/**
* Constructs a result graph.
*
* @param array $arVartable A table containing the result vars and their bindings
* @param GraphPattern $constructPattern The CONSTRUCT pattern
* @return MemModel The result graph which matches the CONSTRUCT pattern
*/
function constructGraph($arVartable, $constructPattern)
{
$resultGraph = new MemModel();
if (!$arVartable) {
return $resultGraph;
}
$tp = $constructPattern->getTriplePatterns();
$bnode = 0;
foreach ($arVartable as $value) {
foreach ($tp as $triple) {
$sub = $triple->getSubject();
$pred = $triple->getPredicate();
$obj = $triple->getObject();
if (is_string($sub) && $sub[1] == '_') {
$sub = new BlankNode("_bN" . $bnode);
}
if (is_string($pred) && $pred[1] == '_') {
$pred = new BlankNode("_bN" . $bnode);
}
if (is_string($obj) && $obj[1] == '_') {
$obj = new BlankNode("_bN" . $bnode);
}
if (is_string($sub)) {
$sub = $value[$sub];
}
if (is_string($pred)) {
$pred = $value[$pred];
}
if (is_string($obj)) {
$obj = $value[$obj];
}
if ($sub !== "" && $pred !== "" && $obj !== "") {
$resultGraph->add(new Statement($sub, $pred, $obj));
}
}
$bnode++;
}
return $resultGraph;
}
/**
* Parses a value constraint.
*
* @param GraphPattern $pattern
* @param boolean $outer If the constraint is an outer one.
*/
protected function _parseConstraint(&$pattern, $outer)
{
require_once 'Erfurt/Sparql/Constraint.php';
$constraint = new Erfurt_Sparql_Constraint();
$constraint->setOuterFilter($outer);
$constraint->setTree($this->_parseConstraintTree());
if (current($this->_tokens) === '}') {
prev($this->_tokens);
}
$pattern->addConstraint($constraint);
}
/**
* Parses a value constraint.
*
* @param GraphPattern $pattern
* @param boolean $outer If the constraint is an outer one.
* @return void
*/
protected function parseConstraint(&$pattern, $outer)
{
$constraint = new Constraint();
$constraint->setOuterFilter($outer);
$this->_fastForward();
$this->_rewind();
$nBeginKey = key($this->tokens);
$constraint->setTree($t = $this->parseConstraintTree());
$nEndKey = key($this->tokens);
if (current($this->tokens) == '}') {
prev($this->tokens);
}
//for backwards compatibility with the normal sparql engine
// which does not use the tree array currently
$expression = trim(implode('', array_slice($this->tokens, $nBeginKey + 1, $nEndKey - $nBeginKey - 1)));
if ($expression[0] == '(' && substr($expression, -1) == ')') {
$expression = trim(substr($expression, 1, -1));
}
$constraint->addExpression($expression);
$pattern->addConstraint($constraint);
}
/**
* Creates some SQL statements from the given triple pattern
* array.
*
* @param QueryTriple $triple Array containing subject, predicate and object
* @param GraphPattern $graphPattern Graph pattern object
*
* @return array Array consisting of on array and two string values:
* SELECT, FROM and WHERE part
*/
function getTripleSql(QueryTriple $triple, GraphPattern $graphPattern, $arResultVars)
{
$arSelect = array();
$strFrom = null;
$strWhere = null;
$strWhereEquality = '';
$bWhereEqualitySubject = false;
$bWhereEqualityPredicate = false;
$bWhereEqualityObject = false;
$subject = $triple->getSubject();
$predicate = $triple->getPredicate();
$object = $triple->getObject();
$arRefVars = array();
$strTablePrefix = 't' . $this->nTableId;
/**
* SELECT part
* We do select only the columns we need for variables
*/
if (SparqlVariable::isVariable($subject)) {
if (isset($this->arUnionVarAssignments[$this->nUnionCount][$subject])) {
//already selected -> add equality check
$bWhereEqualitySubject = true;
$this->arUsedVarTypes[$subject]['s'] = true;
} else {
if (isset($this->arVarAssignments[$subject][0])) {
$strTablePrefix = $this->arVarAssignments[$subject][0];
}
$this->arVarAssignments[$subject] = array($strTablePrefix, 's');
$this->arUnionVarAssignments[$this->nUnionCount][$subject] = array($strTablePrefix, 's');
$this->arUsedVarTypes[$subject]['s'] = true;
if (self::isResultVar($subject, $arResultVars)) {
//new variable that needs to be selected
$arSelect[$subject] = $this->createVariableSelectArray('s', $subject, $strTablePrefix);
if (isset($this->arUsedVarAssignments[$subject])) {
$arRefVars[$subject] = $strTablePrefix . '.subject';
} else {
$this->arUsedVarAssignments[$subject] = $strTablePrefix . '.subject';
}
}
}
}
if (SparqlVariable::isVariable($predicate)) {
if (isset($this->arUnionVarAssignments[$this->nUnionCount][$predicate])) {
//already selected -> add equality check
$bWhereEqualityPredicate = true;
$this->arUsedVarTypes[$predicate]['p'] = true;
} else {
if (isset($this->arVarAssignments[$predicate][0])) {
$strTablePrefix = $this->arVarAssignments[$predicate][0];
}
$this->arVarAssignments[$predicate] = array($strTablePrefix, 'p');
$this->arUnionVarAssignments[$this->nUnionCount][$predicate] = array($strTablePrefix, 'p');
$this->arUsedVarTypes[$predicate]['p'] = true;
if (self::isResultVar($predicate, $arResultVars)) {
$arSelect[$predicate] = $this->createVariableSelectArray('p', $predicate, $strTablePrefix);
if (isset($this->arUsedVarAssignments[$predicate])) {
$arRefVars[$predicate] = $strTablePrefix . '.predicate';
} else {
$this->arUsedVarAssignments[$predicate] = $strTablePrefix . '.predicate';
}
}
}
}
if (SparqlVariable::isVariable($object)) {
if (isset($this->arUnionVarAssignments[$this->nUnionCount][$object])) {
//already selected -> add equality check
$bWhereEqualityObject = true;
$this->arUsedVarTypes[$object]['o'] = true;
} else {
if (isset($this->arVarAssignments[$object][0])) {
$strTablePrefix = $this->arVarAssignments[$object][0];
}
$this->arVarAssignments[$object] = array($strTablePrefix, 'o');
$this->arUnionVarAssignments[$this->nUnionCount][$object] = array($strTablePrefix, 'o');
$this->arUsedVarTypes[$object]['o'] = true;
if (self::isResultVar($object, $arResultVars)) {
$arSelect[$object] = $this->createVariableSelectArray('o', $object, $strTablePrefix);
if (isset($this->arUsedVarAssignments[$object])) {
$arRefVars[$object] = $strTablePrefix . '.object';
} else {
$this->arUsedVarAssignments[$object] = $strTablePrefix . '.object';
}
}
if (isset($this->query->varLanguages[$object]) && $this->query->varLanguages[$object] !== null) {
$strWhereEquality .= ' AND ' . $strTablePrefix . '.l_language = "' . addslashes($this->query->varLanguages[$object]) . '"';
}
if (isset($this->query->varDatatypes[$object]) && $this->query->varDatatypes[$object] !== null) {
$strWhereEquality .= ' AND ' . $strTablePrefix . '.l_datatype = "' . addslashes($this->query->varDatatypes[$object]) . '"';
}
}
}
/**
* WhereEquality - needs to be done now because strTablePrefix may change
*/
if ($bWhereEqualitySubject) {
$strWhereEquality .= ' AND ' . self::getSqlEqualityCondition(array($strTablePrefix, 's'), $this->arVarAssignments[$subject]);
}
if ($bWhereEqualityPredicate) {
$strWhereEquality .= ' AND ' . self::getSqlEqualityCondition(array($strTablePrefix, 'p'), $this->arVarAssignments[$predicate]);
}
if ($bWhereEqualityObject) {
$strWhereEquality .= ' AND ' . self::getSqlEqualityCondition(array($strTablePrefix, 'o'), $this->arVarAssignments[$object]);
}
/**
* FROM part
*/
if ($this->nUnionTriplePatternCount == 0) {
//first FROM
$strFrom = $this->tblStatements . ' as ' . $strTablePrefix;
} else {
//normal join
if (count($this->arModelIds) == 1) {
$strFrom = 'LEFT JOIN ' . $this->tblStatements . ' as ' . $strTablePrefix . ' ON t0.modelID = ' . $strTablePrefix . '.modelID';
} else {
if (count($this->arModelIds) > 1) {
$arIDs = array();
foreach ($this->arModelIds as $nId) {
$arIDs[] = $strTablePrefix . '.modelID = ' . intval($nId);
}
$strFrom = 'LEFT JOIN ' . $this->tblStatements . ' as ' . $strTablePrefix . ' ON (' . implode(' OR ', $arIDs) . ')';
} else {
$strFrom = 'LEFT JOIN ' . $this->tblStatements . ' as ' . $strTablePrefix . ' ON t0.modelID = ' . $strTablePrefix . '.modelID';
}
}
foreach ($arRefVars as $strRefVar => $strSqlVar) {
$strFrom .= ' AND ' . $this->arUsedVarAssignments[$strRefVar] . ' = ' . $strSqlVar;
}
if ($graphPattern->getOptional() !== null) {
$strFrom .= $this->getSqlCondition($subject, $strTablePrefix, 'subject') . $this->getSqlCondition($predicate, $strTablePrefix, 'predicate') . $this->getSqlCondition($object, $strTablePrefix, 'object') . $strWhereEquality;
}
}
/**
* WHERE part
*/
if ($this->nUnionTriplePatternCount == 0) {
if (count($this->arModelIds) == 1) {
$strWhere = $strTablePrefix . '.modelID = ' . intval(reset($this->arModelIds));
} else {
if (count($this->arModelIds) > 1) {
$arIDs = array();
foreach ($this->arModelIds as $nId) {
$arIDs[] = $strTablePrefix . '.modelID = ' . intval($nId);
}
$strWhere = '(' . implode(' OR ', $arIDs) . ')';
} else {
//so that we can append an AND
$strWhere = '1';
}
}
}
if ($graphPattern->getOptional() === null || $this->nGraphPatternCount == 0) {
$strWhere .= $this->getSqlCondition($subject, $strTablePrefix, 'subject') . $this->getSqlCondition($predicate, $strTablePrefix, 'predicate') . $this->getSqlCondition($object, $strTablePrefix, 'object') . $strWhereEquality;
}
return array($arSelect, $strFrom, $strWhere);
}
/**
* Adds a graph pattern to the result part.
*
* @param GraphPattern $pattern
* @return void
*/
public function addGraphPattern($pattern)
{
$pattern->setId($this->graphPatternCounter);
$this->resultPart[] = $pattern;
$this->graphPatternCounter++;
}
/**
* Parses a value constraint.
*
* @param GraphPattern $pattern
* @return void
*/
protected function parseConstraint($pattern, $outer)
{
$constraint = new Constraint();
$constraint->setOuterFilter($outer);
$this->_fastForward();
if (current($this->tokens) == '(') {
$this->parseBrackettedExpression(&$constraint);
} else {
$this->parseExpression(&$constraint);
}
$pattern->addConstraint(&$constraint);
}
/**
* Builds the resultset.
*
* @param GraphPattern $pattern
* @param Array $resmodel
* @return Array
*/
protected function _buildResultSet($pattern, $resmodel)
{
// determine variables and their corresponding values
$result = null;
if (is_string($pattern->getSubject())) {
$n = 0;
foreach ($resmodel['trip'] as $key => $triple) {
if (isset($resmodel['graphvar'][$key])) {
$result[$n][$resmodel['graphvar'][$key]] = $resmodel['graph'][$key];
}
$result[$n++][$pattern->getSubject()] = $triple->subj;
}
}
if (is_string($pattern->getPredicate())) {
$n = 0;
foreach ($resmodel['trip'] as $key => $triple) {
if (isset($resmodel['graphvar'][$key])) {
$result[$n][$resmodel['graphvar'][$key]] = $resmodel['graph'][$key];
}
$result[$n++][$pattern->getPredicate()] = $triple->pred;
}
}
if (is_string($pattern->getObject())) {
$n = 0;
foreach ($resmodel['trip'] as $key => $triple) {
if (isset($resmodel['graphvar'][$key])) {
$result[$n][$resmodel['graphvar'][$key]] = $resmodel['graph'][$key];
}
$result[$n++][$pattern->getObject()] = $triple->obj;
}
}
return $result;
}
