/[pcre]/code/trunk/doc/pcrepattern.3
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revision 643 by ph10, Fri Jul 29 15:56:39 2011 UTC revision 654 by ph10, Tue Aug 2 11:00:40 2011 UTC
# Line 220  Perl, $ and @ cause variable interpolati Line 220  Perl, $ and @ cause variable interpolati
220    \eQabc\eE\e$\eQxyz\eE   abc$xyz        abc$xyz    \eQabc\eE\e$\eQxyz\eE   abc$xyz        abc$xyz
221  .sp  .sp
222  The \eQ...\eE sequence is recognized both inside and outside character classes.  The \eQ...\eE sequence is recognized both inside and outside character classes.
223  An isolated \eE that is not preceded by \eQ is ignored. If \eQ is not followed  An isolated \eE that is not preceded by \eQ is ignored. If \eQ is not followed
224  by \eE later in the pattern, the literal interpretation continues to the end of  by \eE later in the pattern, the literal interpretation continues to the end of
225  the pattern (that is, \eE is assumed at the end). If the isolated \eQ is inside  the pattern (that is, \eE is assumed at the end). If the isolated \eQ is inside
226  a character class, this causes an error, because the character class is not  a character class, this causes an error, because the character class is not
227  terminated.  terminated.
# Line 757  Characters with the "mark" property are Line 757  Characters with the "mark" property are
757  preceding character. None of them have codepoints less than 256, so in  preceding character. None of them have codepoints less than 256, so in
758  non-UTF-8 mode \eX matches any one character.  non-UTF-8 mode \eX matches any one character.
759  .P  .P
760  Note that recent versions of Perl have changed \eX to match what Unicode calls  Note that recent versions of Perl have changed \eX to match what Unicode calls
761  an "extended grapheme cluster", which has a more complicated definition.  an "extended grapheme cluster", which has a more complicated definition.
762  .P  .P
763  Matching characters by Unicode property is not fast, because PCRE has to search  Matching characters by Unicode property is not fast, because PCRE has to search
# Line 1836  capturing is carried out only for positi Line 1836  capturing is carried out only for positi
1836  sense for negative assertions.  sense for negative assertions.
1837  .P  .P
1838  For compatibility with Perl, assertion subpatterns may be repeated; though  For compatibility with Perl, assertion subpatterns may be repeated; though
1839  it makes no sense to assert the same thing several times, the side effect of  it makes no sense to assert the same thing several times, the side effect of
1840  capturing parentheses may occasionally be useful. In practice, there only three  capturing parentheses may occasionally be useful. In practice, there only three
1841  cases:  cases:
1842  .sp  .sp
1843  (1) If the quantifier is {0}, the assertion is never obeyed during matching.  (1) If the quantifier is {0}, the assertion is never obeyed during matching.
1844  However, it may contain internal capturing parenthesized groups that are called  However, it may contain internal capturing parenthesized groups that are called
1845  from elsewhere via the  from elsewhere via the
1846  .\" HTML <a href="#subpatternsassubroutines">  .\" HTML <a href="#subpatternsassubroutines">
1847  .\" </a>  .\" </a>
1848  subroutine mechanism.  subroutine mechanism.
1849  .\"  .\"
1850  .sp  .sp
1851  (2) If quantifier is {0,n} where n is greater than zero, it is treated as if it  (2) If quantifier is {0,n} where n is greater than zero, it is treated as if it
1852  were {0,1}. At run time, the rest of the pattern match is tried with and  were {0,1}. At run time, the rest of the pattern match is tried with and
1853  without the assertion, the order depending on the greediness of the quantifier.  without the assertion, the order depending on the greediness of the quantifier.
1854  .sp  .sp
1855  (3) If the minimum repetition is greater than zero, the quantifier is ignored.  (3) If the minimum repetition is greater than zero, the quantifier is ignored.
1856  The assertion is obeyed just once when encountered during matching.  The assertion is obeyed just once when encountered during matching.
1857  .  .
1858  .  .
# Line 2605  indicates which of the two alternatives Line 2605  indicates which of the two alternatives
2605  of obtaining this information than putting each alternative in its own  of obtaining this information than putting each alternative in its own
2606  capturing parentheses.  capturing parentheses.
2607  .P  .P
2608  If (*MARK) is encountered in a positive assertion, its name is recorded and  If (*MARK) is encountered in a positive assertion, its name is recorded and
2609  passed back if it is the last-encountered. This does not happen for negative  passed back if it is the last-encountered. This does not happen for negative
2610  assetions.  assetions.
2611  .P  .P
2612  A name may also be returned after a failed match if the final path through the  A name may also be returned after a failed match if the final path through the

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