public function optimize(Erfurt_Sparql_Query $query)
{
$resultForm = $query->getResultForm();
$result = $query;
// TODO Not working on all queries yet.
#return $result;
if ($resultForm === 'select distinct') {
$result = $this->_optimizeDistinct($query);
}
return $result;
}
public static function getSelect(Erfurt_Sparql_Query $query, $arSqls, $strAdditional = '')
{
if (count($arSqls) == 1) {
return implode('', $arSqls[0]) . $strAdditional;
}
//union
$strUnion = 'UNION' . ($query->getResultForm() == 'select distinct' ? '' : ' ALL');
$ar = array();
foreach ($arSqls as $arSql) {
$ar[] = implode('', $arSql) . $strAdditional;
}
return '(' . implode(') ' . $strUnion . ' (', $ar) . ')';
}
/**
* Simplify the query by flattening out subqueries.
* Modifies the passed query object directly.
*/
public function simplify(Erfurt_Sparql_Query $query)
{
#return;
$arPatterns = $query->getResultPart();
self::dropEmpty($arPatterns);
$arPlan = $this->createPlan($arPatterns);
if (count($arPlan) == 0) {
$query->setResultPart($arPatterns);
return 0;
}
$this->executePlan($arPatterns, $arPlan);
$query->setResultPart($arPatterns);
}
/**
* Executes multiple SQL queries and returns an array of results.
*
* @param array $arSqls Array of SQL queries.
* @return array Array of query results.
*/
protected function _queryMultiple($arSqls)
{
$arSM = $this->query->getSolutionModifier();
if ($arSM['limit'] === null && $arSM['offset'] === null) {
$nOffset = 0;
$nLimit = null;
$nSql = 0;
} else {
require_once 'Erfurt/Sparql/EngineDb/Offsetter.php';
$offsetter = new Erfurt_Sparql_EngineDb_Offsetter($this, $this->query);
list($nSql, $nOffset) = $offsetter->determineOffset($arSqls);
$nLimit = $arSM['limit'];
}
$nCount = 0;
$arResults = array();
foreach ($arSqls as $nId => $arSql) {
if ($nId < $nSql) {
continue;
}
if ($nLimit != null) {
$nCurrentLimit = $nLimit - $nCount;
} else {
$nCurrentLimit = null;
}
$dbResult = $this->_queryDb($arSql, $nOffset, $nCurrentLimit);
$nCount += count($dbResult);
$arResults[] = $dbResult;
$nOffset = 0;
if ($nLimit !== null && $nCount >= $nLimit) {
break;
}
}
return $arResults;
}
/**
* Checks if $token is a variable.
*
* @param string $token The token
* @return boolean true if the token is a variable false if not
*/
protected function _varCheck($token)
{
if (isset($token[0]) && ($token[0] == '$' || $token[0] == '?')) {
$this->_query->addUsedVar($token);
return true;
}
return false;
}
public function __construct(Erfurt_Sparql_Query $query, array $arModelIdMapping)
{
$this->query = $query;
$this->arModelIds = array();
foreach ($query->getFromPart() as $from) {
if (isset($arModelIdMapping[$from])) {
$this->arModelIds[] = $arModelIdMapping[$from]['modelId'];
} else {
$this->arModelIds[] = -1;
}
}
foreach ($query->getFromNamedPart() as $from) {
if (isset($arModelIdMapping[$from])) {
$this->arModelIds[] = $arModelIdMapping[$from]['modelId'];
} else {
$this->arModelIds[] = -1;
}
}
}
/**
* Converts the database results into the desired output format
* and returns the result.
*
* @param array $arRecordSets Array of (possibly several) SQL query results.
* @param Erfurt_Sparql_Query $query SPARQL query object
* @param $engine Sparql Engine to query the database
* @return array
*/
public function convertFromDbResults($arRecordSets, Erfurt_Sparql_Query $query, $engine, $vars)
{
$this->query = $query;
$this->engine = $engine;
$this->_vars = $vars;
$strResultForm = $this->query->getResultForm();
switch ($strResultForm) {
case 'construct':
case 'select':
case 'select distinct':
switch ($strResultForm) {
case 'construct':
$arResult = $this->_getVariableArrayFromRecordSets($arRecordSets, $strResultForm, true);
break;
default:
$arResult = $this->_getVariableArrayFromRecordSets($arRecordSets, $strResultForm, false);
if (count($this->uriValues) > 0 || count($this->literalValues) > 0) {
// If the query contains a ORDER BY wen need to reorder the result
$sm = $query->getSolutionModifier();
if (null !== $sm['order by']) {
foreach ($sm['order by'] as $order) {
$n = count($arResult);
$id = ltrim($order['val'], '?$');
while (true) {
$hasChanged = false;
for ($i = 0; $i < $n - 1; ++$i) {
switch ($order['type']) {
case 'desc':
if ($arResult[$i][$id] < $arResult[$i + 1][$id]) {
$dummy = $arResult[$i][$id];
$arResult[$i][$id] = $arResult[$i + 1][$id];
$arResult[$i + 1][$id] = $dummy;
$hasChanged = true;
}
break;
case 'asc':
default:
if ($arResult[$i][$id] > $arResult[$i + 1][$id]) {
$dummy = $arResult[$i][$id];
$arResult[$i][$id] = $arResult[$i + 1][$id];
$arResult[$i + 1][$id] = $dummy;
$hasChanged = true;
}
break;
}
}
$n--;
if (!$hasChanged && $n === 0) {
break;
}
}
}
}
}
}
//some result forms need more modification
switch ($strResultForm) {
case 'construct':
$arResult = $this->_constructGraph($arResult, $this->query->getConstructPattern());
break;
case 'describe':
$arResult = $this->describeGraph($arResult);
break;
}
return $arResult;
break;
case 'count':
case 'count-distinct':
case 'ask':
if (count($arRecordSets) > 1) {
require_once 'Erfurt/Exception.php';
throw new Erfurt_Exception('More than one result set for a ' . $strResultForm . ' query!');
}
$nCount = 0;
foreach ($arRecordSets[0] as $row) {
$nCount += intval($row['count']);
break;
}
if ($strResultForm == 'ask') {
return $nCount > 0 ? true : false;
} else {
return $nCount;
}
break;
case 'describe':
default:
throw new Exception('Yet not supported: ' . $strResultForm);
}
}
public function __construct($variable)
{
$this->_variable = $variable;
$this->_language = Erfurt_Sparql_Query::getLanguageTag($variable);
}
