Make Encode.pm implicitly load external CJK tables the first

time they're needed (instead of immediately), from Autrijus
Tang.

p4raw-id: //depot/perl@15130

diff --git a/ext/Encode/Encode.pm b/ext/Encode/Encode.pm
index 445dd24..a279225 100644 (file)
--- a/ext/Encode/Encode.pm
+++ b/ext/Encode/Encode.pm
@@ -57,6 +57,28 @@ our %winlatin2cp   = (
                      'Vietnamese' => 1258,
                     );
 
+our %external_tables = (
+    'euc-cn'           => 'Encode/CN.pm',
+    gb2312             => 'Encode/CN.pm',
+    gb12345            => 'Encode/CN.pm',
+    gbk                        => 'Encode/CN.pm',
+    cp936              => 'Encode/CN.pm',
+    'iso-ir-165'       => 'Encode/CN.pm',
+    'euc-jp'           => 'Encode/JP.pm',
+    shiftjis           => 'Encode/JP.pm',
+    macjapan           => 'Encode/JP.pm',
+    cp932              => 'Encode/JP.pm',
+    'euc-kr'           => 'Encode/KR.pm',
+    ksc5601            => 'Encode/KR.pm',
+    cp949              => 'Encode/KR.pm',
+    big5               => 'Encode/TW.pm',
+    'big5-hkscs'       => 'Encode/TW.pm',
+    cp950              => 'Encode/TW.pm',
+    gb18030            => 'Encode/CN.pm', # HanExtra
+    big5plus           => 'Encode/TW.pm', # HanExtra
+    'euc-tw',          => 'Encode/TW.pm', # HanExtra
+);
+
 sub encodings
 {
  my ($class) = @_;
@@ -220,6 +242,11 @@ sub getEncoding
     {
        return $encoding{$lc};
     }
+    if (exists $external_tables{$lc})
+    {
+       require $external_tables{$lc};
+       return $encoding{$name} if exists $encoding{$name};
+    }
 
     my $oc = $class->findAlias($name);
     return $oc if defined $oc;
@@ -302,11 +329,6 @@ Encode - character encodings
 
     use Encode;
 
-    use Encode::TW; # for Taiwan-based Chinese encodings
-    use Encode::CN; # for China-based Chinese encodings
-    use Encode::JP; # for Japanese encodings
-    use Encode::KR; # for Korean encodings
-
 =head1 DESCRIPTION
 
 The C<Encode> module provides the interfaces between Perl's strings
@@ -330,9 +352,12 @@ When Perl is processing "binary data" the programmer wants Perl to process
 "sequences of bytes". This is not a problem for Perl - as a byte has 256
 possible values it easily fits in Perl's much larger "logical character".
 
-Due to size concerns, before using B<CJK> (Chinese, Japanese & Korean)
-encodings, you have to C<use> the corresponding
-B<Encode::>(B<TW>|B<CN>|B<JP>|B<KR>) modules first.
+Due to size concerns, each of B<CJK> (Chinese, Japanese & Korean) modules
+are not loaded in memory until the first time they're used. Although you
+don't have to C<use> the corresponding B<Encode::>(B<TW>|B<CN>|B<JP>|B<KR>)
+modules first, be aware that those encodings will not be in C<%encodings>
+until their module is loaded (either implicitly through using encodings
+contained in the same module, or via an explicit C<use>).
 
 =head2 TERMINOLOGY