abstract class ExpressionVisitor in Plug 7

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

@author Benjamin Eberlei <[e-mail]>

Hierarchy

• class \Doctrine\Common\Collections\Expr\ExpressionVisitor

File

lib/doctrine/collections/lib/Doctrine/Common/Collections/Expr/ExpressionVisitor.php, line 28

Namespace

Doctrine\Common\Collections\Expr

abstract class ExpressionVisitor {

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

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

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

  /**
   * Dispatches walking an expression to the appropriate handler.
   *
   * @param Expression $expr
   *
   * @return mixed
   *
   * @throws \RuntimeException
   */
  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

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