Documentation update.
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Philip.Hazel
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175b4919f7
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@ -355,7 +355,14 @@ characters:
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</PRE>
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</P>
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<P>
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3. Because a partial match must always contain at least one character, what
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3. The maximum lookbehind count is also important when the result of a partial
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match attempt is "no match". In this case, the maximum lookbehind characters
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from the end of the current segment must be retained at the start of the next
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segment, in case the lookbehind is at the start of the pattern. Matching the
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next segment must then start at the appropriate offset.
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</P>
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<P>
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4. Because a partial match must always contain at least one character, what
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might be considered a partial match of an empty string actually gives a "no
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match" result. For example:
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<pre>
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@ -369,7 +376,7 @@ happen if characters from the previous segment are retained. For this reason, a
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when the pattern contains lookbehinds.
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</P>
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<P>
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4. Matching a subject string that is split into multiple segments may not
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5. Matching a subject string that is split into multiple segments may not
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always produce exactly the same result as matching over one single long string,
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especially when PCRE2_PARTIAL_SOFT is used. The section "Partial Matching and
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Word Boundaries" above describes an issue that arises if the pattern ends with
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@ -411,7 +418,7 @@ multi-segment data. The example above then behaves differently:
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data> gsb\=ph,dfa,dfa_restart
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Partial match: gsb
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</pre>
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5. Patterns that contain alternatives at the top level which do not all start
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6. Patterns that contain alternatives at the top level which do not all start
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with the same pattern item may not work as expected when PCRE2_DFA_RESTART is
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used. For example, consider this pattern:
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<pre>
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@ -456,9 +463,9 @@ Cambridge, England.
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</P>
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<br><a name="SEC10" href="#TOC1">REVISION</a><br>
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<P>
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Last updated: 22 December 2014
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Last updated: 21 June 2019
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<br>
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Copyright © 1997-2014 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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@ -2014,8 +2014,10 @@ no characters with a quantifier that has no upper limit, for example:
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</pre>
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Earlier versions of Perl and PCRE1 used to give an error at compile time for
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such patterns. However, because there are cases where this can be useful, such
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patterns are now accepted, but if any repetition of the group does in fact
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match no characters, the loop is forcibly broken.
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patterns are now accepted, but whenever an iteration of such a group matches no
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characters, matching moves on to the next item in the pattern instead of
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repeatedly matching an empty string. This does not prevent backtracking into
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any of the iterations if a subsequent item fails to match.
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</P>
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<P>
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By default, quantifiers are "greedy", that is, they match as much as possible
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@ -2371,6 +2373,10 @@ A lookaround assertion may also appear as the condition in a
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which branch of the condition is followed.
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</P>
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<P>
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Lookaround assertions are atomic. If an assertion is true, but there is a
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subsequent matching failure, there is no backtracking into the assertion.
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</P>
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<P>
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Assertion groups are not capture groups. If an assertion contains capture
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groups within it, these are counted for the purposes of numbering the capture
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groups in the whole pattern. Within each branch of an assertion, locally
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@ -3519,9 +3525,9 @@ first match attempt, the second attempt would start at the second character
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instead of skipping on to "c".
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</P>
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<P>
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If (*SKIP) is used inside a lookbehind to specify a new starting point that is
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not later than the starting point of the current match, it is ignored, and the
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normal "bumpalong" occurs.
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If (*SKIP) is used inside a lookbehind to specify a new starting position that
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is not later than the starting point of the current match, the position
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specified by (*SKIP) is ignored, and instead the normal "bumpalong" occurs.
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<pre>
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(*SKIP:NAME)
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</pre>
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@ -3748,7 +3754,7 @@ Cambridge, England.
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</P>
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<br><a name="SEC31" href="#TOC1">REVISION</a><br>
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<P>
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Last updated: 20 June 2019
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Last updated: 21 June 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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1221
doc/pcre2.txt
1221
doc/pcre2.txt
File diff suppressed because it is too large
Load Diff
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@ -1,4 +1,4 @@
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.TH PCRE2PARTIAL 3 "22 December 2014" "PCRE2 10.00"
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.TH PCRE2PARTIAL 3 "21 June 2019" "PCRE2 10.34"
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.SH NAME
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PCRE2 - Perl-compatible regular expressions
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.SH "PARTIAL MATCHING IN PCRE2"
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@ -326,7 +326,13 @@ characters:
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Partial match: 123ab
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<<<
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.P
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3. Because a partial match must always contain at least one character, what
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3. The maximum lookbehind count is also important when the result of a partial
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match attempt is "no match". In this case, the maximum lookbehind characters
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from the end of the current segment must be retained at the start of the next
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segment, in case the lookbehind is at the start of the pattern. Matching the
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next segment must then start at the appropriate offset.
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.P
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4. Because a partial match must always contain at least one character, what
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might be considered a partial match of an empty string actually gives a "no
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match" result. For example:
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.sp
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@ -339,7 +345,7 @@ happen if characters from the previous segment are retained. For this reason, a
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"no match" result should be interpreted as "partial match of an empty string"
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when the pattern contains lookbehinds.
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.P
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4. Matching a subject string that is split into multiple segments may not
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5. Matching a subject string that is split into multiple segments may not
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always produce exactly the same result as matching over one single long string,
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especially when PCRE2_PARTIAL_SOFT is used. The section "Partial Matching and
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Word Boundaries" above describes an issue that arises if the pattern ends with
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@ -380,7 +386,7 @@ multi-segment data. The example above then behaves differently:
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data> gsb\e=ph,dfa,dfa_restart
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Partial match: gsb
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.sp
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5. Patterns that contain alternatives at the top level which do not all start
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6. Patterns that contain alternatives at the top level which do not all start
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with the same pattern item may not work as expected when PCRE2_DFA_RESTART is
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used. For example, consider this pattern:
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.sp
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@ -429,6 +435,6 @@ Cambridge, England.
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.rs
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.sp
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.nf
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Last updated: 22 December 2014
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Copyright (c) 1997-2014 University of Cambridge.
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Last updated: 21 June 2019
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Copyright (c) 1997-2019 University of Cambridge.
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.fi
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@ -1,4 +1,4 @@
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.TH PCRE2PATTERN 3 "20 June 2019" "PCRE2 10.34"
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.TH PCRE2PATTERN 3 "21 June 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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.SH "PCRE2 REGULAR EXPRESSION DETAILS"
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@ -2022,8 +2022,10 @@ no characters with a quantifier that has no upper limit, for example:
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.sp
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Earlier versions of Perl and PCRE1 used to give an error at compile time for
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such patterns. However, because there are cases where this can be useful, such
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patterns are now accepted, but if any repetition of the group does in fact
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match no characters, the loop is forcibly broken.
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patterns are now accepted, but whenever an iteration of such a group matches no
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characters, matching moves on to the next item in the pattern instead of
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repeatedly matching an empty string. This does not prevent backtracking into
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any of the iterations if a subsequent item fails to match.
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.P
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By default, quantifiers are "greedy", that is, they match as much as possible
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(up to the maximum number of permitted times), without causing the rest of the
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@ -2378,6 +2380,9 @@ conditional group
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(see below). In this case, the result of matching the assertion determines
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which branch of the condition is followed.
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.P
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Lookaround assertions are atomic. If an assertion is true, but there is a
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subsequent matching failure, there is no backtracking into the assertion.
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.P
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Assertion groups are not capture groups. If an assertion contains capture
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groups within it, these are counted for the purposes of numbering the capture
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groups in the whole pattern. Within each branch of an assertion, locally
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@ -3559,9 +3564,9 @@ effect as this example; although it would suppress backtracking during the
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first match attempt, the second attempt would start at the second character
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instead of skipping on to "c".
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.P
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If (*SKIP) is used inside a lookbehind to specify a new starting point that is
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not later than the starting point of the current match, it is ignored, and the
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normal "bumpalong" occurs.
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If (*SKIP) is used inside a lookbehind to specify a new starting position that
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is not later than the starting point of the current match, the position
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specified by (*SKIP) is ignored, and instead the normal "bumpalong" occurs.
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.sp
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(*SKIP:NAME)
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.sp
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@ -3782,6 +3787,6 @@ Cambridge, England.
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.rs
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.sp
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.nf
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Last updated: 20 June 2019
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Last updated: 21 June 2019
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Copyright (c) 1997-2019 University of Cambridge.
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.fi
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