/[pcre]/code/trunk/doc/pcre.txt

Diff of /code/trunk/doc/pcre.txt

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-revision 43 by nigel,
Sat Feb 24 21:39:21 2007 UTC
+revision 47 by nigel,
Sat Feb 24 21:39:29 2007 UTC
 Line 353 
 INFORMATION ABOUT A PATTERN
       Return information about the first character of any  matched
       string,  for  a  non-anchored  pattern.  If there is a fixed
       first   character,   e.g.   from   a   pattern    such    as
-      (cat|cow|coyote), then it is returned in the integer pointed
+      (cat|cow|coyote),  it  is returned in the integer pointed to
-      to by where. Otherwise, if either
+      by where. Otherwise, if either
       (a) the pattern was compiled with the PCRE_MULTILINE option,
       and every branch starts with "^", or
 Line 363 
 INFORMATION ABOUT A PATTERN
       PCRE_DOTALL is not set (if it were set, the pattern would be
       anchored),
-      then -1 is returned, indicating  that  the  pattern  matches
+      -1 is returned, indicating that the pattern matches only  at
-      only  at  the  start  of  a subject string or after any "\n"
+      the  start  of a subject string or after any "\n" within the
-      within the string. Otherwise -2 is  returned.  For  anchored
+      string. Otherwise -2 is returned.  For anchored patterns, -2
-      patterns, -2 is returned.
+      is returned.
         PCRE_INFO_FIRSTTABLE
 Line 622 
 EXTRACTING CAPTURED SUBSTRINGS
       entire regular expression. This is  the  value  returned  by
       pcre_exec  if  it  is  greater  than  zero.  If  pcre_exec()
       returned zero, indicating that it ran out of space in  ovec-
-      tor, then the value passed as stringcount should be the size
+      tor,  the  value passed as stringcount should be the size of
-      of the vector divided by three.
+      the vector divided by three.
       The functions pcre_copy_substring() and pcre_get_substring()
       extract a single substring, whose number is given as string-
 Line 739 
 DIFFERENCES FROM PERL
       "aba"  against the pattern /^(a(b)?)+$/ sets $2 to the value
       "b", but matching "aabbaa" against /^(aa(bb)?)+$/ leaves  $2
       unset.    However,    if   the   pattern   is   changed   to
-      /^(aa(b(b))?)+$/ then $2 (and $3) get set.
+      /^(aa(b(b))?)+$/ then $2 (and $3) are set.
       In Perl 5.004 $2 is set in both cases, and that is also true
       of PCRE. If in the future Perl changes to a consistent state
 Line 1056 
 FULL STOP (PERIOD, DOT)
       Outside a character class, a dot in the pattern matches  any
       one character in the subject, including a non-printing char-
       acter, but not (by default)  newline.   If  the  PCRE_DOTALL
-      option  is  set,  then dots match newlines as well. The han-
+      option  is set, dots match newlines as well. The handling of
-      dling of dot is entirely independent of the handling of cir-
+      dot is entirely independent of the  handling  of  circumflex
-      cumflex  and  dollar,  the only relationship being that they
+      and  dollar,  the  only  relationship  being  that they both
-      both involve newline characters.  Dot has no special meaning
+      involve newline characters. Dot has no special meaning in  a
-      in a character class.
+      character class.
 Line 1406 
 REPETITION
       fails, because it matches  the  entire  string  due  to  the
       greediness of the .*  item.
-      However, if a quantifier is followed  by  a  question  mark,
+      However, if a quantifier is followed by a question mark,  it
-      then it ceases to be greedy, and instead matches the minimum
+      ceases  to be greedy, and instead matches the minimum number
-      number of times possible, so the pattern
+      of times possible, so the pattern
         /\*.*?\*/
 Line 1425 
 REPETITION
       that is the only way the rest of the pattern matches.
       If the PCRE_UNGREEDY option is set (an option which  is  not
-      available  in  Perl)  then the quantifiers are not greedy by
+      available  in  Perl),  the  quantifiers  are  not  greedy by
       default, but individual ones can be made greedy by following
       them  with  a  question mark. In other words, it inverts the
       default behaviour.
 Line 1437 
 REPETITION
       If a pattern starts with .* or  .{0,}  and  the  PCRE_DOTALL
       option (equivalent to Perl's /s) is set, thus allowing the .
-      to match newlines, then the pattern is implicitly  anchored,
+      to match  newlines,  the  pattern  is  implicitly  anchored,
       because whatever follows will be tried against every charac-
       ter position in the subject string, so there is no point  in
       retrying  the overall match at any position after the first.
 Line 1490 
 BACK REFERENCES
       matches "sense and sensibility" and "response and  responsi-
       bility",  but  not  "sense  and  responsibility". If caseful
-      matching is in force at the time of the back reference, then
+      matching is in force at the time of the back reference,  the
-      the case of letters is relevant. For example,
+      case of letters is relevant. For example,
         ((?i)rah)\s+\1
 Line 1501 
 BACK REFERENCES
       There may be more than one back reference to the  same  sub-
       pattern.  If  a  subpattern  has not actually been used in a
-      particular match, then any  back  references  to  it  always
+      particular match, any back references to it always fail. For
-      fail. For example, the pattern
+      example, the pattern
         (a|(bc))\2
 Line 1510 
 BACK REFERENCES
       Because  there  may  be up to 99 back references, all digits
       following the backslash are taken as  part  of  a  potential
       back reference number. If the pattern continues with a digit
-      character, then some delimiter must be used to terminate the
+      character, some delimiter must be used to terminate the back
-      back reference. If the PCRE_EXTENDED option is set, this can
+      reference.   If the PCRE_EXTENDED option is set, this can be
-      be whitespace.  Otherwise an empty comment can be used.
+      whitespace. Otherwise an empty comment can be used.
       A back reference that occurs inside the parentheses to which
       it  refers  fails when the subpattern is first used, so, for
 Line 1612 
 ASSERTIONS
       matches "foo" preceded by three digits that are  not  "999".
       Notice  that each of the assertions is applied independently
       at the same point in the subject string. First  there  is  a
-      check  that  the  previous  three characters are all digits,
+      check that the previous three characters are all digits, and
       then there is a check that the same three characters are not
       "999".   This  pattern  does not match "foo" preceded by six
       characters, the first of which are digits and the last three
 Line 1713 
 ONCE-ONLY SUBPATTERNS
         ^.*abcd$
-      then the initial .* matches the entire string at first,  but
+      the initial .* matches the entire string at first, but  when
-      when  this  fails  (because  there  is no following "a"), it
+      this  fails  (because  there  is no following "a"), it back-
-      backtracks to match all but the last character, then all but
+      tracks to match all but the last character, then all but the
-      the  last  two  characters, and so on. Once again the search
+      last  two  characters,  and so on. Once again the search for
-      for "a" covers the entire string, from right to left, so  we
+      "a" covers the entire string, from right to left, so we  are
-      are no better off. However, if the pattern is written as
+      no better off. However, if the pattern is written as
         ^(?>.*)(?<=abcd)
-      then there can be no backtracking for the .*  item;  it  can
+      there can be no backtracking for the .* item; it  can  match
-      match  only  the  entire  string.  The subsequent lookbehind
+      only  the entire string. The subsequent lookbehind assertion
-      assertion does a single test on the last four characters. If
+      does a single test on the last four characters. If it fails,
-      it  fails,  the  match  fails immediately. For long strings,
+      the match fails immediately. For long strings, this approach
-      this approach makes a significant difference to the process-
+      makes a significant difference to the processing time.
-      ing time.
       When a pattern contains an unlimited repeat inside a subpat-
       tern  that  can  itself  be  repeated an unlimited number of
-Line 1777 
 CONDITIONAL SUBPATTERNS
+Line 1776 
 CONDITIONAL SUBPATTERNS
       error occurs.
       There are two kinds of condition. If the  text  between  the
-      parentheses  consists  of  a  sequence  of  digits, then the
+      parentheses  consists of a sequence of digits, the condition
-      condition is satisfied if the capturing subpattern  of  that
+      is satisfied if the capturing subpattern of that number  has
-      number  has  previously matched. Consider the following pat-
+      previously  matched.  Consider  the following pattern, which
-      tern, which contains non-significant white space to make  it
+      contains non-significant white space to make it  more  read-
-      more  readable  (assume  the  PCRE_EXTENDED  option)  and to
+      able (assume the PCRE_EXTENDED option) and to divide it into
-      divide it into three parts for ease of discussion:
+      three parts for ease of discussion:
         ( \( )?    [^()]+    (?(1) \) )
-Line 1888 
 RECURSIVE PATTERNS
+Line 1887 
 RECURSIVE PATTERNS
         \( ( ( (?>[^()]+) | (?R) )* ) \)
            ^                        ^
-           ^                        ^ then the string they capture
+           ^                        ^ the string they  capture  is
-      is "ab(cd)ef", the contents of the top level parentheses. If
+      "ab(cd)ef",  the  contents  of the top level parentheses. If
       there are more than 15 capturing parentheses in  a  pattern,
       PCRE  has  to  obtain  extra  memory  to store data during a
       recursion, which it does by using  pcre_malloc,  freeing  it

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