/**
* 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);
}
