NAME
    XML::Generator - Perl extension for generating XML

SYNOPSIS
      use XML::Generator ':pretty';

      print foo(bar({ baz => 3 }, bam()),
                bar([ 'qux' => 'http://qux.com/' ],
                      "Hey there, world"));

      # OR

      require XML::Generator;

      my $X = XML::Generator->new(':pretty');

      print $X->foo($X->bar({ baz => 3 }, $X->bam()),
                    $X->bar([ 'qux' => 'http://qux.com/' ],
                              "Hey there, world"));

    Either of the above yield:

       <foo xmlns:qux="http://qux.com/">
         <bar baz="3">
           <bam />
         </bar>
         <qux:bar>Hey there, world</qux:bar>
       </foo>

DESCRIPTION
    In general, once you have an XML::Generator object, you then simply call
    methods on that object named for each XML tag you wish to generate.

    XML::Generator can also arrange for undefined subroutines in the
    caller's package to generate the corresponding XML, by exporting an
    "AUTOLOAD" subroutine to your package. Just supply an ':import' argument
    to your "use XML::Generator;" call. If you already have an "AUTOLOAD"
    defined then XML::Generator can be configured to cooperate with it. See
    "STACKABLE AUTOLOADs".

    Say you want to generate this XML:

       <person>
         <name>Bob</name>
         <age>34</age>
         <job>Accountant</job>
       </person>

    Here's a snippet of code that does the job, complete with pretty
    printing:

       use XML::Generator;
       my $gen = XML::Generator->new(':pretty');
       print $gen->person(
                $gen->name("Bob"),
                $gen->age(34),
                $gen->job("Accountant")
             );

    The only problem with this is if you want to use a tag name that Perl's
    lexer won't understand as a method name, such as "shoe-size".
    Fortunately, since you can store the name of a method in a variable,
    there's a simple work-around:

       my $shoe_size = "shoe-size";
       $xml = $gen->$shoe_size("12 1/2");

    Which correctly generates:

       <shoe-size>12 1/2</shoe-size>

    You can use a hash ref as the first parameter if the tag should include
    atributes. Normally this means that the order of the attributes will be
    unpredictable, but if you have the Tie::IxHash module, you can use it to
    get the order you want, like this:

      use Tie::IxHash;
      tie my %attr, 'Tie::IxHash';

      %attr = (name => 'Bob', 
               age  => 34,
               job  => 'Accountant',
        'shoe-size' => '12 1/2');

      print $gen->person(\%attr);

    This produces

      <person name="Bob" age="34" job="Accountant" shoe-size="12 1/2" />

    An array ref can also be supplied as the first argument to indicate a
    namespace for the element and the attributes.

    If there is one element in the array, it is considered the URI of the
    default namespace, and the tag will have an xmlns="URI" attribute added
    automatically. If there are two elements, the first should be the tag
    prefix to use for the namespace and the second element should be the
    URI. In this case, the prefix will be used for the tag and an
    xmlns:PREFIX attribute will be automatically added. Prior to version
    0.99, this prefix was also automatically added to each attribute name.
    Now, the default behavior is to leave the attributes alone (although you
    may always explicitly add a prefix to an attribute name). If the prior
    behavior is desired, use the constructor option "qualified_attributes".

    If you specify more than two elements, then each pair should correspond
    to a tag prefix and the corresponding URL. An xmlns:PREFIX attribute
    will be added for each pair, and the prefix from the first such pair
    will be used as the tag's namespace. If you wish to specify a default
    namespace, use '#default' for the prefix. If the default namespace is
    first, then the tag will use the default namespace itself.

    If you want to specify a namespace as well as attributes, you can make
    the second argument a hash ref. If you do it the other way around, the
    array ref will simply get stringified and included as part of the
    content of the tag.

    Here's an example to show how the attribute and namespace parameters
    work:

       $xml = $gen->account(
                $gen->open(['transaction'], 2000),
                $gen->deposit(['transaction'], { date => '1999.04.03'}, 1500)
              );

    This generates:

       <account>
         <open xmlns="transaction">2000</open>
         <deposit xmlns="transaction" date="1999.04.03">1500</deposit>
       </account>

    Because default namespaces inherit, XML::Generator takes care to output
    the xmlns="URI" attribute as few times as strictly necessary. For
    example,

       $xml = $gen->account(
                $gen->open(['transaction'], 2000),
                $gen->deposit(['transaction'], { date => '1999.04.03'},
                  $gen->amount(['transaction'], 1500)
                )
              );

    This generates:

       <account>
         <open xmlns="transaction">2000</open>
         <deposit xmlns="transaction" date="1999.04.03">
           <amount>1500</amount>
         </deposit>
       </account>

    Notice how "xmlns="transaction"" was left out of the "<amount"> tag.

    Here is an example that uses the two-argument form of the namespace:

        $xml = $gen->widget(['wru' => 'http://www.widgets-r-us.com/xml/'],
                            {'id'  => 123}, $gen->contents());

        <wru:widget xmlns:wru="http://www.widgets-r-us.com/xml/" id="123">
          <contents />
        </wru:widget>

    Here is an example that uses multiple namespaces. It generates the first
    example from the RDF primer (<http://www.w3.org/TR/rdf-primer/>).

        my $contactNS = [contact => "http://www.w3.org/2000/10/swap/pim/contact#"];
        $xml = $gen->xml(
                 $gen->RDF([ rdf     => "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
                             @$contactNS ],
                    $gen->Person($contactNS, { 'rdf:about' => "http://www.w3.org/People/EM/contact#me" },
                      $gen->fullName($contactNS, 'Eric Miller'),
                      $gen->mailbox($contactNS, {'rdf:resource' => "mailto:em@w3.org"}),
                      $gen->personalTitle($contactNS, 'Dr.'))));

        <?xml version="1.0" standalone="yes"?>
        <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
                 xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#">
          <contact:Person rdf:about="http://www.w3.org/People/EM/contact#me">
            <contact:fullName>Eric Miller</contact:fullName>
            <contact:mailbox rdf:resource="mailto:em@w3.org" />
            <contact:personalTitle>Dr.</contact:personalTitle> 
          </Person>
        </rdf:RDF>

CONSTRUCTOR
    XML::Generator->new(':option', ...);

    XML::Generator->new(option => 'value', ...);

    (Both styles may be combined)

    The following options are available:

  :std, :standard
    Equivalent to

            escape      => 'always',
            conformance => 'strict',

  :strict
    Equivalent to

            conformance => 'strict',

  :pretty[=N]
    Equivalent to

            escape      => 'always',
            conformance => 'strict',
            pretty      => N         # N defaults to 2

  namespace
    This value of this option must be an array reference containing one or
    two values. If the array contains one value, it should be a URI and will
    be the value of an 'xmlns' attribute in the top-level tag. If there are
    two or more elements, the first of each pair should be the namespace tag
    prefix and the second the URI of the namespace. This will enable
    behavior similar to the namespace behavior in previous versions; the tag
    prefix will be applied to each tag. In addition, an xmlns:NAME="URI"
    attribute will be added to the top-level tag. Prior to version 0.99, the
    tag prefix was also automatically added to each attribute name, unless
    overridden with an explicit prefix. Now, the attribute names are left
    alone, but if the prior behavior is desired, use the constructor option
    "qualified_attributes".

    The value of this option is used as the global default namespace. For
    example,

        my $html = XML::Generator->new(
                     pretty    => 2,
                     namespace => [HTML => "http://www.w3.org/TR/REC-html40"]);
        print $html->html(
                $html->body(
                  $html->font({ face => 'Arial' },
                              "Hello, there")));

    would yield

        <HTML:html xmlns:HTML="http://www.w3.org/TR/REC-html40">
          <HTML:body>
            <HTML:font face="Arial">Hello, there</HTML:font>
          </HTML:body>
        </HTML:html>

    Here is the same example except without all the prefixes:

        my $html = XML::Generator->new(
                     pretty    => 2,
                     namespace => ["http://www.w3.org/TR/REC-html40"]);
        print $html->html(
                $html->body(
                  $html->font({ 'face' => 'Arial' },
                                "Hello, there")));

    would yield

       <html xmlns="http://www.w3.org/TR/REC-html40">
         <body>
            <font face="Arial">Hello, there</font>
         </body>
       </html>

  qualifiedAttributes, qualified_attributes
    Set this to a true value to emulate the attribute prefixing behavior of
    XML::Generator prior to version 0.99. Here is an example:

        my $foo = XML::Generator->new(
                    namespace => [foo => "http://foo.com/"],
                    qualifiedAttributes => 1);
        print $foo->bar({baz => 3});

    yields

        <foo:bar xmlns:foo="http://foo.com/" foo:baz="3" />

  escape
    The contents and the values of each attribute have any illegal XML
    characters escaped if this option is supplied. If the value is 'always',
    then &, < and > (and " within attribute values) will be converted into
    the corresponding XML entity, although & will not be converted if it
    looks like it could be part of a valid entity (but see below). If the
    value is 'unescaped', then the escaping will be turned off
    character-by-character if the character in question is preceded by a
    backslash, or for the entire string if it is supplied as a scalar
    reference. So, for example,

            use XML::Generator escape => 'always';

            one('<');      # <one>&lt;</one>
            two('\&');     # <two>\&amp;</two>
            three(\'<f>'); # <three><f></three> (scalar refs always allowed)
            four('&lt;');  # <four>&lt;</four> (looks like an entity)
            five('&#34;'); # <five>&#34;</five> (looks like an entity)

    but

            use XML::Generator escape => 'unescaped';

            one('<');     # <one>&lt;</one>
            two('\&');    # <two>&</two>
            three(\'<f>');# <three><f></three>  (scalar refs always allowed)
            four('&lt;'); # <four>&amp;lt;</four> (no special case for entities)

    By default, high-bit data will be passed through unmodified, so that
    UTF-8 data can be generated with pre-Unicode perls. If you know that
    your data is ASCII, use the value 'high-bit' for the escape option and
    bytes with the high bit set will be turned into numeric entities. You
    can combine this functionality with the other escape options by
    comma-separating the values:

      my $a = XML::Generator->new(escape => 'always,high-bit');
      print $a->foo("<\242>");

    yields

      <foo>&lt;&#162;&gt;</foo>

    Because XML::Generator always uses double quotes ("") around attribute
    values, it does not escape single quotes. If you want single quotes
    inside attribute values to be escaped, use the value 'apos' along with
    'always' or 'unescaped' for the escape option. For example:

        my $gen = XML::Generator->new(escape => 'always,apos');
        print $gen->foo({'bar' => "It's all good"});

        <foo bar="It&apos;s all good" />

    If you actually want & to be converted to &amp; even if it looks like it
    could be part of a valid entity, use the value 'even-entities' along
    with 'always'. Supplying 'even-entities' to the 'unescaped' option is
    meaningless as entities are already escaped with that option.

  pretty
    To have nice pretty printing of the output XML (great for config files
    that you might also want to edit by hand), supply an integer for the
    number of spaces per level of indenting, eg.

       my $gen = XML::Generator->new(pretty => 2);
       print $gen->foo($gen->bar('baz'),
                       $gen->qux({ tricky => 'no'}, 'quux'));

    would yield

       <foo>
         <bar>baz</bar>
         <qux tricky="no">quux</qux>
       </foo>

    You may also supply a non-numeric string as the argument to 'pretty', in
    which case the indents will consist of repetitions of that string. So if
    you want tabbed indents, you would use:

         my $gen = XML::Generator->new(pretty => "\t");

    Pretty printing does not apply to CDATA sections or Processing
    Instructions.

  conformance
    If the value of this option is 'strict', a number of syntactic checks
    are performed to ensure that generated XML conforms to the formal XML
    specification. In addition, since entity names beginning with 'xml' are
    reserved by the W3C, inclusion of this option enables several special
    tag names: xmlpi, xmlcmnt, xmldecl, xmldtd, xmlcdata, and xml to allow
    generation of processing instructions, comments, XML declarations,
    DTD's, character data sections and "final" XML documents, respectively.

    Invalid characters (http://www.w3.org/TR/xml11/#charsets) will be
    filtered out. To disable this behavior, supply the
    'filter_invalid_chars' option with the value 0.

    See "XML CONFORMANCE" and "SPECIAL TAGS" for more information.

  filterInvalidChars, filter_invalid_chars
    Set this to a 1 to enable filtering of invalid characters, or to 0 to
    disable the filtering. See http://www.w3.org/TR/xml11/#charsets for the
    set of valid characters.

  allowedXMLTags, allowed_xml_tags
    If you have specified 'conformance' => 'strict' but need to use tags
    that start with 'xml', you can supply a reference to an array containing
    those tags and they will be accepted without error. It is not an error
    to supply this option if 'conformance' => 'strict' is not supplied, but
    it will have no effect.

  empty
    There are 5 possible values for this option:

       self    -  create empty tags as <tag />  (default)
       compact -  create empty tags as <tag/>
       close   -  close empty tags as <tag></tag>
       ignore  -  don't do anything (non-compliant!)
       args    -  use count of arguments to decide between <x /> and <x></x>

    Many web browsers like the 'self' form, but any one of the forms besides
    'ignore' is acceptable under the XML standard.

    'ignore' is intended for subclasses that deal with HTML and other SGML
    subsets which allow atomic tags. It is an error to specify both
    'conformance' => 'strict' and 'empty' => 'ignore'.

    'args' will produce <x /> if there are no arguments at all, or if there
    is just a single undef argument, and <x></x> otherwise.

  version
    Sets the default XML version for use in XML declarations. See "xmldecl"
    below.

  encoding
    Sets the default encoding for use in XML declarations.

  dtd
    Specify the dtd. The value should be an array reference with three
    values; the type, the name and the uri.

  xml
    This is an hash ref value that should contain the version, encoding and
    dtd values (same as above). This is used in case "conformance" is set to
    "loose", but you still want to use the xml declaration or prolog.

IMPORT ARGUMENTS
    use XML::Generator ':option';

    use XML::Generator option => 'value';

    (Both styles may be combined)

  :import
    Cause "use XML::Generator;" to export an "AUTOLOAD" to your package that
    makes undefined subroutines generate XML tags corresponding to their
    name. Note that if you already have an "AUTOLOAD" defined, it will be
    overwritten.

  :stacked
    Implies :import, but if there is already an "AUTOLOAD" defined, the
    overriding "AUTOLOAD" will still give it a chance to run. See "STACKABLE
    AUTOLOADs".

  ANYTHING ELSE
    If you supply any other options, :import is implied and the
    XML::Generator object that is created to generate tags will be
    constructed with those options.

XML CONFORMANCE
    When the 'conformance' => 'strict' option is supplied, a number of
    syntactic checks are enabled. All entity and attribute names are checked
    to conform to the XML specification, which states that they must begin
    with either an alphabetic character or an underscore and may then
    consist of any number of alphanumerics, underscores, periods or hyphens.
    Alphabetic and alphanumeric are interpreted according to the current
    locale if 'use locale' is in effect and according to the Unicode
    standard for Perl versions >= 5.6. Furthermore, entity or attribute
    names are not allowed to begin with 'xml' (in any case), although a
    number of special tags beginning with 'xml' are allowed (see "SPECIAL
    TAGS"). Note that you can also supply an explicit list of allowed tags
    with the 'allowed_xml_tags' option.

    Also, the filter_invalid_chars option is automatically set to 1 unless
    it is explicitly set to 0.

SPECIAL TAGS
    The following special tags are available when running under strict
    conformance (otherwise they don't act special):

  xmlpi
    Processing instruction; first argument is target, remaining arguments
    are attribute, value pairs. Attribute names are syntax checked, values
    are escaped.

  xmlcmnt
    Comment. Arguments are concatenated and placed inside <!-- ... -->
    comment delimiters. Any occurences of '--' in the concatenated arguments
    are converted to '&#45;&#45;'

  xmldecl (@args)
    Declaration. This can be used to specify the version, encoding, and
    other XML-related declarations (i.e., anything inside the <?xml?> tag).
    @args can be used to control what is output, as keyword-value pairs.

    By default, the version is set to the value specified in the
    constructor, or to 1.0 if it was not specified. This can be overridden
    by providing a 'version' key in @args. If you do not want the version at
    all, explicitly provide undef as the value in @args.

    By default, the encoding is set to the value specified in the
    constructor; if no value was specified, the encoding will be left out
    altogether. Provide an 'encoding' key in @args to override this.

    If a dtd was set in the constructor, the standalone attribute of the
    declaration will be set to 'no' and the doctype declaration will be
    appended to the XML declartion, otherwise the standalone attribute will
    be set to 'yes'. This can be overridden by providing a 'standalone' key
    in @args. If you do not want the standalone attribute to show up,
    explicitly provide undef as the value.

  xmldtd
    DTD <!DOCTYPE> tag creation. The format of this method is different from
    others. Since DTD's are global and cannot contain namespace information,
    the first argument should be a reference to an array; the elements are
    concatenated together to form the DTD:

       print $xml->xmldtd([ 'html', 'PUBLIC', $xhtml_w3c, $xhtml_dtd ])

    This would produce the following declaration:

       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
            "DTD/xhtml1-transitional.dtd">

    Assuming that $xhtml_w3c and $xhtml_dtd had the correct values.

    Note that you can also specify a DTD on creation using the new()
    method's dtd option.

  xmlcdata
    Character data section; arguments are concatenated and placed inside
    <![CDATA[ ... ]]> character data section delimiters. Any occurences of
    ']]>' in the concatenated arguments are converted to ']]&gt;'.

  xml
    "Final" XML document. Must be called with one and exactly one
    XML::Generator-produced XML document. Any combination of
    XML::Generator-produced XML comments or processing instructions may also
    be supplied as arguments. Prepends an XML declaration, and re-blesses
    the argument into a "final" class that can't be embedded.

CREATING A SUBCLASS
    For a simpler way to implement subclass-like behavior, see "STACKABLE
    AUTOLOADs".

    At times, you may find it desireable to subclass XML::Generator. For
    example, you might want to provide a more application-specific interface
    to the XML generation routines provided. Perhaps you have a custom
    database application and would really like to say:

       my $dbxml = new XML::Generator::MyDatabaseApp;
       print $dbxml->xml($dbxml->custom_tag_handler(@data));

    Here, custom_tag_handler() may be a method that builds a recursive XML
    structure based on the contents of @data. In fact, it may even be named
    for a tag you want generated, such as authors(), whose behavior changes
    based on the contents (perhaps creating recursive definitions in the
    case of multiple elements).

    Creating a subclass of XML::Generator is actually relatively
    straightforward, there are just three things you have to remember:

       1. All of the useful utilities are in XML::Generator::util.

       2. To construct a tag you simply have to call SUPER::tagname,
          where "tagname" is the name of your tag.

       3. You must fully-qualify the methods in XML::Generator::util.

    So, let's assume that we want to provide a custom HTML table() method:

       package XML::Generator::CustomHTML;
       use base 'XML::Generator';

       sub table {
           my $self = shift;

           # parse our args to get namespace and attribute info
           my($namespace, $attr, @content) =
              $self->XML::Generator::util::parse_args(@_)

           # check for strict conformance
           if ( $self->XML::Generator::util::config('conformance') eq 'strict' ) {
              # ... special checks ...
           }

           # ... special formatting magic happens ...

           # construct our custom tags
           return $self->SUPER::table($attr, $self->tr($self->td(@content)));
       }

    That's pretty much all there is to it. We have to explicitly call
    SUPER::table() since we're inside the class's table() method. The others
    can simply be called directly, assuming that we don't have a tr() in the
    current package.

    If you want to explicitly create a specific tag by name, or just want a
    faster approach than AUTOLOAD provides, you can use the tag() method
    directly. So, we could replace that last line above with:

           # construct our custom tags 
           return $self->XML::Generator::util::tag('table', $attr, ...);

    Here, we must explicitly call tag() with the tag name itself as its
    first argument so it knows what to generate. These are the methods that
    you might find useful:

    XML::Generator::util::parse_args()
        This parses the argument list and returns the namespace (arrayref),
        attributes (hashref), and remaining content (array), in that order.

    XML::Generator::util::tag()
        This does the work of generating the appropriate tag. The first
        argument must be the name of the tag to generate.

    XML::Generator::util::config()
        This retrieves options as set via the new() method.

    XML::Generator::util::escape()
        This escapes any illegal XML characters.

    Remember that all of these methods must be fully-qualified with the
    XML::Generator::util package name. This is because AUTOLOAD is used by
    the main XML::Generator package to create tags. Simply calling
    parse_args() will result in a set of XML tags called <parse_args>.

    Finally, remember that since you are subclassing XML::Generator, you do
    not need to provide your own new() method. The one from XML::Generator
    is designed to allow you to properly subclass it.

STACKABLE AUTOLOADs
    As a simpler alternative to traditional subclassing, the "AUTOLOAD" that
    "use XML::Generator;" exports can be configured to work with a
    pre-defined "AUTOLOAD" with the ':stacked' option. Simply ensure that
    your "AUTOLOAD" is defined before "use XML::Generator ':stacked';"
    executes. The "AUTOLOAD" will get a chance to run first; the subroutine
    name will be in your $AUTOLOAD as normal. Return an empty list to let
    the default XML::Generator "AUTOLOAD" run or any other value to abort
    it. This value will be returned as the result of the original method
    call.

    If there is no "import" defined, XML::Generator will create one. All
    that this "import" does is export AUTOLOAD, but that lets your package
    be used as if it were a subclass of XML::Generator.

    An example will help:

            package MyGenerator;

            my %entities = ( copy => '&copy;',
                             nbsp => '&nbsp;', ... );

            sub AUTOLOAD {
              my($tag) = our $AUTOLOAD =~ /.*::(.*)/;

              return $entities{$tag} if defined $entities{$tag};
              return;
            }

            use XML::Generator qw(:pretty :stacked);

    This lets someone do:

            use MyGenerator;

            print html(head(title("My Title", copy())));

    Producing:

            <html>
              <head>
                <title>My Title&copy;</title>
              </head>
            </html>

AUTHORS
    Benjamin Holzman <bholzman@earthlink.net>
        Original author and maintainer

    Bron Gondwana <perlcode@brong.net>
        First modular version

    Nathan Wiger <nate@nateware.com>
        Modular rewrite to enable subclassing

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

SEE ALSO
    The XML::Writer module
        http://search.cpan.org/search?mode=module&query=XML::Writer