*
* @package infModel
* @access public
**/
class InfRule
{
/**
* Array, that hold the trigger subject in key ['s'], the trigger
* predicate in ['p'], and the trigger object in ['o'].
* The array values can be NULL to match anything or be a node that
* has to be matched.
*
* @var array
* @access private
*/
var $trigger;
/**
* Array, that hold the entailment subject in key ['s'], the
* entailment predicate in ['p'], and the entailment object in ['o'].
* The array values can be a node that will be inserted in the
* returning statement, or '' to insert the subject,'' to insert
* the predicate, or '' to insert the object of the checked statement
* to this position in the new returned statement.
*
* @var array
* @access private
*/
var $entailment;
/**
* Constructor
*
*
* @access public
*/
function infRule()
{
//initialising vars
$this->trigger=array();
$this->entailment=array();
}
/**
* Sets the trigger of this rule
* The values can be NULL to match anything or be a node that has to
* be matched.
*
* @param object Node OR NULL $subject
* @param object Node OR NULL $predicate
* @param object Node OR NULL $object
* @access public
* @throws PhpError
*/
function setTrigger ($subject, $predicate, $object)
{
//throw an error if subject, predicate, or object are neither
//node, nor null.
if(!is_a($subject,'Node') && $subject != null)
trigger_error(RDFAPI_ERROR . '(class: Infrule; method:
setTrigger): $subject has to be null or of class Node'
, E_USER_ERROR);
if(!is_a($predicate,'Node') && $predicate != null)
trigger_error(RDFAPI_ERROR . '(class: Infrule; method:
setTrigger): $predicate has to be null or of class Node'
, E_USER_ERROR);
if(!is_a($object,'Node') && $object != null)
trigger_error(RDFAPI_ERROR . '(class: Infrule; method:
setTrigger): $object has to be null or of class Node'
, E_USER_ERROR);
//set the trigger
$this->trigger['s']=$subject;
$this->trigger['p']=$predicate;
$this->trigger['o']=$object;
}
/**
* Sets the entailment of this rule
* The values can be NULL to match anything or be a node that has to
* be matched.
*
* @param object Node OR NULL $subject
* @param object Node OR NULL $predicate
* @param object Node OR NULL $object
* @access public
* @throws PhpError
*/
function setEntailment($subject,$predicate,$object)
{
//throw an error if subject, predicate, or object are neither node,
//nor ,,.
if(!is_a($subject,'Node') && !ereg('<[spo]>', $subject))
trigger_error(RDFAPI_ERROR . '(class: Infrule; method:
setEntailment): $subject has to be ,,or or of class Node'
, E_USER_ERROR);
if(!is_a($predicate,'Node') && !ereg('<[spo]>', $predicate))
trigger_error(RDFAPI_ERROR . '(class: Infrule; method:
setEntailment): $predicate has to be ,,or or of class Node'
, E_USER_ERROR);
if(!is_a($object,'Node') && !ereg('<[spo]>', $object))
trigger_error(RDFAPI_ERROR . '(class: Infrule; method:
setEntailment): $object has to be ,,or or of class Node'
, E_USER_ERROR);
$this->entailment['s']=$subject;
$this->entailment['p']=$predicate;
$this->entailment['o']=$object;
}
/**
* Checks, if the statement satisfies the trigger.
*
* @param object Statement
* @return boolean
* @access public
* @throws PhpError
*/
function checkTrigger(& $statement)
{
//is true, if the trigger is null to match anything
//or equals the statement's subject
$shouldFireS = $this->trigger['s'] == null ||
$this->trigger['s']->equals($statement->getSubject());
//is true, if the trigger is null to match anything
//or equals the statement's predicate
$shouldFireP = $this->trigger['p'] == null ||
$this->trigger['p']->equals($statement->getPredicate());
//is true, if the trigger is null to match anything
//or equals the statement's object
$shouldFireO = $this->trigger['o'] == null ||
$this->trigger['o']->equals($statement->getObject());
//returns true, if ALL are true
return $shouldFireS && $shouldFireP && $shouldFireO;
}
/**
* Checks, if this rule could entail a statement that matches
* a find of $subject,$predicate,$object.
*
* @param object Statement
* @return boolean
* @access public
* @throws PhpError
*/
function checkEntailment ($subject, $predicate, $object)
{
//true, if $subject is null, the entailment's subject matches
//anything, or the $subject equals the entailment-subject.
$matchesS= $subject == null ||
!is_a($this->entailment['s'],'Node') ||
$this->entailment['s']->equals($subject);
//true, if $predicate is null, the entailment's predicate matches
//anything, or the $predicate equals the entailment-predicate.
$matchesP= $predicate == null ||
!is_a($this->entailment['p'],'Node') ||
$this->entailment['p']->equals($predicate);
//true, if $object is null, the entailment's object matches
//anything, or the $object equals the entailment-object.
$matchesO= $object == null ||
!is_a($this->entailment['o'],'Node') ||
$this->entailment['o']->equals($object);
//returns true, if ALL are true
return $matchesS && $matchesP && $matchesO;
}
/**
* Returns a infered InfStatement by evaluating the statement with
* the entailment rule.
*
* @param object Statement
* @return object InfStatement
* @access public
* @throws PhpError
*/
function entail(& $statement)
{
//if the entailment's subject is ,,or , put the statements
//subject,predicate,or object into the subject of the
//entailed statement. If the entailment's subject is a node,
//add that node to the statement.
switch ($this->entailment['s'])
{
case '':
$entailedSubject=$statement->getSubject();
break;
case '':
$entailedSubject=$statement->getPredicate();
break;
case '':
$entailedSubject=$statement->getObject();
break;
default:
$entailedSubject=$this->entailment['s'];
};
//if the entailment's predicate is ,,or , put the
//statements subject,predicate,or object into the predicate of
//the entailed statement. If the entailment's predicate is a node,
//add that node to the statement.
switch ($this->entailment['p'])
{
case '':
$entailedPredicate=$statement->getSubject();
break;
case '':
$entailedPredicate=$statement->getPredicate();
break;
case '':
$entailedPredicate=$statement->getObject();
break;
default:
$entailedPredicate=$this->entailment['p'];
};
//if the entailment's object is ,,or , put the
//statements subject,predicate,or object into the object of
//the entailed statement. If the entailment's object is a node,
//add that node to the statement.
switch ($this->entailment['o'])
{
case '':
$entailedObject=$statement->getSubject();
break;
case '':
$entailedObject=$statement->getPredicate();
break;
case '':
$entailedObject=$statement->getObject();
break;
default:
$entailedObject=$this->entailment['o'];
};
//return the infered statement
return (new InfStatement($entailedSubject,$entailedPredicate,$entailedObject));
}
/**
* Returns a find-query that matches statements, whose entailed
* statements would match the supplied find query.
*
* @param Node OR null $subject
* @param Node OR null $predicate
* @param Node OR null $object
* @return array
* @access public
* @throws PhpError
*/
function getModifiedFind( $subject, $predicate, $object)
{
$findSubject=$this->trigger['s'];
$findPredicate=$this->trigger['p'];
$findObject=$this->trigger['o'];
switch ($this->entailment['s'])
{
case '':
$findSubject=$subject;
break;
case '':
$findPredicate=$subject;
break;
case '':
$findObject=$subject;
break;
};
switch ($this->entailment['p'])
{
case '':
$findSubject=$predicate;
break;
case '':
$findPredicate=$predicate;
break;
case '':
$findObject=$predicate;
break;
};
switch ($this->entailment['o'])
{
case '':
$findSubject=$object;
break;
case '':
$findPredicate=$object;
break;
case '':
$findObject=$object;
break;
};
return array('s' => $findSubject,
'p' => $findPredicate,
'o' => $findObject );
}
function getTrigger()
{
return array ( 's' => $this->trigger['s'],
'p' => $this->trigger['p'],
'o' => $this->trigger['o'],
);
}
function getEntailment()
{
return array ( 's' => $this->entailment['s'],
'p' => $this->entailment['p'],
'o' => $this->entailment['o'],
);
}
}
?>