Documentation is available at InfModelB.php
- <?php
- // ----------------------------------------------------------------------------------
- // Class: InfModelB
- // ----------------------------------------------------------------------------------
- /**
- * A InfModelB extends the InfModel Class, with a backward chaining algorithm.
- * Only the loaded or added base-triples are stored.
- * A find-query evaluates the inference rules and recursively tries to find the statements.
- * InfModelB memorises "Dead-Ends" until the next add() command, thus
- * makin a second find much faster.
- * InfModelB is safe for loops in Ontologies, that would cause infinite loops.
- * WARNING: A find(null,null,null) might take very long.
- *
- * <BR><BR>History:<UL>
- * <LI>10-07-2004 : Function findFirstMatchingStatement() added paramter $offset
- * to set an search offset
- * <LI>09-10-2004 : First version of this class.</LI>
- * <LI>09-15-2004 : Added Index over InRule Entailments
- * to increase performance
- *</UL>
- * @version V0.9.1
- * @author Daniel Westphal <mail at d-westphal dot de>
- *
- * @package infModel
- * @access public
- ***/
- class InfModelB extends InfModel
- {
- /**
- * Array that holds combinations of inference rules with distinct
- * find-querys, that don't lead to any inference.
- * @var array
- * @access private
- */
- var $findDeadEnds;
- /**
- * Constructor
- * You can supply a base_uri
- *
- * @param string $baseURI
- * @access public
- */
- function InfModelB($baseURI = null)
- {
- parent::InfModel($baseURI);
- $this->findDeadEnds=array();
- }
- /**
- * Adds a new triple to the Model without checking, if the statement
- * is already in the Model. So if you want a duplicate free Model use
- * the addWithoutDuplicates() function (which is slower then add())
- *
- * @param object Statement $statement
- * @access public
- * @throws PhpError
- */
- function add($statement)
- {
- parent::add($statement);
- //Reset the found dead-ends.
- $this->findDeadEnds=array();
- }
- /**
- * General method to search for triples.
- * NULL input for any parameter will match anything.
- * Example: $result = $m->find( NULL, NULL, $node );
- * Finds all triples with $node as object.
- * Returns an empty MemModel if nothing is found.
- * To improve the search speed with big Models, call index(INDEX_TYPE)
- * before seaching.
- *
- * It recursively searches in the statements and rules to find
- * matching statements
- *
- * @param object Node $subject
- * @param object Node $predicate
- * @param object Node $object
- * @return object MemModel
- * @access public
- * @throws PhpError
- */
- function find($subject,$predicate,$object)
- {
- $searchStringIndex=array();
- $resultModel=new MemModel();
- //add all infered statements without duplicates to the result model
- foreach ($this->_infFind($subject,$predicate,$object,array())as $statement)
- {
- $resultModel->addWithoutDuplicates($statement);
- };
- return $resultModel;
- }
- /**
- * This is the main inference method of the InfModelB
- * The algorithm works as follows:
- * Find all statements in the base model, that matches the current
- * find-query.
- * Check all rules, if they are able to deliver infered statements,
- * that match the current find-query. Don't use rules with queries,
- * that lead to dead-ends and don't use a rule-query-combination that
- * was used before in this branch (ontology loops).
- * If a rule is possible do deliver such statements, get a new
- * find-query, that is possible to find those statements, that are able
- * to trigger this rule.
- * Call this _infFind method wirh the new find-query and entail the
- * resulting statements.
- * If this rule, wasn't able to return any statements with this distinct
- * query, add this combination to the dead-ends.
- * Return the statements from the base triples and those, which were infered.
- *
- * If $findOnlyFirstMatching is set to true, only the first match in
- * the base-statements is entailed an returned (used in contains() and
- * findFirstMatchingStatement() methods).
- *
- * You can set an offset to look for the first matching statement by setting the
- * $offset var.
- *
- * It recursively searches in the statements and rules to find matching
- * statements
- *
- * @param object Node $subject
- * @param object Node $predicate
- * @param object Node $object
- * @param array $searchStringIndex
- * @param boolean $findOnlyFirstMatching
- * @param integer $offset
- * @param integer $resultCount
- * @return object array Statements
- * @access private
- */
- function _infFind ($subject,$predicate,$object, $searchStringIndex, $findOnlyFirstMatching = false, $offset = 0,$resultCount = 0 )
- {
- $return=array();
- //Find all matching statements in the base statements
- $findResult=parent::find($subject,$predicate,$object);
- //For all found statements
- foreach ($findResult->triples as $statement)
- {
- $return[]=$statement;
- $resultCount++;
- //Return, if only the firstMatchingStatement was wanted
- if ($findOnlyFirstMatching && $resultCount > $offset)
- return $return;
- };
- //Don't infer statements about the schema (rdfs:subClass, etc..)
- //is false
- if ($predicate == null ||
- (is_a($predicate,'Node') &&
- !in_array($predicate->getLabel(),$this->supportedInference))
- )
- //Check only Rules, that the EntailmentIndex returned.
- foreach ($this->_findRuleEntailmentInIndex($subject,$predicate,$object) as $ruleKey)
- {
- $infRule=$this->infRules[$ruleKey];
- $serializedRuleStatement=$ruleKey.serialize($subject).serialize($predicate).serialize($object);
- //If it is to ontology loop and no dead-end
- if (!in_array($serializedRuleStatement, $searchStringIndex) &&
- !in_array($serializedRuleStatement, $this->findDeadEnds))
- {
- //Keep this distinct rule query cobination for
- //this branch to detect loops
- $searchStringIndex[]=$serializedRuleStatement;
- //If the rule is able to deliver statements that match
- //this query
- if ($infRule->checkEntailment($subject,$predicate,$object))
- {
- //Get a modified find-query, that matches statements,
- //that trigger this rule
- $modefiedFind=$infRule->getModifiedFind($subject,$predicate,$object);
- //Call this method with the new find-query
- $infFindResult=$this->_infFind($modefiedFind['s'],
- $modefiedFind['p'],
- $modefiedFind['o'],
- $searchStringIndex,
- $findOnlyFirstMatching,
- $offset,
- $resultCount) ;
- //If it deliverd statements that matches the trigger
- if (isset($infFindResult[0]))
- {
- foreach ($infFindResult as $statement)
- {
- //Entail the statements and check, if they are not about the
- //ontology
- $newStatement=$infRule->entail($statement);
- if (!in_array($newStatement->getLabelPredicate(),$this->supportedInference))
- //Check if, the entailed statements are, what we are looking for
- if($this->_nodeEqualsFind($subject,$newStatement->getSubject()) &&
- $this->_nodeEqualsFind($predicate,$newStatement->getPredicate()) &&
- $this->_nodeEqualsFind($object,$newStatement->getObject() ) )
- {
- //Add to results
- $return[]=$newStatement;
- $resultCount++;
- //or return at once
- if ($findOnlyFirstMatching && $resultCount > $offset)
- return $return;
- }
- }
- } else
- {
- //If there were no results of the rule-query-combination,
- //mark this combination as a dead-end.
- $this->findDeadEnds[]=$serializedRuleStatement;
- }
- }
- }
- }
- //Return the array of the found statements
- return $return;
- }
- /**
- * Tests if the Model contains the given triple.
- * TRUE if the triple belongs to the Model;
- * FALSE otherwise.
- *
- * @param object Statement &$statement
- * @return boolean
- * @access public
- */
- function contains(&$statement)
- {
- //throws an error, if $statement is not of class Statement
- if(!is_a($statement,'Statement'))
- trigger_error(RDFAPI_ERROR . '(class: InfModelB; method: contains):
- $statement has to be object of class Statement', E_USER_ERROR);
- //Call the _infFind method, but let it stop, if it finds the first match.
- if (count( $this->_infFind($statement->getSubject(),
- $statement->getPredicate(),
- $statement->getObject(),
- array(),true) ) >0)
- {
- return true;
- } else
- {
- return false;
- };
- }
- /**
- * Searches for triples and returns the first matching statement.
- * NULL input for any parameter will match anything.
- * Example: $result = $m->findFirstMatchingStatement( NULL, NULL, $node );
- * Returns the first statement of the MemModel where the object equals $node.
- * Returns an NULL if nothing is found.
- * You can define an offset to search for. Default = 0
- *
- * @param object Node $subject
- * @param object Node $predicate
- * @param object Node $object
- * @param integer $offset
- * @return object Statement
- * @access public
- */
- function findFirstMatchingStatement($subject, $predicate, $object, $offset = 0)
- {
- //Call the _infFind method, but let it stop, if it finds the
- //first match.
- $res= $this->_infFind($subject,$predicate,$object,array(),true,$offset);
- if (isset($res[$offset]))
- {
- return $res[$offset];
- } else
- {
- return NULL;
- };
- }
- /**
- * Returns a StatementIterator for traversing the Model.
- * @access public
- * @return object StatementIterator
- */
- function & getStatementIterator()
- {
- // Import Package Utility
- include_once(RDFAPI_INCLUDE_DIR.PACKAGE_UTILITY);
- // Gets a MemModel by executing a find(null,null,null) to get a
- //inferable statements.
- // WARNING: might be slow
- return new StatementIterator($this->getMemModel());
- }
- /**
- * Number of all inferable triples in the Model.
- * WARNING: uses a find(null,null,null) to find all statements! (might take a while)
- *
- * @param boolean
- * @return integer
- * @access public
- */
- function size()
- {
- // Gets a MemModel by executing a find(null,null,null) to get a
- //inferable statements.
- // WARNING: might be slow
- $res = $this->getMemModel();
- return $res->size();
- }
- /**
- * Create a MemModel containing all the triples (including inferred
- * statements) of the current InfModelB
- *
- * @return object MemModel
- * @access public
- */
- function & getMemModel()
- {
- $return=$this->find(null,null,null);
- $return->setBaseURI($this->baseURI);
- $return->addParsedNamespaces($this->getParsedNamespaces());
- return $return;
- }
- /**
- * Create a MemModel containing only the base triples (without inferred
- * statements) of the current InfModelB
- *
- * @return object MemModel
- * @access public
- */
- function & getBaseMemModel()
- {
- $return= new MemModel();
- $return->setBaseURI($this->baseURI);
- foreach ($this->triples as $statement)
- $return->add($statement);
- $retun->addParsedNamespaces($this->getParsedNamespaces());
- return $return;
- }
- /**
- * Short Dump of the InfModelB.
- *
- * @access public
- * @return string
- */
- function toString()
- {
- return 'InfModelB[baseURI=' . $this->getBaseURI() . '; size=' . $this->size(true) . ']';
- }
- /**
- * Dumps of the InfModelB including ALL inferable triples.
- *
- * @access public
- * @return string
- */
- function toStringIncludingTriples()
- {
- $dump = $this->toString() . chr(13);
- $stateIt=new StatementIterator($this->find(null,null,null));
- while($statement=$stateIt->next())
- {
- $dump .= $statement->toString() . chr(13);
- }
- return $dump;
- }
- /**
- * Saves the RDF,N3 or N-Triple serialization of the full InfModelB
- * (including inferred triples) to a file.
- * You can decide to which format the model should be serialized by
- * using a corresponding suffix-string as $type parameter. If no $type
- * parameter is placed this method will serialize the model to XML/RDF
- * format.
- * Returns FALSE if the InfModelB couldn't be saved to the file.
- *
- * @access public
- * @param string $filename
- * @param string $type
- * @throw PhpError
- * @return boolean
- */
- function saveAs($filename, $type ='rdf')
- {
- $memmodel=$this->getMemModel();
- return $memmodel->saveAs($filename, $type);
- }
- /**
- * Writes the RDF serialization of the Model including ALL inferable
- * triples as HTML.
- *
- * @access public
- */
- function writeAsHtml()
- {
- require_once(RDFAPI_INCLUDE_DIR.PACKAGE_SYNTAX_RDF);
- $ser = new RdfSerializer();
- $rdf =& $ser->serialize($this->getMemModel());
- $rdf = htmlspecialchars($rdf, ENT_QUOTES);
- $rdf = str_replace(' ', ' ', $rdf);
- $rdf = nl2br($rdf);
- echo $rdf;
- }
- /**
- * Writes the RDF serialization of the Model including ALL inferable
- * triples as HTML table.
- *
- * @access public
- */
- function writeAsHtmlTable()
- {
- // Import Package Utility
- include_once(RDFAPI_INCLUDE_DIR.PACKAGE_UTILITY);
- RDFUtil::writeHTMLTable($this->getMemModel());
- }
- /**
- * Writes the RDF serialization of the Model including ALL inferable
- * triples.
- *
- * @access public
- * @return string
- */
- function writeRdfToString()
- {
- // Import Package Syntax
- include_once(RDFAPI_INCLUDE_DIR.PACKAGE_SYNTAX_RDF);
- $ser = new RdfSerializer();
- $rdf =& $ser->serialize($this->getMemModel());
- return $rdf;
- }
- /**
- * Removes the triple from the MemModel.
- * TRUE if the triple is removed.
- * FALSE otherwise.
- *
- * Checks, if it touches any statements, that added inference rules
- * to the model
- *
- * @param object Statement $statement
- * @return boolean
- * @access public
- * @throws PhpError
- */
- function remove($statement)
- {
- if (parent::contains($statement))
- {
- if (in_array($statement->getLabelPredicate(),$this->supportedInference));
- while (count($this->_removeFromInference($statement))>0);
- $this->findDeadEnds=array();
- return parent::remove($statement);
- } else
- {
- return false;
- }
- }
- /**
- * Checks, if a single node matches a single find pattern.
- * TRUE if the node matches.
- * FALSE otherwise.
- *
- * Checks, if it touches any statements, that added inference rules
- * to the model
- *
- * @param object Statement $statement
- * @return boolean
- * @access private
- */
- function _nodeEqualsFind(& $find, $node)
- {
- //If the find pattern is a node, use the nodes equal-method and
- //return the result.
- if (is_a($find,'Node'))
- return $node->equals($find);
- //Null-pattern matches anything.
- if ($find == null)
- {
- return true;
- } else
- {
- return false;
- }
- }
- /**
- * Returns a FindIterator for traversing the MemModel.
- * Disabled in InfModelB
- * @access public
- * @return object FindIterator
- */
- function & findAsIterator($sub=null,$pred=null,$obj=null) {
- $errmsg = RDFAPI_ERROR . '(class: InfModelB; method: findAsIterator):
- This function is disabled in the
- Inference Model';
- trigger_error($errmsg, E_USER_ERROR);
- }
- }
- ?>
Documentation generated on Fri, 17 Dec 2004 16:15:10 +0100 by phpDocumentor 1.3.0RC3