Author: sorear
Date: 2010-05-30 07:07:05 +0200 (Sun, 30 May 2010)
New Revision: 30974
Modified:
docs/Perl6/Spec/S05-regex.pod
Log:
[S05] Describe alternation left-factoring in rules, long implemented by gimme5
Modified: docs/Perl6/Spec/S05-regex.pod
===================================================================
--- docs/Perl6/Spec/S05-regex.pod 2010-05-30 04:27:15 UTC (rev 30973)
+++ docs/Perl6/Spec/S05-regex.pod 2010-05-30 05:07:05 UTC (rev 30974)
@@ -2471,6 +2471,13 @@
considers its "longest token" to be just the left square bracket, because
the first thing the C<expr> rule will do is traverse optional whitespace.
+As an exception to this, and in order to promote readability, a special
+exception is made for alternations inside rules. If an alteration in a
+rule, or any other context where C<:sigspace> is active, has whitespace
+before a group of alternations, then any leading whitespace on the
+alternatives is ignored. That is, C<rule { [ a | b ] }> is treated as
+if it were C<rule { [a |b ] }>, and the LTM match begins with the first
+non-sigspace atom.
The initial token matcher must take into account case sensitivity
(or any other canonicalization primitives) and do the right thing even
