--- embedaddon/pcre/doc/pcrematching.3	2012/02/21 23:05:52	1.1
+++ embedaddon/pcre/doc/pcrematching.3	2014/06/15 19:46:05	1.1.1.5
@@ -1,4 +1,4 @@
-.TH PCREMATCHING 3
+.TH PCREMATCHING 3 "12 November 2013" "PCRE 8.34"
 .SH NAME
 PCRE - Perl-compatible regular expressions
 .SH "PCRE MATCHING ALGORITHMS"
@@ -6,12 +6,18 @@ PCRE - Perl-compatible regular expressions
 .sp
 This document describes the two different algorithms that are available in PCRE
 for matching a compiled regular expression against a given subject string. The
-"standard" algorithm is the one provided by the \fBpcre_exec()\fP function.
-This works in the same was as Perl's matching function, and provides a
-Perl-compatible matching operation.
+"standard" algorithm is the one provided by the \fBpcre_exec()\fP,
+\fBpcre16_exec()\fP and \fBpcre32_exec()\fP functions. These work in the same
+as as Perl's matching function, and provide a Perl-compatible matching operation.
+The just-in-time (JIT) optimization that is described in the
+.\" HREF
+\fBpcrejit\fP
+.\"
+documentation is compatible with these functions.
 .P
-An alternative algorithm is provided by the \fBpcre_dfa_exec()\fP function;
-this operates in a different way, and is not Perl-compatible. It has advantages
+An alternative algorithm is provided by the \fBpcre_dfa_exec()\fP,
+\fBpcre16_dfa_exec()\fP and \fBpcre32_dfa_exec()\fP functions; they operate in
+a different way, and are not Perl-compatible. This alternative has advantages
 and disadvantages compared with the standard algorithm, and these are described
 below.
 .P
@@ -28,6 +34,7 @@ is matched against the string
 there are three possible answers. The standard algorithm finds only one of
 them, whereas the alternative algorithm finds all three.
 .
+.
 .SH "REGULAR EXPRESSIONS AS TREES"
 .rs
 .sp
@@ -38,6 +45,7 @@ string (from a given starting point) can be thought of
 There are two ways to search a tree: depth-first and breadth-first, and these
 correspond to the two matching algorithms provided by PCRE.
 .
+.
 .SH "THE STANDARD MATCHING ALGORITHM"
 .rs
 .sp
@@ -63,6 +71,7 @@ straightforward for this algorithm to keep track of th
 matched by portions of the pattern in parentheses. This provides support for
 capturing parentheses and back references.
 .
+.
 .SH "THE ALTERNATIVE MATCHING ALGORITHM"
 .rs
 .sp
@@ -97,6 +106,14 @@ the three strings "caterpillar", "cater", and "cat" th
 character of the subject. The algorithm does not automatically move on to find
 matches that start at later positions.
 .P
+PCRE's "auto-possessification" optimization usually applies to character
+repeats at the end of a pattern (as well as internally). For example, the
+pattern "a\ed+" is compiled as if it were "a\ed++" because there is no point
+even considering the possibility of backtracking into the repeated digits. For
+DFA matching, this means that only one possible match is found. If you really
+do want multiple matches in such cases, either use an ungreedy repeat
+("a\ed+?") or set the PCRE_NO_AUTO_POSSESS option when compiling.
+.P
 There are a number of features of PCRE regular expressions that are not
 supported by the alternative matching algorithm. They are as follows:
 .P
@@ -131,14 +148,15 @@ and not on others), is not supported. It causes an err
 6. Callouts are supported, but the value of the \fIcapture_top\fP field is
 always 1, and the value of the \fIcapture_last\fP field is always -1.
 .P
-7. The \eC escape sequence, which (in the standard algorithm) matches a single
-byte, even in UTF-8 mode, is not supported in UTF-8 mode, because the
-alternative algorithm moves through the subject string one character at a time,
-for all active paths through the tree.
+7. The \eC escape sequence, which (in the standard algorithm) always matches a
+single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is not supported in
+these modes, because the alternative algorithm moves through the subject string
+one character (not data unit) at a time, for all active paths through the tree.
 .P
 8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not
 supported. (*FAIL) is supported, and behaves like a failing negative assertion.
 .
+.
 .SH "ADVANTAGES OF THE ALTERNATIVE ALGORITHM"
 .rs
 .sp
@@ -150,11 +168,11 @@ match using the standard algorithm, you have to do klu
 callouts.
 .P
 2. Because the alternative algorithm scans the subject string just once, and
-never needs to backtrack, it is possible to pass very long subject strings to
-the matching function in several pieces, checking for partial matching each
-time. Although it is possible to do multi-segment matching using the standard
-algorithm (\fBpcre_exec()\fP), by retaining partially matched substrings, it is
-more complicated. The
+never needs to backtrack (except for lookbehinds), it is possible to pass very
+long subject strings to the matching function in several pieces, checking for
+partial matching each time. Although it is possible to do multi-segment
+matching using the standard algorithm by retaining partially matched
+substrings, it is more complicated. The
 .\" HREF
 \fBpcrepartial\fP
 .\"
@@ -191,6 +209,6 @@ Cambridge CB2 3QH, England.
 .rs
 .sp
 .nf
-Last updated: 19 November 2011
-Copyright (c) 1997-2010 University of Cambridge.
+Last updated: 12 November 2013
+Copyright (c) 1997-2012 University of Cambridge.
 .fi