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,
`"$self-"{Nodes}>' that can be used by subclasses. The current
element is pushed on the stacks before calling an element-name start method
and popped off the stacks after calling the element-name end method.
See XML::Handler::Subs for additional methods.
In addition to the standard PerlSAX handler methods (see PerlSAX for
descriptions), XML::Handler::XMLWriter supports the following methods:
- new( OPTIONS )
- Creates and returns a new instance of
XML::Handler::XMLWriter with the given OPTIONS. Options may be
changed at any time by modifying them directly in the hash returned.
OPTIONS can be a list of key, value pairs or a hash. The following
OPTIONS are supported:
- Output
- An IO::Handle or one of it's subclasses (such as IO::File),
if this parameter is not present and the AsString option is not used, the
module will write to standard output.
- AsString
- Return the generated XML as a string from the
`"parse()"' method of the PerlSAX event generator.
- Newlines
- A true or false value; if this parameter is present and its
value is true, then the module will insert an extra newline before the
closing delimiter of start, end, and empty tags to guarantee that the
document does not end up as a single, long line. If the parameter is not
present, the module will not insert the newlines.
- IsSGML
- A true or false value; if this parameter is present and its
value is true, then the module will generate SGML rather than XML.
- print_start_element($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)
