--- /dev/null
+<?php
+
+/**
+ * EasyRdf
+ *
+ * LICENSE
+ *
+ * Copyright (c) 2009-2013 Nicholas J Humfrey. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ * 3. The name of the author 'Nicholas J Humfrey" may be used to endorse or
+ * promote products derived from this software without specific prior
+ * written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * @package EasyRdf
+ * @copyright Copyright (c) 2009-2013 Nicholas J Humfrey
+ * @license http://www.opensource.org/licenses/bsd-license.php
+ */
+
+/**
+ * Parent class for the EasyRdf serialiser
+ *
+ * @package EasyRdf
+ * @copyright Copyright (c) 2009-2013 Nicholas J Humfrey
+ * @license http://www.opensource.org/licenses/bsd-license.php
+ */
+class EasyRdf_Serialiser
+{
+ protected $prefixes = array();
+
+ public function __construct()
+ {
+ }
+
+ /**
+ * Keep track of the prefixes used while serialising
+ * @ignore
+ */
+ protected function addPrefix($qname)
+ {
+ list ($prefix) = explode(':', $qname);
+ $this->prefixes[$prefix] = true;
+ }
+
+ /**
+ * Check and cleanup parameters passed to serialise() method
+ * @ignore
+ */
+ protected function checkSerialiseParams(&$graph, &$format)
+ {
+ if (is_null($graph) or !is_object($graph) or !($graph instanceof EasyRdf_Graph)) {
+ throw new InvalidArgumentException(
+ "\$graph should be an EasyRdf_Graph object and cannot be null"
+ );
+ }
+
+ if (is_null($format) or $format == '') {
+ throw new InvalidArgumentException(
+ "\$format cannot be null or empty"
+ );
+ } elseif (is_object($format) and ($format instanceof EasyRdf_Format)) {
+ $format = $format->getName();
+ } elseif (!is_string($format)) {
+ throw new InvalidArgumentException(
+ "\$format should be a string or an EasyRdf_Format object"
+ );
+ }
+ }
+
+ /**
+ * Protected method to get the number of reverse properties for a resource
+ * If a resource only has a single property, the number of values for that
+ * property is returned instead.
+ * @ignore
+ */
+ protected function reversePropertyCount($resource)
+ {
+ $properties = $resource->reversePropertyUris();
+ $count = count($properties);
+ if ($count == 1) {
+ $property = $properties[0];
+ return $resource->countValues("^<$property>");
+ } else {
+ return $count;
+ }
+ }
+
+ /**
+ * Sub-classes must follow this protocol
+ * @ignore
+ */
+ public function serialise($graph, $format, array $options = array())
+ {
+ throw new EasyRdf_Exception(
+ "This method should be overridden by sub-classes."
+ );
+ }
+}