Revision: 575
http://www.exim.org/viewvc/pcre2?view=rev&revision=575
Author: ph10
Date: 2016-10-23 16:43:42 +0100 (Sun, 23 Oct 2016)
Log Message:
-----------
Document current assert capture limitation.
Modified Paths:
--------------
code/trunk/doc/pcre2pattern.3
Modified: code/trunk/doc/pcre2pattern.3
===================================================================
--- code/trunk/doc/pcre2pattern.3 2016-10-18 15:37:31 UTC (rev 574)
+++ code/trunk/doc/pcre2pattern.3 2016-10-23 15:43:42 UTC (rev 575)
@@ -1,4 +1,4 @@
-.TH PCRE2PATTERN 3 "14 October 2016" "PCRE2 10.23"
+.TH PCRE2PATTERN 3 "23 October 2016" "PCRE2 10.23"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH "PCRE2 REGULAR EXPRESSION DETAILS"
@@ -2222,6 +2222,13 @@
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; it may get removed in a future
+reworking.
+.P
For compatibility with Perl, most 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. However, an assertion that
@@ -3470,6 +3477,6 @@
.rs
.sp
.nf
-Last updated: 14 October 2016
+Last updated: 23 October 2016
Copyright (c) 1997-2016 University of Cambridge.
.fi
