X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlre.pod;h=75717293c2c828db5988931ab50dcd77f23b3187;hb=2095dafae09cfface71d4202b3188926ea0ccc1c;hp=a1a118f371ec4d1893b9a432d586a6a55d305a89;hpb=9373385978348b5aad2d5fb3ea78b7db27600a69;p=p5sagit%2Fp5-mst-13.2.git
diff --git a/pod/perlre.pod b/pod/perlre.pod
index a1a118f..7571729 100644
--- a/pod/perlre.pod
+++ b/pod/perlre.pod
@@ -1,52 +1,70 @@
=head1 NAME
+X
Backslashed metacharacters in Perl are alphanumeric, such as C<\b>,
C<\w>, C<\n>. Unlike some other regular expression languages, there
are no backslashed symbols that aren't alphanumeric. So anything
-that looks like \\, \(, \), \E 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 = $animal\n";
+
+Inside the C<(?{...})> block, C<$_> refers to the string the regular
+expression is matching against. You can also use C
is properly scoped in the following sense: If the assertion
is backtracked (compare L<"Backtracking">), all changes introduced after
C
),
+or indirectly with functions such as C is evaluated
at run time, at the moment this subexpression may match. The result
of evaluation is considered as a regular expression and matched as
-if it were inserted instead of this construct.
+if it were inserted instead of this construct. Note that this means
+that the contents of capture buffers defined inside an eval'ed pattern
+are not available outside of the pattern, and vice versa, there is no
+way for the inner pattern to refer to a capture buffer defined outside.
+Thus,
+
+ ('a' x 100)=~/(??{'(.)' x 100})/
+
+B
is not interpolated. As before, the rules to determine
where the C
ends are currently somewhat convoluted.
@@ -586,23 +999,218 @@ The following pattern matches a parenthesized group:
(?:
(?> [^()]+ ) # Non-parens without backtracking
|
- (?p{ $re }) # Group with matching parens
+ (??{ $re }) # Group with matching parens
)*
\)
}x;
-=item C<(?E
),
+or indirectly with functions such as C is a double-quoted string. C<\1> in
+PerlThink, the righthand side of an C is a double-quoted string. C<\1> in
the usual double-quoted string means a control-A. The customary Unix
meaning of C<\1> is kludged in for C. However, if you get into the habit
of doing that, you get yourself into trouble if you then add an C
@@ -974,7 +1876,7 @@ C<${1}000>. The operation of interpolation should not be confused
with the operation of matching a backreference. Certainly they mean two
different things on the I.
-=head2 Repeated patterns matching zero-length substring
+=head2 Repeated Patterns Matching a Zero-length Substring
B