php man page for libxml_set_external_entity_loader

LIBXML_SET_EXTERNAL_ENTITY_LOADER(3)					 1				      LIBXML_SET_EXTERNAL_ENTITY_LOADER(3)

libxml_set_external_entity_loader - Changes the default external entity loader

SYNOPSIS
       void libxml_set_external_entity_loader (callable  $resolver_function)

DESCRIPTION
	Changes the default external entity loader.

PARAMETERS
	      o $resolver_function
		-  A  callable	that takes three arguments. Two strings, a public id and system id, and a context (an array with four keys) as the
		third argument. This callback should return a resource, a string from which a resource can be opened, or NULL.

RETURN VALUES
	No value is returned.

EXAMPLES
       Example #1

	      libxml_set_external_entity_loader(3) example

	      <?php
	      $xml = <<<XML
	      <!DOCTYPE foo PUBLIC "-//FOO/BAR" "http://example.com/foobar">
	      <foo>bar</foo>
	      XML;

	      $dtd = <<<DTD
	      <!ELEMENT foo (#PCDATA)>
	      DTD;

	      libxml_set_external_entity_loader(
		  function ($public, $system, $context) use($dtd) {
		      var_dump($public);
		      var_dump($system);
		      var_dump($context);
		      $f = fopen("php://temp", "r+");
		      fwrite($f, $dtd);
		      rewind($f);
		      return $f;
		  }
	      );

	      $dd = new DOMDocument;
	      $r  = $dd->loadXML($xml);

	      var_dump($dd->validate());
	      ?>

	      The above example will output:

	      string(10) "-//FOO/BAR"
	      string(25) "http://example.com/foobar"
	      array(4) {
		  ["directory"]    => NULL
		  ["intSubName"]   => NULL
		  ["extSubURI"]    => NULL
		  ["extSubSystem"] => NULL
	      }
	      bool(true)

SEE ALSO
       libxml_disable_entity_loader(3).

PHP Documentation Group 										      LIBXML_SET_EXTERNAL_ENTITY_LOADER(3)