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Diffstat (limited to 'doc/html/pcre2pattern.html')
-rw-r--r-- | doc/html/pcre2pattern.html | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/doc/html/pcre2pattern.html b/doc/html/pcre2pattern.html index 8188a65..ee416e9 100644 --- a/doc/html/pcre2pattern.html +++ b/doc/html/pcre2pattern.html @@ -3758,11 +3758,20 @@ retained in both cases. </P> <P> The remaining verbs act only when a later failure causes a backtrack to -reach them. This means that their effect is confined to the assertion, -because lookaround assertions are atomic. A backtrack that occurs after an -assertion is complete does not jump back into the assertion. Note in particular -that a (*MARK) name that is set in an assertion is not "seen" by an instance of -(*SKIP:NAME) latter in the pattern. +reach them. This means that, for the Perl-compatible assertions, their effect +is confined to the assertion, because Perl lookaround assertions are atomic. A +backtrack that occurs after such an assertion is complete does not jump back +into the assertion. Note in particular that a (*MARK) name that is set in an +assertion is not "seen" by an instance of (*SKIP:NAME) later in the pattern. +</P> +<P> +PCRE2 now supports non-atomic positive assertions, as described in the section +entitled +<a href="#nonatomicassertions"> "Non-atomic assertions"</a> +above. These assertions must be standalone (not used as conditions). They are +not Perl-compatible. For these assertions, a later backtrack does jump back +into the assertion, and therefore verbs such as (*COMMIT) can be triggered by +backtracks from later in the pattern. </P> <P> The effect of (*THEN) is not allowed to escape beyond an assertion. If there @@ -3820,7 +3829,7 @@ Cambridge, England. </P> <br><a name="SEC32" href="#TOC1">REVISION</a><br> <P> -Last updated: 13 July 2019 +Last updated: 28 July 2019 <br> Copyright © 1997-2019 University of Cambridge. <br> |