X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlre.pod;h=bb521139ca5887be64a11ced5c165cf25d2c448a;hb=b31b80f9d91ded188b47dd78c18a0a1effe2584d;hp=c0d4e8955b1c74f7a7864c29dea59fd07d96f883;hpb=491fd90a109f6263a896300e5709e6fd255f075f;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlre.pod b/pod/perlre.pod index c0d4e89..bb52113 100644 --- a/pod/perlre.pod +++ b/pod/perlre.pod @@ -392,11 +392,14 @@ Several special variables also refer back to portions of the previous match. C<$+> returns whatever the last bracket match matched. C<$&> returns the entire matched string. (At one point C<$0> did also, but now it returns the name of the program.) C<$`> returns -everything before the matched string. And C<$'> returns everything -after the matched string. +everything before the matched string. C<$'> returns everything +after the matched string. And C<$^N> contains whatever was matched by +the most-recently closed group (submatch). C<$^N> can be used in +extended patterns (see below), for example to assign a submatch to a +variable. The numbered variables ($1, $2, $3, etc.) and the related punctuation -set (C<$+>, C<$&>, C<$`>, and C<$'>) are all dynamically scoped +set (C<$+>, C<$&>, C<$`>, C<$'>, and C<$^N>) are all dynamically scoped until the end of the enclosing block or until the next successful match, whichever comes first. (See L.) @@ -563,6 +566,14 @@ This zero-width assertion evaluate any embedded Perl code. It always succeeds, and its C is not interpolated. Currently, the rules to determine where the C ends are somewhat convoluted. +This feature can be used together with the special variable C<$^N> to +capture the results of submatches in variables without having to keep +track of the number of nested parentheses. For example: + + $_ = "The brown fox jumps over the lazy dog"; + /the (\S+)(?{ $color = $^N }) (\S+)(?{ $animal = $^N })/i; + print "color = $color, animal = $animal\n"; + The C is properly scoped in the following sense: If the assertion is backtracked (compare L<"Backtracking">), all changes introduced after Cization are undone, so that @@ -873,7 +884,7 @@ multiple ways it might succeed, you need to understand backtracking to know which variety of success you will achieve. When using look-ahead assertions and negations, this can all get even -tricker. Imagine you'd like to find a sequence of non-digits not +trickier. Imagine you'd like to find a sequence of non-digits not followed by "123". You might try to write that as $_ = "ABC123";