Programming PHP

If your external entity reference handler returns a false value (which it will if it
returns no value), XML parsing stops with an XML_ERROR_EXTERNAL_ENTITY_HANDLING
error. If it returns true, parsing continues.
Example 11-6 shows how you would parse externally referenced XML documents.
Define two functions, create_parser( ) and parse( ), to do the actual work of creating
and feeding the XML parser. You can use them both to parse the top-level document
and any documents included via external references. Such functions are
described later, in “Using the Parser.” The external entity reference handler simply
identifies the right file to send to those functions.
Example 11-6. External entity reference handler
function external_entity_reference($inParser, $inNames, $inBase,
$inSystemID, $inPublicID) {
if($inSystemID) {
if(!list($parser, $fp) = create_parser($inSystemID)) {
echo "Error opening external entity $inSystemID \n";
return false;
}
return parse($parser, $fp);
}
return false;
}
Unparsed entities
An unparsed entity declaration must be accompanied by a notation declaration:
]>
Register a notation declaration handler with xml_set_notation_decl_handler( ):
xml_set_notation_decl_handler(parser, handler);
The handler will be called with five parameters:
my_notation_handler(parser, notation, base, system, public);
The base parameter is the base URI for resolving the identifier of the notation (which
is currently always empty). Either the system identifier or the public identifier for the
notation will be set, but not both.
Register an unparsed entity declaration with the xml_set_unparsed_entity_decl_
handler( ) function:
xml_set_unparsed_entity_decl_handler(parser, handler);
The handler will be called with six parameters:
my_unp_entity_handler(parser, entity, base, system, public, notation);
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Parsing XML | 269