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XML::Handler::XMLWriter.3pm

NAME

XML::Handler::XMLWriter - a PerlSAX handler for writing readable XML

SYNOPSIS

  use XML::Parser::PerlSAX;
  use XML::Handler::XMLWriter;
 
  $my_handler = XML::Handler::XMLWriter->new( I<OPTIONS> );
 
  XML::Parser::PerlSAX->new->parse(Source => { SystemId => 'REC-xml-19980210.xml' },
                                   Handler => $my_handler);
 
 

DESCRIPTION

"XML::Handler::XMLWriter" is a PerlSAX handler for writing readable XML (in contrast to Canonical XML, for example). XML::Handler::XMLWriter can be used with a parser to reformat XML, with XML::DOM or XML::Grove to write out XML, or with other PerlSAX modules that generate events.

"XML::Handler::XMLWriter" is intended to be used with PerlSAX event generators and does not perform any checking itself (for example, matching start and end element events). If you want to generate XML directly from your Perl code, use the XML::Writer module. XML::Writer has an easy to use interface and performs many checks to make sure that the XML you generate is well-formed.

"XML::Handler::XMLWriter" is a subclass of "XML::Handler::Subs". "XML::Handler::XMLWriter" can be further subclassed to alter it's behavior or to add element-specific handling. In the subclass, each time an element starts, a method by that name prefixed with `s_' is called with the element to be processed. Each time an element ends, a method with that name prefixed with `e_' is called. Any special characters in the element name are replaced by underscores. If there isn't a start or end method for an element, the default action is to write the start or end tag. Start and end methods can use the `"print_start_element()"' and `"print_end_element()"' methods to print start or end tags. Subclasses can call the `"print()"' method to write additional output.

Subclassing XML::Handler::XMLWriter in this way is similar to XML::Parser's Stream style.

XML::Handler::Subs maintains a stack of element names, `"$self-"{Names}', and a stack of element nodes, `"$self-"{Nodes}>' that can be used by subclasses. The current element is pushed on the stacks before calling an element-name start method and popped off the stacks after calling the element-name end method.

See XML::Handler::Subs for additional methods.

In addition to the standard PerlSAX handler methods (see PerlSAX for descriptions), XML::Handler::XMLWriter supports the following methods:

new( OPTIONS )

Creates and returns a new instance of XML::Handler::XMLWriter with the given OPTIONS. Options may be changed at any time by modifying them directly in the hash returned. OPTIONS can be a list of key, value pairs or a hash. The following OPTIONS are supported:

Output

An IO::Handle or one of it's subclasses (such as IO::File), if this parameter is not present and the AsString option is not used, the module will write to standard output.

AsString

Return the generated XML as a string from the `"parse()"' method of the PerlSAX event generator.

Newlines

A true or false value; if this parameter is present and its value is true, then the module will insert an extra newline before the closing delimiter of start, end, and empty tags to guarantee that the document does not end up as a single, long line. If the paramter is not present, the module will not insert the newlines.

IsSGML

A true or false value; if this parameter is present and its value is true, then the module will generate SGML rather than XML.

print_start_element($element)

Print a start tag for `$element'. This is the default action for the PerlSAX `"start_element()"' handler, but subclasses may use this if they define a start method for an element.

print_end_element($element)

Prints an end tag for `$element'. This is the default action for the PerlSAX `"end_element()"' handler, but subclasses may use this if they define a start method for an element.

print($output)

Write `$output' to Output and/or append it to the string to be returned. Subclasses may use this to write additional output.

TODO

*

An Elements option that provides finer control over newlines than the Newlines option, where you can choose before and after newline for element start and end tags. Inspired by the Python XMLWriter.

*

Support Doctype and XML declarations.

AUTHOR

Ken MacLeod, ken@bitsko.slc.ut.us This module is partially derived from XML::Writer by David Megginson.

SEE ALSO

perl(1), PerlSAX.pod(3)