vendor/doctrine/collections/lib/Doctrine/Common/Collections/Expr/ExpressionVisitor.php

   1 <?php
   2 /*
   3  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   4  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   5  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   6  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   7  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   8  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   9  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  10  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  11  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  12  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  13  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  14  *
  15  * This software consists of voluntary contributions made by many individuals
  16  * and is licensed under the MIT license. For more information, see
  17  * <http://www.doctrine-project.org>.
  18  */
  19
  20 namespace Doctrine\Common\Collections\Expr;
  21
  22 /**
  23  * An Expression visitor walks a graph of expressions and turns them into a
  24  * query for the underlying implementation.
  25  *
  26  * @author Benjamin Eberlei <kontakt@beberlei.de>
  27  */
  28 abstract class ExpressionVisitor
  29 {
  30     /**
  31      * Converts a comparison expression into the target query language output.
  32      *
  33      * @param Comparison $comparison
  34      *
  35      * @return mixed
  36      */
  37     abstract public function walkComparison(Comparison $comparison);
  38
  39     /**
  40      * Converts a value expression into the target query language part.
  41      *
  42      * @param Value $value
  43      *
  44      * @return mixed
  45      */
  46     abstract public function walkValue(Value $value);
  47
  48     /**
  49      * Converts a composite expression into the target query language output.
  50      *
  51      * @param CompositeExpression $expr
  52      *
  53      * @return mixed
  54      */
  55     abstract public function walkCompositeExpression(CompositeExpression $expr);
  56
  57     /**
  58      * Dispatches walking an expression to the appropriate handler.
  59      *
  60      * @param Expression $expr
  61      *
  62      * @return mixed
  63      *
  64      * @throws \RuntimeException
  65      */
  66     public function dispatch(Expression $expr)
  67     {
  68         switch (true) {
  69             case ($expr instanceof Comparison):
  70                 return $this->walkComparison($expr);
  71
  72             case ($expr instanceof Value):
  73                 return $this->walkValue($expr);
  74
  75             case ($expr instanceof CompositeExpression):
  76                 return $this->walkCompositeExpression($expr);
  77
  78             default:
  79                 throw new \RuntimeException("Unknown Expression " . get_class($expr));
  80         }
  81     }
  82 }