NAME
    XML::Bare - Minimal XML parser implemented via a C state engine

VERSION
    version 0.47

SYNOPSIS
      use XML::Bare;

      my $ob = new XML::Bare( text => '<xml><name>Bob</name></xml>' );

      # Parse the xml into a hash tree
      my $root = $ob->parse();

      # Print the content of the name node
      print $root->{xml}->{name}->{value};

      # --------------------------------------------------------------

      # Load xml from a file ( assume same contents as first example )
      my $ob2 = new XML::Bare( file => 'test.xml' );

      my $root2 = $ob2->parse();

      $root2->{xml}->{name}->{value} = 'Tim';

      # Save the changes back to the file
      $ob2->save();

      # --------------------------------------------------------------

      # Load xml and verify against XBS ( XML Bare Schema )
      my $xml_text = '<xml><item name=bob/></xml>';
      my $schema_text = '<xml><item* name=[a-z]+></item*></xml>';
      my $ob3 = new XML::Bare( text => $xml_text, schema => { text => $schema_text } );
      $ob3->parse(); # this will error out if schema is invalid

DESCRIPTION
    This module is a 'Bare' XML parser. It is implemented in C. The parser
    itself is a simple state engine that is less than 500 lines of C. The
    parser builds a C struct tree from input text. That C struct tree is
    converted to a Perl hash by a Perl function that makes basic calls back
    to the C to go through the nodes sequentially.

    The parser itself will only cease parsing if it encounters tags that are
    not closed properly. All other inputs will parse, even invalid inputs.
    To allowing checking for validity, a schema checker is included in the
    module as well.

    The schema format is custom and is meant to be as simple as possible. It
    is based loosely around the way multiplicity is handled in Perl regular
    expressions.

  Supported XML
    To demonstrate what sort of XML is supported, consider the following
    examples. Each of the PERL statements evaluates to true.

    * Node containing just text

        XML: <xml>blah</xml>
        PERL: $root->{xml}->{value} eq "blah";

    * Subset nodes

        XML: <xml><name>Bob</name></xml>
        PERL: $root->{xml}->{name}->{value} eq "Bob";

    * Attributes unquoted

        XML: <xml><a href=index.htm>Link</a></xml>
        PERL: $root->{xml}->{a}->{href}->{value} eq "index.htm";

    * Attributes quoted

        XML: <xml><a href="index.htm">Link</a></xml>
        PERL: $root->{xml}->{a}->{href}->{value} eq "index.htm";

    * CDATA nodes

        XML: <xml><raw><![CDATA[some raw $~<!bad xml<>]]></raw></xml>
        PERL: $root->{xml}->{raw}->{value} eq "some raw \$~<!bad xml<>";

    * Multiple nodes; form array

        XML: <xml><item>1</item><item>2</item></xml>
        PERL: $root->{xml}->{item}->[0]->{value} eq "1";

    * Forcing array creation

        XML: <xml><multi_item/><item>1</item></xml>
        PERL: $root->{xml}->{item}->[0]->{value} eq "1";

    * One comment supported per node

        XML: <xml><!--test--></xml>
        PERL: $root->{xml}->{comment} eq 'test';

  Schema Checking
    Schema checking is done by providing the module with an XBS (XML::Bare
    Schema) to check the XML against. If the XML checks as valid against the
    schema, parsing will continue as normal. If the XML is invalid, the
    parse function will die, providing information about the failure.

    The following information is provided in the error message:

    * The type of error

    * Where the error occurred ( line and char )

    * A short snippet of the XML at the point of failure

  XBS ( XML::Bare Schema ) Format
    * Required nodes

        XML: <xml></xml>
        XBS: <xml/>

    * Optional nodes - allow one

        XML: <xml></xml>
        XBS: <xml item?/>
        or XBS: <xml><item?/></xml>

    * Optional nodes - allow 0 or more

        XML: <xml><item/></xml>
        XBS: <xml item*/>

    * Required nodes - allow 1 or more

        XML: <xml><item/><item/></xml>
        XBS: <xml item+/>

    * Nodes - specified minimum and maximum number

        XML: <xml><item/><item/></xml>
        XBS: <xml item{1,2}/>
        or XBS: <xml><item{1,2}/></xml>
        or XBS: <xml><item{1,2}></item{1,2}></xml>

    * Multiple acceptable node formats

        XML: <xml><item type=box volume=20/><item type=line length=10/></xml>
        XBS: <xml><item type=box volume/><item type=line length/></xml>

    * Regular expressions checking for values

        XML: <xml name=Bob dir=up num=10/>
        XBS: <xml name=[A-Za-z]+ dir=up|down num=[0-9]+/>

    * Require multi_ tags

        XML: <xml><multi_item/></xml>
        XBS: <xml item@/>

  Parsed Hash Structure
    The hash structure returned from XML parsing is created in a specific
    format. Besides as described above, the structure contains some
    additional nodes in order to preserve information that will allow that
    structure to be correctly converted back to XML.

    Nodes may contain the following 3 additional subnodes:

    * _i

      The character offset within the original parsed XML of where the node
      begins. This is used to provide line information for errors when XML
      fails a schema check.

    * _pos

      This is a number indicating the ordering of nodes. It is used to allow
      items in a perl hash to be sorted when writing back to xml. Note that
      items are not sorted after parsing in order to save time if all you
      are doing is reading and you do not care about the order.

      In future versions of this module an option will be added to allow you
      to sort your nodes so that you can read them in order. ( note that
      multiple nodes of the same name are stored in order )

    * _att

      This is a boolean value that exists and is 1 iff the node is an
      attribute.

  Parsing Limitations / Features
    * CDATA parsed correctly, but stripped if unneeded

      Currently the contents of a node that are CDATA are read and put into
      the value hash, but the hash structure does not have a value
      indicating the node contains CDATA.

      When converting back to XML, the contents of the value hash are parsed
      to check for xml incompatible data using a regular expression. If
      'CDATA like' stuff is encountered, the node is output as CDATA.

    * Standard XML quoted characters are decoded

      The basic XML quoted characters - "&amp;" "&gt;" "&lt;" "quot;" and
      "&apos;" - are recognised and decoded when reading values. However
      when writing the builder will put any values that need quoting into a
      CDATA wrapper as described above.

    * Node position stored, but hash remains unsorted

      The ordering of nodes is noted using the '_pos' value, but the hash
      itself is not ordered after parsing. Currently items will be out of
      order when looking at them in the hash.

      Note that when converted back to XML, the nodes are then sorted and
      output in the correct order to XML. Note that nodes of the same name
      with the same parent will be grouped together; the position of the
      first item to appear will determine the output position of the group.

    * Comments are parsed but only one is stored per node.

      For each node, there can be a comment within it, and that comment will
      be saved and output back when dumping to XML.

    * Comments override output of immediate value

      If a node contains only a comment node and a text value, only the
      comment node will be displayed. This is in line with treating a
      comment node as a node and only displaying immediate values when a
      node contains no subnodes.

    * PI sections are parsed, but discarded

    * Unknown "<!" sections are parsed, but discarded

    * Attributes may use no quotes, single quotes, quotes

    * Quoted attributes cannot contain escaped quotes

      No escape character is recognized within quotes. As a result, regular
      quotes cannot be stored to XML, or the written XML will not be
      correct, due to all attributes always being written using quotes.

    * Attributes are always written back to XML with quotes

    * Nodes cannot contain subnodes as well as an immediate value

      Actually nodes can in fact contain a value as well, but that value
      will be discarded if you write back to XML. That value is equal to the
      first continuous string of text besides a subnode.

        <node>text<subnode/>text2</node>
        ( the value of node is text )

        <node><subnode/>text</node>
        ( the value of node is text )

        <node>
          <subnode/>text
        </node>
        ( the value of node is "\n  " )

  Module Functions
    * "$ob = new XML::Bare( text => "[some xml]" )"

      Create a new XML object, with the given text as the xml source.

    * "$object = new XML::Bare( file => "[filename]" )"

      Create a new XML object, with the given filename/path as the xml
      source

    * "$object = new XML::Bare( text => "[some xml]", file => "[filename]"
      )"

      Create a new XML object, with the given text as the xml input, and the
      given filename/path as the potential output ( used by save() )

    * "$object = new XML::Bare( file => "data.xml", scheme => { file =>
      "scheme.xbs" } )"

      Create a new XML object and check to ensure it is valid xml by way of
      the XBS scheme.

    * "$tree = $object->parse()"

      Parse the xml of the object and return a tree reference

    * "$tree = $object->simple()"

      Alternate to the parse function which generates a tree similar to that
      generated by XML::Simple. Note that the sets of nodes are turned into
      arrays always, regardless of whether they have a 'name' attribute,
      unlike XML::Simple.

      Note that currently the generated tree cannot be used with any of the
      functions in this module that operate upon trees. The function is
      provided purely as a quick and dirty way to read simple XML files.

    * "$tree = xmlin( $xmlext, keeproot => 1 )"

      The xmlin function is a shortcut to creating an XML::Bare object and
      parsing it using the simple function. It behaves similarly to the
      XML::Simple function by the same name. The keeproot option is optional
      and if left out the root node will be discarded, same as the function
      in XML::Simple.

    * "$text = $object->xml( [root] )"

      Take the hash tree in [root] and turn it into cleanly indented ( 2
      spaces ) XML text.

    * "$text = $object->html( [root], [root node name] )"

      Take the hash tree in [root] and turn it into nicely colorized and
      styled html. [root node name] is optional.

    * "$object->save()"

      The the current tree in the object, cleanly indent it, and save it to
      the file parameter specified when creating the object.

    * "$value = xval $node, $default"

      Returns the value of $node or $default if the node does not exist. If
      default is not passed to the function, then '' is returned as a
      default value when the node does not exist.

    * "( $name, $age ) = xget( $personnode, qw/name age/ )"

      Shortcut function to grab a number of values from a node all at the
      same time. Note that this function assumes that all of the subnodes
      exist; it will fail if they do not.

    * "$text = XML::Bare::clean( text => "[some xml]" )"

      Shortcut to creating an xml object and immediately turning it into
      clean xml text.

    * "$text = XML::Bare::clean( file => "[filename]" )"

      Similar to previous.

    * "XML::Bare::clean( file => "[filename]", save => 1 )"

      Clean up the xml in the file, saving the results back to the file

    * "XML::Bare::clean( text => "[some xml]", save => "[filename]" )"

      Clean up the xml provided, and save it into the specified file.

    * "XML::Bare::clean( file => "[filename1]", save => "[filename2]" )"

      Clean up the xml in filename1 and save the results to filename2.

    * "$html = XML::Bare::tohtml( text => "[some xml]", root => 'xml' )"

      Shortcut to creating an xml object and immediately turning it into
      html. Root is optional, and specifies the name of the root node for
      the xml ( which defaults to 'xml' )

    * "$object->add_node( [node], [nodeset name], name => value, name2 =>
      value2, ... )"

        Example:
          $object->add_node( $root->{xml}, 'item', name => 'Bob' );

        Result:
          <xml>
            <item>
              <name>Bob</name>
            </item>
          </xml>

    * "$object->add_node_after( [node], [subnode within node to add after],
      [nodeset name], ... )"

    * "$object->del_node( [node], [nodeset name], name => value )"

        Example:
          Starting XML:
            <xml>
              <a>
                <b>1</b>
              </a>
              <a>
                <b>2</b>
              </a>
            </xml>

          Code:
            $xml->del_node( $root->{xml}, 'a', b=>'1' );

          Ending XML:
            <xml>
              <a>
                <b>2</b>
              </a>
            </xml>

    * "$object->find_node( [node], [nodeset name], name => value )"

        Example:
          Starting XML:
            <xml>
              <ob>
                <key>1</key>
                <val>a</val>
              </ob>
              <ob>
                <key>2</key>
                <val>b</val>
              </ob>
            </xml>

          Code:
            $object->find_node( $root->{xml}, 'ob', key => '1' )->{val}->{value} = 'test';

          Ending XML:
            <xml>
              <ob>
                <key>1</key>
                <val>test</val>
              </ob>
              <ob>
                <key>2</key>
                <val>b</val>
              </ob>
            </xml>

    * "$object->find_by_perl( [nodeset], "[perl code]" )"

      find_by_perl evaluates some perl code for each node in a set of nodes,
      and returns the nodes where the perl code evaluates as true. In order
      to easily reference node values, node values can be directly referred
      to from within the perl code by the name of the node with a dash(-) in
      front of the name. See the example below.

      Note that this function returns an array reference as opposed to a
      single node unlike the find_node function.

        Example:
          Starting XML:
            <xml>
              <ob>
                <key>1</key>
                <val>a</val>
              </ob>
              <ob>
                <key>2</key>
                <val>b</val>
              </ob>
            </xml>

          Code:
            $object->find_by_perl( $root->{xml}->{ob}, "-key eq '1'" )->[0]->{val}->{value} = 'test';

          Ending XML:
            <xml>
              <ob>
                <key>1</key>
                <val>test</val>
              </ob>
              <ob>
                <key>2</key>
                <val>b</val>
              </ob>
            </xml>

    * "XML::Bare::merge( [nodeset1], [nodeset2], [id node name] )"

      Merges the nodes from nodeset2 into nodeset1, matching the contents of
      each node based up the content in the id node.

      Example:

        Code:
          my $ob1 = new XML::Bare( text => "
            <xml>
              <multi_a/>
              <a>bob</a>
              <a>
                <id>1</id>
                <color>blue</color>
              </a>
            </xml>" );
          my $ob2 = new XML::Bare( text => "
            <xml>
              <multi_a/>
              <a>john</a>
              <a>
                <id>1</id>
                <name>bob</name>
                <bob>1</bob>
              </a>
            </xml>" );
          my $root1 = $ob1->parse();
          my $root2 = $ob2->parse();
          merge( $root1->{'xml'}->{'a'}, $root2->{'xml'}->{'a'}, 'id' );
          print $ob1->xml( $root1 );

        Output:
          <xml>
            <multi_a></multi_a>
            <a>bob</a>
            <a>
              <id>1</id>
              <color>blue</color>
              <name>bob</name>
              <bob>1</bob>
            </a>
          </xml>

    * "XML::Bare::del_by_perl( ... )"

      Works exactly like find_by_perl, but deletes whatever matches.

    * "XML::Bare::forcearray( [noderef] )"

      Turns the node reference into an array reference, whether that node is
      just a single node, or is already an array reference.

    * "XML::Bare::new_node( ... )"

      Creates a new node...

    * "XML::Bare::newhash( ... )"

      Creates a new hash with the specified value.

    * "XML::Bare::simplify( [noderef] )"

      Take a node with children that have immediate values and creates a
      hashref to reference those values by the name of each child.

  Functions Used Internally
    * "check() checkone() readxbs() free_tree_c()"

    * "lineinfo() c_parse() c_parsefile() free_tree() xml2obj()"

    * "obj2xml() get_root() obj2html() xml2obj_simple()"

  Performance
    In comparison to other available perl xml parsers that create trees,
    XML::Bare is extremely fast. In order to measure the performance of
    loading and parsing compared to the alternatives, a templated speed
    comparison mechanism has been created and included with XML::Bare.

    The include makebench.pl file runs when you make the module and creates
    perl files within the bench directory corresponding to the .tmpl
    contained there.

    Currently there are three types of modules that can be tested against,
    executable parsers ( exe.tmpl ), tree parsers ( tree.tmpl ), and parsers
    that do not generated trees ( notree.tmpl ).

    A full list of modules currently tested against is as follows:

      Tiny XML (exe)
      EzXML (exe)
      XMLIO (exe)
      XML::LibXML (notree)
      XML::Parser (notree)
      XML::Parser::Expat (notree)
      XML::Descent (notree)
      XML::Parser::EasyTree
      XML::Handler::Trees
      XML::Twig
      XML::Smart
      XML::Simple using XML::Parser
      XML::Simple using XML::SAX::PurePerl
      XML::Simple using XML::LibXML::SAX::Parser
      XML::Simple using XML::Bare::SAX::Parser
      XML::TreePP
      XML::Trivial
      XML::SAX::Simple
      XML::Grove::Builder
      XML::XPath::XMLParser
      XML::DOM

    To run the comparisons, run the appropriate perl file within the bench
    directory. ( exe.pl, tree.pl, or notree.pl )

    The script measures the milliseconds of loading and parsing, and
    compares the time against the time of XML::Bare. So a 7 means it takes 7
    times as long as XML::Bare.

    Here is a combined table of the script run against each alternative
    using the included test.xml:

      -Module-                   load     parse    total
      XML::Bare                  1        1        1
      XML::TreePP                2.3063   33.1776  6.1598
      XML::Parser::EasyTree      4.9405   25.7278  7.4571
      XML::Handler::Trees        7.2303   26.5688  9.6447
      XML::Trivial               5.0636   12.4715  7.3046
      XML::Smart                 6.8138   78.7939  15.8296
      XML::Simple (XML::Parser)  2.3346   50.4772  10.7455
      XML::Simple (PurePerl)     2.361    261.4571 33.6524
      XML::Simple (LibXML)       2.3187   163.7501 23.1816
      XML::Simple (XML::Bare)    2.3252   59.1254  10.9163
      XML::SAX::Simple           8.7792   170.7313 28.3634
      XML::Twig                  27.8266  56.4476  31.3594
      XML::Grove::Builder        7.1267   26.1672  9.4064
      XML::XPath::XMLParser      9.7783   35.5486  13.0002
      XML::LibXML (notree)       11.0038  4.5758   10.6881
      XML::Parser (notree)       4.4698   17.6448  5.8609
      XML::Parser::Expat(notree) 3.7681   50.0382  6.0069
      XML::Descent (notree)      6.0525   37.0265  11.0322
      Tiny XML (exe)                               1.0095
      EzXML (exe)                                  1.1284
      XMLIO (exe)                                  1.0165

    Here is a combined table of the script run against each alternative
    using the included feed2.xml:

      -Module-                   load     parse    total
      XML::Bare                  1        1        1
      XML::TreePP                2.3068   23.7554  7.6921
      XML::Parser::EasyTree      4.8799   25.3691  9.6257
      XML::Handler::Trees        6.8545   33.1007  13.0575
      XML::Trivial               5.0105   32.0043  11.4113
      XML::Simple (XML::Parser)  2.3498   41.9007  12.3062
      XML::Simple (PurePerl)     2.3551   224.3027 51.7832
      XML::Simple (LibXML)       2.3617   88.8741  23.215
      XML::Simple (XML::Bare)    2.4319   37.7355  10.2343
      XML::Simple                2.7168   90.7203  26.7525
      XML::SAX::Simple           8.7386   94.8276  29.2166
      XML::Twig                  28.3206  48.1014  33.1222
      XML::Grove::Builder        7.2021   30.7926  12.9334
      XML::XPath::XMLParser      9.6869   43.5032  17.4941
      XML::LibXML (notree)       11.0023  5.022    10.5214
      XML::Parser (notree)       4.3748   25.0213  5.9803
      XML::Parser::Expat(notree) 3.6555   51.6426  7.4316
      XML::Descent (notree)      5.9206   155.0289 18.7767
      Tiny XML (exe)                               1.2212
      EzXML (exe)                                  1.3618
      XMLIO (exe)                                  1.0145

    These results show that XML::Bare is, at least on the test machine,
    running all tests within cygwin, faster at loading and parsing than
    everything being tested against.

    The following things are shown as well: - XML::Bare can parse XML and
    create a hash tree in less time than it takes LibXML just to parse. -
    XML::Bare can parse XML and create a tree in less time than all three
    binary parsers take just to parse.

    Note that the executable parsers are not perl modules and are timed
    using dummy programs that just uses the library to load and parse the
    example files. The executables are not included with this program. Any
    source modifications used to generate the shown test results can be
    found in the bench/src directory of the distribution

CONTRIBUTED CODE
    The XML dequoting code used is taken from XML::Quote by *Sergey
    Skvortsov* (*GDSL* on CPAN) with very minor modifications.

INSTALLATION
    See perlmodinstall for information and options on installing Perl
    modules.

BUGS AND LIMITATIONS
    No bugs have been reported.

    Please report any bugs or feature requests through the web interface at
    <http://rt.cpan.org/Public/Dist/Display.html?Name=XML-Bare>.

AVAILABILITY
    The project homepage is <https://metacpan.org/release/XML-Bare>.

    The latest version of this module is available from the Comprehensive
    Perl Archive Network (CPAN). Visit <http://www.perl.com/CPAN/> to find a
    CPAN site near you, or see <http://search.cpan.org/dist/XML-Bare/>.

    The development version lives at <http://github.com/nigelm/xml-bare> and
    may be cloned from <git://github.com/nigelm/xml-bare.git>. Instead of
    sending patches, please fork this project using the standard git and
    github infrastructure.

AUTHORS
    *   David Helkowski <cpan@codechild.com>

    *   Nigel Metheringham <nigelm@cpan.org>

COPYRIGHT AND LICENSE
    This software is Copyright (c) 2012 by David Helkowski.

    This is free software, licensed under:

      The GNU General Public License, Version 2, June 1991

