--- embedaddon/pcre/doc/pcrepartial.3	2012/02/21 23:50:25	1.1.1.2
+++ embedaddon/pcre/doc/pcrepartial.3	2012/10/09 09:19:17	1.1.1.3
@@ -1,4 +1,4 @@
-.TH PCREPARTIAL 3
+.TH PCREPARTIAL 3 "24 February 2012" "PCRE 8.31"
 .SH NAME
 PCRE - Perl-compatible regular expressions
 .SH "PARTIAL MATCHING IN PCRE"
@@ -32,9 +32,18 @@ or not a partial match is preferred to an alternative 
 the details differ between the two types of matching function. If both options
 are set, PCRE_PARTIAL_HARD takes precedence.
 .P
-Setting a partial matching option disables the use of any just-in-time code
-that was set up by studying the compiled pattern with the
-PCRE_STUDY_JIT_COMPILE option. It also disables two of PCRE's standard
+If you want to use partial matching with just-in-time optimized code, you must
+call \fBpcre_study()\fP or \fBpcre16_study()\fP with one or both of these
+options:
+.sp
+  PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+  PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+.sp
+PCRE_STUDY_JIT_COMPILE should also be set if you are going to run non-partial
+matches on the same pattern. If the appropriate JIT study mode has not been set
+for a match, the interpretive matching code is used.
+.P
+Setting a partial matching option disables two of PCRE's standard
 optimizations. PCRE remembers the last literal data unit in a pattern, and
 abandons matching immediately if it is not present in the subject string. This
 optimization cannot be used for a subject string that might match only
@@ -293,14 +302,16 @@ treat the end of a segment as the end of the subject w
 .sp
 At this stage, an application could discard the text preceding "23ja", add on
 text from the next segment, and call the matching function again. Unlike the
-DFA matching functions the entire matching string must always be available, and
-the complete matching process occurs for each call, so more memory and more
+DFA matching functions, the entire matching string must always be available,
+and the complete matching process occurs for each call, so more memory and more
 processing time is needed.
 .P
 \fBNote:\fP If the pattern contains lookbehind assertions, or \eK, or starts
 with \eb or \eB, the string that is returned for a partial match includes
 characters that precede the partially matched string itself, because these must
 be retained when adding on more characters for a subsequent matching attempt.
+However, in some cases you may need to retain even earlier characters, as
+discussed in the next section.
 .
 .
 .SH "ISSUES WITH MULTI-SEGMENT MATCHING"
@@ -315,14 +326,31 @@ beginning of a line. There is also a PCRE_NOTEOL optio
 doing multi-segment matching you should be using PCRE_PARTIAL_HARD, which
 includes the effect of PCRE_NOTEOL.
 .P
-2. Lookbehind assertions at the start of a pattern are catered for in the
-offsets that are returned for a partial match. However, in theory, a lookbehind
-assertion later in the pattern could require even earlier characters to be
-inspected, and it might not have been reached when a partial match occurs. This
-is probably an extremely unlikely case; you could guard against it to a certain
-extent by always including extra characters at the start.
+2. Lookbehind assertions that have already been obeyed are catered for in the
+offsets that are returned for a partial match. However a lookbehind assertion
+later in the pattern could require even earlier characters to be inspected. You
+can handle this case by using the PCRE_INFO_MAXLOOKBEHIND option of the
+\fBpcre_fullinfo()\fP or \fBpcre16_fullinfo()\fP functions to obtain the length
+of the largest lookbehind in the pattern. This length is given in characters,
+not bytes. If you always retain at least that many characters before the
+partially matched string, all should be well. (Of course, near the start of the
+subject, fewer characters may be present; in that case all characters should be
+retained.)
 .P
-3. Matching a subject string that is split into multiple segments may not
+3. Because a partial match must always contain at least one character, what
+might be considered a partial match of an empty string actually gives a "no
+match" result. For example:
+.sp
+    re> /c(?<=abc)x/
+  data> ab\eP
+  No match
+.sp
+If the next segment begins "cx", a match should be found, but this will only
+happen if characters from the previous segment are retained. For this reason, a
+"no match" result should be interpreted as "partial match of an empty string"
+when the pattern contains lookbehinds.
+.P
+4. Matching a subject string that is split into multiple segments may not
 always produce exactly the same result as matching over one single long string,
 especially when PCRE_PARTIAL_SOFT is used. The section "Partial Matching and
 Word Boundaries" above describes an issue that arises if the pattern ends with
@@ -363,7 +391,7 @@ multi-segment data. The example above then behaves dif
   data> gsb\eR\eP\eP\eD
   Partial match: gsb
 .sp
-4. Patterns that contain alternatives at the top level which do not all start
+5. Patterns that contain alternatives at the top level which do not all start
 with the same pattern item may not work as expected when PCRE_DFA_RESTART is
 used. For example, consider this pattern:
 .sp
@@ -412,6 +440,6 @@ Cambridge CB2 3QH, England.
 .rs
 .sp
 .nf
-Last updated: 21 January 2012
+Last updated: 24 February 2012
 Copyright (c) 1997-2012 University of Cambridge.
 .fi