Revision: 1671
http://vcs.pcre.org/viewvc?view=rev&revision=1671
Author: ph10
Date: 2016-10-23 16:44:15 +0100 (Sun, 23 Oct 2016)
Log Message:
-----------
Document assertion capture limitation.
Modified Paths:
--------------
code/trunk/doc/pcrepattern.3
Modified: code/trunk/doc/pcrepattern.3
===================================================================
--- code/trunk/doc/pcrepattern.3 2016-10-18 15:38:16 UTC (rev 1670)
+++ code/trunk/doc/pcrepattern.3 2016-10-23 15:44:15 UTC (rev 1671)
@@ -1,4 +1,4 @@
-.TH PCREPATTERN 3 "14 October 2016" "PCRE 8.40"
+.TH PCREPATTERN 3 "23 October 2016" "PCRE 8.40"
.SH NAME
PCRE - Perl-compatible regular expressions
.SH "PCRE REGULAR EXPRESSION DETAILS"
@@ -2167,6 +2167,13 @@
capturing is carried out only for positive assertions. (Perl sometimes, but not
always, does do capturing in negative assertions.)
.P
+WARNING: If a positive assertion containing one or more capturing subpatterns
+succeeds, but failure to match later in the pattern causes backtracking over
+this assertion, the captures within the assertion are reset only if no higher
+numbered captures are already set. This is, unfortunately, a fundamental
+limitation of the current implementation, and as PCRE1 is now in
+maintenance-only status, it is unlikely ever to change.
+.P
For compatibility with Perl, assertion subpatterns may be repeated; though
it makes no sense to assert the same thing several times, the side effect of
capturing parentheses may occasionally be useful. In practice, there only three
@@ -3292,6 +3299,6 @@
.rs
.sp
.nf
-Last updated: 14 October 2016
+Last updated: 23 October 2016
Copyright (c) 1997-2016 University of Cambridge.
.fi
