abstract class ExpressionVisitor

An Expression visitor walks a graph of expressions and turns them into a query for the underlying implementation.

@author Benjamin Eberlei <kontakt@beberlei.de>

Hierarchy

Expanded class hierarchy of ExpressionVisitor

File

drupal/core/vendor/doctrine/common/lib/Doctrine/Common/Collections/Expr/ExpressionVisitor.php, line 28

Namespace

Doctrine\Common\Collections\Expr
View source
abstract class ExpressionVisitor {

  /**
   * Convert a comparison expression into the target query language output
   *
   * @param Comparison $comparison
   *
   * @return mixed
   */
  public abstract function walkComparison(Comparison $comparison);

  /**
   * Convert a value expression into the target query language part.
   *
   * @param Value $value
   *
   * @return mixed
   */
  public abstract function walkValue(Value $value);

  /**
   * Convert a composite expression into the target query language output
   *
   * @param CompositeExpression $expr
   *
   * @return mixed
   */
  public abstract function walkCompositeExpression(CompositeExpression $expr);

  /**
   * Dispatch walking an expression to the appropriate handler.
   *
   * @param Expression
   *
   * @return mixed
   */
  public function dispatch(Expression $expr) {
    switch (true) {
      case $expr instanceof Comparison:
        return $this
          ->walkComparison($expr);
      case $expr instanceof Value:
        return $this
          ->walkValue($expr);
      case $expr instanceof CompositeExpression:
        return $this
          ->walkCompositeExpression($expr);
      default:
        throw new \RuntimeException("Unknown Expression " . get_class($expr));
    }
  }

}

Members

Namesort descending Modifiers Type Description Overrides
ExpressionVisitor::dispatch public function Dispatch walking an expression to the appropriate handler.
ExpressionVisitor::walkComparison abstract public function Convert a comparison expression into the target query language output 1
ExpressionVisitor::walkCompositeExpression abstract public function Convert a composite expression into the target query language output 1
ExpressionVisitor::walkValue abstract public function Convert a value expression into the target query language part. 1