50 lines
1.9 KiB
Diff
50 lines
1.9 KiB
Diff
From ee124b6b235a560fc5bfc18cc27e280af7e021d2 Mon Sep 17 00:00:00 2001
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From: ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15>
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Date: Sun, 23 Oct 2016 15:44:15 +0000
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Subject: [PATCH] Document assertion capture limitation.
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1671 2f5784b3-3f2a-0410-8824-cb99058d5e15
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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doc/pcrepattern.3 | 11 +++++++++--
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1 file changed, 9 insertions(+), 2 deletions(-)
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diff --git a/doc/pcrepattern.3 b/doc/pcrepattern.3
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index 1e25371..c221682 100644
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--- a/doc/pcrepattern.3
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+++ b/doc/pcrepattern.3
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@@ -1,4 +1,4 @@
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-.TH PCREPATTERN 3 "14 October 2016" "PCRE 8.40"
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+.TH PCREPATTERN 3 "23 October 2016" "PCRE 8.40"
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.SH NAME
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PCRE - Perl-compatible regular expressions
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.SH "PCRE REGULAR EXPRESSION DETAILS"
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@@ -2167,6 +2167,13 @@ numbering the capturing subpatterns in the whole pattern. However, substring
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capturing is carried out only for positive assertions. (Perl sometimes, but not
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always, does do capturing in negative assertions.)
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.P
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+WARNING: If a positive assertion containing one or more capturing subpatterns
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+succeeds, but failure to match later in the pattern causes backtracking over
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+this assertion, the captures within the assertion are reset only if no higher
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+numbered captures are already set. This is, unfortunately, a fundamental
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+limitation of the current implementation, and as PCRE1 is now in
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+maintenance-only status, it is unlikely ever to change.
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+.P
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For compatibility with Perl, assertion subpatterns may be repeated; though
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it makes no sense to assert the same thing several times, the side effect of
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capturing parentheses may occasionally be useful. In practice, there only three
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@@ -3292,6 +3299,6 @@ Cambridge CB2 3QH, England.
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.rs
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.sp
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.nf
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-Last updated: 14 October 2016
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+Last updated: 23 October 2016
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Copyright (c) 1997-2016 University of Cambridge.
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.fi
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--
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2.7.4
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