NAME

XML::Grove::Subst - substitute values into a template

SYNOPSIS

 use XML::Grove::Subst;
 # Using subst method on XML::Grove::Document or XML::Grove::Element:
 $new_grove = $source_grove->subst( ARGS );
 $new_grove = $source_grove->subst_hash( ARG );
 # Using an XML::Grove::Subst instance:
 $subster = XML::Grove::Subst->new();
 $new_grove = $subster->subst( $source_grove, ARGS );
 $new_grove = $subster->subst_hash( $source_grove, ARG );

DESCRIPTION

"XML::Grove::Subst" implements XML templates. "XML::Grove::Subst" traverses through a source grove replacing all elements with names `"SUB:XXX"' or `"SUB:key"' with their corresponding values from ARGS (a list) or ARG (a hash), repsectively.

METHODS

$grove_obj->subst( ARGS ) =item $subster->subst( $grove_obj, ARGS ): Search for `"SUB:XXX"' elements, where XXX is an array index, and replace the element with the value from ARGS, a list of values. The return value is a new grove with the substitutions applied.
$grove_obj->subst_hash( ARG ) =item $subster->subst_hash( $grove_obj, ARG ): Search for `"SUB:key"' elements and replace the element with the value from ARG, a hash of values. The hash key is taken from the `"key"' attribute of the `"SUB:key"' element, for example, `"<SUB:key key='foo'>"'. The return value is a new grove with the substitutions applied.

EXAMPLE

The following template, in a file `"template.xml"', could be used for a simple parts database conversion to HTML:

    <html>
      <head>
        <title><SUB:key key='Name'></title>
      </head>
      <body>
        <h1><SUB:key key='Name'></title>
        <p>Information for part number <SUB:key key='Number'>:</p>
        <SUB:key key='Description'>
      </body>
    </html>

To use this template you would first parse it and convert it to a grove, and then use `"subst_hash()"' every time you needed a new page:

    use XML::Parser::PerlSAX;
    use XML::Grove;
    use XML::Grove::Builder;
    use XML::Grove::Subst;
    use XML::Grove::PerlSAX;
    use XML::Handler::XMLWriter;
    # Load the template
    $b = XML::Grove::Builder->new();
    $p = XML::Parser::PerlSAX->new( Handler = $b );
    $source_grove = $p->parse( Source => { SystemId => 'template.xml' } );
    # Apply the substitutions
    $new_grove = $source_grove->subst_hash( { Name => 'Acme DCX-2000 Filter',
                                              Number => 'N4728',
                                              Description => 'The Best' } );
    # Write the new grove to standard output
    $w = XML::Handler::XMLWriter->new();
    $wp = XML::Grove::PerlSAX->new( Handler => $w );
    $wp->parse( Source => { Grove => $new_grove } );

AUTHOR

Ken MacLeod, ken@bitsko.slc.ut.us