Change 13046 by jhi@alpha on 2001/11/16 14:14:38
Document the negated lookeahead trick to emulate
character class subtraction.
Affected files ...
.... //depot/perl/pod/perlunicode.pod#54 edit
Differences ...
==== //depot/perl/pod/perlunicode.pod#54 (text) ====
Index: perl/pod/perlunicode.pod
--- perl/pod/perlunicode.pod.~1~ Fri Nov 16 07:30:06 2001
+++ perl/pod/perlunicode.pod Fri Nov 16 07:30:06 2001
@@ -632,14 +632,23 @@
[ 1] \x{...}
[ 2] \N{...}
[ 3] . \p{Is...} \P{Is...}
- [ 4] now scripts (see UTR#24 Script Names) in addition to blocks
+ [ 4] now scripts (see UTR#24 Script Names) in addition to blocks
[ 5] have negation
- [ 6] can use look-ahead to emulate subtracion
+ [ 6] can use look-ahead to emulate subtraction (*)
[ 7] include Letters in word characters
[ 8] see UTR#21 Case Mappings: Perl implements 1:1 mappings
[ 9] see UTR#13 Unicode Newline Guidelines
[10] should do ^ and $ also on \x{2028} and \x{2029}
+(*) Instead of [\u0370-\u03FF-[{UNASSIGNED}]] as suggested by the TR
+18 you can use negated lookahead: to match currently assigned modern
+Greek characters use for example
+
+ /(?!\p{Cn})[\x{0370}-\x{03ff}]/
+
+In other words: the matched character must not be a non-assigned
+character, but it must be in the block of modern Greek characters.
+
=item *
Level 2 - Extended Unicode Support
End of Patch.
