-#!../../../perl -w
+#!./perl
BEGIN {
- # fiddle with @INC iff I am a part of perl dist
- if ($^X =~ m/\bminiperl$/o){
- warn "Fixing \@INC for perl core.\n";
- unshift @INC, qw(../../lib ../../../lib ../../../../lib);
- $ENV{PATH} .= ';../..;../../..;../../../..' if $^O eq 'MSWin32';
- }
+ # @INC poking no longer needed w/ new MakeMaker and Makefile.PL's
+ # with $ENV{PERL_CORE} set
+ # In case we need it in future...
+ require Config; import Config;
}
use strict;
use Getopt::Std;
my @orig_ARGV = @ARGV;
-our $VERSION = do { my @r = (q$Revision: 1.1 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
-
+our $VERSION = do { my @r = (q$Revision: 1.30 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
# These may get re-ordered.
# RAW is a do_now as inserted by &enter
# AGG is an aggreagated do_now, as built up by &process
+
use constant {
RAW_NEXT => 0,
RAW_IN_LEN => 1,
AGG_OUT_LEN => 5,
AGG_FALLBACK => 6,
};
+
# (See the algorithm in encengine.c - we're building structures for it)
# There are two sorts of structures.
# -o <output> to specify the output file name (else it's the first arg)
# -f <inlist> to give a file with a list of input files (else use the args)
# -n <name> to name the encoding (else use the basename of the input file.
-getopts('M:SQqOo:f:n:',\%opt);
+getopts('CM:SQqOo:f:n:',\%opt);
$opt{M} and make_makefile_pl($opt{M}, @ARGV);
+$opt{C} and make_configlocal_pm($opt{C}, @ARGV);
# This really should go first, else the die here causes empty (non-erroneous)
# output files to be written.
if ($cname =~ /\.(c|xs)$/)
{
$doC = 1;
- $dname =~ s/(\.[^\.]*)?$/_def.h/;
+ $dname =~ s/(\.[^\.]*)?$/.exh/;
chmod(0666,$dname) if -f $cname && !-w $dname;
open(D,">$dname") || die "Cannot open $dname:$!";
$hname =~ s/(\.[^\.]*)?$/.h/;
my ($e2u,$u2e,$erep,$min_el,$max_el) = @{$encoding{$name}};
output(\*C,$name.'_utf8',$e2u);
output(\*C,'utf8_'.$name,$u2e);
- push(@{$encoding{$name}},outstring(\*C,$e2u->{Cname}.'_def',$erep));
+ # push(@{$encoding{$name}},outstring(\*C,$e2u->{Cname}.'_def',$erep));
}
foreach my $enc (sort cmp_name keys %encoding)
{
- my ($e2u,$u2e,$rep,$min_el,$max_el,$rsym) = @{$encoding{$enc}};
- my @info = ($e2u->{Cname},$u2e->{Cname},$rsym,length($rep),$min_el,$max_el);
+ # my ($e2u,$u2e,$rep,$min_el,$max_el,$rsym) = @{$encoding{$enc}};
+ my ($e2u,$u2e,$rep,$min_el,$max_el) = @{$encoding{$enc}};
+ #my @info = ($e2u->{Cname},$u2e->{Cname},$rsym,length($rep),$min_el,$max_el);
+ my $replen = 0;
+ $replen++ while($rep =~ /\G\\x[0-9A-Fa-f]/g);
+ my @info = ($e2u->{Cname},$u2e->{Cname},qq((U8 *)"$rep"),$replen,$min_el,$max_el);
my $sym = "${enc}_encoding";
$sym =~ s/\W+/_/g;
print C "encode_t $sym = \n";
+ # This is to make null encoding work -- dankogai
+ for (my $i = (scalar @info) - 1; $i >= 0; --$i){
+ $info[$i] ||= 1;
+ }
+ # end of null tweak -- dankogai
print C " {",join(',',@info,"{\"$enc\",(const char *)0}"),"};\n\n";
}
my $min_el;
if (exists $attr{'subchar'})
{
- my @byte;
- $attr{'subchar'} =~ /^\s*/cg;
- push(@byte,$1) while $attr{'subchar'} =~ /\G\\x([0-9a-f]+)/icg;
- $erep = join('',map(chr(hex($_)),@byte));
+ #my @byte;
+ #$attr{'subchar'} =~ /^\s*/cg;
+ #push(@byte,$1) while $attr{'subchar'} =~ /\G\\x([0-9a-f]+)/icg;
+ #$erep = join('',map(chr(hex($_)),@byte));
+ $erep = $attr{'subchar'};
+ $erep =~ s/^\s+//; $erep =~ s/\s+$//;
}
print "Reading $name ($cs)\n";
my $nfb = 0;
s/#.*$//;
last if /^\s*END\s+CHARMAP\s*$/i;
next if /^\s*$/;
- my ($u,@byte);
- my $fb = '';
- $u = $1 if (/^<U([0-9a-f]+)>\s+/igc);
- push(@byte,$1) while /\G\\x([0-9a-f]+)/igc;
- $fb = $1 if /\G\s*(\|[0-3])/gc;
- # warn "$_: $u @byte | $fb\n";
- die "Bad line:$_" unless /\G\s*(#.*)?$/gc;
- if (defined($u))
+ my (@uni, @byte) = ();
+ my ($uni, $byte, $fb) = m/^(\S+)\s+(\S+)\s+(\S+)\s+/o
+ or die "Bad line: $_";
+ while ($uni =~ m/\G<([U0-9a-fA-F\+]+)>/g){
+ push @uni, map { substr($_, 1) } split(/\+/, $1);
+ }
+ while ($byte =~ m/\G\\x([0-9a-fA-F]+)/g){
+ push @byte, $1;
+ }
+ if (@uni)
{
- my $uch = encode_U(hex($u));
+ my $uch = join('', map { encode_U(hex($_)) } @uni );
my $ech = join('',map(chr(hex($_)),@byte));
my $el = length($ech);
$max_el = $el if (!defined($max_el) || $el > $max_el);
}
if ($a->{'Forward'})
{
- print $fh "\nstatic encpage_t $name\[",scalar(@{$a->{'Entries'}}),"];\n";
+ my $var = $^O eq 'MacOS' ? 'extern' : 'static';
+ print $fh "\n$var encpage_t $name\[",scalar(@{$a->{'Entries'}}),"];\n";
}
$a->{'Done'} = 1;
foreach my $b (@{$a->{'Entries'}})
foreach my $b (@{$a->{'Entries'}})
{
my ($sc,$ec,$out,$t,$end,$l,$fb) = @$b;
- $end |= 0x80 if $fb;
+ # $end |= 0x80 if $fb; # what the heck was on your mind, Nick? -- Dan
print $fh "{";
if ($l)
{
print $fh "END CHARMAP\n";
}
+use vars qw(
+ $_Enc2xs
+ $_Version
+ $_Inc
+ $_E2X
+ $_Name
+ $_TableFiles
+ $_Now
+);
+
+sub find_e2x{
+ eval { require File::Find };
+ my (@inc, %e2x_dir);
+ for my $inc (@INC){
+ push @inc, $inc unless $inc eq '.'; #skip current dir
+ }
+ File::Find::find(
+ sub {
+ my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
+ $atime,$mtime,$ctime,$blksize,$blocks)
+ = lstat($_) or return;
+ -f _ or return;
+ if (/^.*\.e2x$/o){
+ $e2x_dir{$File::Find::dir} ||= $mtime;
+ }
+ return;
+ }, @inc);
+ warn join("\n", keys %e2x_dir), "\n";
+ for my $d (sort {$e2x_dir{$a} <=> $e2x_dir{$b}} keys %e2x_dir){
+ $_E2X = $d;
+ # warn "$_E2X => ", scalar localtime($e2x_dir{$d});
+ return $_E2X;
+ }
+}
+
sub make_makefile_pl
{
eval { require Encode; };
$@ and die "You need to install Encode to use enc2xs -M\nerror: $@\n";
- eval { require File::Basename; };
- $@ and die "File::Basename needed. Are you on miniperl?;\nerror: $@\n";
- File::Basename->import();
- my $inc = dirname($INC{"Encode/Internal.pm"});
- my $name = shift;
- my $table_files = join(",", map {qq('$_')} @_);
- my $now = scalar localtime();
- open my $fh, ">Makefile.PL" or die "$!";
- print $fh <<"END_OF_HEADER";
-#
-# This file is auto-generated by:
-# $0
-# $now
-#
-use 5.7.2;
-use strict;
-use ExtUtils::MakeMaker;
-
-# Please edit the following to the taste!
-my \$name = '$name';
-my \%tables = (
- encode_t => [ $table_files ],
- );
-
-# And leave the rest!
-my \$enc2xs = '$0';
-WriteMakefile(
- INC => "-I$inc",
-END_OF_HEADER
-
- print $fh <<'END_OF_MAKEFILE_PL';
- NAME => 'Encode::'.$name,
- VERSION_FROM => "$name.pm",
- OBJECT => '$(O_FILES)',
- 'dist' => {
- COMPRESS => 'gzip -9f',
- SUFFIX => 'gz',
- DIST_DEFAULT => 'all tardist',
- },
- MAN3PODS => {},
- # OS 390 winges about line numbers > 64K ???
- XSOPT => '-nolinenumbers',
- );
-
-package MY;
-
-sub post_initialize
+ # our used for variable expanstion
+ $_Enc2xs = $0;
+ $_Version = $VERSION;
+ $_E2X = find_e2x();
+ $_Name = shift;
+ $_TableFiles = join(",", map {qq('$_')} @_);
+ $_Now = scalar localtime();
+
+ eval { require File::Spec; };
+ _print_expand(File::Spec->catfile($_E2X,"Makefile_PL.e2x"),"Makefile.PL");
+ _print_expand(File::Spec->catfile($_E2X,"_PM.e2x"), "$_Name.pm");
+ _print_expand(File::Spec->catfile($_E2X,"_T.e2x"), "t/$_Name.t");
+ _print_expand(File::Spec->catfile($_E2X,"README.e2x"), "README");
+ _print_expand(File::Spec->catfile($_E2X,"Changes.e2x"), "Changes");
+ exit;
+}
+
+use vars qw(
+ $_ModLines
+ $_LocalVer
+ );
+
+sub make_configlocal_pm
{
- my ($self) = @_;
- my %o;
- my $x = $self->{'OBJ_EXT'};
- # Add the table O_FILES
- foreach my $e (keys %tables)
- {
- $o{$e.$x} = 1;
- }
- $o{"$name$x"} = 1;
- $self->{'O_FILES'} = [sort keys %o];
- my @files = ("$name.xs");
- $self->{'C'} = ["$name.c"];
- # $self->{'H'} = [$self->catfile($self->updir,'encode.h')];
- my %xs;
- foreach my $table (keys %tables) {
- push (@{$self->{'C'}},"$table.c");
- # Do NOT add $table.h etc. to H_FILES unless we own up as to how they
- # get built.
- foreach my $ext (qw($(OBJ_EXT) .c .h _def.h .fnm)) {
- push (@files,$table.$ext);
+ eval { require Encode; };
+ $@ and die "Unable to require Encode: $@\n";
+ eval { require File::Spec; };
+ # our used for variable expanstion
+ my %in_core = map {$_=>1}('ascii','iso-8859-1','utf8');
+ my %LocalMod = ();
+ for my $d (@INC){
+ my $inc = File::Spec->catfile($d, "Encode");
+ -d $inc or next;
+ opendir my $dh, $inc or die "$inc:$!";
+ warn "Checking $inc...\n";
+ for my $f (grep /\.pm$/o, readdir($dh)){
+ -f File::Spec->catfile($inc, "$f") or next;
+ $INC{"Encode/$f"} and next;
+ warn "require Encode/$f;\n";
+ eval { require "Encode/$f"; };
+ $@ and die "Can't require Encode/$f: $@\n";
+ for my $enc (Encode->encodings()){
+ $in_core{$enc} and next;
+ $Encode::Config::ExtModule{$enc} and next;
+ my $mod = "Encode/$f";
+ $mod =~ s/\.pm$//o; $mod =~ s,/,::,og;
+ $LocalMod{$enc} ||= $mod;
+ }
}
}
- $self->{'XS'} = { "$name.xs" => "$name.c" };
- $self->{'clean'}{'FILES'} .= join(' ',@files);
- open(XS,">$name.xs") || die "Cannot open $name.xs:$!";
- print XS <<'END';
-#include <EXTERN.h>
-#include <perl.h>
-#include <XSUB.h>
-#define U8 U8
-#include "encode.h"
-END
- foreach my $table (keys %tables) {
- print XS qq[#include "${table}.h"\n];
+ $_ModLines = "";
+ for my $enc (sort keys %LocalMod){
+ $_ModLines .=
+ qq(\$Encode::ExtModule{'$enc'} =\t"$LocalMod{$enc}";\n);
}
- print XS <<"END";
-
-static void
-Encode_XSEncoding(pTHX_ encode_t *enc)
-{
- dSP;
- HV *stash = gv_stashpv("Encode::XS", TRUE);
- SV *sv = sv_bless(newRV_noinc(newSViv(PTR2IV(enc))),stash);
- int i = 0;
- PUSHMARK(sp);
- XPUSHs(sv);
- while (enc->name[i])
- {
- const char *name = enc->name[i++];
- XPUSHs(sv_2mortal(newSVpvn(name,strlen(name))));
- }
- PUTBACK;
- call_pv("Encode::define_encoding",G_DISCARD);
- SvREFCNT_dec(sv);
+ warn $_ModLines;
+ $_LocalVer = _mkversion();
+ $_E2X = find_e2x();
+ $_Inc = $INC{"Encode.pm"}; $_Inc =~ s/\.pm$//o;
+ _print_expand(File::Spec->catfile($_E2X,"ConfigLocal_PM.e2x"),
+ File::Spec->catfile($_Inc,"ConfigLocal.pm"),
+ 1);
+ exit;
}
-MODULE = Encode::$name PACKAGE = Encode::$name
-PROTOTYPES: DISABLE
-BOOT:
-{
-END
- foreach my $table (keys %tables) {
- print XS qq[#include "${table}_def.h"\n];
- }
- print XS "}\n";
- close(XS);
- return "# Built $name.xs\n\n";
+sub _mkversion{
+ my ($ss,$mm,$hh,$dd,$mo,$yyyy) = localtime();
+ $yyyy += 1900, $mo +=1;
+ return sprintf("v%04d.%04d.%04d", $yyyy, $mo*100+$dd, $hh*100+$mm);
}
-sub postamble
-{
- my $self = shift;
- my $dir = "."; # $self->catdir('Encode');
- my $str = "# $name\$(OBJ_EXT) depends on .h and _def.h files not .c files - but all written by enc2xs\n";
- $str .= "$name.c : $name.xs ";
- foreach my $table (keys %tables)
- {
- $str .= " $table.c";
+sub _print_expand{
+ eval { require File::Basename; };
+ $@ and die "File::Basename needed. Are you on miniperl?;\nerror: $@\n";
+ File::Basename->import();
+ my ($src, $dst, $clobber) = @_;
+ if (!$clobber and -e $dst){
+ warn "$dst exists. skipping\n";
+ return;
}
- $str .= "\n\n";
- $str .= "$name\$(OBJ_EXT) : $name.c\n\n";
-
- foreach my $table (keys %tables)
- {
- my $numlines = 1;
- my $lengthsofar = length($str);
- my $continuator = '';
- $str .= "$table.c : Makefile.PL";
- foreach my $file (@{$tables{$table}})
- {
- $str .= $continuator.' '.$self->catfile($dir,$file);
- if ( length($str)-$lengthsofar > 128*$numlines )
- {
- $continuator .= " \\\n\t";
- $numlines++;
- } else {
- $continuator = '';
- }
- }
- $str .= $^O eq 'VMS' # In VMS quote to preserve case
- ? qq{\n\t\$(PERL) $enc2xs -"Q" -"O" -o \$\@ -f $table.fnm\n\n}
- : qq{\n\t\$(PERL) $enc2xs -Q -O -o \$\@ -f $table.fnm\n\n};
- open (FILELIST, ">$table.fnm")
- || die "Could not open $table.fnm: $!";
- foreach my $file (@{$tables{$table}})
- {
- print FILELIST $self->catfile($dir,$file) . "\n";
- }
- close(FILELIST);
+ warn "Generating $dst...\n";
+ open my $in, $src or die "$src : $!";
+ if ((my $d = dirname($dst)) ne '.'){
+ -d $d or mkdir $d, 0755 or die "mkdir $d : $!";
+ }
+ open my $out, ">$dst" or die "$!";
+ my $asis = 0;
+ while (<$in>){
+ if (/^#### END_OF_HEADER/){
+ $asis = 1; next;
+ }
+ s/(\$_[A-Z][A-Za-z0-9]+)_/$1/gee unless $asis;
+ print $out $_;
}
- return $str;
}
-END_OF_MAKEFILE_PL
- close $fh;
- (my $pm =<<"END_OF_PM") =~ s/^# //gm;
-# package Encode::$name;
-# our \$VERSION = "0.01";
-#
-# use Encode;
-# use XSLoader;
-# XSLoader::load('Encode::$name', \$VERSION);
-#
-# 1;
-# __END__
-#
-# =head1 NAME
-#
-# Encode::$name - New Encoding
-#
-# =head1 SYNOPSIS
-#
-# You got to fill this in!
-#
-# =head1 SEE ALSO
-#
-# L<Encode>
-#
-# =cut
-END_OF_PM
- open $fh, ">$name.pm" or die "$name.pm:$!";
- print $fh $pm;
- close $fh;
- -d 't' or mkdir 't', 0755 or die "mkdir t:$!";
- open $fh, ">t/$name.t" or die "t/$name.t:$!";
-print $fh <<"END_OF_TEST";
-use strict;
-# Adjust the number here!
-use Test::More tests => 2;
-
-use_ok('Encode');
-use_ok('Encode::$name');
-# Add more test here!
-END_OF_TEST
- close $fh;
- exit;
-}
-
__END__
=head1 NAME
=head1 SYNOPSIS
- enc2xs -M ModName mapfiles...
enc2xs -[options]
+ enc2xs -M ModName mapfiles...
+ enc2xs -C
=head1 DESCRIPTION
F<enc2xs> builds a Perl extension for use by Encode from either
-Unicode Character Mapping files (.ucm) or Tcl Encoding Files
-(.enc) Besides internally used during the build process of Encode
-module, you can use F<enc2xs> to add your own encoding to perl. No
-knowledge on XS is necessary.
+Unicode Character Mapping files (.ucm) or Tcl Encoding Files (.enc).
+Besides being used internally during the build process of the Encode
+module, you can use F<enc2xs> to add your own encoding to perl.
+No knowledge of XS is necessary.
=head1 Quick Guide
-If what you want to know as little about Perl possible but needs to
+If you want to know as little about Perl as possible but need to
add a new encoding, just read this chapter and forget the rest.
=over 4
=item 0.
-Have a .ucm file ready. You can get it from somewhere or you can
-write your own from scratch or you can grab one from Encode
-distribution and customize. For UCM format, see the next Chapter.
-In the example below, I'll call my theoretical encoding myascii,
-defined inI<my.ucm>. C<$> is a shell prompt.
+Have a .ucm file ready. You can get it from somewhere or you can write
+your own from scratch or you can grab one from the Encode distribution
+and customize it. For the UCM format, see the next Chapter. In the
+example below, I'll call my theoretical encoding myascii, defined
+in I<my.ucm>. C<$> is a shell prompt.
$ ls -F
my.ucm
Issue a command as follows;
$ enc2xs -M My my.ucm
+ generating Makefile.PL
+ generating My.pm
+ generating README
+ generating Changes
Now take a look at your current directory. It should look like this.
$ ls -F
Makefile.PL My.pm my.ucm t/
-The following files are created.
+The following files were created.
- Makefle.PL - MakeMaker script
- My.pm - Encode Submodule
- t/My.t - test file
+ Makefile.PL - MakeMaker script
+ My.pm - Encode submodule
+ t/My.t - test file
+
+=over 4
=item 1.1.
$ mv *.ucm Encode
$ enc2xs -M My Encode/*ucm
+=back
+
=item 2.
Edit the files generated. You don't have to if you have no time AND no
intention to give it to someone else. But it is a good idea to edit
-pod and add more tests.
+the pod and to add more tests.
=item 3.
-Now issue a command all Perl Mongers love;
+Now issue a command all Perl Mongers love:
- $ perl5.7.3 Makefile.PL
+ $ perl Makefile.PL
Writing Makefile for Encode::My
=item 4.
chmod 644 blib/arch/auto/Encode/My/My.bs
$
-The time it takes varies how fast your machine is and how large your
-encoding is. Unless you are working on something big like euc-tw, it
-won't take too long.
+The time it takes varies depending on how fast your machine is and
+how large your encoding is. Unless you are working on something big
+like euc-tw, it won't take too long.
=item 5.
If you are content with the test result, just "make install"
+=item 7.
+
+If you want to add your encoding to Encode's demand-loading list
+(so you don't have to "use Encode::YourEncoding"), run
+
+ enc2xs -C
+
+to update Encode::ConfigLocal, a module that controls local settings.
+After that, "use Encode;" is enough to load your encodings on demand.
+
=back
=head1 The Unicode Character Map
-Encode uses The Unicode Character Map (UCM) for source character
-mappings. This format is used by ICU package of IBM and adopted by
-Nick Ing-Simmons. Since UCM is more flexible than Tcl's Encoding Map
-and far more user-friendly, This is the recommended formet for
-Encode now.
+Encode uses the Unicode Character Map (UCM) format for source character
+mappings. This format is used by IBM's ICU package and was adopted
+by Nick Ing-Simmons for use with the Encode module. Since UCM is
+more flexible than Tcl's Encoding Map and far more user-friendly,
+this is the recommended formet for Encode now.
-UCM file looks like this.
+A UCM file looks like this.
#
# Comments
=item *
-Anything that follows C<#> is treated as comments.
+Anything that follows C<#> is treated as a comment.
=item *
-The header section continues until CHARMAP. This section Has a form of
-I<E<lt>keywordE<gt> value>, one at a line. For a value, strings must
-be quoted. Barewords are treated as numbers. I<\xXX> represents a
-byte.
+The header section continues until a line containing the word
+CHARMAP. This section has a form of I<E<lt>keywordE<gt> value>, one
+pair per line. Strings used as values must be quoted. Barewords are
+treated as numbers. I<\xXX> represents a byte.
Most of the keywords are self-explanatory. I<subchar> means
substitution character, not subcharacter. When you decode a Unicode
sequence to this encoding but no matching character is found, the byte
sequence defined here will be used. For most cases, the value here is
-\x3F, in ASCII this is a question mark.
+\x3F; in ASCII, this is a question mark.
=item *
CHARMAP starts the character map section. Each line has a form as
-follows;
+follows:
<UXXXX> \xXX.. |0 # comment
^ ^ ^
| +-------- Encoded byte sequence
+-------------- Unicode Character ID in hex
-The format is roughly the same as a header section except for fallback
-flag. It is | followed by 0..3. And their meaning as follows
+The format is roughly the same as a header section except for the
+fallback flag: | followed by 0..3. The meaning of the possible
+values is as follows:
-=over 2
+=over 4
=item |0
-Round trip safe. A character decoded to Unicode encodes back to the
-same byte sequence. most character belong to this.
+Round trip safe. A character decoded to Unicode encodes back to the
+same byte sequence. Most characters have this flag.
=item |1
Fallback for unicode -> encoding. When seen, enc2xs adds this
-character for encode map only
+character for the encode map only.
=item |2
=item |3
Fallback for encoding -> unicode. When seen, enc2xs adds this
-character for decode map only
+character for the decode map only.
=back
=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 an existing encoding which is close to yours, rather 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.
+is, unless your environment is EBCDIC.
B<CAVEAT>: not all features in UCM are implemented. For example,
icu:state is not used. Because of that, you need to write a perl
-module if you want to support algorithmical encodings, notablly
-ISO-2022 series. Such modules include L<Encode::JP::2022_JP>,
+module if you want to support algorithmical encodings, notably
+the 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 4
+
+=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 the '|1' or '|3' entry FOLLOWS the '|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 a UCM file. Check under the
+Encode/bin directory for this.
+
+
=head1 Bookmarks
+=over 4
+
+=item *
+
ICU Home Page
L<http://oss.software.ibm.com/icu/>
+=item *
+
ICU Character Mapping Tables
L<http://oss.software.ibm.com/icu/charset/>
+=item *
+
ICU:Conversion Data
L<http://oss.software.ibm.com/icu/userguide/conversion-data.html>
+=back
+
=head1 SEE ALSO
L<Encode>,