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class EasyRdf_Serialiser_Turtle in Zircon Profile 8

Same name and namespace in other branches
  1. 8.0 vendor/easyrdf/easyrdf/lib/EasyRdf/Serialiser/Turtle.php \EasyRdf_Serialiser_Turtle

Class to serialise an EasyRdf_Graph to Turtle with no external dependancies.

http://www.w3.org/TR/turtle/

@package EasyRdf @copyright Copyright (c) 2009-2013 Nicholas J Humfrey @license http://www.opensource.org/licenses/bsd-license.php

Hierarchy

Expanded class hierarchy of EasyRdf_Serialiser_Turtle

1 string reference to 'EasyRdf_Serialiser_Turtle'
Format.php in vendor/easyrdf/easyrdf/lib/EasyRdf/Format.php

File

vendor/easyrdf/easyrdf/lib/EasyRdf/Serialiser/Turtle.php, line 48

View source 
class EasyRdf_Serialiser_Turtle extends EasyRdf_Serialiser {
  private $outputtedBnodes = array();

  /**
   * Given a IRI string, escape and enclose in angle brackets.
   *
   * @param  string $resourceIri
   * @return string
   */
  public static function escapeIri($resourceIri) {
    $escapedIri = str_replace('>', '\\>', $resourceIri);
    return "<{$escapedIri}>";
  }

  /**
   * Given a string, enclose in quotes and escape any quotes in the string.
   * Strings containing tabs, linefeeds or carriage returns will be
   * enclosed in three double quotes (""").
   *
   * @param  string $value
   * @return string
   */
  public static function quotedString($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 . '"';
    }
  }

  /**
   * Given a an EasyRdf_Resource or URI, convert it into a string, suitable to
   * be written to a Turtle document. URIs will be shortened into CURIES
   * where possible.
   *
   * @param  EasyRdf_Resource $resource   The resource to convert to a Turtle string
   * @param  boolean $createNamespace     If true, a new namespace may be created
   * @return string
   */
  public function serialiseResource($resource, $createNamespace = false) {
    if (is_object($resource)) {
      if ($resource
        ->isBNode()) {
        return $resource
          ->getUri();
      }
      $resource = $resource
        ->getUri();
    }
    $short = EasyRdf_Namespace::shorten($resource, $createNamespace);
    if ($short) {
      $this
        ->addPrefix($short);
      return $short;
    }
    return self::escapeIri($resource);
  }

  /**
   * Given an EasyRdf_Literal object, convert it into a string, suitable to
   * be written to a Turtle document. Supports multiline literals and literals with
   * datatypes or languages.
   *
   * @param  EasyRdf_Literal $literal
   * @return string
   */
  public function serialiseLiteral($literal) {
    $value = strval($literal);
    $quoted = self::quotedString($value);
    if ($datatype = $literal
      ->getDatatypeUri()) {
      if ($datatype == 'http://www.w3.org/2001/XMLSchema#integer') {
        return sprintf('%d', $value);
      }
      elseif ($datatype == 'http://www.w3.org/2001/XMLSchema#decimal') {
        return sprintf('%s', $value);
      }
      elseif ($datatype == 'http://www.w3.org/2001/XMLSchema#double') {
        return sprintf('%e', $value);
      }
      elseif ($datatype == 'http://www.w3.org/2001/XMLSchema#boolean') {
        return sprintf('%s', $value);
      }
      else {
        $escaped = $this
          ->serialiseResource($datatype, true);
        return sprintf('%s^^%s', $quoted, $escaped);
      }
    }
    elseif ($lang = $literal
      ->getLang()) {
      return $quoted . '@' . $lang;
    }
    else {
      return $quoted;
    }
  }

  /**
   * Convert an EasyRdf object into a string suitable to
   * be written to a Turtle document.
   *
   * @param  EasyRdf_Resource|EasyRdf_Literal $object
   * @return string
   */
  public function serialiseObject($object) {
    if ($object instanceof EasyRdf_Resource) {
      return $this
        ->serialiseResource($object);
    }
    elseif ($object instanceof EasyRdf_Literal) {
      return $this
        ->serialiseLiteral($object);
    }
    else {
      throw new InvalidArgumentException("serialiseObject() requires \$object to be " . "of type EasyRdf_Resource or EasyRdf_Literal");
    }
  }

  /**
   * Protected method to serialise a RDF collection
   * @ignore
   */
  protected function serialiseCollection($node, $indent) {
    $turtle = '(';
    $count = 0;
    while ($node) {
      if ($id = $node
        ->getBNodeId()) {
        $this->outputtedBnodes[$id] = true;
      }
      $value = $node
        ->get('rdf:first');
      $node = $node
        ->get('rdf:rest');
      if ($node and $node
        ->hasProperty('rdf:first')) {
        $count++;
      }
      if ($value !== null) {
        $serialised = $this
          ->serialiseObject($value);
        if ($count) {
          $turtle .= "\n{$indent}  {$serialised}";
        }
        else {
          $turtle .= " " . $serialised;
        }
      }
    }
    if ($count) {
      $turtle .= "\n{$indent})";
    }
    else {
      $turtle .= " )";
    }
    return $turtle;
  }

  /**
   * 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 $property) {
      if ($property === 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type') {
        $pStr = 'a';
      }
      else {
        $pStr = $this
          ->serialiseResource($property, true);
      }
      if ($pCount) {
        $turtle .= " ;\n{$indent}";
      }
      $turtle .= ' ' . $pStr;
      $oCount = 0;
      foreach ($res
        ->all("<{$property}>") as $object) {
        if ($oCount) {
          $turtle .= ',';
        }
        if ($object instanceof EasyRdf_Collection) {
          $turtle .= ' ' . $this
            ->serialiseCollection($object, $indent);
        }
        elseif ($object instanceof EasyRdf_Resource and $object
          ->isBNode()) {
          $id = $object
            ->getBNodeId();
          $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;
  }

  /**
   * @ignore
   */
  protected function serialiseSubjects(EasyRdf_Graph $graph, $filterType) {
    $turtle = '';
    foreach ($graph
      ->resources() as $resource) {

      /** @var $resource EasyRdf_Resource */

      // If the resource has no properties - don't serialise it
      $properties = $resource
        ->propertyUris();
      if (count($properties) == 0) {
        continue;
      }

      // Is this node of the right type?
      $thisType = $resource
        ->isBNode() ? 'bnode' : 'uri';
      if ($thisType != $filterType) {
        continue;
      }
      if ($thisType == 'bnode') {
        $id = $resource
          ->getBNodeId();
        if (isset($this->outputtedBnodes[$id])) {

          // Already been serialised
          continue;
        }
        $this->outputtedBnodes[$id] = true;
        $rpcount = $this
          ->reversePropertyCount($resource);
        if ($rpcount == 0) {
          $turtle .= '[]';
        }
        else {
          $turtle .= $this
            ->serialiseResource($resource);
        }
      }
      else {
        $turtle .= $this
          ->serialiseResource($resource);
      }
      $turtle .= $this
        ->serialiseProperties($resource);
      $turtle .= "\n";
    }
    return $turtle;
  }

  /**
   * Serialise an EasyRdf_Graph to Turtle.
   *
   * @param EasyRdf_Graph $graph   An EasyRdf_Graph object.
   * @param string        $format  The name of the format to convert to.
   * @param array         $options
   * @throws EasyRdf_Exception
   * @return string The RDF in the new desired format.
   */
  public function serialise($graph, $format, array $options = array()) {
    parent::checkSerialiseParams($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 = '';
    $turtle .= $this
      ->serialiseSubjects($graph, 'uri');
    $turtle .= $this
      ->serialiseSubjects($graph, 'bnode');
    if (count($this->prefixes)) {
      return $this
        ->serialisePrefixes() . "\n" . $turtle;
    }
    else {
      return $turtle;
    }
  }

}

Members

Namesort descending Modifiers Type Description Overrides
EasyRdf_Serialiser::$prefixes protected property
EasyRdf_Serialiser::addPrefix protected function Keep track of the prefixes used while serialising @ignore
EasyRdf_Serialiser::checkSerialiseParams protected function Check and cleanup parameters passed to serialise() method @ignore
EasyRdf_Serialiser::reversePropertyCount protected function Protected method to get the number of reverse properties for a resource If a resource only has a single property, the number of values for that property is returned instead. @ignore
EasyRdf_Serialiser::__construct public function 4
EasyRdf_Serialiser_Turtle::$outputtedBnodes private property
EasyRdf_Serialiser_Turtle::escapeIri public static function Given a IRI string, escape and enclose in angle brackets.
EasyRdf_Serialiser_Turtle::quotedString public static function Given a string, enclose in quotes and escape any quotes in the string. Strings containing tabs, linefeeds or carriage returns will be enclosed in three double quotes (""").
EasyRdf_Serialiser_Turtle::serialise public function Serialise an EasyRdf_Graph to Turtle. Overrides EasyRdf_Serialiser::serialise
EasyRdf_Serialiser_Turtle::serialiseCollection protected function Protected method to serialise a RDF collection @ignore
EasyRdf_Serialiser_Turtle::serialiseLiteral public function Given an EasyRdf_Literal object, convert it into a string, suitable to be written to a Turtle document. Supports multiline literals and literals with datatypes or languages.
EasyRdf_Serialiser_Turtle::serialiseObject public function Convert an EasyRdf object into a string suitable to be written to a Turtle document.
EasyRdf_Serialiser_Turtle::serialisePrefixes protected function @ignore
EasyRdf_Serialiser_Turtle::serialiseProperties protected function Protected method to serialise the properties of a resource @ignore
EasyRdf_Serialiser_Turtle::serialiseResource public function Given a an EasyRdf_Resource or URI, convert it into a string, suitable to be written to a Turtle document. URIs will be shortened into CURIES where possible.
EasyRdf_Serialiser_Turtle::serialiseSubjects protected function @ignore