Documentation update.
This commit is contained in:
Philip.Hazel
parent
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@ -1762,17 +1762,22 @@ subject string does not happen. The first match attempt is run starting from
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the overall result is "no match".
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</P>
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<P>
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There are also other start-up optimizations. For example, a minimum length for
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the subject may be recorded. Consider the pattern
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As another start-up optimization makes use of a minimum length for a matching
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subject, which is recorded when possible. Consider the pattern
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<pre>
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(*MARK:A)(X|Y)
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(*MARK:1)B(*MARK:2)(X|Y)
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</pre>
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The minimum length for a match is one character. If the subject is "ABC", there
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will be attempts to match "ABC", "BC", and "C". An attempt to match an empty
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string at the end of the subject does not take place, because PCRE2 knows that
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the subject is now too short, and so the (*MARK) is never encountered. In this
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case, the optimization does not affect the overall match result, which is still
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"no match", but it does affect the auxiliary information that is returned.
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The minimum length for a match is two characters. If the subject is "XXBB", the
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"starting character" optimization skips "XX", then tries to match "BB", which
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is long enough. In the process, (*MARK:2) is encountered and remembered. When
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the match attempt fails, the next "B" is found, but there is only one character
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left, so there are no more attempts, and "no match" is returned with the "last
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mark seen" set to "2". If NO_START_OPTIMIZE is set, however, matches are tried
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at every possible starting position, including at the end of the subject, where
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(*MARK:1) is encountered, but there is no "B", so the "last mark seen" that is
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returned is "1". In this case, the optimizations do not affect the overall
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match result, which is still "no match", but they do affect the auxiliary
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information that is returned.
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<pre>
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PCRE2_NO_UTF_CHECK
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</pre>
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@ -3831,7 +3836,7 @@ Cambridge, England.
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</P>
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<br><a name="SEC42" href="#TOC1">REVISION</a><br>
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<P>
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Last updated: 23 May 2019
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Last updated: 30 May 2019
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<br>
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Copyright © 1997-2019 University of Cambridge.
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<br>
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@ -741,13 +741,22 @@ ignored when used with <b>-L</b> (list files without matches), because the grand
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total would always be zero.
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</P>
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<P>
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<b>-u</b>, <b>--utf-8</b>
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<b>-u</b>, <b>--utf</b>
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Operate in UTF-8 mode. This option is available only if PCRE2 has been compiled
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with UTF-8 support. All patterns (including those for any <b>--exclude</b> and
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<b>--include</b> options) and all subject lines that are scanned must be valid
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strings of UTF-8 characters.
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</P>
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<P>
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<b>-U</b>, <b>--utf-allow-invalid</b>
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As <b>--utf</b>, but in addition subject lines may contain invalid UTF-8 code
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unit sequences. These can never form part of any pattern match. This facility
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allows valid UTF-8 strings to be sought in executable or other binary files.
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For more details about matching in non-valid UTF-8 strings, see the
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<a href="pcre2unicode.html"><b>pcre2unicode</b>(3)</a>
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documentation.
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</P>
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<P>
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<b>-V</b>, <b>--version</b>
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Write the version numbers of <b>pcre2grep</b> and the PCRE2 library to the
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standard output and then exit. Anything else on the command line is
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@ -806,9 +815,9 @@ as in the GNU <b>grep</b> program. Any long option of the form
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<b>--file-offsets</b>, <b>--heap-limit</b>, <b>--include-dir</b>,
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<b>--line-offsets</b>, <b>--locale</b>, <b>--match-limit</b>, <b>-M</b>,
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<b>--multiline</b>, <b>-N</b>, <b>--newline</b>, <b>--om-separator</b>,
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<b>--output</b>, <b>-u</b>, and <b>--utf-8</b> options are specific to
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<b>pcre2grep</b>, as is the use of the <b>--only-matching</b> option with a
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capturing parentheses number.
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<b>--output</b>, <b>-u</b>, <b>--utf</b>, <b>-U</b>, and <b>--utf-allow-invalid</b>
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options are specific to <b>pcre2grep</b>, as is the use of the
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<b>--only-matching</b> option with a capturing parentheses number.
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</P>
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<P>
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Although most of the common options work the same way, a few are different in
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@ -971,9 +980,9 @@ Cambridge, England.
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</P>
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<br><a name="SEC16" href="#TOC1">REVISION</a><br>
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<P>
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Last updated: 24 November 2018
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Last updated: 28 May 2019
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<br>
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Copyright © 1997-2018 University of Cambridge.
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Copyright © 1997-2019 University of Cambridge.
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<br>
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<p>
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Return to the <a href="index.html">PCRE2 index page</a>.
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@ -1741,18 +1741,23 @@ COMPILING A PATTERN
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(*COMMIT) prevents any further matches being tried, so the overall
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result is "no match".
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There are also other start-up optimizations. For example, a minimum
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length for the subject may be recorded. Consider the pattern
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As another start-up optimization makes use of a minimum length for a
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matching subject, which is recorded when possible. Consider the pattern
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(*MARK:A)(X|Y)
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(*MARK:1)B(*MARK:2)(X|Y)
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The minimum length for a match is one character. If the subject is
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"ABC", there will be attempts to match "ABC", "BC", and "C". An attempt
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to match an empty string at the end of the subject does not take place,
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because PCRE2 knows that the subject is now too short, and so the
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(*MARK) is never encountered. In this case, the optimization does not
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affect the overall match result, which is still "no match", but it does
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affect the auxiliary information that is returned.
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The minimum length for a match is two characters. If the subject is
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"XXBB", the "starting character" optimization skips "XX", then tries to
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match "BB", which is long enough. In the process, (*MARK:2) is encoun-
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tered and remembered. When the match attempt fails, the next "B" is
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found, but there is only one character left, so there are no more
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attempts, and "no match" is returned with the "last mark seen" set to
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"2". If NO_START_OPTIMIZE is set, however, matches are tried at every
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possible starting position, including at the end of the subject, where
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(*MARK:1) is encountered, but there is no "B", so the "last mark seen"
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that is returned is "1". In this case, the optimizations do not affect
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the overall match result, which is still "no match", but they do affect
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the auxiliary information that is returned.
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PCRE2_NO_UTF_CHECK
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@ -3698,7 +3703,7 @@ AUTHOR
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REVISION
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Last updated: 23 May 2019
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Last updated: 30 May 2019
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Copyright (c) 1997-2019 University of Cambridge.
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------------------------------------------------------------------------------
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@ -1,4 +1,4 @@
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.TH PCRE2API 3 "23 May 2019" "PCRE2 10.34"
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.TH PCRE2API 3 "30 May 2019" "PCRE2 10.34"
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.SH NAME
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PCRE2 - Perl-compatible regular expressions (revised API)
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.sp
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@ -1701,17 +1701,22 @@ subject string does not happen. The first match attempt is run starting from
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"D" and when this fails, (*COMMIT) prevents any further matches being tried, so
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the overall result is "no match".
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.P
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There are also other start-up optimizations. For example, a minimum length for
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the subject may be recorded. Consider the pattern
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As another start-up optimization makes use of a minimum length for a matching
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subject, which is recorded when possible. Consider the pattern
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.sp
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(*MARK:A)(X|Y)
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(*MARK:1)B(*MARK:2)(X|Y)
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.sp
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The minimum length for a match is one character. If the subject is "ABC", there
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will be attempts to match "ABC", "BC", and "C". An attempt to match an empty
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string at the end of the subject does not take place, because PCRE2 knows that
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the subject is now too short, and so the (*MARK) is never encountered. In this
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case, the optimization does not affect the overall match result, which is still
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"no match", but it does affect the auxiliary information that is returned.
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The minimum length for a match is two characters. If the subject is "XXBB", the
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"starting character" optimization skips "XX", then tries to match "BB", which
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is long enough. In the process, (*MARK:2) is encountered and remembered. When
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the match attempt fails, the next "B" is found, but there is only one character
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left, so there are no more attempts, and "no match" is returned with the "last
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mark seen" set to "2". If NO_START_OPTIMIZE is set, however, matches are tried
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at every possible starting position, including at the end of the subject, where
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(*MARK:1) is encountered, but there is no "B", so the "last mark seen" that is
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returned is "1". In this case, the optimizations do not affect the overall
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match result, which is still "no match", but they do affect the auxiliary
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information that is returned.
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.sp
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PCRE2_NO_UTF_CHECK
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.sp
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@ -3843,6 +3848,6 @@ Cambridge, England.
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.rs
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.sp
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.nf
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Last updated: 23 May 2019
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Last updated: 30 May 2019
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Copyright (c) 1997-2019 University of Cambridge.
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.fi
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@ -650,7 +650,7 @@ with UTF-8 support. All patterns (including those for any \fB--exclude\fP and
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\fB--include\fP options) and all subject lines that are scanned must be valid
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strings of UTF-8 characters.
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.TP
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\fb-U\fP, \fB--utf-allow-invalid\fP
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\fB-U\fP, \fB--utf-allow-invalid\fP
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As \fB--utf\fP, but in addition subject lines may contain invalid UTF-8 code
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unit sequences. These can never form part of any pattern match. This facility
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allows valid UTF-8 strings to be sought in executable or other binary files.
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@ -719,13 +719,20 @@ OPTIONS
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(list files without matches), because the grand total would
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always be zero.
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-u, --utf-8
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Operate in UTF-8 mode. This option is available only if PCRE2
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-u, --utf Operate in UTF-8 mode. This option is available only if PCRE2
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has been compiled with UTF-8 support. All patterns (including
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those for any --exclude and --include options) and all sub-
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ject lines that are scanned must be valid strings of UTF-8
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characters.
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-U, --utf-allow-invalid
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As --utf, but in addition subject lines may contain invalid
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UTF-8 code unit sequences. These can never form part of any
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pattern match. This facility allows valid UTF-8 strings to be
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sought in executable or other binary files. For more details
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about matching in non-valid UTF-8 strings, see the pcre2uni-
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code(3) documentation.
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-V, --version
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Write the version numbers of pcre2grep and the PCRE2 library
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to the standard output and then exit. Anything else on the
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@ -785,9 +792,9 @@ OPTIONS COMPATIBILITY
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terminology) is also available as --xxx-regex (PCRE2 terminology). How-
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ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
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--include-dir, --line-offsets, --locale, --match-limit, -M, --multi-
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line, -N, --newline, --om-separator, --output, -u, and --utf-8 options
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are specific to pcre2grep, as is the use of the --only-matching option
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with a capturing parentheses number.
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line, -N, --newline, --om-separator, --output, -u, --utf, -U, and
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--utf-allow-invalid options are specific to pcre2grep, as is the use of
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the --only-matching option with a capturing parentheses number.
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Although most of the common options work the same way, a few are dif-
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ferent in pcre2grep. For example, the --include option's argument is a
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@ -948,5 +955,5 @@ AUTHOR
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REVISION
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Last updated: 24 November 2018
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Copyright (c) 1997-2018 University of Cambridge.
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Last updated: 28 May 2019
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Copyright (c) 1997-2019 University of Cambridge.
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