man XML::UM (3): Convert UTF-8 strings to any encoding supported by XML::Encoding

SYNOPSIS

use XML::UM;
# Set directory with .xml files that comes with XML::Encoding distribution
# Always include the trailing slash!
$XML::UM::ENCDIR = '/home1/enno/perlModules/XML-Encoding-1.01/maps/';
# Create the encoding routine
my $encode = XML::UM::get_encode (
Encoding => 'ISO-8859-2',
EncodeUnmapped => \&XML::UM::encode_unmapped_dec);
# Convert a string from UTF-8 to the specified Encoding
my $encoded_str = $encode->($utf8_str);
# Remove circular references for garbage collection
XML::UM::dispose_encoding ('ISO-8859-2');

DESCRIPTION

This module provides methods to convert UTF-8 strings to any XML encoding that XML::Encoding supports. It creates mapping routines from the .xml files that can be found in the maps/ directory in the XML::Encoding distribution. Note that the XML::Encoding distribution does install the .enc files in your perl directory, but not the.xml files they were created from. That's why you have to specify $ENCDIR as in the SYNOPSIS.

This implementation uses the XML::Encoding class to parse the .xml file and creates a hash that maps UTF-8 characters (each consisting of up to 4 bytes) to their equivalent byte sequence in the specified encoding. Note that large mappings may consume a lot of memory!

Future implementations may parse the .enc files directly, or do the conversions entirely in XS (i.e. C code.)

get_encode (Encoding => STRING, EncodeUnmapped => SUB)

The central entry point to this module is the XML::UM::get_encode() method. It forwards the call to the global $XML::UM::FACTORY, which is defined as an instance of XML::UM::SlowMapperFactory by default. Override this variable to plug in your own mapper factory.

The XML::UM::SlowMapperFactory creates an instance of XML::UM::SlowMapper (and caches it for subsequent use) that reads in the .xml encoding file and creates a hash that maps UTF-8 characters to encoded characters.

The get_encode() method of XML::UM::SlowMapper is called, finally, which generates an anonimous subroutine that uses the hash to convert multi-character UTF-8 blocks to the proper encoding.

dispose_encoding ($encoding_name)

Call this to free the memory used by the SlowMapper for a specific encoding. Note that in order to free the big conversion hash, the user should no longer have references to the subroutines generated by get_encode().

The parameters to the get_encode() method (defined as name/value pairs) are:

Encoding
The name of the desired encoding, e.g. 'ISO-8859-2'
EncodeUnmapped (Default: \&XML::UM::encode_unmapped_dec)
Defines how Unicode characters not found in the mapping file (of the specified encoding) are printed. By default, they are converted to decimal entity references, like '{'
Use \&XML::UM::encode_unmapped_hex for hexadecimal constants, like '«'

CAVEATS

I'm not exactly sure about which Unicode characters in the range (0 .. 127) should be mapped to themselves. See comments in XML/UM.pm near %DEFAULT_ASCII_MAPPINGS.

The encodings that expat supports by default are currently not supported, (e.g. UTF-16, ISO-8859-1), because there are no .enc files available for these encodings. This module needs some more work. If you have the time, please help!

AUTHOR

Original Author is Enno Derksen.