<?php
/**
* EasyRdf
*
* LICENSE
*
* Copyright (c) 2009-2012 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) 2009-2012 Nicholas J Humfrey
* @license http://www.opensource.org/licenses/bsd-license.php
* @version $Id$
*/
/**
* Class to serialise an EasyRdf_Graph to Turtle
* with no external dependancies.
*
* http://www.dajobe.org/2004/01/turtle
*
* @package EasyRdf
* @copyright Copyright (c) 2009-2012 Nicholas J Humfrey
* @license http://www.opensource.org/licenses/bsd-license.php
*/
class EasyRdf_Serialiser_Turtle extends EasyRdf_Serialiser {
private $outputtedBnodes = array();
/**
* @ignore
*/
protected function serialiseResource($resource) {
if ($resource
->isBnode()) {
return $resource
->getUri();
}
else {
$short = $resource
->shorten();
if ($short) {
$this
->addPrefix($short);
return $short;
}
else {
$uri = str_replace('>', '\\>', $resource);
return "<{$resource}>";
}
}
}
/**
* @ignore
*/
protected function quotedString($value) {
if (preg_match("/[\t\n\r]/", $value)) {
$escaped = str_replace(array(
'\\',
'"""',
), array(
'\\\\',
'\\"""',
), $value);
return '"""' . $escaped . '"""';
}
else {
$escaped = str_replace(array(
'\\',
'"',
), array(
'\\\\',
'\\"',
), $value);
return '"' . $escaped . '"';
}
}
/**
* @ignore
*/
protected function serialiseObject($object) {
if ($object instanceof EasyRdf_Resource) {
return $this
->serialiseResource($object);
}
else {
$value = strval($object);
$quoted = $this
->quotedString($value);
if ($datatype = $object
->getDatatypeUri()) {
$short = EasyRdf_Namespace::shorten($datatype, true);
if ($short) {
$this
->addPrefix($short);
if ($short == 'xsd:integer') {
return sprintf('%d', $value);
}
elseif ($short == 'xsd:decimal') {
return sprintf('%g', $value);
}
elseif ($short == 'xsd:double') {
return sprintf('%e', $value);
}
elseif ($short == 'xsd:boolean') {
return sprintf('%s', $value ? 'true' : 'false');
}
else {
return sprintf('%s^^%s', $quoted, $short);
}
}
else {
$datatypeUri = str_replace('>', '\\>', $datatype);
return sprintf('%s^^<%s>', $quoted, $datatypeUri);
}
}
elseif ($lang = $object
->getLang()) {
return $quoted . '@' . $lang;
}
else {
return $quoted;
}
}
}
/**
* Protected method to serialise the properties of a resource
* @ignore
*/
protected function serialiseProperties($res, $depth = 1) {
$properties = $res
->propertyUris();
$indent = str_repeat(' ', $depth * 2 - 1);
$turtle = '';
if (count($properties) > 1) {
$turtle .= "\n{$indent}";
}
$pCount = 0;
foreach ($properties as $property) {
$short = EasyRdf_Namespace::shorten($property, true);
if ($short) {
if ($short == 'rdf:type') {
$pStr = 'a';
}
else {
$this
->addPrefix($short);
$pStr = $short;
}
}
else {
$pStr = '<' . str_replace('>', '\\>', $property) . '>';
}
if ($pCount) {
$turtle .= " ;\n{$indent}";
}
$turtle .= ' ' . $pStr;
$oCount = 0;
foreach ($res
->all("<{$property}>") as $object) {
if ($oCount) {
$turtle .= ',';
}
if ($object instanceof EasyRdf_Resource and $object
->isBnode()) {
$id = $object
->getNodeId();
$rpcount = $this
->reversePropertyCount($object);
if ($rpcount <= 1 and !isset($this->outputtedBnodes[$id])) {
// Nested unlabelled Blank Node
$this->outputtedBnodes[$id] = true;
$turtle .= ' [';
$turtle .= $this
->serialiseProperties($object, $depth + 1);
$turtle .= ' ]';
}
else {
// Multiple properties pointing to this blank node
$turtle .= ' ' . $this
->serialiseObject($object);
}
}
else {
$turtle .= ' ' . $this
->serialiseObject($object);
}
$oCount++;
}
$pCount++;
}
if ($depth == 1) {
$turtle .= " .";
if ($pCount > 1) {
$turtle .= "\n";
}
}
elseif ($pCount > 1) {
$turtle .= "\n" . str_repeat(' ', ($depth - 1) * 2 - 1);
}
return $turtle;
}
/**
* @ignore
*/
protected function serialisePrefixes() {
$turtle = '';
foreach ($this->prefixes as $prefix => $count) {
$url = EasyRdf_Namespace::get($prefix);
$turtle .= "@prefix {$prefix}: <{$url}> .\n";
}
return $turtle;
}
/**
* Serialise an EasyRdf_Graph to Turtle.
*
* @param object EasyRdf_Graph $graph An EasyRdf_Graph object.
* @param string $format The name of the format to convert to.
* @return string The RDF in the new desired format.
*/
public function serialise($graph, $format) {
parent::checkSerialiseParams($graph, $format);
if ($format != 'turtle' and $format != 'n3') {
throw new EasyRdf_Exception("EasyRdf_Serialiser_Turtle does not support: {$format}");
}
$this->prefixes = array();
$this->outputtedBnodes = array();
$turtle = '';
foreach ($graph
->resources() as $resource) {
// If the resource has no properties - don't serialise it
$properties = $resource
->propertyUris();
if (count($properties) == 0) {
continue;
}
if ($resource
->isBnode()) {
$id = $resource
->getNodeId();
$rpcount = $this
->reversePropertyCount($resource);
if (isset($this->outputtedBnodes[$id])) {
// Already been serialised
continue;
}
else {
$this->outputtedBnodes[$id] = true;
if ($rpcount == 0) {
$turtle .= '[]';
}
else {
$turtle .= $this
->serialiseResource($resource);
}
}
}
else {
$turtle .= $this
->serialiseResource($resource);
}
$turtle .= $this
->serialiseProperties($resource);
$turtle .= "\n";
}
if (count($this->prefixes)) {
return $this
->serialisePrefixes() . "\n" . $turtle;
}
else {
return $turtle;
}
}
}
Name | Description |
---|---|
EasyRdf_Serialiser_Turtle | Class to serialise an EasyRdf_Graph to Turtle with no external dependancies. |