/[pcre]/code/trunk/doc/pcre.txt
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revision 50 by nigel, Sat Feb 24 21:39:33 2007 UTC revision 51 by nigel, Sat Feb 24 21:39:37 2007 UTC
# Line 1462  REPETITION Line 1462  REPETITION
1462    
1463         /* first command */  not comment  /* second comment */         /* first command */  not comment  /* second comment */
1464    
1465       fails, because it matches  the  entire  string  due  to  the       fails, because it matches the entire  string  owing  to  the
1466       greediness of the .*  item.       greediness of the .*  item.
1467    
1468       However, if a quantifier is followed by a question mark,  it       However, if a quantifier is followed by a question mark,  it
# Line 1838  CONDITIONAL SUBPATTERNS Line 1838  CONDITIONAL SUBPATTERNS
1838       There are two kinds of condition. If the  text  between  the       There are two kinds of condition. If the  text  between  the
1839       parentheses  consists of a sequence of digits, the condition       parentheses  consists of a sequence of digits, the condition
1840       is satisfied if the capturing subpattern of that number  has       is satisfied if the capturing subpattern of that number  has
1841       previously  matched.  Consider  the following pattern, which       previously  matched.  The  number must be greater than zero.
1842       contains non-significant white space to make it  more  read-       Consider  the  following  pattern,   which   contains   non-
1843       able (assume the PCRE_EXTENDED option) and to divide it into       significant white space to make it more readable (assume the
1844       three parts for ease of discussion:       PCRE_EXTENDED option) and to divide it into three parts  for
1845         ease of discussion:
1846    
1847         ( \( )?    [^()]+    (?(1) \) )         ( \( )?    [^()]+    (?(1) \) )
1848    
# Line 2001  PERFORMANCE Line 2002  PERFORMANCE
2002       repeat can match 0, 1, 2, 3, or 4 times,  and  for  each  of       repeat can match 0, 1, 2, 3, or 4 times,  and  for  each  of
2003       those  cases other than 0, the + repeats can match different       those  cases other than 0, the + repeats can match different
2004       numbers of times.) When the remainder of the pattern is such       numbers of times.) When the remainder of the pattern is such
2005       that  the  entire  match  is  going  to  fail,  PCRE  has in       that  the entire match is going to fail, PCRE has in princi-
2006       principle to try every possible variation, and this can take       ple to try every possible variation, and this  can  take  an
2007       an extremely long time.       extremely long time.
2008    
2009       An optimization catches some of the more simple  cases  such       An optimization catches some of the more simple  cases  such
2010       as       as
# Line 2105  UTF-8 SUPPORT Line 2106  UTF-8 SUPPORT
2106    
2107       The following UTF-8 features of  Perl  5.6  are  not  imple-       The following UTF-8 features of  Perl  5.6  are  not  imple-
2108       mented:       mented:
   
2109       1. The escape sequence \C to match a single byte.       1. The escape sequence \C to match a single byte.
2110    
2111       2. The use of Unicode tables and properties and escapes  \p,       2. The use of Unicode tables and properties and escapes  \p,
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