,  calling  these functions with a zero substring number
+       the match.  For example, if the pattern  (?=ab\K)  is  matched  against
+       "ab",  the  start  and  end offset values for the match are 2 and 0. In
+       this situation, calling these functions with a  zero  substring  number
        extracts a zero-length empty string.


-       You can find the length in code units of a captured  substring  without
-       extracting  it  by calling pcre2_substring_length_bynumber(). The first
-       argument is a pointer to the match data block, the second is the  group
-       number,  and the third is a pointer to a variable into which the length
-       is placed. If you just want to know whether or not  the  substring  has
+       You  can  find the length in code units of a captured substring without
+       extracting it by calling pcre2_substring_length_bynumber().  The  first
+       argument  is a pointer to the match data block, the second is the group
+       number, and the third is a pointer to a variable into which the  length
+       is  placed.  If  you just want to know whether or not the substring has
        been captured, you can pass the third argument as NULL.


-       The  pcre2_substring_copy_bynumber()  function  copies  a captured sub-
-       string into a supplied buffer,  whereas  pcre2_substring_get_bynumber()
-       copies  it  into  new memory, obtained using the same memory allocation
-       function that was used for the match data block. The  first  two  argu-
-       ments  of  these  functions are a pointer to the match data block and a
+       The pcre2_substring_copy_bynumber() function  copies  a  captured  sub-
+       string  into  a supplied buffer, whereas pcre2_substring_get_bynumber()
+       copies it into new memory, obtained using the  same  memory  allocation
+       function  that  was  used for the match data block. The first two argu-
+       ments of these functions are a pointer to the match data  block  and  a
        capture group number.


        The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -3046,25 +3047,25 @@
        for the extracted substring, excluding the terminating zero.


        For pcre2_substring_get_bynumber() the third and fourth arguments point
-       to variables that are updated with a pointer to the new memory and  the
-       number  of  code units that comprise the substring, again excluding the
-       terminating zero. When the substring is no longer  needed,  the  memory
+       to  variables that are updated with a pointer to the new memory and the
+       number of code units that comprise the substring, again  excluding  the
+       terminating  zero.  When  the substring is no longer needed, the memory
        should be freed by calling pcre2_substring_free().


-       The  return  value  from  all these functions is zero for success, or a
-       negative error code. If the pattern match  failed,  the  match  failure
-       code  is returned.  If a substring number greater than zero is used af-
-       ter a partial match, PCRE2_ERROR_PARTIAL is  returned.  Other  possible
+       The return value from all these functions is zero  for  success,  or  a
+       negative  error  code.  If  the pattern match failed, the match failure
+       code is returned.  If a substring number greater than zero is used  af-
+       ter  a  partial  match, PCRE2_ERROR_PARTIAL is returned. Other possible
        error codes are:


          PCRE2_ERROR_NOMEMORY


-       The  buffer  was  too small for pcre2_substring_copy_bynumber(), or the
+       The buffer was too small for  pcre2_substring_copy_bynumber(),  or  the
        attempt to get memory failed for pcre2_substring_get_bynumber().


          PCRE2_ERROR_NOSUBSTRING


-       There is no substring with that number in the  pattern,  that  is,  the
+       There  is  no  substring  with that number in the pattern, that is, the
        number is greater than the number of capturing parentheses.


          PCRE2_ERROR_UNAVAILABLE
@@ -3075,8 +3076,8 @@


          PCRE2_ERROR_UNSET


-       The  substring  did  not  participate in the match. For example, if the
-       pattern is (abc)|(def) and the subject is "def", and the  ovector  con-
+       The substring did not participate in the match.  For  example,  if  the
+       pattern  is  (abc)|(def) and the subject is "def", and the ovector con-
        tains at least two capturing slots, substring number 1 is unset.



@@ -3087,31 +3088,31 @@

        void pcre2_substring_list_free(PCRE2_SPTR *list);


-       The  pcre2_substring_list_get()  function  extracts  all available sub-
-       strings and builds a list of pointers to  them.  It  also  (optionally)
-       builds  a  second list that contains their lengths (in code units), ex-
-       cluding a terminating zero that is added to each of them. All  this  is
+       The pcre2_substring_list_get() function  extracts  all  available  sub-
+       strings  and  builds  a  list of pointers to them. It also (optionally)
+       builds a second list that contains their lengths (in code  units),  ex-
+       cluding  a  terminating zero that is added to each of them. All this is
        done in a single block of memory that is obtained using the same memory
        allocation function that was used to get the match data block.


-       This function must be called only after a successful match.  If  called
+       This  function  must be called only after a successful match. If called
        after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.


-       The  address of the memory block is returned via listptr, which is also
+       The address of the memory block is returned via listptr, which is  also
        the start of the list of string pointers. The end of the list is marked
-       by  a  NULL pointer. The address of the list of lengths is returned via
-       lengthsptr. If your strings do not contain binary zeros and you do  not
+       by a NULL pointer. The address of the list of lengths is  returned  via
+       lengthsptr.  If your strings do not contain binary zeros and you do not
        therefore need the lengths, you may supply NULL as the lengthsptr argu-
-       ment to disable the creation of a list of lengths.  The  yield  of  the
-       function  is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
-       ory block could not be obtained. When the list is no longer needed,  it
+       ment  to  disable  the  creation of a list of lengths. The yield of the
+       function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the  mem-
+       ory  block could not be obtained. When the list is no longer needed, it
        should be freed by calling pcre2_substring_list_free().


        If this function encounters a substring that is unset, which can happen
-       when capture group number n+1 matches some part  of  the  subject,  but
-       group  n has not been used at all, it returns an empty string. This can
+       when  capture  group  number  n+1 matches some part of the subject, but
+       group n has not been used at all, it returns an empty string. This  can
        be distinguished from a genuine zero-length substring by inspecting the
-       appropriate  offset in the ovector, which contain PCRE2_UNSET for unset
+       appropriate offset in the ovector, which contain PCRE2_UNSET for  unset
        substrings, or by calling pcre2_substring_length_bynumber().



@@ -3131,7 +3132,7 @@

        void pcre2_substring_free(PCRE2_UCHAR *buffer);


-       To extract a substring by name, you first have to find associated  num-
+       To  extract a substring by name, you first have to find associated num-
        ber.  For example, for this pattern:


          (a+)b(?<xxx>\d+)...
@@ -3139,32 +3140,32 @@
        the number of the capture group called "xxx" is 2. If the name is known
        to be unique (PCRE2_DUPNAMES was not set), you can find the number from
        the name by calling pcre2_substring_number_from_name(). The first argu-
-       ment is the compiled pattern, and the second is the name. The yield  of
-       the  function  is the group number, PCRE2_ERROR_NOSUBSTRING if there is
-       no group with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if  there  is
-       more  than one group with that name.  Given the number, you can extract
-       the substring directly from the ovector, or use one of  the  "bynumber"
+       ment  is the compiled pattern, and the second is the name. The yield of
+       the function is the group number, PCRE2_ERROR_NOSUBSTRING if  there  is
+       no  group  with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if there is
+       more than one group with that name.  Given the number, you can  extract
+       the  substring  directly from the ovector, or use one of the "bynumber"
        functions described above.


-       For  convenience,  there are also "byname" functions that correspond to
+       For convenience, there are also "byname" functions that  correspond  to
        the "bynumber" functions, the only difference being that the second ar-
-       gument  is  a  name  instead  of a number. If PCRE2_DUPNAMES is set and
+       gument is a name instead of a number.  If  PCRE2_DUPNAMES  is  set  and
        there are duplicate names, these functions scan all the groups with the
-       given  name,  and  return  the  captured substring from the first named
+       given name, and return the captured  substring  from  the  first  named
        group that is set.


-       If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING  is
-       returned.  If  all  groups  with the name have numbers that are greater
+       If  there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
+       returned. If all groups with the name have  numbers  that  are  greater
        than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is re-
-       turned.  If there is at least one group with a slot in the ovector, but
+       turned. If there is at least one group with a slot in the ovector,  but
        no group is found to be set, PCRE2_ERROR_UNSET is returned.


        Warning: If the pattern uses the (?| feature to set up multiple capture
-       groups  with  the same number, as described in the section on duplicate
+       groups with the same number, as described in the section  on  duplicate
        group numbers in the pcre2pattern page, you cannot use names to distin-
-       guish  the  different capture groups, because names are not included in
-       the compiled code. The matching process uses  only  numbers.  For  this
-       reason,  the  use  of  different  names for groups with the same number
+       guish the different capture groups, because names are not  included  in
+       the  compiled  code.  The  matching process uses only numbers. For this
+       reason, the use of different names for  groups  with  the  same  number
        causes an error at compile time.



@@ -3177,54 +3178,54 @@
          PCRE2_SIZE rlength, PCRE2_UCHAR *outputbuffer,
          PCRE2_SIZE *outlengthptr);


-       This function calls pcre2_match() and then makes a copy of the  subject
-       string  in  outputbuffer, replacing one or more parts that were matched
+       This  function calls pcre2_match() and then makes a copy of the subject
+       string in outputbuffer, replacing one or more parts that  were  matched
        with the replacement string, whose length is supplied in rlength.  This
-       can  be  given  as  PCRE2_ZERO_TERMINATED for a zero-terminated string.
-       The default is to perform just one replacement, but there is an  option
-       that  requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL below
+       can be given as PCRE2_ZERO_TERMINATED  for  a  zero-terminated  string.
+       The  default is to perform just one replacement, but there is an option
+       that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL  below
        for details).


-       Matches in which a \K item in a lookahead in  the  pattern  causes  the
-       match  to  end  before it starts are not supported, and give rise to an
+       Matches  in  which  a  \K item in a lookahead in the pattern causes the
+       match to end before it starts are not supported, and give  rise  to  an
        error return. For global replacements, matches in which \K in a lookbe-
-       hind  causes the match to start earlier than the point that was reached
+       hind causes the match to start earlier than the point that was  reached
        in the previous iteration are also not supported.


-       The first seven arguments of pcre2_substitute() are  the  same  as  for
+       The  first  seven  arguments  of pcre2_substitute() are the same as for
        pcre2_match(), except that the partial matching options are not permit-
-       ted, and match_data may be passed as NULL, in which case a  match  data
-       block  is obtained and freed within this function, using memory manage-
-       ment functions from the match context, if provided, or else those  that
+       ted,  and  match_data may be passed as NULL, in which case a match data
+       block is obtained and freed within this function, using memory  manage-
+       ment  functions from the match context, if provided, or else those that
        were used to allocate memory for the compiled code.


-       If  an  external  match_data block is provided, its contents afterwards
-       are those set by the final call to pcre2_match(). For  global  changes,
-       this  will  have ended in a matching error. The contents of the ovector
+       If an external match_data block is provided,  its  contents  afterwards
+       are  those  set by the final call to pcre2_match(). For global changes,
+       this will have ended in a matching error. The contents of  the  ovector
        within the match data block may or may not have been changed.


-       The outlengthptr argument must point to a variable  that  contains  the
-       length,  in  code  units, of the output buffer. If the function is suc-
-       cessful, the value is updated to contain the length of the new  string,
+       The  outlengthptr  argument  must point to a variable that contains the
+       length, in code units, of the output buffer. If the  function  is  suc-
+       cessful,  the value is updated to contain the length of the new string,
        excluding the trailing zero that is automatically added.


-       If  the  function is not successful, the value set via outlengthptr de-
-       pends on the type of  error.  For  syntax  errors  in  the  replacement
+       If the function is not successful, the value set via  outlengthptr  de-
+       pends  on  the  type  of  error.  For  syntax errors in the replacement
        string, the value is the offset in the replacement string where the er-
-       ror was detected. For other errors, the value  is  PCRE2_UNSET  by  de-
+       ror  was  detected.  For  other errors, the value is PCRE2_UNSET by de-
        fault. This includes the case of the output buffer being too small, un-
        less PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which case
-       the  value is the minimum length needed, including space for the trail-
+       the value is the minimum length needed, including space for the  trail-
        ing zero. Note that in order to compute the required length, pcre2_sub-
        stitute() has to simulate all the matching and copying, instead of giv-
        ing an error return as soon as the buffer overflows. Note also that the
        length is in code units, not bytes.


-       In  the replacement string, which is interpreted as a UTF string in UTF
+       In the replacement string, which is interpreted as a UTF string in  UTF
        mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK op-
        tion is set, a dollar character is an escape character that can specify
-       the insertion of characters from capture groups or names  from  (*MARK)
-       or  other  control verbs in the pattern. The following forms are always
+       the  insertion  of characters from capture groups or names from (*MARK)
+       or other control verbs in the pattern. The following forms  are  always
        recognized:


          $$                  insert a dollar character
@@ -3231,18 +3232,18 @@
          $<n> or ${<n>}      insert the contents of group <n>
          $*MARK or ${*MARK}  insert a control verb name


-       Either a group number or a group name  can  be  given  for  <n>.  Curly
-       brackets  are  required only if the following character would be inter-
+       Either  a  group  number  or  a  group name can be given for <n>. Curly
+       brackets are required only if the following character would  be  inter-
        preted as part of the number or name. The number may be zero to include
-       the  entire  matched  string.   For  example,  if  the pattern a(b)c is
-       matched with "=abc=" and the replacement string "+$1$0$1+", the  result
+       the entire matched string.   For  example,  if  the  pattern  a(b)c  is
+       matched  with "=abc=" and the replacement string "+$1$0$1+", the result
        is "=+babcb+=".


-       $*MARK  inserts the name from the last encountered backtracking control
-       verb on the matching path that has a name. (*MARK) must always  include
-       a  name,  but  the  other  verbs  need not. For example, in the case of
+       $*MARK inserts the name from the last encountered backtracking  control
+       verb  on the matching path that has a name. (*MARK) must always include
+       a name, but the other verbs need not.  For  example,  in  the  case  of
        (*MARK:A)(*PRUNE) the name inserted is "A", but for (*MARK:A)(*PRUNE:B)
-       the  relevant  name is "B". This facility can be used to perform simple
+       the relevant name is "B". This facility can be used to  perform  simple
        simultaneous substitutions, as this pcre2test example shows:


          /(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3249,19 +3250,19 @@
              apple lemon
           2: pear orange


-       As well as the usual options for pcre2_match(), a number of  additional
+       As  well as the usual options for pcre2_match(), a number of additional
        options can be set in the options argument of pcre2_substitute().


        PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
-       string, replacing every matching substring. If this option is not  set,
-       only  the  first matching substring is replaced. The search for matches
-       takes place in the original subject string (that is, previous  replace-
-       ments  do  not  affect  it).  Iteration is implemented by advancing the
-       startoffset value for each search, which is always  passed  the  entire
+       string,  replacing every matching substring. If this option is not set,
+       only the first matching substring is replaced. The search  for  matches
+       takes  place in the original subject string (that is, previous replace-
+       ments do not affect it).  Iteration is  implemented  by  advancing  the
+       startoffset  value  for  each search, which is always passed the entire
        subject string. If an offset limit is set in the match context, search-
        ing stops when that limit is reached.


-       You can restrict the effect of a global substitution to  a  portion  of
+       You  can  restrict  the effect of a global substitution to a portion of
        the subject string by setting either or both of startoffset and an off-
        set limit. Here is a pcre2test example:


@@ -3269,87 +3270,87 @@
          ABC ABC ABC ABC\=offset=3,offset_limit=12
           2: ABC A!C A!C ABC


-       When continuing with global substitutions after  matching  a  substring
+       When  continuing  with  global substitutions after matching a substring
        with zero length, an attempt to find a non-empty match at the same off-
        set is performed.  If this is not successful, the offset is advanced by
        one character except when CRLF is a valid newline sequence and the next
-       two characters are CR, LF. In this case, the offset is advanced by  two
+       two  characters are CR, LF. In this case, the offset is advanced by two
        characters.


-       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH  changes  what happens when the output
+       PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when  the  output
        buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
-       ORY  immediately.  If  this  option is set, however, pcre2_substitute()
+       ORY immediately. If this option  is  set,  however,  pcre2_substitute()
        continues to go through the motions of matching and substituting (with-
-       out,  of course, writing anything) in order to compute the size of buf-
-       fer that is needed. This value is  passed  back  via  the  outlengthptr
-       variable,  with  the  result  of  the  function  still  being PCRE2_ER-
+       out, of course, writing anything) in order to compute the size of  buf-
+       fer  that  is  needed.  This  value is passed back via the outlengthptr
+       variable, with  the  result  of  the  function  still  being  PCRE2_ER-
        ROR_NOMEMORY.


-       Passing a buffer size of zero is a permitted way  of  finding  out  how
-       much  memory  is needed for given substitution. However, this does mean
+       Passing  a  buffer  size  of zero is a permitted way of finding out how
+       much memory is needed for given substitution. However, this  does  mean
        that the entire operation is carried out twice. Depending on the appli-
-       cation,  it  may  be more efficient to allocate a large buffer and free
-       the  excess  afterwards,  instead   of   using   PCRE2_SUBSTITUTE_OVER-
+       cation, it may be more efficient to allocate a large  buffer  and  free
+       the   excess   afterwards,   instead  of  using  PCRE2_SUBSTITUTE_OVER-
        FLOW_LENGTH.


        PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capture groups that
        do not appear in the pattern to be treated as unset groups. This option
-       should  be used with care, because it means that a typo in a group name
+       should be used with care, because it means that a typo in a group  name
        or number no longer causes the PCRE2_ERROR_NOSUBSTRING error.


        PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capture groups (including un-
-       known  groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be treated
-       as empty strings when inserted as described above. If  this  option  is
+       known groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be  treated
+       as  empty  strings  when inserted as described above. If this option is
        not set, an attempt to insert an unset group causes the PCRE2_ERROR_UN-
-       SET error. This option does not  influence  the  extended  substitution
+       SET  error.  This  option  does not influence the extended substitution
        syntax described below.


-       PCRE2_SUBSTITUTE_EXTENDED  causes extra processing to be applied to the
-       replacement string. Without this option, only the dollar  character  is
-       special,  and  only  the  group insertion forms listed above are valid.
+       PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to  the
+       replacement  string.  Without this option, only the dollar character is
+       special, and only the group insertion forms  listed  above  are  valid.
        When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:


-       Firstly, backslash in a replacement string is interpreted as an  escape
+       Firstly,  backslash in a replacement string is interpreted as an escape
        character. The usual forms such as \n or \x{ddd} can be used to specify
-       particular character codes, and backslash followed by any  non-alphanu-
-       meric  character  quotes  that character. Extended quoting can be coded
+       particular  character codes, and backslash followed by any non-alphanu-
+       meric character quotes that character. Extended quoting  can  be  coded
        using \Q...\E, exactly as in pattern strings.


-       There are also four escape sequences for forcing the case  of  inserted
-       letters.   The  insertion  mechanism has three states: no case forcing,
+       There  are  also four escape sequences for forcing the case of inserted
+       letters.  The insertion mechanism has three states:  no  case  forcing,
        force upper case, and force lower case. The escape sequences change the
        current state: \U and \L change to upper or lower case forcing, respec-
-       tively, and \E (when not terminating a \Q quoted sequence)  reverts  to
-       no  case  forcing. The sequences \u and \l force the next character (if
-       it is a letter) to upper or lower  case,  respectively,  and  then  the
+       tively,  and  \E (when not terminating a \Q quoted sequence) reverts to
+       no case forcing. The sequences \u and \l force the next  character  (if
+       it  is  a  letter)  to  upper or lower case, respectively, and then the
        state automatically reverts to no case forcing. Case forcing applies to
-       all inserted  characters, including those from capture groups and  let-
+       all  inserted  characters, including those from capture groups and let-
        ters within \Q...\E quoted sequences.


        Note that case forcing sequences such as \U...\E do not nest. For exam-
-       ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc";  the  final
-       \E  has  no  effect.  Note  also  that the PCRE2_ALT_BSUX and PCRE2_EX-
+       ple,  the  result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
+       \E has no effect. Note  also  that  the  PCRE2_ALT_BSUX  and  PCRE2_EX-
        TRA_ALT_BSUX options do not apply to not apply to replacement strings.


-       The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to  add  more
-       flexibility  to  capture  group  substitution. The syntax is similar to
+       The  second  effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
+       flexibility to capture group substitution. The  syntax  is  similar  to
        that used by Bash:


          ${<n>:-<string>}
          ${<n>:+<string1>:<string2>}


-       As before, <n> may be a group number or a name. The first  form  speci-
-       fies  a  default  value. If group <n> is set, its value is inserted; if
-       not, <string> is expanded and the  result  inserted.  The  second  form
-       specifies  strings that are expanded and inserted when group <n> is set
-       or unset, respectively. The first form is just a  convenient  shorthand
+       As  before,  <n> may be a group number or a name. The first form speci-
+       fies a default value. If group <n> is set, its value  is  inserted;  if
+       not,  <string>  is  expanded  and  the result inserted. The second form
+       specifies strings that are expanded and inserted when group <n> is  set
+       or  unset,  respectively. The first form is just a convenient shorthand
        for


          ${<n>:+${<n>}:<string>}


-       Backslash  can  be  used to escape colons and closing curly brackets in
-       the replacement strings. A change of the case forcing  state  within  a
-       replacement  string  remains  in  force  afterwards,  as  shown in this
+       Backslash can be used to escape colons and closing  curly  brackets  in
+       the  replacement  strings.  A change of the case forcing state within a
+       replacement string remains  in  force  afterwards,  as  shown  in  this
        pcre2test example:


          /(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -3358,16 +3359,16 @@
              somebody
           1: HELLO


-       The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these  extended
-       substitutions.  However,  PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause un-
+       The  PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
+       substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does  cause  un-
        known groups in the extended syntax forms to be treated as unset.


-       If successful, pcre2_substitute()  returns  the  number  of  successful
-       matches.  This  may  be  zero  if  no  matches were found, and is never
+       If  successful,  pcre2_substitute()  returns  the  number of successful
+       matches. This may be zero if  no  matches  were  found,  and  is  never
        greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.


        In the event of an error, a negative error code is returned. Except for
-       PCRE2_ERROR_NOMATCH    (which   is   never   returned),   errors   from
+       PCRE2_ERROR_NOMATCH   (which   is   never   returned),   errors    from
        pcre2_match() are passed straight back.


        PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
@@ -3374,26 +3375,26 @@
        tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set.


        PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
-       ing an unknown substring when  PCRE2_SUBSTITUTE_UNKNOWN_UNSET  is  set)
-       when  the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN-
+       ing  an  unknown  substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
+       when the simple (non-extended) syntax is used and  PCRE2_SUBSTITUTE_UN-
        SET_EMPTY is not set.


-       PCRE2_ERROR_NOMEMORY is returned  if  the  output  buffer  is  not  big
+       PCRE2_ERROR_NOMEMORY  is  returned  if  the  output  buffer  is not big
        enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
-       of buffer that is needed is returned via outlengthptr. Note  that  this
+       of  buffer  that is needed is returned via outlengthptr. Note that this
        does not happen by default.


-       PCRE2_ERROR_BADREPLACEMENT  is  used for miscellaneous syntax errors in
-       the replacement string, with more  particular  errors  being  PCRE2_ER-
+       PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax  errors  in
+       the  replacement  string,  with  more particular errors being PCRE2_ER-
        ROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE
-       (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION  (syntax
-       error  in  extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN
+       (closing  curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax
+       error in extended group substitution),  and  PCRE2_ERROR_BADSUBSPATTERN
        (the pattern match ended before it started or the match started earlier
-       than  the  current  position  in the subject, which can happen if \K is
+       than the current position in the subject, which can  happen  if  \K  is
        used in an assertion).


        As for all PCRE2 errors, a text message that describes the error can be
-       obtained  by  calling  the pcre2_get_error_message() function (see "Ob-
+       obtained by calling the pcre2_get_error_message()  function  (see  "Ob-
        taining a textual error message" above).


    Substitution callouts
@@ -3402,15 +3403,15 @@
          int (*callout_function)(pcre2_substitute_callout_block *, void *),
          void *callout_data);


-       The pcre2_set_substitution_callout() function can be used to specify  a
-       callout  function for pcre2_substitute(). This information is passed in
+       The  pcre2_set_substitution_callout() function can be used to specify a
+       callout function for pcre2_substitute(). This information is passed  in
        a match context. The callout function is called after each substitution
        has been processed, but it can cause the replacement not to happen. The
-       callout function is not called for simulated substitutions that  happen
+       callout  function is not called for simulated substitutions that happen
        as a result of the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option.


        The first argument of the callout function is a pointer to a substitute
-       callout block structure, which contains the following fields, not  nec-
+       callout  block structure, which contains the following fields, not nec-
        essarily in this order:


          uint32_t    version;
@@ -3421,9 +3422,9 @@
          uint32_t    oveccount;
          PCRE2_SIZE  output_offsets[2];


-       The  version field contains the version number of the block format. The
-       current version is 0. The version number will  increase  in  future  if
-       more  fields are added, but the intention is never to remove any of the
+       The version field contains the version number of the block format.  The
+       current  version  is  0.  The version number will increase in future if
+       more fields are added, but the intention is never to remove any of  the
        existing fields.


        The subscount field is the number of the current match. It is 1 for the
@@ -3430,25 +3431,25 @@
        first callout, 2 for the second, and so on. The input and output point-
        ers are copies of the values passed to pcre2_substitute().


-       The ovector field points to the ovector, which contains the  result  of
+       The  ovector  field points to the ovector, which contains the result of
        the most recent match. The oveccount field contains the number of pairs
        that are set in the ovector, and is always greater than zero.


-       The output_offsets vector contains the offsets of  the  replacement  in
-       the  output  string. This has already been processed for dollar and (if
+       The  output_offsets  vector  contains the offsets of the replacement in
+       the output string. This has already been processed for dollar  and  (if
        requested) backslash substitutions as described above.


-       The second argument of the callout function  is  the  value  passed  as
-       callout_data  when  the  function was registered. The value returned by
+       The  second  argument  of  the  callout function is the value passed as
+       callout_data when the function was registered. The  value  returned  by
        the callout function is interpreted as follows:


-       If the value is zero, the replacement is accepted, and,  if  PCRE2_SUB-
-       STITUTE_GLOBAL  is set, processing continues with a search for the next
-       match. If the value is not zero, the current  replacement  is  not  ac-
-       cepted.  If  the  value is greater than zero, processing continues when
-       PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than  zero
-       or  PCRE2_SUBSTITUTE_GLOBAL  is  not set), the the rest of the input is
-       copied to the output and the call to pcre2_substitute() exits,  return-
+       If  the  value is zero, the replacement is accepted, and, if PCRE2_SUB-
+       STITUTE_GLOBAL is set, processing continues with a search for the  next
+       match.  If  the  value  is not zero, the current replacement is not ac-
+       cepted. If the value is greater than zero,  processing  continues  when
+       PCRE2_SUBSTITUTE_GLOBAL  is set. Otherwise (the value is less than zero
+       or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of  the  input  is
+       copied  to the output and the call to pcre2_substitute() exits, return-
        ing the number of matches so far.



@@ -3457,56 +3458,56 @@
        int pcre2_substring_nametable_scan(const pcre2_code *code,
          PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);


-       When  a  pattern  is compiled with the PCRE2_DUPNAMES option, names for
-       capture groups are not required to be unique. Duplicate names  are  al-
-       ways  allowed for groups with the same number, created by using the (?|
+       When a pattern is compiled with the PCRE2_DUPNAMES  option,  names  for
+       capture  groups  are not required to be unique. Duplicate names are al-
+       ways allowed for groups with the same number, created by using the  (?|
        feature. Indeed, if such groups are named, they are required to use the
        same names.


-       Normally,  patterns  that  use duplicate names are such that in any one
-       match, only one of each set of identically-named  groups  participates.
+       Normally, patterns that use duplicate names are such that  in  any  one
+       match,  only  one of each set of identically-named groups participates.
        An example is shown in the pcre2pattern documentation.


-       When   duplicates   are   present,   pcre2_substring_copy_byname()  and
-       pcre2_substring_get_byname() return the first  substring  corresponding
-       to  the given name that is set. Only if none are set is PCRE2_ERROR_UN-
-       SET is returned. The  pcre2_substring_number_from_name()  function  re-
-       turns  the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate
+       When  duplicates   are   present,   pcre2_substring_copy_byname()   and
+       pcre2_substring_get_byname()  return  the first substring corresponding
+       to the given name that is set. Only if none are set is  PCRE2_ERROR_UN-
+       SET  is  returned.  The pcre2_substring_number_from_name() function re-
+       turns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are  duplicate
        names.


-       If you want to get full details of all captured substrings for a  given
-       name,  you  must use the pcre2_substring_nametable_scan() function. The
-       first argument is the compiled pattern, and the second is the name.  If
-       the  third  and fourth arguments are NULL, the function returns a group
+       If  you want to get full details of all captured substrings for a given
+       name, you must use the pcre2_substring_nametable_scan()  function.  The
+       first  argument is the compiled pattern, and the second is the name. If
+       the third and fourth arguments are NULL, the function returns  a  group
        number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise.


        When the third and fourth arguments are not NULL, they must be pointers
-       to  variables  that are updated by the function. After it has run, they
+       to variables that are updated by the function. After it has  run,  they
        point to the first and last entries in the name-to-number table for the
-       given  name,  and the function returns the length of each entry in code
-       units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there  are
+       given name, and the function returns the length of each entry  in  code
+       units.  In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
        no entries for the given name.


        The format of the name table is described above in the section entitled
-       Information about a pattern. Given all the  relevant  entries  for  the
-       name,  you  can  extract  each of their numbers, and hence the captured
+       Information  about  a  pattern.  Given all the relevant entries for the
+       name, you can extract each of their numbers,  and  hence  the  captured
        data.



FINDING ALL POSSIBLE MATCHES AT ONE POSITION

-       The traditional matching function uses a  similar  algorithm  to  Perl,
-       which  stops when it finds the first match at a given point in the sub-
+       The  traditional  matching  function  uses a similar algorithm to Perl,
+       which stops when it finds the first match at a given point in the  sub-
        ject. If you want to find all possible matches, or the longest possible
-       match  at  a  given  position,  consider using the alternative matching
-       function (see below) instead. If you cannot use the  alternative  func-
+       match at a given position,  consider  using  the  alternative  matching
+       function  (see  below) instead. If you cannot use the alternative func-
        tion, you can kludge it up by making use of the callout facility, which
        is described in the pcre2callout documentation.


        What you have to do is to insert a callout right at the end of the pat-
-       tern.   When your callout function is called, extract and save the cur-
-       rent matched substring. Then return 1, which  forces  pcre2_match()  to
-       backtrack  and  try other alternatives. Ultimately, when it runs out of
+       tern.  When your callout function is called, extract and save the  cur-
+       rent  matched  substring.  Then return 1, which forces pcre2_match() to
+       backtrack and try other alternatives. Ultimately, when it runs  out  of
        matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH.



@@ -3518,26 +3519,26 @@
          pcre2_match_context *mcontext,
          int *workspace, PCRE2_SIZE wscount);


-       The function pcre2_dfa_match() is called  to  match  a  subject  string
-       against  a  compiled pattern, using a matching algorithm that scans the
+       The  function  pcre2_dfa_match()  is  called  to match a subject string
+       against a compiled pattern, using a matching algorithm that  scans  the
        subject string just once (not counting lookaround assertions), and does
-       not  backtrack.  This has different characteristics to the normal algo-
-       rithm, and is not compatible with Perl. Some of the features  of  PCRE2
-       patterns  are  not  supported.  Nevertheless, there are times when this
-       kind of matching can be useful. For a discussion of  the  two  matching
+       not backtrack.  This has different characteristics to the normal  algo-
+       rithm,  and  is not compatible with Perl. Some of the features of PCRE2
+       patterns are not supported.  Nevertheless, there are  times  when  this
+       kind  of  matching  can be useful. For a discussion of the two matching
        algorithms, and a list of features that pcre2_dfa_match() does not sup-
        port, see the pcre2matching documentation.


-       The arguments for the pcre2_dfa_match() function are the  same  as  for
+       The  arguments  for  the pcre2_dfa_match() function are the same as for
        pcre2_match(), plus two extras. The ovector within the match data block
        is used in a different way, and this is described below. The other com-
-       mon  arguments  are used in the same way as for pcre2_match(), so their
+       mon arguments are used in the same way as for pcre2_match(),  so  their
        description is not repeated here.


-       The two additional arguments provide workspace for  the  function.  The
-       workspace  vector  should  contain at least 20 elements. It is used for
+       The  two  additional  arguments provide workspace for the function. The
+       workspace vector should contain at least 20 elements. It  is  used  for
        keeping  track  of  multiple  paths  through  the  pattern  tree.  More
-       workspace  is needed for patterns and subjects where there are a lot of
+       workspace is needed for patterns and subjects where there are a lot  of
        potential matches.


        Here is an example of a simple call to pcre2_dfa_match():
@@ -3557,45 +3558,45 @@


    Option bits for pcre_dfa_match()


-       The unused bits of the options argument for pcre2_dfa_match()  must  be
-       zero.   The   only   bits   that   may   be   set  are  PCRE2_ANCHORED,
-       PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL,  PCRE2_NO-
+       The  unused  bits of the options argument for pcre2_dfa_match() must be
+       zero.  The  only   bits   that   may   be   set   are   PCRE2_ANCHORED,
+       PCRE2_COPY_MATCHED_SUBJECT,  PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
        TEOL,   PCRE2_NOTEMPTY,   PCRE2_NOTEMPTY_ATSTART,   PCRE2_NO_UTF_CHECK,
-       PCRE2_PARTIAL_HARD,   PCRE2_PARTIAL_SOFT,    PCRE2_DFA_SHORTEST,    and
-       PCRE2_DFA_RESTART.  All but the last four of these are exactly the same
+       PCRE2_PARTIAL_HARD,    PCRE2_PARTIAL_SOFT,    PCRE2_DFA_SHORTEST,   and
+       PCRE2_DFA_RESTART. All but the last four of these are exactly the  same
        as for pcre2_match(), so their description is not repeated here.


          PCRE2_PARTIAL_HARD
          PCRE2_PARTIAL_SOFT


-       These have the same general effect as they do  for  pcre2_match(),  but
-       the  details are slightly different. When PCRE2_PARTIAL_HARD is set for
-       pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if  the  end  of  the
+       These  have  the  same general effect as they do for pcre2_match(), but
+       the details are slightly different. When PCRE2_PARTIAL_HARD is set  for
+       pcre2_dfa_match(),  it  returns  PCRE2_ERROR_PARTIAL  if the end of the
        subject is reached and there is still at least one matching possibility
        that requires additional characters. This happens even if some complete
-       matches  have  already  been found. When PCRE2_PARTIAL_SOFT is set, the
-       return code PCRE2_ERROR_NOMATCH is converted  into  PCRE2_ERROR_PARTIAL
-       if  the  end  of  the  subject  is reached, there have been no complete
+       matches have already been found. When PCRE2_PARTIAL_SOFT  is  set,  the
+       return  code  PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
+       if the end of the subject is  reached,  there  have  been  no  complete
        matches, but there is still at least one matching possibility. The por-
-       tion  of  the  string that was inspected when the longest partial match
+       tion of the string that was inspected when the  longest  partial  match
        was found is set as the first matching string in both cases. There is a
-       more  detailed  discussion  of partial and multi-segment matching, with
+       more detailed discussion of partial and  multi-segment  matching,  with
        examples, in the pcre2partial documentation.


          PCRE2_DFA_SHORTEST


-       Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm  to
+       Setting  the PCRE2_DFA_SHORTEST option causes the matching algorithm to
        stop as soon as it has found one match. Because of the way the alterna-
-       tive algorithm works, this is necessarily the shortest  possible  match
+       tive  algorithm  works, this is necessarily the shortest possible match
        at the first possible matching point in the subject string.


          PCRE2_DFA_RESTART


-       When  pcre2_dfa_match() returns a partial match, it is possible to call
+       When pcre2_dfa_match() returns a partial match, it is possible to  call
        it again, with additional subject characters, and have it continue with
        the same match. The PCRE2_DFA_RESTART option requests this action; when
-       it is set, the workspace and wscount options must  reference  the  same
-       vector  as  before  because data about the match so far is left in them
+       it  is  set,  the workspace and wscount options must reference the same
+       vector as before because data about the match so far is  left  in  them
        after a partial match. There is more discussion of this facility in the
        pcre2partial documentation.


@@ -3603,8 +3604,8 @@

        When pcre2_dfa_match() succeeds, it may have matched more than one sub-
        string in the subject. Note, however, that all the matches from one run
-       of  the  function  start  at the same point in the subject. The shorter
-       matches are all initial substrings of the longer matches. For  example,
+       of the function start at the same point in  the  subject.  The  shorter
+       matches  are all initial substrings of the longer matches. For example,
        if the pattern


          <.*>
@@ -3619,80 +3620,80 @@
          <something> <something else>
          <something>


-       On  success,  the  yield of the function is a number greater than zero,
-       which is the number of matched substrings.  The  offsets  of  the  sub-
-       strings  are returned in the ovector, and can be extracted by number in
-       the same way as for pcre2_match(), but the numbers bear no relation  to
-       any  capture groups that may exist in the pattern, because DFA matching
+       On success, the yield of the function is a number  greater  than  zero,
+       which  is  the  number  of  matched substrings. The offsets of the sub-
+       strings are returned in the ovector, and can be extracted by number  in
+       the  same way as for pcre2_match(), but the numbers bear no relation to
+       any capture groups that may exist in the pattern, because DFA  matching
        does not support capturing.


-       Calls to the convenience functions that extract substrings by name  re-
+       Calls  to the convenience functions that extract substrings by name re-
        turn the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used af-
-       ter a DFA match. The convenience functions that extract  substrings  by
+       ter  a  DFA match. The convenience functions that extract substrings by
        number never return PCRE2_ERROR_NOSUBSTRING.


-       The  matched  strings  are  stored  in  the ovector in reverse order of
-       length; that is, the longest matching string is first.  If  there  were
-       too  many matches to fit into the ovector, the yield of the function is
+       The matched strings are stored in  the  ovector  in  reverse  order  of
+       length;  that  is,  the longest matching string is first. If there were
+       too many matches to fit into the ovector, the yield of the function  is
        zero, and the vector is filled with the longest matches.


-       NOTE: PCRE2's "auto-possessification" optimization usually  applies  to
-       character  repeats at the end of a pattern (as well as internally). For
-       example, the pattern "a\d+" is compiled as if it were "a\d++". For  DFA
-       matching,  this means that only one possible match is found. If you re-
+       NOTE:  PCRE2's  "auto-possessification" optimization usually applies to
+       character repeats at the end of a pattern (as well as internally).  For
+       example,  the pattern "a\d+" is compiled as if it were "a\d++". For DFA
+       matching, this means that only one possible match is found. If you  re-
        ally do want multiple matches in such cases, either use an ungreedy re-
-       peat  such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com-
+       peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when  com-
        piling.


    Error returns from pcre2_dfa_match()


        The pcre2_dfa_match() function returns a negative number when it fails.
-       Many  of  the  errors  are  the same as for pcre2_match(), as described
+       Many of the errors are the same  as  for  pcre2_match(),  as  described
        above.  There are in addition the following errors that are specific to
        pcre2_dfa_match():


          PCRE2_ERROR_DFA_UITEM


-       This  return  is  given  if pcre2_dfa_match() encounters an item in the
-       pattern that it does not support, for instance, the use of \C in a  UTF
+       This return is given if pcre2_dfa_match() encounters  an  item  in  the
+       pattern  that it does not support, for instance, the use of \C in a UTF
        mode or a backreference.


          PCRE2_ERROR_DFA_UCOND


-       This  return  is given if pcre2_dfa_match() encounters a condition item
+       This return is given if pcre2_dfa_match() encounters a  condition  item
        that uses a backreference for the condition, or a test for recursion in
        a specific capture group. These are not supported.


          PCRE2_ERROR_DFA_UINVALID_UTF


-       This  return is given if pcre2_dfa_match() is called for a pattern that
-       was compiled with PCRE2_MATCH_INVALID_UTF. This is  not  supported  for
+       This return is given if pcre2_dfa_match() is called for a pattern  that
+       was  compiled  with  PCRE2_MATCH_INVALID_UTF. This is not supported for
        DFA matching.


          PCRE2_ERROR_DFA_WSSIZE


-       This  return  is  given  if  pcre2_dfa_match() runs out of space in the
+       This return is given if pcre2_dfa_match() runs  out  of  space  in  the
        workspace vector.


          PCRE2_ERROR_DFA_RECURSE


        When a recursion or subroutine call is processed, the matching function
-       calls  itself  recursively,  using  private  memory for the ovector and
-       workspace.  This error is given if the internal ovector  is  not  large
-       enough.  This  should  be  extremely  rare, as a vector of size 1000 is
+       calls itself recursively, using private  memory  for  the  ovector  and
+       workspace.   This  error  is given if the internal ovector is not large
+       enough. This should be extremely rare, as a  vector  of  size  1000  is
        used.


          PCRE2_ERROR_DFA_BADRESTART


-       When pcre2_dfa_match() is called  with  the  PCRE2_DFA_RESTART  option,
-       some  plausibility  checks  are  made on the contents of the workspace,
-       which should contain data about the previous partial match. If  any  of
+       When  pcre2_dfa_match()  is  called  with the PCRE2_DFA_RESTART option,
+       some plausibility checks are made on the  contents  of  the  workspace,
+       which  should  contain data about the previous partial match. If any of
        these checks fail, this error is given.



SEE ALSO

-       pcre2build(3),    pcre2callout(3),    pcre2demo(3),   pcre2matching(3),
+       pcre2build(3),   pcre2callout(3),    pcre2demo(3),    pcre2matching(3),
        pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).



@@ -3705,7 +3706,7 @@

REVISION

-       Last updated: 20 July 2019
+       Last updated: 22 July 2019
        Copyright (c) 1997-2019 University of Cambridge.
 ------------------------------------------------------------------------------


@@ -5703,13 +5704,15 @@
        the subject string is reached successfully, but  matching  cannot  con-
        tinue  because  more  characters are needed, and in addition, either at
        least one character in the subject has been inspected  or  the  pattern
-       contains a lookbehind. An inspected character need not form part of the
-       final matched string; lookbehind assertions and the \K escape  sequence
-       provide  ways  of  inspecting  characters before the start of a matched
-       string.
+       contains  a lookbehind, or (when PCRE2_PARTIAL_HARD is set) the pattern
+       could match an empty string. An inspected character need not form  part
+       of  the  final  matched string; lookbehind assertions and the \K escape
+       sequence provide ways of inspecting characters before the  start  of  a
+       matched string.


-       The two additional requirements define  the  cases  where  adding  more
-       characters  to  the  existing  subject  may complete the match. Without
+       The  three  additional  requirements define the cases where adding more
+       characters to the existing subject may complete  the  same  match  that
+       would  occur  if  they had all been present in the first place. Without
        these conditions there would be a partial match of an empty  string  at
        the  end  of  the subject for all unanchored patterns (and also for an-
        chored patterns if the subject itself is empty).
@@ -6068,7 +6071,7 @@


REVISION

-       Last updated: 21 July 2019
+       Last updated: 22 July 2019
        Copyright (c) 1997-2019 University of Cambridge.
 ------------------------------------------------------------------------------



Modified: code/trunk/doc/pcre2api.3
===================================================================
--- code/trunk/doc/pcre2api.3    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/pcre2api.3    2019-07-22 16:30:44 UTC (rev 1142)
@@ -2720,7 +2720,8 @@
 These options turn on the partial matching feature. A partial match occurs if
 the end of the subject string is reached successfully, but there are not enough
 subject characters to complete the match. In addition, either at least one 
-character must have been inspected or the pattern must contain a lookbehind.
+character must have been inspected or the pattern must contain a lookbehind, or 
+the pattern must be one that could match an empty string.
 .P
 If this situation arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD)
 is set, matching continues by testing any remaining alternatives. Only if no


Modified: code/trunk/doc/pcre2partial.3
===================================================================
--- code/trunk/doc/pcre2partial.3    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/pcre2partial.3    2019-07-22 16:30:44 UTC (rev 1142)
@@ -1,4 +1,4 @@
-.TH PCRE2PARTIAL 3 "21 July 2019" "PCRE2 10.34"
+.TH PCRE2PARTIAL 3 "22 July 2019" "PCRE2 10.34"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions
 .SH "PARTIAL MATCHING IN PCRE2"
@@ -56,15 +56,17 @@
 A partial match occurs during a call to \fBpcre2_match()\fP when the end of the
 subject string is reached successfully, but matching cannot continue because
 more characters are needed, and in addition, either at least one character in
-the subject has been inspected or the pattern contains a lookbehind. An
+the subject has been inspected or the pattern contains a lookbehind, or (when 
+PCRE2_PARTIAL_HARD is set) the pattern could match an empty string. An
 inspected character need not form part of the final matched string; lookbehind
 assertions and the \eK escape sequence provide ways of inspecting characters
 before the start of a matched string.
 .P
-The two additional requirements define the cases where adding more characters
-to the existing subject may complete the match. Without these conditions there
-would be a partial match of an empty string at the end of the subject for all 
-unanchored patterns (and also for anchored patterns if the subject itself is 
+The three additional requirements define the cases where adding more characters
+to the existing subject may complete the same match that would occur if they
+had all been present in the first place. Without these conditions there would
+be a partial match of an empty string at the end of the subject for all
+unanchored patterns (and also for anchored patterns if the subject itself is
 empty).
 .P
 When a partial match is returned, the first two elements in the ovector point
@@ -422,6 +424,6 @@
 .rs
 .sp
 .nf
-Last updated: 21 July 2019
+Last updated: 22 July 2019
 Copyright (c) 1997-2019 University of Cambridge.
 .fi


Modified: code/trunk/src/pcre2_dfa_match.c
===================================================================
--- code/trunk/src/pcre2_dfa_match.c    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/src/pcre2_dfa_match.c    2019-07-22 16:30:44 UTC (rev 1142)
@@ -3185,8 +3185,8 @@
           ptr >= end_subject &&              /* End of subject and */
             (                                  /* either */
             ptr > mb->start_used_ptr ||        /* Inspected non-empty string */
-            mb->haslookbehind                  /* or pattern has lookbehind */
-            )
+            mb->allowemptypartial              /* or pattern has lookbehind */
+            )                                  /* or could match empty */
           )
         ))
       match_count = PCRE2_ERROR_PARTIAL;
@@ -3417,7 +3417,8 @@
 mb->start_subject = subject;
 mb->end_subject = end_subject;
 mb->start_offset = start_offset;
-mb->haslookbehind = (re->max_lookbehind > 0);
+mb->allowemptypartial = (re->max_lookbehind > 0) ||
+  (re->flags & PCRE2_MATCH_EMPTY) != 0;
 mb->moptions = options;
 mb->poptions = re->overall_options;
 mb->match_call_count = 0;


Modified: code/trunk/src/pcre2_intmodedep.h
===================================================================
--- code/trunk/src/pcre2_intmodedep.h    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/src/pcre2_intmodedep.h    2019-07-22 16:30:44 UTC (rev 1142)
@@ -854,7 +854,7 @@
   uint32_t match_call_count;      /* Number of times a new frame is created */
   BOOL hitend;                    /* Hit the end of the subject at some point */
   BOOL hasthen;                   /* Pattern contains (*THEN) */
-  BOOL haslookbehind;             /* Pattern contains sigificant lookbehind */ 
+  BOOL allowemptypartial;         /* Allow empty hard partial */ 
   const uint8_t *lcc;             /* Points to lower casing table */
   const uint8_t *fcc;             /* Points to case-flipping table */
   const uint8_t *ctypes;          /* Points to table of type maps */
@@ -910,7 +910,7 @@
   uint32_t poptions;              /* Pattern options */
   uint32_t nltype;                /* Newline type */
   uint32_t nllen;                 /* Newline string length */
-  BOOL haslookbehind;             /* Pattern contains significant lookbehind */ 
+  BOOL allowemptypartial;         /* Allow empty hard partial */ 
   PCRE2_UCHAR nl[4];              /* Newline string when fixed */
   uint16_t bsr_convention;        /* \R interpretation */
   pcre2_callout_block *cb;        /* Points to a callout block */


Modified: code/trunk/src/pcre2_match.c
===================================================================
--- code/trunk/src/pcre2_match.c    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/src/pcre2_match.c    2019-07-22 16:30:44 UTC (rev 1142)
@@ -508,7 +508,8 @@
     }


 #define SCHECK_PARTIAL()\
-  if (mb->partial != 0 && (Feptr > mb->start_used_ptr || mb->haslookbehind)) \
+  if (mb->partial != 0 && \
+      (Feptr > mb->start_used_ptr || mb->allowemptypartial)) \
     { \
     mb->hitend = TRUE; \
     if (mb->partial > 1) return PCRE2_ERROR_PARTIAL; \
@@ -6451,7 +6452,8 @@
 mb->start_offset = start_offset;
 mb->end_subject = end_subject;
 mb->hasthen = (re->flags & PCRE2_HASTHEN) != 0;
-mb->haslookbehind = (re->max_lookbehind > 0);
+mb->allowemptypartial = (re->max_lookbehind > 0) || 
+    (re->flags & PCRE2_MATCH_EMPTY) != 0;
 mb->poptions = re->overall_options;          /* Pattern options */
 mb->ignore_skip_arg = 0;
 mb->mark = mb->nomatch_mark = NULL;          /* In case never set */


Modified: code/trunk/testdata/testinput2
===================================================================
--- code/trunk/testdata/testinput2    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testinput2    2019-07-22 16:30:44 UTC (rev 1142)
@@ -5719,4 +5719,10 @@
    abc\n\=ph,no_jit
    abc\n\=ps


+/(?![ab]).*/
+    ab\=ph,no_jit
+
+/c*+/
+    ab\=ph,offset=2,no_jit
+
 # End of testinput2


Modified: code/trunk/testdata/testinput6
===================================================================
--- code/trunk/testdata/testinput6    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testinput6    2019-07-22 16:30:44 UTC (rev 1142)
@@ -5020,4 +5020,10 @@
     bxyz 
     xyz


+/(?![ab]).*/
+    ab\=ph
+
+/c*+/
+    ab\=ph,offset=2
+
 # End of testinput6


Modified: code/trunk/testdata/testoutput2
===================================================================
--- code/trunk/testdata/testoutput2    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testoutput2    2019-07-22 16:30:44 UTC (rev 1142)
@@ -17231,6 +17231,14 @@
    abc\n\=ps
  0: 


+/(?![ab]).*/
+    ab\=ph,no_jit
+Partial match: 
+
+/c*+/
+    ab\=ph,offset=2,no_jit
+Partial match: 
+
 # End of testinput2
 Error -70: PCRE2_ERROR_BADDATA (unknown error number)
 Error -62: bad serialized data


Modified: code/trunk/testdata/testoutput6
===================================================================
--- code/trunk/testdata/testoutput6    2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testoutput6    2019-07-22 16:30:44 UTC (rev 1142)
@@ -7887,4 +7887,12 @@
     xyz
  0: 


+/(?![ab]).*/
+    ab\=ph
+Partial match: 
+
+/c*+/
+    ab\=ph,offset=2
+Partial match: 
+
 # End of testinput6