/[pcre]/code/trunk/doc/pcrepattern.3

Diff of /code/trunk/doc/pcrepattern.3

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-revision 175 by ph10,
Mon Jun 11 13:38:38 2007 UTC
+revision 182 by ph10,
Wed Jun 13 15:09:54 2007 UTC
 Line 262 
 following are always recognized:
  .sp
    \ed     any decimal digit
    \eD     any character that is not a decimal digit
+   \eh     any horizontal whitespace character
+   \eH     any character that is not a horizontal whitespace character
    \es     any whitespace character
    \eS     any character that is not a whitespace character
+   \ev     any vertical whitespace character
+   \eV     any character that is not a vertical whitespace character
    \ew     any "word" character
    \eW     any "non-word" character
  .sp
-Line 277 
 there is no character to match.
+Line 281 
 there is no character to match.
  .P
  For compatibility with Perl, \es does not match the VT character (code 11).
  This makes it different from the the POSIX "space" class. The \es characters
- are HT (9), LF (10), FF (12), CR (13), and space (32). (If "use locale;" is
+ are HT (9), LF (10), FF (12), CR (13), and space (32). If "use locale;" is
  included in a Perl script, \es may match the VT character. In PCRE, it never
- does.)
+ does.
+ .P
+ In UTF-8 mode, characters with values greater than 128 never match \ed, \es, or
+ \ew, and always match \eD, \eS, and \eW. This is true even when Unicode
+ character property support is available. These sequences retain their original
+ meanings from before UTF-8 support was available, mainly for efficiency
+ reasons.
+ .P
+ The sequences \eh, \eH, \ev, and \eV are Perl 5.10 features. In contrast to the
+ other sequences, these do match certain high-valued codepoints in UTF-8 mode.
+ The horizontal space characters are:
+ .sp
+   U+0009     Horizontal tab
+   U+0020     Space
+   U+00A0     Non-break space
+   U+1680     Ogham space mark
+   U+180E     Mongolian vowel separator
+   U+2000     En quad
+   U+2001     Em quad
+   U+2002     En space
+   U+2003     Em space
+   U+2004     Three-per-em space
+   U+2005     Four-per-em space
+   U+2006     Six-per-em space
+   U+2007     Figure space
+   U+2008     Punctuation space
+   U+2009     Thin space
+   U+200A     Hair space
+   U+202F     Narrow no-break space
+   U+205F     Medium mathematical space
+   U+3000     Ideographic space
+ .sp
+ The vertical space characters are:
+ .sp
+   U+000A     Linefeed
+   U+000B     Vertical tab
+   U+000C     Formfeed
+   U+000D     Carriage return
+   U+0085     Next line
+   U+2028     Line separator
+   U+2029     Paragraph separator
  .P
  A "word" character is an underscore or any character less than 256 that is a
  letter or digit. The definition of letters and digits is controlled by PCRE's
-Line 295 
 in the
+Line 339 
 in the
  .\"
  page). For example, in a French locale such as "fr_FR" in Unix-like systems,
  or "french" in Windows, some character codes greater than 128 are used for
- accented letters, and these are matched by \ew.
+ accented letters, and these are matched by \ew. The use of locales with Unicode
- .P
+ is discouraged.
- In UTF-8 mode, characters with values greater than 128 never match \ed, \es, or
- \ew, and always match \eD, \eS, and \eW. This is true even when Unicode
- character property support is available. The use of locales with Unicode is
- discouraged.
  .
  .
  .SS "Newline sequences"
  .rs
  .sp
  Outside a character class, the escape sequence \eR matches any Unicode newline
- sequence. This is an extension to Perl. In non-UTF-8 mode \eR is equivalent to
+ sequence. This is a Perl 5.10 feature. In non-UTF-8 mode \eR is equivalent to
  the following:
  .sp
    (?>\er\en|\en|\ex0b|\ef|\er|\ex85)
-Line 961 
 the above patterns match "SUNDAY" as wel
+Line 1001 
 the above patterns match "SUNDAY" as wel
  .SH "DUPLICATE SUBPATTERN NUMBERS"
  .rs
  .sp
  Perl 5.10 introduced a feature whereby each alternative in a subpattern uses
  the same numbers for its capturing parentheses. Such a subpattern starts with
  (?| and is itself a non-capturing subpattern. For example, consider this
  pattern:
  .sp
    (?|(Sat)ur|(Sun))day
  .sp
  Because the two alternatives are inside a (?| group, both sets of capturing
  parentheses are numbered one. Thus, when the pattern matches, you can look
  at captured substring number one, whichever alternative matched. This construct
  is useful when you want to capture part, but not all, of one of a number of
  alternatives. Inside a (?| group, parentheses are numbered as usual, but the
  number is reset at the start of each branch. The numbers of any capturing
  buffers that follow the subpattern start after the highest number used in any
  branch. The following example is taken from the Perl documentation.
  The numbers underneath show in which buffer the captured content will be
  stored.
  .sp
    # before  ---------------branch-reset----------- after
    / ( a )  (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
    # 1            2         2  3        2     3     4
  .sp
  A backreference or a recursive call to a numbered subpattern always refers to
  the first one in the pattern with the given number.
  .P
-Line 1039 
 abbreviation. This pattern (ignoring the
+Line 1079 
 abbreviation. This pattern (ignoring the
    (?<DN>Sat)(?:urday)?
  .sp
  There are five capturing substrings, but only one is ever set after a match.
  (An alternative way of solving this problem is to use a "branch reset"
  subpattern, as described in the previous section.)
  .P
  The convenience function for extracting the data by name returns the substring
-Line 1933 
 Cambridge CB2 3QH, England.
+Line 1973 
 Cambridge CB2 3QH, England.
  .rs
  .sp
  .nf
- Last updated: 11 June 2007
+ Last updated: 13 June 2007
  Copyright (c) 1997-2007 University of Cambridge.
  .fi

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