NAME
    XML::Hash::XS - Simple and fast hash to XML and XML to hash conversion
    written in C

SYNOPSIS
        use XML::Hash::XS;

        my $xmlstr = hash2xml \%hash;
        hash2xml \%hash, output => $fh;

        my $hash = xml2hash $xmlstr;
        my $hash = xml2hash \$xmlstr;
        my $hash = xml2hash 'test.xml', encoding => 'cp1251';
        my $hash = xml2hash $fh;
        my $hash = xml2hash *STDIN;

    Or OOP way:

        use XML::Hash::XS qw();

        my $conv   = XML::Hash::XS->new(utf8 => 0, encoding => 'utf-8')
        my $xmlstr = $conv->hash2xml(\%hash, utf8 => 1);
        my $hash   = $conv->xml2hash($xmlstr, encoding => 'cp1251');

DESCRIPTION
    This module implements simple hash to XML and XML to hash conversion
    written in C.

    During conversion uses minimum of memory, XML or hash is written
    directly without building DOM.

    Some features are optional and are available with appropriate libraries:

    * XML::LibXML library is required in order to build DOM

    * ICU or iconv library is required in order to perform charset
      conversions

FUNCTIONS
  hash2xml $hash, [ %options ]
    $hash is reference to hash

        hash2xml
            {
                node1 => 'value1',
                node2 => [ 'value21', { node22 => 'value22' } ],
                node3 => \'value3',
                node4 => sub { return 'value4' },
                node5 => sub { return { node51 => 'value51' } },
            },
            canonical => 1,
            indent    => 2,
        ;

    will convert to:

        <?xml version="1.0" encoding="utf-8"?>
        <root>
          <node1>value1</node1>
          <node2>value21</node2>
          <node2>
            <node22>value22</node22>
          </node2>
          <node3>value3</node3>
          <node4>value4</node4>
          <node5>
            <node51>value51</node51>
          </node5>
        </root>

    and (use_attr=1):

        hash2xml
            {
                node1 => 'value1',
                node2 => [ 'value21', { node22 => 'value22' } ],
                node3 => \'value3',
                node4 => sub { return 'value4' },
                node5 => sub { return { node51 => 'value51' } },
            },
            use_attr  => 1,
            canonical => 1,
            indent    => 2,
        ;

    will convert to:

        <?xml version="1.0" encoding="utf-8"?>
        <root node1="value1" node3="value3" node4="value4">
          <node2>value21</node2>
          <node2 node22="value22"/>
          <node5 node51="value51"/>
        </root>

  xml2hash $xml, [ %options ]
    $xml may be string, reference to string, file handle or tied file
    handle:

        xml2hash '<root>text</root>';
        # output: 'text'

        xml2hash '<root a="1" b="2">text</root>';
        # output: { a => '1', b => '2', content => 'text' }

        open(my $fh, '<', 'test.xml');
        xml2hash $fh;

        xml2hash *STDIN;

OPTIONS
    doc [ => 0 ] *# hash2xml*
        if doc is '1', then returned value is XML::LibXML::Document.

    root [ = 'root' ] *# hash2xml*
        Root node name.

    version [ = '1.0' ] *# hash2xml*
        XML document version

    encoding [ = 'utf-8' ] *# hash2xml+xml2hash*
        XML input/output encoding

    indent [ = 0 ] *# hash2xml*
        if indent great than "0", XML output should be indented according to
        its hierarchic structure. This value determines the number of
        spaces.

        if indent is "0", XML output will all be on one line.

    output [ = undef ] *# hash2xml*
        XML output method

        if output is undefined, XML document dumped into string.

        if output is FH, XML document writes directly to a filehandle or a
        stream.

    canonical [ = 0 ] *# hash2xml*
        if canonical is "1", converter will be write hashes sorted by key.

        if canonical is "0", order of the element will be pseudo-randomly.

    use_attr [ = 0 ] *# hash2xml*
        if use_attr is "1", converter will be use the attributes.

        if use_attr is "0", converter will be use tags only.

    content [ = undef ] *# hash2xml+xml2hash*
        if defined that the key name for the text content(used only if
        use_attr=1).

    force_array => [ = undef ] *# xml2hash*
        This option is similar to "ForceArray" from XML::Simple module:
        <https://metacpan.org/pod/XML::Simple#ForceArray-=%3E-1-%23-in-impor
        tant>.

    force_content => [ = 0 ] *# xml2hash*
        This option is similar to "ForceContent" from XML::Simple module:
        <https://metacpan.org/pod/XML::Simple#ForceContent-=%3E-1-%23-in-sel
        dom-used>.

    merge_text [ = 0 ] *# xml2hash*
        Setting this option to "1" will cause merge adjacent text nodes.

    xml_decl [ = 1 ] *# hash2xml*
        if xml_decl is "1", output will start with the XML declaration
        '<?xml version="1.0" encoding="utf-8"?>'.

        if xml_decl is "0", XML declaration will not be output.

    trim [ = 0 ] *# hash2xml+xml2hash*
        Trim leading and trailing whitespace from text nodes.

    suppress_empty => [ = 0 ] *# xml2hash*
        This option is similar to "SuppressEmpty" from XMl::Simple module:
        <https://metacpan.org/pod/XML::Simple#SuppressEmpty-=%3E-1-%7C-''-%7
        C-undef-%23-in+out-handy>.

    utf8 [ = 1 ] *# hash2xml+xml2hash*
        Turn on utf8 flag for strings if enabled.

    max_depth [ = 1024 ] *# xml2hash*
        Maximum recursion depth.

    buf_size [ = 4096 ] *# hash2xml+xml2hash*
        Buffer size for reading end encoding data.

    keep_root [ = 0 ] *# xml2hash*
        Keep root element.

    filter [ = undef ] *# xml2hash*
        Filter nodes matched by pattern and return reference to array of
        nodes.

        Sample:

            my $xml = <<'XML';
                <root>
                   <item1>111</item1>
                   <item2>222</item2>
                   <item3>333</item3>
                </root>
            XML

            my $nodes = xml2hash($xml, filter => '/root/item1');
            # $nodes = [ 111 ]

            my $nodes = xml2hash($xml, filter => ['/root/item1', '/root/item2']);
            # $nodes = [ 111, 222 ]

            my $nodes = xml2hash($xml, filter => qr[/root/item\d$]);
            # $nodes = [ 111, 222, 333 ]

        It may be used to parse large XML because does not require a lot of
        memory.

    cb [ = undef ] *# xml2hash*
        This option is used in conjunction with "filter" option and defines
        callback that will called for each matched node.

        Sample:

            xml2hash($xml, filter => qr[/root/item\d$], cb => sub {
                print $_[0], "\n";
            });
            # 111
            # 222
            # 333

    method [ = 'NATIVE' ] *# hash2xml*
        experimental support the conversion methods other libraries

        if method is 'LX' then conversion result is the same as using
        XML::Hash::LX library

        Note: for 'LX' method following additional options are available:
        attr cdata text comm

OBJECT SERIALISATION(hash2xml)
    1. When object has a "toString" method
      In this case, the <toString> method of object is invoked in scalar
      context. It must return a single scalar that can be directly encoded
      into XML.

      Example:

          use XML::LibXML;
          local $XML::LibXML::skipXMLDeclaration = 1;
          my $doc = XML::LibXML->new->parse_string('<foo bar="1"/>');
          print hash2xml({ doc => $doc }, indent => 2, xml_decl => 0);
          =>
          <root>
            <doc><foo bar="1"/></doc>
          </root>

    2. When object has overloaded stringification
      In this case, the stringification method of object is invoked and
      result is directly encoded into XML.

      Example:

          package Test {
              use overload '""' => sub { shift->stringify }, fallback => 1;
              sub new {
                  my ($class, $str) = @_;
                  bless { str => $str }, $class;
              }
              sub stringify {
                  shift->{str}
              }
          }
          my $obj = Test->new('test string');
          print hash2xml({ obj => $obj }, indent => 2, xml_decl => 0);
          =>
          <root>
            <obj>test string</obj>
          </root>

    3. When object has a "iternext" method ("NATIVE" method only)
      In this case, the <iternext> method method will invoke a few times
      until the return value is not undefined.

      Example:

          my $count = 0;
          my $o = bless {}, 'Iterator';
          *Iterator::iternext = sub { $count++ < 3 ? { count => $count } : undef };
          print hash2xml({ item => $o }, use_attr => 1, indent => 2, xml_decl => 0);
          =>
          <root>
            <item count="1"/>
            <item count="2"/>
            <item count="3"/>
          </root>

      This can be used to generate a large XML using minimum memory, example
      with DBI:

          my $sth = $dbh->prepare('SELECT * FROM foo WHERE bar=?');
          $sth->execute(...);
          my $o = bless {}, 'Iterator';
          *Iterator::iternext = sub { $sth->fetchrow_hashref() };
          open(my $fh, '>', 'data.xml');
          hash2xml({ row => $o }, use_attr => 1, indent => 2, xml_decl => 0, output => $fh);
          =>
          <root>
            <row bar="..." ... />
            <row bar="..." ... />
            ...
          </root>

BENCHMARK
    Performance benchmark in comparison with some popular modules(hash2xml):

                        Rate     XML::Hash XML::Hash::LX   XML::Simple XML::Hash::XS
        XML::Hash     65.0/s            --           -6%          -37%          -99%
        XML::Hash::LX 68.8/s            6%            --          -33%          -99%
        XML::Simple    103/s           58%           49%            --          -98%
        XML::Hash::XS 4879/s         7404%         6988%         4658%            --

    Benchmark was done on <http://search.cpan.org/uploads.rdf>

AUTHOR
    Yuriy Ustushenko, <yoreek@yahoo.com>

COPYRIGHT AND LICENSE
    Copyright (C) 2012-2021 Yuriy Ustushenko

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.