PDF::API3::Compat::API2::Basic::TTF::XMLparse(3)

NAME
PDF::API3::Compat::API2::Basic::TTF::XMLparse - provides support for XML parsing. Requires Expat module XML::Parser::Expat

SYNOPSIS
    use PDF::API3::Compat::API2::Basic::TTF::Font;
    use PDF::API3::Compat::API2::Basic::TTF::XMLparse;

    $f = PDF::API3::Compat::API2::Basic::TTF::Font->new;
    read_xml($f, $ARGV[0]);
    $f->out($ARGV[1]);

DESCRIPTION
This module contains the support routines for parsing XML and generating the Truetype font structures as a result. The module has been separated from the rest of the package in order to reduce the dependency that this would bring, of the whole package on XML::Parser. This way, people without the XML::Parser can still use the rest of the package.

The package interacts with another package through the use of a context containing and element 'receiver' which is an object which can possibly receive one of the following messages:

XML_start
    This message is called when an open tag occurs. It is called with the context, tag name and the attributes. The return value has no meaning.

XML_end
    This messages is called when a close tag occurs. It is called with the context, tag name and attributes (held over from when the tag was opened). There are 3 possible return values from such a message:

    undef
        This is the default return value indicating that default processing should occur in which either the current element on the tree, or the text of this element should be stored in the parent object.

    $context
        This magic value marks that the element should be deleted from the parent. Nothing is stored in the parent. (This rather than '' is used to allow 0 returns.)

    anything
        Anything else is taken as the element content to be stored in the parent.

In addition, the context hash passed to these messages contains the following keys:

xml This is the expat xml object. The context is also available as $context->{'xml'}{' mycontext'}. But that is a long winded way of not saying much!

font
    This is the base object that was passed in for XML parsing.

receiver
    This holds the current receiver of parsing events. It may be set in associated application to adjust which objects should receive messages when. It is also stored in the parsing stack to ensure that where an object changes it during XML_start, that that same object that received XML_start will receive the corresponding XML_end

stack
    This is the parsing stack, used internally to hold the current receiver and attributes for each element open, as a complete hierarchy back to the root element.

tree
    This element contains the storage tree corresponding to the parent of each element in the stack. The default action is to push undef onto this stack during XML_start and then to resolve this, either in the associated application (by changing $context->{'tree'}[-1]) or during XML_end of a child element, by which time we know whether we are dealing with an array or a hash or what.

text
    Character processing is to insert all the characters into the text element of the context for available use later.

METHODS