83 lines
2.6 KiB
PHP
83 lines
2.6 KiB
PHP
<?php
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/*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This software consists of voluntary contributions made by many individuals
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* and is licensed under the MIT license. For more information, see
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* <http://www.doctrine-project.org>.
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*/
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namespace Doctrine\Common\Collections\Expr;
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/**
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* An Expression visitor walks a graph of expressions and turns them into a
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* query for the underlying implementation.
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*
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* @author Benjamin Eberlei <kontakt@beberlei.de>
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*/
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abstract class ExpressionVisitor
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{
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/**
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* Converts a comparison expression into the target query language output.
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*
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* @param Comparison $comparison
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*
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* @return mixed
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*/
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abstract public function walkComparison(Comparison $comparison);
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/**
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* Converts a value expression into the target query language part.
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*
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* @param Value $value
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*
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* @return mixed
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*/
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abstract public function walkValue(Value $value);
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/**
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* Converts a composite expression into the target query language output.
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*
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* @param CompositeExpression $expr
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*
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* @return mixed
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*/
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abstract public function walkCompositeExpression(CompositeExpression $expr);
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/**
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* Dispatches walking an expression to the appropriate handler.
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*
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* @param Expression $expr
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*
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* @return mixed
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*
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* @throws \RuntimeException
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*/
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public function dispatch(Expression $expr)
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{
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switch (true) {
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case ($expr instanceof Comparison):
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return $this->walkComparison($expr);
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case ($expr instanceof Value):
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return $this->walkValue($expr);
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case ($expr instanceof CompositeExpression):
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return $this->walkCompositeExpression($expr);
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default:
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throw new \RuntimeException("Unknown Expression " . get_class($expr));
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}
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}
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}
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