Regex: Update PCRE to v8.35.
I was über lazy at first, so took libs from SM. But actually it's quite easy to compile, so let's update to latest version \o/.
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Arkshine
@ -1,4 +1,4 @@
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.TH PCRECALLOUT 3 "24 June 2012" "PCRE 8.30"
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.TH PCRECALLOUT 3 "12 November 2013" "PCRE 8.34"
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.SH NAME
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PCRE - Perl-compatible regular expressions
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.SH SYNOPSIS
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@ -41,26 +41,64 @@ it is processed as if it were
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(?C255)A(?C255)((?C255)\ed{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255)
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.sp
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Notice that there is a callout before and after each parenthesis and
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alternation bar. Automatic callouts can be used for tracking the progress of
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pattern matching. The
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alternation bar. If the pattern contains a conditional group whose condition is
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an assertion, an automatic callout is inserted immediately before the
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condition. Such a callout may also be inserted explicitly, for example:
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.sp
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(?(?C9)(?=a)ab|de)
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.sp
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This applies only to assertion conditions (because they are themselves
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independent groups).
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.P
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Automatic callouts can be used for tracking the progress of pattern matching.
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The
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.\" HREF
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\fBpcretest\fP
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.\"
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command has an option that sets automatic callouts; when it is used, the output
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indicates how the pattern is matched. This is useful information when you are
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trying to optimize the performance of a particular pattern.
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.P
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The use of callouts in a pattern makes it ineligible for optimization by the
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just-in-time compiler. Studying such a pattern with the PCRE_STUDY_JIT_COMPILE
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option always fails.
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program has a pattern qualifier (/C) that sets automatic callouts; when it is
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used, the output indicates how the pattern is being matched. This is useful
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information when you are trying to optimize the performance of a particular
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pattern.
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.
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.
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.SH "MISSING CALLOUTS"
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.rs
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.sp
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You should be aware that, because of optimizations in the way PCRE matches
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patterns by default, callouts sometimes do not happen. For example, if the
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pattern is
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You should be aware that, because of optimizations in the way PCRE compiles and
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matches patterns, callouts sometimes do not happen exactly as you might expect.
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.P
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At compile time, PCRE "auto-possessifies" repeated items when it knows that
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what follows cannot be part of the repeat. For example, a+[bc] is compiled as
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if it were a++[bc]. The \fBpcretest\fP output when this pattern is anchored and
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then applied with automatic callouts to the string "aaaa" is:
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.sp
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--->aaaa
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+0 ^ ^
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+1 ^ a+
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+3 ^ ^ [bc]
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No match
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.sp
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This indicates that when matching [bc] fails, there is no backtracking into a+
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and therefore the callouts that would be taken for the backtracks do not occur.
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You can disable the auto-possessify feature by passing PCRE_NO_AUTO_POSSESS
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to \fBpcre_compile()\fP, or starting the pattern with (*NO_AUTO_POSSESS). If
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this is done in \fBpcretest\fP (using the /O qualifier), the output changes to
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this:
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.sp
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--->aaaa
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+0 ^ ^
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+1 ^ a+
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+3 ^ ^ [bc]
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+3 ^ ^ [bc]
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+3 ^ ^ [bc]
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+3 ^^ [bc]
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No match
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.sp
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This time, when matching [bc] fails, the matcher backtracks into a+ and tries
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again, repeatedly, until a+ itself fails.
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.P
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Other optimizations that provide fast "no match" results also affect callouts.
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For example, if the pattern is
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.sp
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ab(?C4)cd
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.sp
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@ -84,11 +122,11 @@ callouts such as the example above are obeyed.
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.rs
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.sp
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During matching, when PCRE reaches a callout point, the external function
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defined by \fIpcre_callout\fP or \fIpcre[16|32]_callout\fP is called
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(if it is set). This applies to both normal and DFA matching. The only
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argument to the callout function is a pointer to a \fBpcre_callout\fP
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or \fBpcre[16|32]_callout\fP block.
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These structures contains the following fields:
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defined by \fIpcre_callout\fP or \fIpcre[16|32]_callout\fP is called (if it is
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set). This applies to both normal and DFA matching. The only argument to the
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callout function is a pointer to a \fBpcre_callout\fP or
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\fBpcre[16|32]_callout\fP block. These structures contains the following
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fields:
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.sp
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int \fIversion\fP;
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int \fIcallout_number\fP;
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@ -119,10 +157,10 @@ automatically generated callouts).
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.P
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The \fIoffset_vector\fP field is a pointer to the vector of offsets that was
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passed by the caller to the matching function. When \fBpcre_exec()\fP or
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\fBpcre[16|32]_exec()\fP is used, the contents can be inspected, in order to extract
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substrings that have been matched so far, in the same way as for extracting
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substrings after a match has completed. For the DFA matching functions, this
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field is not useful.
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\fBpcre[16|32]_exec()\fP is used, the contents can be inspected, in order to
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extract substrings that have been matched so far, in the same way as for
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extracting substrings after a match has completed. For the DFA matching
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functions, this field is not useful.
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.P
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The \fIsubject\fP and \fIsubject_length\fP fields contain copies of the values
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that were passed to the matching function.
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@ -144,8 +182,10 @@ value of \fIcapture_top\fP is one. This is always the case when the DFA
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functions are used, because they do not support captured substrings.
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.P
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The \fIcapture_last\fP field contains the number of the most recently captured
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substring. If no substrings have been captured, its value is -1. This is always
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the case for the DFA matching functions.
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substring. However, when a recursion exits, the value reverts to what it was
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outside the recursion, as do the values of all captured substrings. If no
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substrings have been captured, the value of \fIcapture_last\fP is -1. This is
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always the case for the DFA matching functions.
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.P
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The \fIcallout_data\fP field contains a value that is passed to a matching
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function specifically so that it can be passed back in callouts. It is passed
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@ -173,11 +213,12 @@ help in distinguishing between different automatic callouts, which all have the
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same callout number. However, they are set for all callouts.
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.P
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The \fImark\fP field is present from version 2 of the callout structure. In
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callouts from \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP it contains a pointer to
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the zero-terminated name of the most recently passed (*MARK), (*PRUNE), or
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(*THEN) item in the match, or NULL if no such items have been passed. Instances
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of (*PRUNE) or (*THEN) without a name do not obliterate a previous (*MARK). In
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callouts from the DFA matching functions this field always contains NULL.
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callouts from \fBpcre_exec()\fP or \fBpcre[16|32]_exec()\fP it contains a
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pointer to the zero-terminated name of the most recently passed (*MARK),
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(*PRUNE), or (*THEN) item in the match, or NULL if no such items have been
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passed. Instances of (*PRUNE) or (*THEN) without a name do not obliterate a
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previous (*MARK). In callouts from the DFA matching functions this field always
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contains NULL.
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.
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.
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.SH "RETURN VALUES"
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@ -209,6 +250,6 @@ 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: 24 June 2012
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Copyright (c) 1997-2012 University of Cambridge.
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Last updated: 12 November 2013
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Copyright (c) 1997-2013 University of Cambridge.
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.fi
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