Upgrade to Encode 1.52, from Dan Kogai.

[p5sagit/p5-mst-13.2.git] / ext / Encode / bin / enc2xs

diff --git a/ext/Encode/bin/enc2xs b/ext/Encode/bin/enc2xs
index 9fb57bc..f837a47 100644 (file)
--- a/ext/Encode/bin/enc2xs
+++ b/ext/Encode/bin/enc2xs
@@ -8,7 +8,7 @@ BEGIN {
 use strict;
 use Getopt::Std;
 my @orig_ARGV = @ARGV;
-our $VERSION  = do { my @r = (q$Revision: 1.23 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
+our $VERSION  = do { my @r = (q$Revision: 1.24 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
 
 # These may get re-ordered.
 # RAW is a do_now as inserted by &enter
@@ -1196,9 +1196,9 @@ And finally, END OF CHARMAP ends the section.
 
 =back
 
-Needless to say, if you are manually creating a UCM file, you should
-copy ascii.ucm or existing encoding which is close to yours than write
-your own from scratch. 
+When you are manually creating a UCM file, you should copy ascii.ucm
+or existing encoding which is close to yours than write your own from
+scratch.
 
 When you do so, make sure you leave at least B<U0000> to B<U0020> as
 is, unless your environment is on EBCDIC.
@@ -1209,6 +1209,55 @@ module if you want to support algorithmical encodings, notablly
 ISO-2022 series.  Such modules include L<Encode::JP::2022_JP>,
 L<Encode::KR::2022_KR>, and L<Encode::TW::HZ>.
 
+=head2 Coping with duplicate mappings
+
+When you create a map, you SHOULD make your mappings round-trip safe.
+That is, C<encode('your-encoding', decode('your-encoding', $data)) eq
+$data> stands for all characters that are marked as C<|0>.  Here is
+how to make sure;
+
+=over 2
+
+=item * 
+
+Sort your map in Unicode order.
+
+=item *
+
+When you have a duplicate entry, mark either one with '|1' or '|3'.
+  
+=item * 
+
+And make sure '|1' or '|3' FOLLOWS '|0' entry.
+
+=back
+
+Here is an example from big5-eten.
+
+  <U2550> \xF9\xF9 |0
+  <U2550> \xA2\xA4 |3
+
+Internally Encoding -> Unicode and Unicode -> Encoding Map looks like
+this;
+
+  E to U               U to E
+  --------------------------------------
+  \xF9\xF9 => U2550    U2550 => \xF9\xF9
+  \xA2\xA4 => U2550
+ 
+So it is round-trip safe for \xF9\xF9.  But if the line above is upside
+down, here is what happens.
+
+  E to U               U to E
+  --------------------------------------
+  \xA2\xA4 => U2550    U2550 => \xF9\xF9
+  (\xF9\xF9 => U2550 is now overwritten!)
+
+The Encode package comes with F<ucmlint>, a crude but sufficient
+utility to check the integrity of ucm file.  Check under Encode/bin
+directory for this.
+  
+
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