vendor/doctrine/lib/Doctrine/ORM/Query/Parser.php
changeset 0 7f95f8617b0b
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/doctrine/lib/Doctrine/ORM/Query/Parser.php	Sat Sep 24 15:40:41 2011 +0200
@@ -0,0 +1,2863 @@
+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\ORM\Query;
+
+use Doctrine\ORM\Query;
+use Doctrine\ORM\Mapping\ClassMetadata;
+
+/**
+ * An LL(*) recursive-descent parser for the context-free grammar of the Doctrine Query Language.
+ * Parses a DQL query, reports any errors in it, and generates an AST.
+ *
+ * @since   2.0
+ * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>
+ * @author  Jonathan Wage <jonwage@gmail.com>
+ * @author  Roman Borschel <roman@code-factory.org>
+ * @author  Janne Vanhala <jpvanhal@cc.hut.fi>
+ */
+class Parser
+{
+    /** READ-ONLY: Maps BUILT-IN string function names to AST class names. */
+    private static $_STRING_FUNCTIONS = array(
+        'concat'    => 'Doctrine\ORM\Query\AST\Functions\ConcatFunction',
+        'substring' => 'Doctrine\ORM\Query\AST\Functions\SubstringFunction',
+        'trim'      => 'Doctrine\ORM\Query\AST\Functions\TrimFunction',
+        'lower'     => 'Doctrine\ORM\Query\AST\Functions\LowerFunction',
+        'upper'     => 'Doctrine\ORM\Query\AST\Functions\UpperFunction'
+    );
+
+    /** READ-ONLY: Maps BUILT-IN numeric function names to AST class names. */
+    private static $_NUMERIC_FUNCTIONS = array(
+        'length'    => 'Doctrine\ORM\Query\AST\Functions\LengthFunction',
+        'locate'    => 'Doctrine\ORM\Query\AST\Functions\LocateFunction',
+        'abs'       => 'Doctrine\ORM\Query\AST\Functions\AbsFunction',
+        'sqrt'      => 'Doctrine\ORM\Query\AST\Functions\SqrtFunction',
+        'mod'       => 'Doctrine\ORM\Query\AST\Functions\ModFunction',
+        'size'      => 'Doctrine\ORM\Query\AST\Functions\SizeFunction',
+        'date_diff' => 'Doctrine\ORM\Query\AST\Functions\DateDiffFunction',
+    );
+
+    /** READ-ONLY: Maps BUILT-IN datetime function names to AST class names. */
+    private static $_DATETIME_FUNCTIONS = array(
+        'current_date'      => 'Doctrine\ORM\Query\AST\Functions\CurrentDateFunction',
+        'current_time'      => 'Doctrine\ORM\Query\AST\Functions\CurrentTimeFunction',
+        'current_timestamp' => 'Doctrine\ORM\Query\AST\Functions\CurrentTimestampFunction',
+        'date_add'          => 'Doctrine\ORM\Query\AST\Functions\DateAddFunction',
+        'date_sub'          => 'Doctrine\ORM\Query\AST\Functions\DateSubFunction',
+    );
+
+    /**
+     * Expressions that were encountered during parsing of identifiers and expressions
+     * and still need to be validated.
+     */
+    private $_deferredIdentificationVariables = array();
+    private $_deferredPartialObjectExpressions = array();
+    private $_deferredPathExpressions = array();
+    private $_deferredResultVariables = array();
+
+    /**
+     * The lexer.
+     *
+     * @var Doctrine\ORM\Query\Lexer
+     */
+    private $_lexer;
+
+    /**
+     * The parser result.
+     *
+     * @var Doctrine\ORM\Query\ParserResult
+     */
+    private $_parserResult;
+
+    /**
+     * The EntityManager.
+     *
+     * @var EnityManager
+     */
+    private $_em;
+
+    /**
+     * The Query to parse.
+     *
+     * @var Query
+     */
+    private $_query;
+
+    /**
+     * Map of declared query components in the parsed query.
+     *
+     * @var array
+     */
+    private $_queryComponents = array();
+
+    /**
+     * Keeps the nesting level of defined ResultVariables
+     *
+     * @var integer
+     */
+    private $_nestingLevel = 0;
+
+    /**
+     * Any additional custom tree walkers that modify the AST.
+     *
+     * @var array
+     */
+    private $_customTreeWalkers = array();
+
+    /**
+     * The custom last tree walker, if any, that is responsible for producing the output.
+     *
+     * @var TreeWalker
+     */
+    private $_customOutputWalker;
+
+    /**
+     * @var array
+     */
+    private $_identVariableExpressions = array();
+
+    /**
+     * Creates a new query parser object.
+     *
+     * @param Query $query The Query to parse.
+     */
+    public function __construct(Query $query)
+    {
+        $this->_query = $query;
+        $this->_em = $query->getEntityManager();
+        $this->_lexer = new Lexer($query->getDql());
+        $this->_parserResult = new ParserResult();
+    }
+
+    /**
+     * Sets a custom tree walker that produces output.
+     * This tree walker will be run last over the AST, after any other walkers.
+     *
+     * @param string $className
+     */
+    public function setCustomOutputTreeWalker($className)
+    {
+        $this->_customOutputWalker = $className;
+    }
+
+    /**
+     * Adds a custom tree walker for modifying the AST.
+     *
+     * @param string $className
+     */
+    public function addCustomTreeWalker($className)
+    {
+        $this->_customTreeWalkers[] = $className;
+    }
+
+    /**
+     * Gets the lexer used by the parser.
+     *
+     * @return Doctrine\ORM\Query\Lexer
+     */
+    public function getLexer()
+    {
+        return $this->_lexer;
+    }
+
+    /**
+     * Gets the ParserResult that is being filled with information during parsing.
+     *
+     * @return Doctrine\ORM\Query\ParserResult
+     */
+    public function getParserResult()
+    {
+        return $this->_parserResult;
+    }
+
+    /**
+     * Gets the EntityManager used by the parser.
+     *
+     * @return EntityManager
+     */
+    public function getEntityManager()
+    {
+        return $this->_em;
+    }
+
+    /**
+     * Parse and build AST for the given Query.
+     *
+     * @return \Doctrine\ORM\Query\AST\SelectStatement |
+     *         \Doctrine\ORM\Query\AST\UpdateStatement |
+     *         \Doctrine\ORM\Query\AST\DeleteStatement
+     */
+    public function getAST()
+    {
+        // Parse & build AST
+        $AST = $this->QueryLanguage();
+
+        // Process any deferred validations of some nodes in the AST.
+        // This also allows post-processing of the AST for modification purposes.
+        $this->_processDeferredIdentificationVariables();
+
+        if ($this->_deferredPartialObjectExpressions) {
+            $this->_processDeferredPartialObjectExpressions();
+        }
+
+        if ($this->_deferredPathExpressions) {
+            $this->_processDeferredPathExpressions($AST);
+        }
+
+        if ($this->_deferredResultVariables) {
+            $this->_processDeferredResultVariables();
+        }
+
+        return $AST;
+    }
+
+    /**
+     * Attempts to match the given token with the current lookahead token.
+     *
+     * If they match, updates the lookahead token; otherwise raises a syntax
+     * error.
+     *
+     * @param int token type
+     * @return void
+     * @throws QueryException If the tokens dont match.
+     */
+    public function match($token)
+    {
+        // short-circuit on first condition, usually types match
+        if ($this->_lexer->lookahead['type'] !== $token &&
+                $token !== Lexer::T_IDENTIFIER &&
+                $this->_lexer->lookahead['type'] <= Lexer::T_IDENTIFIER
+         ) {
+            $this->syntaxError($this->_lexer->getLiteral($token));
+        }
+
+        $this->_lexer->moveNext();
+    }
+
+    /**
+     * Free this parser enabling it to be reused
+     *
+     * @param boolean $deep     Whether to clean peek and reset errors
+     * @param integer $position Position to reset
+     */
+    public function free($deep = false, $position = 0)
+    {
+        // WARNING! Use this method with care. It resets the scanner!
+        $this->_lexer->resetPosition($position);
+
+        // Deep = true cleans peek and also any previously defined errors
+        if ($deep) {
+            $this->_lexer->resetPeek();
+        }
+
+        $this->_lexer->token = null;
+        $this->_lexer->lookahead = null;
+    }
+
+    /**
+     * Parses a query string.
+     *
+     * @return ParserResult
+     */
+    public function parse()
+    {
+        $AST = $this->getAST();
+
+        $this->fixIdentificationVariableOrder($AST);
+        $this->assertSelectEntityRootAliasRequirement();
+
+        if (($customWalkers = $this->_query->getHint(Query::HINT_CUSTOM_TREE_WALKERS)) !== false) {
+            $this->_customTreeWalkers = $customWalkers;
+        }
+
+        if (($customOutputWalker = $this->_query->getHint(Query::HINT_CUSTOM_OUTPUT_WALKER)) !== false) {
+            $this->_customOutputWalker = $customOutputWalker;
+        }
+
+        // Run any custom tree walkers over the AST
+        if ($this->_customTreeWalkers) {
+            $treeWalkerChain = new TreeWalkerChain($this->_query, $this->_parserResult, $this->_queryComponents);
+
+            foreach ($this->_customTreeWalkers as $walker) {
+                $treeWalkerChain->addTreeWalker($walker);
+            }
+
+            if ($AST instanceof AST\SelectStatement) {
+                $treeWalkerChain->walkSelectStatement($AST);
+            } else if ($AST instanceof AST\UpdateStatement) {
+                $treeWalkerChain->walkUpdateStatement($AST);
+            } else {
+                $treeWalkerChain->walkDeleteStatement($AST);
+            }
+        }
+
+        if ($this->_customOutputWalker) {
+            $outputWalker = new $this->_customOutputWalker(
+                $this->_query, $this->_parserResult, $this->_queryComponents
+            );
+        } else {
+            $outputWalker = new SqlWalker(
+                $this->_query, $this->_parserResult, $this->_queryComponents
+            );
+        }
+
+        // Assign an SQL executor to the parser result
+        $this->_parserResult->setSqlExecutor($outputWalker->getExecutor($AST));
+
+        return $this->_parserResult;
+    }
+    
+    private function assertSelectEntityRootAliasRequirement()
+    {
+        if ( count($this->_identVariableExpressions) > 0) {
+            $foundRootEntity = false;
+            foreach ($this->_identVariableExpressions AS $dqlAlias => $expr) {
+                if (isset($this->_queryComponents[$dqlAlias]) && $this->_queryComponents[$dqlAlias]['parent'] === null) {
+                    $foundRootEntity = true;
+                }
+            }
+            
+            if (!$foundRootEntity) {
+                $this->semanticalError('Cannot select entity through identification variables without choosing at least one root entity alias.');
+            }
+        }
+    }
+    
+    /**
+     * Fix order of identification variables.
+     * 
+     * They have to appear in the select clause in the same order as the
+     * declarations (from ... x join ... y join ... z ...) appear in the query
+     * as the hydration process relies on that order for proper operation.
+     * 
+     * @param AST\SelectStatement|AST\DeleteStatement|AST\UpdateStatement $AST
+     * @return void
+     */
+    private function fixIdentificationVariableOrder($AST)
+    {
+        if ( count($this->_identVariableExpressions) > 1) {
+            foreach ($this->_queryComponents as $dqlAlias => $qComp) {
+                if (isset($this->_identVariableExpressions[$dqlAlias])) {
+                    $expr = $this->_identVariableExpressions[$dqlAlias];
+                    $key = array_search($expr, $AST->selectClause->selectExpressions);
+                    unset($AST->selectClause->selectExpressions[$key]);
+                    $AST->selectClause->selectExpressions[] = $expr;
+                }
+            }
+        }
+    }
+
+    /**
+     * Generates a new syntax error.
+     *
+     * @param string $expected Expected string.
+     * @param array $token Got token.
+     *
+     * @throws \Doctrine\ORM\Query\QueryException
+     */
+    public function syntaxError($expected = '', $token = null)
+    {
+        if ($token === null) {
+            $token = $this->_lexer->lookahead;
+        }
+
+        $tokenPos = (isset($token['position'])) ? $token['position'] : '-1';
+        $message  = "line 0, col {$tokenPos}: Error: ";
+
+        if ($expected !== '') {
+            $message .= "Expected {$expected}, got ";
+        } else {
+            $message .= 'Unexpected ';
+        }
+
+        if ($this->_lexer->lookahead === null) {
+            $message .= 'end of string.';
+        } else {
+            $message .= "'{$token['value']}'";
+        }
+
+        throw QueryException::syntaxError($message);
+    }
+
+    /**
+     * Generates a new semantical error.
+     *
+     * @param string $message Optional message.
+     * @param array $token Optional token.
+     *
+     * @throws \Doctrine\ORM\Query\QueryException
+     */
+    public function semanticalError($message = '', $token = null)
+    {
+        if ($token === null) {
+            $token = $this->_lexer->lookahead;
+        }
+
+        // Minimum exposed chars ahead of token
+        $distance = 12;
+
+        // Find a position of a final word to display in error string
+        $dql = $this->_query->getDql();
+        $length = strlen($dql);
+        $pos = $token['position'] + $distance;
+        $pos = strpos($dql, ' ', ($length > $pos) ? $pos : $length);
+        $length = ($pos !== false) ? $pos - $token['position'] : $distance;
+
+        // Building informative message
+        $message = 'line 0, col ' . (
+            (isset($token['position']) && $token['position'] > 0) ? $token['position'] : '-1'
+        ) . " near '" . substr($dql, $token['position'], $length) . "': Error: " . $message;
+
+        throw \Doctrine\ORM\Query\QueryException::semanticalError($message);
+    }
+
+    /**
+     * Peeks beyond the specified token and returns the first token after that one.
+     *
+     * @param array $token
+     * @return array
+     */
+    private function _peekBeyond($token)
+    {
+        $peek = $this->_lexer->peek();
+
+        while ($peek['value'] != $token) {
+            $peek = $this->_lexer->peek();
+        }
+
+        $peek = $this->_lexer->peek();
+        $this->_lexer->resetPeek();
+
+        return $peek;
+    }
+
+    /**
+     * Peek beyond the matched closing parenthesis and return the first token after that one.
+     *
+     * @return array
+     */
+    private function _peekBeyondClosingParenthesis()
+    {
+        $token = $this->_lexer->peek();
+        $numUnmatched = 1;
+
+        while ($numUnmatched > 0 && $token !== null) {
+            if ($token['value'] == ')') {
+                --$numUnmatched;
+            } else if ($token['value'] == '(') {
+                ++$numUnmatched;
+            }
+
+            $token = $this->_lexer->peek();
+        }
+        
+        $this->_lexer->resetPeek();
+
+        return $token;
+    }
+
+    /**
+     * Checks if the given token indicates a mathematical operator.
+     *
+     * @return boolean TRUE if the token is a mathematical operator, FALSE otherwise.
+     */
+    private function _isMathOperator($token)
+    {
+        return in_array($token['value'], array("+", "-", "/", "*"));
+    }
+
+    /**
+     * Checks if the next-next (after lookahead) token starts a function.
+     *
+     * @return boolean TRUE if the next-next tokens start a function, FALSE otherwise.
+     */
+    private function _isFunction()
+    {
+        $peek = $this->_lexer->peek();
+        $nextpeek = $this->_lexer->peek();
+        $this->_lexer->resetPeek();
+
+        // We deny the COUNT(SELECT * FROM User u) here. COUNT won't be considered a function
+        return ($peek['value'] === '(' && $nextpeek['type'] !== Lexer::T_SELECT);
+    }
+
+    /**
+     * Checks whether the given token type indicates an aggregate function.
+     *
+     * @return boolean TRUE if the token type is an aggregate function, FALSE otherwise.
+     */
+    private function _isAggregateFunction($tokenType)
+    {
+        return $tokenType == Lexer::T_AVG || $tokenType == Lexer::T_MIN ||
+               $tokenType == Lexer::T_MAX || $tokenType == Lexer::T_SUM ||
+               $tokenType == Lexer::T_COUNT;
+    }
+
+    /**
+     * Checks whether the current lookahead token of the lexer has the type
+     * T_ALL, T_ANY or T_SOME.
+     *
+     * @return boolean
+     */
+    private function _isNextAllAnySome()
+    {
+        return $this->_lexer->lookahead['type'] === Lexer::T_ALL ||
+               $this->_lexer->lookahead['type'] === Lexer::T_ANY ||
+               $this->_lexer->lookahead['type'] === Lexer::T_SOME;
+    }
+
+    /**
+     * Checks whether the next 2 tokens start a subselect.
+     *
+     * @return boolean TRUE if the next 2 tokens start a subselect, FALSE otherwise.
+     */
+    private function _isSubselect()
+    {
+        $la = $this->_lexer->lookahead;
+        $next = $this->_lexer->glimpse();
+
+        return ($la['value'] === '(' && $next['type'] === Lexer::T_SELECT);
+    }
+
+    /**
+     * Validates that the given <tt>IdentificationVariable</tt> is semantically correct.
+     * It must exist in query components list.
+     *
+     * @return void
+     */
+    private function _processDeferredIdentificationVariables()
+    {
+        foreach ($this->_deferredIdentificationVariables as $deferredItem) {
+            $identVariable = $deferredItem['expression'];
+
+            // Check if IdentificationVariable exists in queryComponents
+            if ( ! isset($this->_queryComponents[$identVariable])) {
+                $this->semanticalError(
+                    "'$identVariable' is not defined.", $deferredItem['token']
+                );
+            }
+
+            $qComp = $this->_queryComponents[$identVariable];
+
+            // Check if queryComponent points to an AbstractSchemaName or a ResultVariable
+            if ( ! isset($qComp['metadata'])) {
+                $this->semanticalError(
+                    "'$identVariable' does not point to a Class.", $deferredItem['token']
+                );
+            }
+
+            // Validate if identification variable nesting level is lower or equal than the current one
+            if ($qComp['nestingLevel'] > $deferredItem['nestingLevel']) {
+                $this->semanticalError(
+                    "'$identVariable' is used outside the scope of its declaration.", $deferredItem['token']
+                );
+            }
+        }
+    }
+
+    /**
+     * Validates that the given <tt>PartialObjectExpression</tt> is semantically correct.
+     * It must exist in query components list.
+     *
+     * @return void
+     */
+    private function _processDeferredPartialObjectExpressions()
+    {
+        foreach ($this->_deferredPartialObjectExpressions as $deferredItem) {
+            $expr = $deferredItem['expression'];
+            $class = $this->_queryComponents[$expr->identificationVariable]['metadata'];
+
+            foreach ($expr->partialFieldSet as $field) {
+                if ( ! isset($class->fieldMappings[$field])) {
+                    $this->semanticalError(
+                        "There is no mapped field named '$field' on class " . $class->name . ".",
+                        $deferredItem['token']
+                    );
+                }
+            }
+
+            if (array_intersect($class->identifier, $expr->partialFieldSet) != $class->identifier) {
+                $this->semanticalError(
+                    "The partial field selection of class " . $class->name . " must contain the identifier.",
+                    $deferredItem['token']
+                );
+            }
+        }
+    }
+
+    /**
+     * Validates that the given <tt>ResultVariable</tt> is semantically correct.
+     * It must exist in query components list.
+     *
+     * @return void
+     */
+    private function _processDeferredResultVariables()
+    {
+        foreach ($this->_deferredResultVariables as $deferredItem) {
+            $resultVariable = $deferredItem['expression'];
+
+            // Check if ResultVariable exists in queryComponents
+            if ( ! isset($this->_queryComponents[$resultVariable])) {
+                $this->semanticalError(
+                    "'$resultVariable' is not defined.", $deferredItem['token']
+                );
+            }
+
+            $qComp = $this->_queryComponents[$resultVariable];
+
+            // Check if queryComponent points to an AbstractSchemaName or a ResultVariable
+            if ( ! isset($qComp['resultVariable'])) {
+                $this->semanticalError(
+                    "'$identVariable' does not point to a ResultVariable.", $deferredItem['token']
+                );
+            }
+
+            // Validate if identification variable nesting level is lower or equal than the current one
+            if ($qComp['nestingLevel'] > $deferredItem['nestingLevel']) {
+                $this->semanticalError(
+                    "'$resultVariable' is used outside the scope of its declaration.", $deferredItem['token']
+                );
+            }
+        }
+    }
+
+    /**
+     * Validates that the given <tt>PathExpression</tt> is semantically correct for grammar rules:
+     *
+     * AssociationPathExpression             ::= CollectionValuedPathExpression | SingleValuedAssociationPathExpression
+     * SingleValuedPathExpression            ::= StateFieldPathExpression | SingleValuedAssociationPathExpression
+     * StateFieldPathExpression              ::= IdentificationVariable "." StateField
+     * SingleValuedAssociationPathExpression ::= IdentificationVariable "." SingleValuedAssociationField
+     * CollectionValuedPathExpression        ::= IdentificationVariable "." CollectionValuedAssociationField
+     *
+     * @param array $deferredItem
+     * @param mixed $AST
+     */
+    private function _processDeferredPathExpressions($AST)
+    {
+        foreach ($this->_deferredPathExpressions as $deferredItem) {
+            $pathExpression = $deferredItem['expression'];
+
+            $qComp = $this->_queryComponents[$pathExpression->identificationVariable];
+            $class = $qComp['metadata'];
+
+            if (($field = $pathExpression->field) === null) {
+                $field = $pathExpression->field = $class->identifier[0];
+            }
+            
+            // Check if field or association exists
+            if ( ! isset($class->associationMappings[$field]) && ! isset($class->fieldMappings[$field])) {
+                $this->semanticalError(
+                    'Class ' . $class->name . ' has no field or association named ' . $field,
+                    $deferredItem['token']
+                );
+            }
+
+            if (isset($class->fieldMappings[$field])) {
+                $fieldType = AST\PathExpression::TYPE_STATE_FIELD;
+            } else {
+                $assoc = $class->associationMappings[$field];
+                $class = $this->_em->getClassMetadata($assoc['targetEntity']);
+
+                if ($assoc['type'] & ClassMetadata::TO_ONE) {
+                    $fieldType = AST\PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION;
+                } else {
+                    $fieldType = AST\PathExpression::TYPE_COLLECTION_VALUED_ASSOCIATION;
+                }
+            }
+
+            // Validate if PathExpression is one of the expected types
+            $expectedType = $pathExpression->expectedType;
+
+            if ( ! ($expectedType & $fieldType)) {
+                // We need to recognize which was expected type(s)
+                $expectedStringTypes = array();
+
+                // Validate state field type
+                if ($expectedType & AST\PathExpression::TYPE_STATE_FIELD) {
+                    $expectedStringTypes[] = 'StateFieldPathExpression';
+                }
+
+                // Validate single valued association (*-to-one)
+                if ($expectedType & AST\PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION) {
+                    $expectedStringTypes[] = 'SingleValuedAssociationField';
+                }
+
+                // Validate single valued association (*-to-many)
+                if ($expectedType & AST\PathExpression::TYPE_COLLECTION_VALUED_ASSOCIATION) {
+                    $expectedStringTypes[] = 'CollectionValuedAssociationField';
+                }
+
+                // Build the error message
+                $semanticalError = 'Invalid PathExpression. ';
+
+                if (count($expectedStringTypes) == 1) {
+                    $semanticalError .= 'Must be a ' . $expectedStringTypes[0] . '.';
+                } else {
+                    $semanticalError .= implode(' or ', $expectedStringTypes) . ' expected.';
+                }
+
+                $this->semanticalError($semanticalError, $deferredItem['token']);
+            }
+            
+            // We need to force the type in PathExpression
+            $pathExpression->type = $fieldType;
+        }
+    }
+
+    /**
+     * QueryLanguage ::= SelectStatement | UpdateStatement | DeleteStatement
+     *
+     * @return \Doctrine\ORM\Query\AST\SelectStatement |
+     *         \Doctrine\ORM\Query\AST\UpdateStatement |
+     *         \Doctrine\ORM\Query\AST\DeleteStatement
+     */
+    public function QueryLanguage()
+    {
+        $this->_lexer->moveNext();
+
+        switch ($this->_lexer->lookahead['type']) {
+            case Lexer::T_SELECT:
+                $statement = $this->SelectStatement();
+                break;
+            case Lexer::T_UPDATE:
+                $statement = $this->UpdateStatement();
+                break;
+            case Lexer::T_DELETE:
+                $statement = $this->DeleteStatement();
+                break;
+            default:
+                $this->syntaxError('SELECT, UPDATE or DELETE');
+                break;
+        }
+
+        // Check for end of string
+        if ($this->_lexer->lookahead !== null) {
+            $this->syntaxError('end of string');
+        }
+
+        return $statement;
+    }
+
+    /**
+     * SelectStatement ::= SelectClause FromClause [WhereClause] [GroupByClause] [HavingClause] [OrderByClause]
+     *
+     * @return \Doctrine\ORM\Query\AST\SelectStatement
+     */
+    public function SelectStatement()
+    {
+        $selectStatement = new AST\SelectStatement($this->SelectClause(), $this->FromClause());
+
+        $selectStatement->whereClause = $this->_lexer->isNextToken(Lexer::T_WHERE)
+            ? $this->WhereClause() : null;
+
+        $selectStatement->groupByClause = $this->_lexer->isNextToken(Lexer::T_GROUP)
+            ? $this->GroupByClause() : null;
+
+        $selectStatement->havingClause = $this->_lexer->isNextToken(Lexer::T_HAVING)
+            ? $this->HavingClause() : null;
+
+        $selectStatement->orderByClause = $this->_lexer->isNextToken(Lexer::T_ORDER)
+            ? $this->OrderByClause() : null;
+
+        return $selectStatement;
+    }
+
+    /**
+     * UpdateStatement ::= UpdateClause [WhereClause]
+     *
+     * @return \Doctrine\ORM\Query\AST\UpdateStatement
+     */
+    public function UpdateStatement()
+    {
+        $updateStatement = new AST\UpdateStatement($this->UpdateClause());
+        $updateStatement->whereClause = $this->_lexer->isNextToken(Lexer::T_WHERE)
+                ? $this->WhereClause() : null;
+
+        return $updateStatement;
+    }
+
+    /**
+     * DeleteStatement ::= DeleteClause [WhereClause]
+     *
+     * @return \Doctrine\ORM\Query\AST\DeleteStatement
+     */
+    public function DeleteStatement()
+    {
+        $deleteStatement = new AST\DeleteStatement($this->DeleteClause());
+        $deleteStatement->whereClause = $this->_lexer->isNextToken(Lexer::T_WHERE)
+                ? $this->WhereClause() : null;
+
+        return $deleteStatement;
+    }
+
+    /**
+     * IdentificationVariable ::= identifier
+     *
+     * @return string
+     */
+    public function IdentificationVariable()
+    {
+        $this->match(Lexer::T_IDENTIFIER);
+
+        $identVariable = $this->_lexer->token['value'];
+
+        $this->_deferredIdentificationVariables[] = array(
+            'expression'   => $identVariable,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $this->_lexer->token,
+        );
+
+        return $identVariable;
+    }
+
+    /**
+     * AliasIdentificationVariable = identifier
+     *
+     * @return string
+     */
+    public function AliasIdentificationVariable()
+    {
+        $this->match(Lexer::T_IDENTIFIER);
+
+        $aliasIdentVariable = $this->_lexer->token['value'];
+        $exists = isset($this->_queryComponents[$aliasIdentVariable]);
+
+        if ($exists) {
+            $this->semanticalError(
+                "'$aliasIdentVariable' is already defined.", $this->_lexer->token
+            );
+        }
+
+        return $aliasIdentVariable;
+    }
+
+    /**
+     * AbstractSchemaName ::= identifier
+     *
+     * @return string
+     */
+    public function AbstractSchemaName()
+    {
+        $this->match(Lexer::T_IDENTIFIER);
+
+        $schemaName = ltrim($this->_lexer->token['value'], '\\');
+
+        if (strrpos($schemaName, ':') !== false) {
+            list($namespaceAlias, $simpleClassName) = explode(':', $schemaName);
+            $schemaName = $this->_em->getConfiguration()->getEntityNamespace($namespaceAlias) . '\\' . $simpleClassName;
+        }
+
+        $exists = class_exists($schemaName, true);
+
+        if ( ! $exists) {
+            $this->semanticalError("Class '$schemaName' is not defined.", $this->_lexer->token);
+        }
+
+        return $schemaName;
+    }
+
+    /**
+     * AliasResultVariable ::= identifier
+     *
+     * @return string
+     */
+    public function AliasResultVariable()
+    {
+        $this->match(Lexer::T_IDENTIFIER);
+
+        $resultVariable = $this->_lexer->token['value'];
+        $exists = isset($this->_queryComponents[$resultVariable]);
+
+        if ($exists) {
+            $this->semanticalError(
+                "'$resultVariable' is already defined.", $this->_lexer->token
+            );
+        }
+
+        return $resultVariable;
+    }
+
+    /**
+     * ResultVariable ::= identifier
+     *
+     * @return string
+     */
+    public function ResultVariable()
+    {
+        $this->match(Lexer::T_IDENTIFIER);
+
+        $resultVariable = $this->_lexer->token['value'];
+
+        // Defer ResultVariable validation
+        $this->_deferredResultVariables[] = array(
+            'expression'   => $resultVariable,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $this->_lexer->token,
+        );
+
+        return $resultVariable;
+    }
+
+    /**
+     * JoinAssociationPathExpression ::= IdentificationVariable "." (CollectionValuedAssociationField | SingleValuedAssociationField)
+     *
+     * @return \Doctrine\ORM\Query\AST\JoinAssociationPathExpression
+     */
+    public function JoinAssociationPathExpression()
+    {
+        $token = $this->_lexer->lookahead;
+        $identVariable = $this->IdentificationVariable();
+
+        if (!isset($this->_queryComponents[$identVariable])) {
+            $this->semanticalError('Identification Variable ' . $identVariable .' used in join path expression but was not defined before.');
+        }
+
+        $this->match(Lexer::T_DOT);
+        $this->match(Lexer::T_IDENTIFIER);
+
+        $field = $this->_lexer->token['value'];
+
+        // Validate association field
+        $qComp = $this->_queryComponents[$identVariable];
+        $class = $qComp['metadata'];
+
+        if ( ! isset($class->associationMappings[$field])) {
+            $this->semanticalError('Class ' . $class->name . ' has no association named ' . $field);
+        }
+
+        return new AST\JoinAssociationPathExpression($identVariable, $field);
+    }
+
+    /**
+     * Parses an arbitrary path expression and defers semantical validation
+     * based on expected types.
+     *
+     * PathExpression ::= IdentificationVariable "." identifier
+     *
+     * @param integer $expectedTypes
+     * @return \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function PathExpression($expectedTypes)
+    {
+        $token = $this->_lexer->lookahead;
+        $identVariable = $this->IdentificationVariable();
+        $field = null;
+
+        if ($this->_lexer->isNextToken(Lexer::T_DOT)) {
+            $this->match(Lexer::T_DOT);
+            $this->match(Lexer::T_IDENTIFIER);
+
+            $field = $this->_lexer->token['value'];
+        }
+        
+        // Creating AST node
+        $pathExpr = new AST\PathExpression($expectedTypes, $identVariable, $field);
+
+        // Defer PathExpression validation if requested to be defered
+        $this->_deferredPathExpressions[] = array(
+            'expression'   => $pathExpr,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $this->_lexer->token,
+        );
+
+        return $pathExpr;
+    }
+
+    /**
+     * AssociationPathExpression ::= CollectionValuedPathExpression | SingleValuedAssociationPathExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function AssociationPathExpression()
+    {
+        return $this->PathExpression(
+            AST\PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION |
+            AST\PathExpression::TYPE_COLLECTION_VALUED_ASSOCIATION
+        );
+    }
+
+    /**
+     * SingleValuedPathExpression ::= StateFieldPathExpression | SingleValuedAssociationPathExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function SingleValuedPathExpression()
+    {
+        return $this->PathExpression(
+            AST\PathExpression::TYPE_STATE_FIELD |
+            AST\PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION
+        );
+    }
+
+    /**
+     * StateFieldPathExpression ::= IdentificationVariable "." StateField
+     *
+     * @return \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function StateFieldPathExpression()
+    {
+        return $this->PathExpression(AST\PathExpression::TYPE_STATE_FIELD);
+    }
+
+    /**
+     * SingleValuedAssociationPathExpression ::= IdentificationVariable "." SingleValuedAssociationField
+     *
+     * @return \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function SingleValuedAssociationPathExpression()
+    {
+        return $this->PathExpression(AST\PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION);
+    }
+
+    /**
+     * CollectionValuedPathExpression ::= IdentificationVariable "." CollectionValuedAssociationField
+     *
+     * @return \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function CollectionValuedPathExpression()
+    {
+        return $this->PathExpression(AST\PathExpression::TYPE_COLLECTION_VALUED_ASSOCIATION);
+    }
+
+    /**
+     * SelectClause ::= "SELECT" ["DISTINCT"] SelectExpression {"," SelectExpression}
+     *
+     * @return \Doctrine\ORM\Query\AST\SelectClause
+     */
+    public function SelectClause()
+    {
+        $isDistinct = false;
+        $this->match(Lexer::T_SELECT);
+
+        // Check for DISTINCT
+        if ($this->_lexer->isNextToken(Lexer::T_DISTINCT)) {
+            $this->match(Lexer::T_DISTINCT);
+            $isDistinct = true;
+        }
+
+        // Process SelectExpressions (1..N)
+        $selectExpressions = array();
+        $selectExpressions[] = $this->SelectExpression();
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $selectExpressions[] = $this->SelectExpression();
+        }
+
+        return new AST\SelectClause($selectExpressions, $isDistinct);
+    }
+
+    /**
+     * SimpleSelectClause ::= "SELECT" ["DISTINCT"] SimpleSelectExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\SimpleSelectClause
+     */
+    public function SimpleSelectClause()
+    {
+        $isDistinct = false;
+        $this->match(Lexer::T_SELECT);
+
+        if ($this->_lexer->isNextToken(Lexer::T_DISTINCT)) {
+            $this->match(Lexer::T_DISTINCT);
+            $isDistinct = true;
+        }
+
+        return new AST\SimpleSelectClause($this->SimpleSelectExpression(), $isDistinct);
+    }
+
+    /**
+     * UpdateClause ::= "UPDATE" AbstractSchemaName ["AS"] AliasIdentificationVariable "SET" UpdateItem {"," UpdateItem}*
+     *
+     * @return \Doctrine\ORM\Query\AST\UpdateClause
+     */
+    public function UpdateClause()
+    {
+        $this->match(Lexer::T_UPDATE);
+        $token = $this->_lexer->lookahead;
+        $abstractSchemaName = $this->AbstractSchemaName();
+
+        if ($this->_lexer->isNextToken(Lexer::T_AS)) {
+            $this->match(Lexer::T_AS);
+        }
+
+        $aliasIdentificationVariable = $this->AliasIdentificationVariable();
+
+        $class = $this->_em->getClassMetadata($abstractSchemaName);
+
+        // Building queryComponent
+        $queryComponent = array(
+            'metadata'     => $class,
+            'parent'       => null,
+            'relation'     => null,
+            'map'          => null,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $token,
+        );
+        $this->_queryComponents[$aliasIdentificationVariable] = $queryComponent;
+
+        $this->match(Lexer::T_SET);
+
+        $updateItems = array();
+        $updateItems[] = $this->UpdateItem();
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $updateItems[] = $this->UpdateItem();
+        }
+
+        $updateClause = new AST\UpdateClause($abstractSchemaName, $updateItems);
+        $updateClause->aliasIdentificationVariable = $aliasIdentificationVariable;
+
+        return $updateClause;
+    }
+
+    /**
+     * DeleteClause ::= "DELETE" ["FROM"] AbstractSchemaName ["AS"] AliasIdentificationVariable
+     *
+     * @return \Doctrine\ORM\Query\AST\DeleteClause
+     */
+    public function DeleteClause()
+    {
+        $this->match(Lexer::T_DELETE);
+
+        if ($this->_lexer->isNextToken(Lexer::T_FROM)) {
+            $this->match(Lexer::T_FROM);
+        }
+
+        $token = $this->_lexer->lookahead;
+        $deleteClause = new AST\DeleteClause($this->AbstractSchemaName());
+
+        if ($this->_lexer->isNextToken(Lexer::T_AS)) {
+            $this->match(Lexer::T_AS);
+        }
+
+        $aliasIdentificationVariable = $this->AliasIdentificationVariable();
+
+        $deleteClause->aliasIdentificationVariable = $aliasIdentificationVariable;
+        $class = $this->_em->getClassMetadata($deleteClause->abstractSchemaName);
+
+        // Building queryComponent
+        $queryComponent = array(
+            'metadata'     => $class,
+            'parent'       => null,
+            'relation'     => null,
+            'map'          => null,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $token,
+        );
+        $this->_queryComponents[$aliasIdentificationVariable] = $queryComponent;
+
+        return $deleteClause;
+    }
+
+    /**
+     * FromClause ::= "FROM" IdentificationVariableDeclaration {"," IdentificationVariableDeclaration}*
+     *
+     * @return \Doctrine\ORM\Query\AST\FromClause
+     */
+    public function FromClause()
+    {
+        $this->match(Lexer::T_FROM);
+        $identificationVariableDeclarations = array();
+        $identificationVariableDeclarations[] = $this->IdentificationVariableDeclaration();
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $identificationVariableDeclarations[] = $this->IdentificationVariableDeclaration();
+        }
+
+        return new AST\FromClause($identificationVariableDeclarations);
+    }
+
+    /**
+     * SubselectFromClause ::= "FROM" SubselectIdentificationVariableDeclaration {"," SubselectIdentificationVariableDeclaration}*
+     *
+     * @return \Doctrine\ORM\Query\AST\SubselectFromClause
+     */
+    public function SubselectFromClause()
+    {
+        $this->match(Lexer::T_FROM);
+        $identificationVariables = array();
+        $identificationVariables[] = $this->SubselectIdentificationVariableDeclaration();
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $identificationVariables[] = $this->SubselectIdentificationVariableDeclaration();
+        }
+
+        return new AST\SubselectFromClause($identificationVariables);
+    }
+
+    /**
+     * WhereClause ::= "WHERE" ConditionalExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\WhereClause
+     */
+    public function WhereClause()
+    {
+        $this->match(Lexer::T_WHERE);
+
+        return new AST\WhereClause($this->ConditionalExpression());
+    }
+
+    /**
+     * HavingClause ::= "HAVING" ConditionalExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\HavingClause
+     */
+    public function HavingClause()
+    {
+        $this->match(Lexer::T_HAVING);
+
+        return new AST\HavingClause($this->ConditionalExpression());
+    }
+
+    /**
+     * GroupByClause ::= "GROUP" "BY" GroupByItem {"," GroupByItem}*
+     *
+     * @return \Doctrine\ORM\Query\AST\GroupByClause
+     */
+    public function GroupByClause()
+    {
+        $this->match(Lexer::T_GROUP);
+        $this->match(Lexer::T_BY);
+
+        $groupByItems = array($this->GroupByItem());
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $groupByItems[] = $this->GroupByItem();
+        }
+
+        return new AST\GroupByClause($groupByItems);
+    }
+
+    /**
+     * OrderByClause ::= "ORDER" "BY" OrderByItem {"," OrderByItem}*
+     *
+     * @return \Doctrine\ORM\Query\AST\OrderByClause
+     */
+    public function OrderByClause()
+    {
+        $this->match(Lexer::T_ORDER);
+        $this->match(Lexer::T_BY);
+
+        $orderByItems = array();
+        $orderByItems[] = $this->OrderByItem();
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $orderByItems[] = $this->OrderByItem();
+        }
+
+        return new AST\OrderByClause($orderByItems);
+    }
+
+    /**
+     * Subselect ::= SimpleSelectClause SubselectFromClause [WhereClause] [GroupByClause] [HavingClause] [OrderByClause]
+     *
+     * @return \Doctrine\ORM\Query\AST\Subselect
+     */
+    public function Subselect()
+    {
+        // Increase query nesting level
+        $this->_nestingLevel++;
+
+        $subselect = new AST\Subselect($this->SimpleSelectClause(), $this->SubselectFromClause());
+
+        $subselect->whereClause = $this->_lexer->isNextToken(Lexer::T_WHERE)
+            ? $this->WhereClause() : null;
+
+        $subselect->groupByClause = $this->_lexer->isNextToken(Lexer::T_GROUP)
+            ? $this->GroupByClause() : null;
+
+        $subselect->havingClause = $this->_lexer->isNextToken(Lexer::T_HAVING)
+            ? $this->HavingClause() : null;
+
+        $subselect->orderByClause = $this->_lexer->isNextToken(Lexer::T_ORDER)
+            ? $this->OrderByClause() : null;
+
+        // Decrease query nesting level
+        $this->_nestingLevel--;
+
+        return $subselect;
+    }
+
+    /**
+     * UpdateItem ::= SingleValuedPathExpression "=" NewValue
+     *
+     * @return \Doctrine\ORM\Query\AST\UpdateItem
+     */
+    public function UpdateItem()
+    {
+        $pathExpr = $this->SingleValuedPathExpression();
+
+        $this->match(Lexer::T_EQUALS);
+
+        $updateItem = new AST\UpdateItem($pathExpr, $this->NewValue());
+
+        return $updateItem;
+    }
+
+    /**
+     * GroupByItem ::= IdentificationVariable | SingleValuedPathExpression
+     *
+     * @return string | \Doctrine\ORM\Query\AST\PathExpression
+     */
+    public function GroupByItem()
+    {
+        // We need to check if we are in a IdentificationVariable or SingleValuedPathExpression
+        $glimpse = $this->_lexer->glimpse();
+
+        if ($glimpse['type'] != Lexer::T_DOT) {
+            $token = $this->_lexer->lookahead;
+            $identVariable = $this->IdentificationVariable();
+
+            if (!isset($this->_queryComponents[$identVariable])) {
+                $this->semanticalError('Cannot group by undefined identification variable.');
+            }
+
+            return $identVariable;
+        }
+
+        return $this->SingleValuedPathExpression();
+    }
+
+    /**
+     * OrderByItem ::= (ResultVariable | StateFieldPathExpression) ["ASC" | "DESC"]
+     *
+     * @todo Post 2.0 release. Support general SingleValuedPathExpression instead
+     * of only StateFieldPathExpression.
+     *
+     * @return \Doctrine\ORM\Query\AST\OrderByItem
+     */
+    public function OrderByItem()
+    {
+        $type = 'ASC';
+
+        // We need to check if we are in a ResultVariable or StateFieldPathExpression
+        $glimpse = $this->_lexer->glimpse();
+
+        if ($glimpse['type'] != Lexer::T_DOT) {
+            $token = $this->_lexer->lookahead;
+            $expr = $this->ResultVariable();
+        } else {
+            $expr = $this->StateFieldPathExpression();
+        }
+
+        $item = new AST\OrderByItem($expr);
+
+        if ($this->_lexer->isNextToken(Lexer::T_ASC)) {
+            $this->match(Lexer::T_ASC);
+        } else if ($this->_lexer->isNextToken(Lexer::T_DESC)) {
+            $this->match(Lexer::T_DESC);
+            $type = 'DESC';
+        }
+
+        $item->type = $type;
+        return $item;
+    }
+
+    /**
+     * NewValue ::= SimpleArithmeticExpression | StringPrimary | DatetimePrimary | BooleanPrimary |
+     *      EnumPrimary | SimpleEntityExpression | "NULL"
+     *
+     * NOTE: Since it is not possible to correctly recognize individual types, here is the full
+     * grammar that needs to be supported:
+     *
+     * NewValue ::= SimpleArithmeticExpression | "NULL"
+     *
+     * SimpleArithmeticExpression covers all *Primary grammar rules and also SimplEntityExpression
+     */
+    public function NewValue()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_NULL)) {
+            $this->match(Lexer::T_NULL);
+            return null;
+        } else if ($this->_lexer->isNextToken(Lexer::T_INPUT_PARAMETER)) {
+            $this->match(Lexer::T_INPUT_PARAMETER);
+            return new AST\InputParameter($this->_lexer->token['value']);
+        }
+
+        return $this->SimpleArithmeticExpression();
+    }
+
+    /**
+     * IdentificationVariableDeclaration ::= RangeVariableDeclaration [IndexBy] {JoinVariableDeclaration}*
+     *
+     * @return \Doctrine\ORM\Query\AST\IdentificationVariableDeclaration
+     */
+    public function IdentificationVariableDeclaration()
+    {
+        $rangeVariableDeclaration = $this->RangeVariableDeclaration();
+        $indexBy = $this->_lexer->isNextToken(Lexer::T_INDEX) ? $this->IndexBy() : null;
+        $joinVariableDeclarations = array();
+
+        while (
+            $this->_lexer->isNextToken(Lexer::T_LEFT) ||
+            $this->_lexer->isNextToken(Lexer::T_INNER) ||
+            $this->_lexer->isNextToken(Lexer::T_JOIN)
+        ) {
+            $joinVariableDeclarations[] = $this->JoinVariableDeclaration();
+        }
+
+        return new AST\IdentificationVariableDeclaration(
+            $rangeVariableDeclaration, $indexBy, $joinVariableDeclarations
+        );
+    }
+
+    /**
+     * SubselectIdentificationVariableDeclaration ::= IdentificationVariableDeclaration | (AssociationPathExpression ["AS"] AliasIdentificationVariable)
+     *
+     * @return \Doctrine\ORM\Query\AST\SubselectIdentificationVariableDeclaration |
+     *         \Doctrine\ORM\Query\AST\IdentificationVariableDeclaration
+     */
+    public function SubselectIdentificationVariableDeclaration()
+    {
+        $glimpse = $this->_lexer->glimpse();
+
+        /* NOT YET IMPLEMENTED!
+
+        if ($glimpse['type'] == Lexer::T_DOT) {
+            $subselectIdVarDecl = new AST\SubselectIdentificationVariableDeclaration();
+            $subselectIdVarDecl->associationPathExpression = $this->AssociationPathExpression();
+            $this->match(Lexer::T_AS);
+            $subselectIdVarDecl->aliasIdentificationVariable = $this->AliasIdentificationVariable();
+
+            return $subselectIdVarDecl;
+        }
+        */
+
+        return $this->IdentificationVariableDeclaration();
+    }
+
+    /**
+     * JoinVariableDeclaration ::= Join [IndexBy]
+     *
+     * @return \Doctrine\ORM\Query\AST\JoinVariableDeclaration
+     */
+    public function JoinVariableDeclaration()
+    {
+        $join = $this->Join();
+        $indexBy = $this->_lexer->isNextToken(Lexer::T_INDEX)
+                ? $this->IndexBy() : null;
+
+        return new AST\JoinVariableDeclaration($join, $indexBy);
+    }
+
+    /**
+     * RangeVariableDeclaration ::= AbstractSchemaName ["AS"] AliasIdentificationVariable
+     *
+     * @return Doctrine\ORM\Query\AST\RangeVariableDeclaration
+     */
+    public function RangeVariableDeclaration()
+    {
+        $abstractSchemaName = $this->AbstractSchemaName();
+
+        if ($this->_lexer->isNextToken(Lexer::T_AS)) {
+            $this->match(Lexer::T_AS);
+        }
+
+        $token = $this->_lexer->lookahead;
+        $aliasIdentificationVariable = $this->AliasIdentificationVariable();
+        $classMetadata = $this->_em->getClassMetadata($abstractSchemaName);
+
+        // Building queryComponent
+        $queryComponent = array(
+            'metadata'     => $classMetadata,
+            'parent'       => null,
+            'relation'     => null,
+            'map'          => null,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $token
+        );
+        $this->_queryComponents[$aliasIdentificationVariable] = $queryComponent;
+
+        return new AST\RangeVariableDeclaration($abstractSchemaName, $aliasIdentificationVariable);
+    }
+
+    /**
+     * PartialObjectExpression ::= "PARTIAL" IdentificationVariable "." PartialFieldSet
+     * PartialFieldSet ::= "{" SimpleStateField {"," SimpleStateField}* "}"
+     *
+     * @return array
+     */
+    public function PartialObjectExpression()
+    {
+        $this->match(Lexer::T_PARTIAL);
+
+        $partialFieldSet = array();
+
+        $identificationVariable = $this->IdentificationVariable();
+        $this->match(Lexer::T_DOT);
+
+        $this->match(Lexer::T_OPEN_CURLY_BRACE);
+        $this->match(Lexer::T_IDENTIFIER);
+        $partialFieldSet[] = $this->_lexer->token['value'];
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $this->match(Lexer::T_IDENTIFIER);
+            $partialFieldSet[] = $this->_lexer->token['value'];
+        }
+        
+        $this->match(Lexer::T_CLOSE_CURLY_BRACE);
+
+        $partialObjectExpression = new AST\PartialObjectExpression($identificationVariable, $partialFieldSet);
+
+        // Defer PartialObjectExpression validation
+        $this->_deferredPartialObjectExpressions[] = array(
+            'expression'   => $partialObjectExpression,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $this->_lexer->token,
+        );
+
+        return $partialObjectExpression;
+    }
+
+    /**
+     * Join ::= ["LEFT" ["OUTER"] | "INNER"] "JOIN" JoinAssociationPathExpression
+     *          ["AS"] AliasIdentificationVariable ["WITH" ConditionalExpression]
+     *
+     * @return Doctrine\ORM\Query\AST\Join
+     */
+    public function Join()
+    {
+        // Check Join type
+        $joinType = AST\Join::JOIN_TYPE_INNER;
+
+        if ($this->_lexer->isNextToken(Lexer::T_LEFT)) {
+            $this->match(Lexer::T_LEFT);
+
+            // Possible LEFT OUTER join
+            if ($this->_lexer->isNextToken(Lexer::T_OUTER)) {
+                $this->match(Lexer::T_OUTER);
+                $joinType = AST\Join::JOIN_TYPE_LEFTOUTER;
+            } else {
+                $joinType = AST\Join::JOIN_TYPE_LEFT;
+            }
+        } else if ($this->_lexer->isNextToken(Lexer::T_INNER)) {
+            $this->match(Lexer::T_INNER);
+        }
+
+        $this->match(Lexer::T_JOIN);
+
+        $joinPathExpression = $this->JoinAssociationPathExpression();
+
+        if ($this->_lexer->isNextToken(Lexer::T_AS)) {
+            $this->match(Lexer::T_AS);
+        }
+
+        $token = $this->_lexer->lookahead;
+        $aliasIdentificationVariable = $this->AliasIdentificationVariable();
+
+        // Verify that the association exists.
+        $parentClass = $this->_queryComponents[$joinPathExpression->identificationVariable]['metadata'];
+        $assocField = $joinPathExpression->associationField;
+
+        if ( ! $parentClass->hasAssociation($assocField)) {
+            $this->semanticalError(
+                "Class " . $parentClass->name . " has no association named '$assocField'."
+            );
+        }
+
+        $targetClassName = $parentClass->associationMappings[$assocField]['targetEntity'];
+
+        // Building queryComponent
+        $joinQueryComponent = array(
+            'metadata'     => $this->_em->getClassMetadata($targetClassName),
+            'parent'       => $joinPathExpression->identificationVariable,
+            'relation'     => $parentClass->getAssociationMapping($assocField),
+            'map'          => null,
+            'nestingLevel' => $this->_nestingLevel,
+            'token'        => $token
+        );
+        $this->_queryComponents[$aliasIdentificationVariable] = $joinQueryComponent;
+
+        // Create AST node
+        $join = new AST\Join($joinType, $joinPathExpression, $aliasIdentificationVariable);
+
+        // Check for ad-hoc Join conditions
+        if ($this->_lexer->isNextToken(Lexer::T_WITH)) {
+            $this->match(Lexer::T_WITH);
+            $join->conditionalExpression = $this->ConditionalExpression();
+        }
+
+        return $join;
+    }
+
+    /**
+     * IndexBy ::= "INDEX" "BY" StateFieldPathExpression
+     *
+     * @return Doctrine\ORM\Query\AST\IndexBy
+     */
+    public function IndexBy()
+    {
+        $this->match(Lexer::T_INDEX);
+        $this->match(Lexer::T_BY);
+        $pathExpr = $this->StateFieldPathExpression();
+
+        // Add the INDEX BY info to the query component
+        $this->_queryComponents[$pathExpr->identificationVariable]['map'] = $pathExpr->field;
+
+        return new AST\IndexBy($pathExpr);
+    }
+
+    /**
+     * ScalarExpression ::= SimpleArithmeticExpression | StringPrimary | DateTimePrimary |
+     *                      StateFieldPathExpression | BooleanPrimary | CaseExpression |
+     *                      EntityTypeExpression
+     *
+     * @return mixed One of the possible expressions or subexpressions.
+     */
+    public function ScalarExpression()
+    {
+        $lookahead = $this->_lexer->lookahead['type'];
+        if ($lookahead === Lexer::T_IDENTIFIER) {
+            $this->_lexer->peek(); // lookahead => '.'
+            $this->_lexer->peek(); // lookahead => token after '.'
+            $peek = $this->_lexer->peek(); // lookahead => token after the token after the '.'
+            $this->_lexer->resetPeek();
+
+            if ($this->_isMathOperator($peek)) {
+                return $this->SimpleArithmeticExpression();
+            }
+
+            return $this->StateFieldPathExpression();
+        } else if ($lookahead == Lexer::T_INTEGER || $lookahead == Lexer::T_FLOAT) {
+            return $this->SimpleArithmeticExpression();
+        } else if ($lookahead == Lexer::T_CASE || $lookahead == Lexer::T_COALESCE || $lookahead == Lexer::T_NULLIF) {
+            // Since NULLIF and COALESCE can be identified as a function, 
+            // we need to check if before check for FunctionDeclaration
+            return $this->CaseExpression();
+        } else if ($this->_isFunction() || $this->_isAggregateFunction($this->_lexer->lookahead['type'])) {
+            // We may be in an ArithmeticExpression (find the matching ")" and inspect for Math operator)
+            $this->_lexer->peek(); // "("
+            $peek = $this->_peekBeyondClosingParenthesis();
+
+            if ($this->_isMathOperator($peek)) {
+                return $this->SimpleArithmeticExpression();
+            }
+
+            if ($this->_isAggregateFunction($this->_lexer->lookahead['type'])) {
+                return $this->AggregateExpression();
+            } else {
+                return $this->FunctionDeclaration();
+            }
+        } else if ($lookahead == Lexer::T_STRING) {
+            return $this->StringPrimary();
+        } else if ($lookahead == Lexer::T_INPUT_PARAMETER) {
+            return $this->InputParameter();
+        } else if ($lookahead == Lexer::T_TRUE || $lookahead == Lexer::T_FALSE) {
+            $this->match($lookahead);
+            return new AST\Literal(AST\Literal::BOOLEAN, $this->_lexer->token['value']);
+        } else {
+            $this->syntaxError();
+        }
+    }
+
+    public function CaseExpression()
+    {
+        $lookahead = $this->_lexer->lookahead['type'];
+        
+        // if "CASE" "WHEN" => GeneralCaseExpression
+        // else if "CASE" => SimpleCaseExpression
+        // [DONE] else if "COALESCE" => CoalesceExpression
+        // [DONE] else if "NULLIF" => NullifExpression
+        switch ($lookahead) {
+            case Lexer::T_NULLIF:
+                return $this->NullIfExpression();
+                
+            case Lexer::T_COALESCE:
+                return $this->CoalesceExpression();
+                
+            default:
+                $this->semanticalError('CaseExpression not yet supported.');
+                return null;
+        }
+    }
+    
+    /**
+     * CoalesceExpression ::= "COALESCE" "(" ScalarExpression {"," ScalarExpression}* ")"
+     * 
+     * @return Doctrine\ORM\Query\AST\CoalesceExpression 
+     */
+    public function CoalesceExpression()
+    {
+        $this->match(Lexer::T_COALESCE);
+        $this->match(Lexer::T_OPEN_PARENTHESIS);
+        
+        // Process ScalarExpressions (1..N)
+        $scalarExpressions = array();
+        $scalarExpressions[] = $this->ScalarExpression();
+
+        while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+            $this->match(Lexer::T_COMMA);
+            $scalarExpressions[] = $this->ScalarExpression();
+        }
+        
+        $this->match(Lexer::T_CLOSE_PARENTHESIS);
+        
+        return new AST\CoalesceExpression($scalarExpressions);
+    }
+    
+    /**
+     * NullIfExpression ::= "NULLIF" "(" ScalarExpression "," ScalarExpression ")"
+     * 
+     * @return Doctrine\ORM\Query\AST\ExistsExpression 
+     */
+    public function NullIfExpression()
+    {
+        $this->match(Lexer::T_NULLIF);
+        $this->match(Lexer::T_OPEN_PARENTHESIS);
+        
+        $firstExpression = $this->ScalarExpression();
+        $this->match(Lexer::T_COMMA);
+        $secondExpression = $this->ScalarExpression();
+        
+        $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+        return new AST\NullIfExpression($firstExpression, $secondExpression);
+    }
+
+    /**
+     * SelectExpression ::=
+     *      IdentificationVariable | StateFieldPathExpression |
+     *      (AggregateExpression | "(" Subselect ")" | ScalarExpression) [["AS"] AliasResultVariable]
+     *
+     * @return Doctrine\ORM\Query\AST\SelectExpression
+     */
+    public function SelectExpression()
+    {
+        $expression = null;
+        $identVariable = null;
+        $fieldAliasIdentificationVariable = null;
+        $peek = $this->_lexer->glimpse();
+
+        $supportsAlias = true;
+
+        if ($peek['value'] != '(' && $this->_lexer->lookahead['type'] === Lexer::T_IDENTIFIER) {
+            if ($peek['value'] == '.') {
+                // ScalarExpression
+                $expression = $this->ScalarExpression();
+            } else {
+                $supportsAlias = false;
+                $expression = $identVariable = $this->IdentificationVariable();
+            }
+        } else if ($this->_lexer->lookahead['value'] == '(') {
+            if ($peek['type'] == Lexer::T_SELECT) {
+                // Subselect
+                $this->match(Lexer::T_OPEN_PARENTHESIS);
+                $expression = $this->Subselect();
+                $this->match(Lexer::T_CLOSE_PARENTHESIS);
+            } else {
+                // Shortcut: ScalarExpression => SimpleArithmeticExpression
+                $expression = $this->SimpleArithmeticExpression();
+            }
+        } else if ($this->_isFunction()) {
+            $this->_lexer->peek(); // "("
+            
+            $lookaheadType = $this->_lexer->lookahead['type'];
+            $beyond        = $this->_peekBeyondClosingParenthesis();
+            
+            if ($this->_isMathOperator($beyond)) {
+                $expression = $this->ScalarExpression();
+            } else if ($this->_isAggregateFunction($this->_lexer->lookahead['type'])) {
+                $expression = $this->AggregateExpression();
+            } else if (in_array ($lookaheadType, array(Lexer::T_CASE, Lexer::T_COALESCE, Lexer::T_NULLIF))) {
+                $expression = $this->CaseExpression();
+            } else {
+                // Shortcut: ScalarExpression => Function
+                $expression = $this->FunctionDeclaration();
+            }
+        } else if ($this->_lexer->lookahead['type'] == Lexer::T_PARTIAL) {
+            $supportsAlias = false;
+            $expression = $this->PartialObjectExpression();
+            $identVariable = $expression->identificationVariable;
+        } else if ($this->_lexer->lookahead['type'] == Lexer::T_INTEGER ||
+                $this->_lexer->lookahead['type'] == Lexer::T_FLOAT ||
+                $this->_lexer->lookahead['type'] == Lexer::T_STRING) {
+            // Shortcut: ScalarExpression => SimpleArithmeticExpression
+            $expression = $this->SimpleArithmeticExpression();
+        } else {
+            $this->syntaxError('IdentificationVariable | StateFieldPathExpression'
+                    . ' | AggregateExpression | "(" Subselect ")" | ScalarExpression',
+                    $this->_lexer->lookahead);
+        }
+
+        if ($supportsAlias) {
+            if ($this->_lexer->isNextToken(Lexer::T_AS)) {
+                $this->match(Lexer::T_AS);
+            }
+
+            if ($this->_lexer->isNextToken(Lexer::T_IDENTIFIER)) {
+                $token = $this->_lexer->lookahead;
+                $fieldAliasIdentificationVariable = $this->AliasResultVariable();
+
+                // Include AliasResultVariable in query components.
+                $this->_queryComponents[$fieldAliasIdentificationVariable] = array(
+                    'resultVariable' => $expression,
+                    'nestingLevel'   => $this->_nestingLevel,
+                    'token'          => $token,
+                );
+            }
+        }
+
+        $expr = new AST\SelectExpression($expression, $fieldAliasIdentificationVariable);
+        if (!$supportsAlias) {
+            $this->_identVariableExpressions[$identVariable] = $expr;
+        }
+        return $expr;
+    }
+
+    /**
+     * SimpleSelectExpression ::=
+     *      StateFieldPathExpression | IdentificationVariable |
+     *      ((AggregateExpression | "(" Subselect ")" | ScalarExpression) [["AS"] AliasResultVariable])
+     *
+     * @return \Doctrine\ORM\Query\AST\SimpleSelectExpression
+     */
+    public function SimpleSelectExpression()
+    {
+        $peek = $this->_lexer->glimpse();
+
+        if ($peek['value'] != '(' && $this->_lexer->lookahead['type'] === Lexer::T_IDENTIFIER) {
+            // SingleValuedPathExpression | IdentificationVariable
+            if ($peek['value'] == '.') {
+                $expression = $this->StateFieldPathExpression();
+            } else {
+                $expression = $this->IdentificationVariable();
+            }
+
+            return new AST\SimpleSelectExpression($expression);
+        } else if ($this->_lexer->lookahead['value'] == '(') {
+            if ($peek['type'] == Lexer::T_SELECT) {
+                // Subselect
+                $this->match(Lexer::T_OPEN_PARENTHESIS);
+                $expression = $this->Subselect();
+                $this->match(Lexer::T_CLOSE_PARENTHESIS);
+            } else {
+                // Shortcut: ScalarExpression => SimpleArithmeticExpression
+                $expression = $this->SimpleArithmeticExpression();
+            }
+
+            return new AST\SimpleSelectExpression($expression);
+        }
+
+        $this->_lexer->peek();
+
+        $expression = $this->ScalarExpression();
+
+        $expr = new AST\SimpleSelectExpression($expression);
+
+        if ($this->_lexer->isNextToken(Lexer::T_AS)) {
+            $this->match(Lexer::T_AS);
+        }
+
+        if ($this->_lexer->isNextToken(Lexer::T_IDENTIFIER)) {
+            $token = $this->_lexer->lookahead;
+            $resultVariable = $this->AliasResultVariable();
+            $expr->fieldIdentificationVariable = $resultVariable;
+
+            // Include AliasResultVariable in query components.
+            $this->_queryComponents[$resultVariable] = array(
+                'resultvariable' => $expr,
+                'nestingLevel'   => $this->_nestingLevel,
+                'token'          => $token,
+            );
+        }
+
+        return $expr;
+    }
+
+    /**
+     * ConditionalExpression ::= ConditionalTerm {"OR" ConditionalTerm}*
+     *
+     * @return \Doctrine\ORM\Query\AST\ConditionalExpression
+     */
+    public function ConditionalExpression()
+    {
+        $conditionalTerms = array();
+        $conditionalTerms[] = $this->ConditionalTerm();
+
+        while ($this->_lexer->isNextToken(Lexer::T_OR)) {
+            $this->match(Lexer::T_OR);
+            $conditionalTerms[] = $this->ConditionalTerm();
+        }
+
+        // Phase 1 AST optimization: Prevent AST\ConditionalExpression
+        // if only one AST\ConditionalTerm is defined
+        if (count($conditionalTerms) == 1) {
+            return $conditionalTerms[0];
+        }
+
+        return new AST\ConditionalExpression($conditionalTerms);
+    }
+
+    /**
+     * ConditionalTerm ::= ConditionalFactor {"AND" ConditionalFactor}*
+     *
+     * @return \Doctrine\ORM\Query\AST\ConditionalTerm
+     */
+    public function ConditionalTerm()
+    {
+        $conditionalFactors = array();
+        $conditionalFactors[] = $this->ConditionalFactor();
+
+        while ($this->_lexer->isNextToken(Lexer::T_AND)) {
+            $this->match(Lexer::T_AND);
+            $conditionalFactors[] = $this->ConditionalFactor();
+        }
+
+        // Phase 1 AST optimization: Prevent AST\ConditionalTerm
+        // if only one AST\ConditionalFactor is defined
+        if (count($conditionalFactors) == 1) {
+            return $conditionalFactors[0];
+        }
+
+        return new AST\ConditionalTerm($conditionalFactors);
+    }
+
+    /**
+     * ConditionalFactor ::= ["NOT"] ConditionalPrimary
+     *
+     * @return \Doctrine\ORM\Query\AST\ConditionalFactor
+     */
+    public function ConditionalFactor()
+    {
+        $not = false;
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $not = true;
+        }
+        
+        $conditionalPrimary = $this->ConditionalPrimary();
+
+        // Phase 1 AST optimization: Prevent AST\ConditionalFactor
+        // if only one AST\ConditionalPrimary is defined
+        if ( ! $not) {
+            return $conditionalPrimary;
+        }
+
+        $conditionalFactor = new AST\ConditionalFactor($conditionalPrimary);
+        $conditionalFactor->not = $not;
+
+        return $conditionalFactor;
+    }
+
+    /**
+     * ConditionalPrimary ::= SimpleConditionalExpression | "(" ConditionalExpression ")"
+     *
+     * @return Doctrine\ORM\Query\AST\ConditionalPrimary
+     */
+    public function ConditionalPrimary()
+    {
+        $condPrimary = new AST\ConditionalPrimary;
+
+        if ($this->_lexer->isNextToken(Lexer::T_OPEN_PARENTHESIS)) {
+            // Peek beyond the matching closing paranthesis ')'
+            $peek = $this->_peekBeyondClosingParenthesis();
+
+            if (in_array($peek['value'], array("=",  "<", "<=", "<>", ">", ">=", "!=")) ||
+                    $peek['type'] === Lexer::T_NOT ||
+                    $peek['type'] === Lexer::T_BETWEEN ||
+                    $peek['type'] === Lexer::T_LIKE ||
+                    $peek['type'] === Lexer::T_IN ||
+                    $peek['type'] === Lexer::T_IS ||
+                    $peek['type'] === Lexer::T_EXISTS) {
+                $condPrimary->simpleConditionalExpression = $this->SimpleConditionalExpression();
+            } else {
+                $this->match(Lexer::T_OPEN_PARENTHESIS);
+                $condPrimary->conditionalExpression = $this->ConditionalExpression();
+                $this->match(Lexer::T_CLOSE_PARENTHESIS);
+            }
+        } else {
+            $condPrimary->simpleConditionalExpression = $this->SimpleConditionalExpression();
+        }
+
+        return $condPrimary;
+    }
+
+    /**
+     * SimpleConditionalExpression ::=
+     *      ComparisonExpression | BetweenExpression | LikeExpression |
+     *      InExpression | NullComparisonExpression | ExistsExpression |
+     *      EmptyCollectionComparisonExpression | CollectionMemberExpression |
+     *      InstanceOfExpression
+     */
+    public function SimpleConditionalExpression()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $token = $this->_lexer->glimpse();
+        } else {
+            $token = $this->_lexer->lookahead;
+        }
+
+        if ($token['type'] === Lexer::T_EXISTS) {
+            return $this->ExistsExpression();
+        }
+
+        $peek = $this->_lexer->glimpse();
+
+        if ($token['type'] === Lexer::T_IDENTIFIER || $token['type'] === Lexer::T_INPUT_PARAMETER) {
+            if ($peek['value'] == '(') {
+                // Peek beyond the matching closing paranthesis ')'
+                $this->_lexer->peek();
+                $token = $this->_peekBeyondClosingParenthesis();
+            } else {
+                // Peek beyond the PathExpression (or InputParameter)
+                $peek = $this->_lexer->peek();
+
+                while ($peek['value'] === '.') {
+                    $this->_lexer->peek();
+                    $peek = $this->_lexer->peek();
+                }
+
+                // Also peek beyond a NOT if there is one
+                if ($peek['type'] === Lexer::T_NOT) {
+                    $peek = $this->_lexer->peek();
+                }
+
+                $token = $peek;
+
+                // We need to go even further in case of IS (differenciate between NULL and EMPTY)
+                $lookahead = $this->_lexer->peek();
+
+                // Also peek beyond a NOT if there is one
+                if ($lookahead['type'] === Lexer::T_NOT) {
+                    $lookahead = $this->_lexer->peek();
+                }
+
+                $this->_lexer->resetPeek();
+            }
+        }
+
+        switch ($token['type']) {
+            case Lexer::T_BETWEEN:
+                return $this->BetweenExpression();
+            case Lexer::T_LIKE:
+                return $this->LikeExpression();
+            case Lexer::T_IN:
+                return $this->InExpression();
+            case Lexer::T_INSTANCE:
+                return $this->InstanceOfExpression();
+            case Lexer::T_IS:
+                if ($lookahead['type'] == Lexer::T_NULL) {
+                    return $this->NullComparisonExpression();
+                }
+                return $this->EmptyCollectionComparisonExpression();
+            case Lexer::T_MEMBER:
+                return $this->CollectionMemberExpression();
+            default:
+                return $this->ComparisonExpression();
+        }
+    }
+
+    /**
+     * EmptyCollectionComparisonExpression ::= CollectionValuedPathExpression "IS" ["NOT"] "EMPTY"
+     *
+     * @return \Doctrine\ORM\Query\AST\EmptyCollectionComparisonExpression
+     */
+    public function EmptyCollectionComparisonExpression()
+    {
+        $emptyColletionCompExpr = new AST\EmptyCollectionComparisonExpression(
+            $this->CollectionValuedPathExpression()
+        );
+        $this->match(Lexer::T_IS);
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $emptyColletionCompExpr->not = true;
+        }
+
+        $this->match(Lexer::T_EMPTY);
+
+        return $emptyColletionCompExpr;
+    }
+
+    /**
+     * CollectionMemberExpression ::= EntityExpression ["NOT"] "MEMBER" ["OF"] CollectionValuedPathExpression
+     *
+     * EntityExpression ::= SingleValuedAssociationPathExpression | SimpleEntityExpression
+     * SimpleEntityExpression ::= IdentificationVariable | InputParameter
+     *
+     * @return \Doctrine\ORM\Query\AST\CollectionMemberExpression
+     */
+    public function CollectionMemberExpression()
+    {
+        $not = false;
+
+        $entityExpr = $this->EntityExpression();
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $not = true;
+            $this->match(Lexer::T_NOT);
+        }
+
+        $this->match(Lexer::T_MEMBER);
+
+        if ($this->_lexer->isNextToken(Lexer::T_OF)) {
+            $this->match(Lexer::T_OF);
+        }
+
+        $collMemberExpr = new AST\CollectionMemberExpression(
+            $entityExpr, $this->CollectionValuedPathExpression()
+        );
+        $collMemberExpr->not = $not;
+
+        return $collMemberExpr;
+    }
+
+    /**
+     * Literal ::= string | char | integer | float | boolean
+     *
+     * @return string
+     */
+    public function Literal()
+    {
+        switch ($this->_lexer->lookahead['type']) {
+            case Lexer::T_STRING:
+                $this->match(Lexer::T_STRING);
+                return new AST\Literal(AST\Literal::STRING, $this->_lexer->token['value']);
+
+            case Lexer::T_INTEGER:
+            case Lexer::T_FLOAT:
+                $this->match(
+                    $this->_lexer->isNextToken(Lexer::T_INTEGER) ? Lexer::T_INTEGER : Lexer::T_FLOAT
+                );
+                return new AST\Literal(AST\Literal::NUMERIC, $this->_lexer->token['value']);
+
+            case Lexer::T_TRUE:
+            case Lexer::T_FALSE:
+                $this->match(
+                    $this->_lexer->isNextToken(Lexer::T_TRUE) ? Lexer::T_TRUE : Lexer::T_FALSE
+                );
+                return new AST\Literal(AST\Literal::BOOLEAN, $this->_lexer->token['value']);
+
+            default:
+                $this->syntaxError('Literal');
+        }
+    }
+
+    /**
+     * InParameter ::= Literal | InputParameter
+     *
+     * @return string | \Doctrine\ORM\Query\AST\InputParameter
+     */
+    public function InParameter()
+    {
+        if ($this->_lexer->lookahead['type'] == Lexer::T_INPUT_PARAMETER) {
+            return $this->InputParameter();
+        }
+
+        return $this->Literal();
+    }
+
+    /**
+     * InputParameter ::= PositionalParameter | NamedParameter
+     *
+     * @return \Doctrine\ORM\Query\AST\InputParameter
+     */
+    public function InputParameter()
+    {
+        $this->match(Lexer::T_INPUT_PARAMETER);
+
+        return new AST\InputParameter($this->_lexer->token['value']);
+    }
+
+    /**
+     * ArithmeticExpression ::= SimpleArithmeticExpression | "(" Subselect ")"
+     *
+     * @return \Doctrine\ORM\Query\AST\ArithmeticExpression
+     */
+    public function ArithmeticExpression()
+    {
+        $expr = new AST\ArithmeticExpression;
+
+        if ($this->_lexer->isNextToken(Lexer::T_OPEN_PARENTHESIS)) {
+            $peek = $this->_lexer->glimpse();
+
+            if ($peek['type'] === Lexer::T_SELECT) {
+                $this->match(Lexer::T_OPEN_PARENTHESIS);
+                $expr->subselect = $this->Subselect();
+                $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+                return $expr;
+            }
+        }
+
+        $expr->simpleArithmeticExpression = $this->SimpleArithmeticExpression();
+
+        return $expr;
+    }
+
+    /**
+     * SimpleArithmeticExpression ::= ArithmeticTerm {("+" | "-") ArithmeticTerm}*
+     *
+     * @return \Doctrine\ORM\Query\AST\SimpleArithmeticExpression
+     */
+    public function SimpleArithmeticExpression()
+    {
+        $terms = array();
+        $terms[] = $this->ArithmeticTerm();
+
+        while (($isPlus = $this->_lexer->isNextToken(Lexer::T_PLUS)) || $this->_lexer->isNextToken(Lexer::T_MINUS)) {
+            $this->match(($isPlus) ? Lexer::T_PLUS : Lexer::T_MINUS);
+
+            $terms[] = $this->_lexer->token['value'];
+            $terms[] = $this->ArithmeticTerm();
+        }
+
+        // Phase 1 AST optimization: Prevent AST\SimpleArithmeticExpression
+        // if only one AST\ArithmeticTerm is defined
+        if (count($terms) == 1) {
+            return $terms[0];
+        }
+
+        return new AST\SimpleArithmeticExpression($terms);
+    }
+
+    /**
+     * ArithmeticTerm ::= ArithmeticFactor {("*" | "/") ArithmeticFactor}*
+     *
+     * @return \Doctrine\ORM\Query\AST\ArithmeticTerm
+     */
+    public function ArithmeticTerm()
+    {
+        $factors = array();
+        $factors[] = $this->ArithmeticFactor();
+
+        while (($isMult = $this->_lexer->isNextToken(Lexer::T_MULTIPLY)) || $this->_lexer->isNextToken(Lexer::T_DIVIDE)) {
+            $this->match(($isMult) ? Lexer::T_MULTIPLY : Lexer::T_DIVIDE);
+
+            $factors[] = $this->_lexer->token['value'];
+            $factors[] = $this->ArithmeticFactor();
+        }
+
+        // Phase 1 AST optimization: Prevent AST\ArithmeticTerm
+        // if only one AST\ArithmeticFactor is defined
+        if (count($factors) == 1) {
+            return $factors[0];
+        }
+
+        return new AST\ArithmeticTerm($factors);
+    }
+
+    /**
+     * ArithmeticFactor ::= [("+" | "-")] ArithmeticPrimary
+     *
+     * @return \Doctrine\ORM\Query\AST\ArithmeticFactor
+     */
+    public function ArithmeticFactor()
+    {
+        $sign = null;
+
+        if (($isPlus = $this->_lexer->isNextToken(Lexer::T_PLUS)) || $this->_lexer->isNextToken(Lexer::T_MINUS)) {
+            $this->match(($isPlus) ? Lexer::T_PLUS : Lexer::T_MINUS);
+            $sign = $isPlus;
+        }
+        
+        $primary = $this->ArithmeticPrimary();
+
+        // Phase 1 AST optimization: Prevent AST\ArithmeticFactor
+        // if only one AST\ArithmeticPrimary is defined
+        if ($sign === null) {
+            return $primary;
+        }
+
+        return new AST\ArithmeticFactor($primary, $sign);
+    }
+
+    /**
+     * ArithmeticPrimary ::= SingleValuedPathExpression | Literal | "(" SimpleArithmeticExpression ")"
+     *          | FunctionsReturningNumerics | AggregateExpression | FunctionsReturningStrings
+     *          | FunctionsReturningDatetime | IdentificationVariable
+     */
+    public function ArithmeticPrimary()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_OPEN_PARENTHESIS)) {
+            $this->match(Lexer::T_OPEN_PARENTHESIS);
+            $expr = $this->SimpleArithmeticExpression();
+
+            $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+            return $expr;
+        }
+
+        switch ($this->_lexer->lookahead['type']) {
+            case Lexer::T_IDENTIFIER:
+                $peek = $this->_lexer->glimpse();
+
+                if ($peek['value'] == '(') {
+                    return $this->FunctionDeclaration();
+                }
+
+                if ($peek['value'] == '.') {
+                    return $this->SingleValuedPathExpression();
+                }
+
+                return $this->StateFieldPathExpression();
+
+            case Lexer::T_INPUT_PARAMETER:
+                return $this->InputParameter();
+
+            default:
+                $peek = $this->_lexer->glimpse();
+
+                if ($peek['value'] == '(') {
+                    if ($this->_isAggregateFunction($this->_lexer->lookahead['type'])) {
+                        return $this->AggregateExpression();
+                    }
+
+                    return $this->FunctionDeclaration();
+                } else {
+                    return $this->Literal();
+                }
+        }
+    }
+
+    /**
+     * StringExpression ::= StringPrimary | "(" Subselect ")"
+     *
+     * @return \Doctrine\ORM\Query\AST\StringPrimary |
+     *         \Doctrine]ORM\Query\AST\Subselect
+     */
+    public function StringExpression()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_OPEN_PARENTHESIS)) {
+            $peek = $this->_lexer->glimpse();
+
+            if ($peek['type'] === Lexer::T_SELECT) {
+                $this->match(Lexer::T_OPEN_PARENTHESIS);
+                $expr = $this->Subselect();
+                $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+                return $expr;
+            }
+        }
+
+        return $this->StringPrimary();
+    }
+
+    /**
+     * StringPrimary ::= StateFieldPathExpression | string | InputParameter | FunctionsReturningStrings | AggregateExpression
+     */
+    public function StringPrimary()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_IDENTIFIER)) {
+            $peek = $this->_lexer->glimpse();
+
+            if ($peek['value'] == '.') {
+                return $this->StateFieldPathExpression();
+            } else if ($peek['value'] == '(') {
+                // do NOT directly go to FunctionsReturningString() because it doesnt check for custom functions.
+                return $this->FunctionDeclaration();
+            } else {
+                $this->syntaxError("'.' or '('");
+            }
+        } else if ($this->_lexer->isNextToken(Lexer::T_STRING)) {
+            $this->match(Lexer::T_STRING);
+
+            return $this->_lexer->token['value'];
+        } else if ($this->_lexer->isNextToken(Lexer::T_INPUT_PARAMETER)) {
+            return $this->InputParameter();
+        } else if ($this->_isAggregateFunction($this->_lexer->lookahead['type'])) {
+            return $this->AggregateExpression();
+        }
+
+        $this->syntaxError('StateFieldPathExpression | string | InputParameter | FunctionsReturningStrings | AggregateExpression');
+    }
+
+    /**
+     * EntityExpression ::= SingleValuedAssociationPathExpression | SimpleEntityExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\SingleValuedAssociationPathExpression |
+     *         \Doctrine\ORM\Query\AST\SimpleEntityExpression
+     */
+    public function EntityExpression()
+    {
+        $glimpse = $this->_lexer->glimpse();
+
+        if ($this->_lexer->isNextToken(Lexer::T_IDENTIFIER) && $glimpse['value'] === '.') {
+            return $this->SingleValuedAssociationPathExpression();
+        }
+
+        return $this->SimpleEntityExpression();
+    }
+
+    /**
+     * SimpleEntityExpression ::= IdentificationVariable | InputParameter
+     *
+     * @return string | \Doctrine\ORM\Query\AST\InputParameter
+     */
+    public function SimpleEntityExpression()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_INPUT_PARAMETER)) {
+            return $this->InputParameter();
+        }
+
+        return $this->IdentificationVariable();
+    }
+
+    /**
+     * AggregateExpression ::=
+     *  ("AVG" | "MAX" | "MIN" | "SUM") "(" ["DISTINCT"] StateFieldPathExpression ")" |
+     *  "COUNT" "(" ["DISTINCT"] (IdentificationVariable | SingleValuedPathExpression) ")"
+     *
+     * @return \Doctrine\ORM\Query\AST\AggregateExpression
+     */
+    public function AggregateExpression()
+    {
+        $isDistinct = false;
+        $functionName = '';
+
+        if ($this->_lexer->isNextToken(Lexer::T_COUNT)) {
+            $this->match(Lexer::T_COUNT);
+            $functionName = $this->_lexer->token['value'];
+            $this->match(Lexer::T_OPEN_PARENTHESIS);
+
+            if ($this->_lexer->isNextToken(Lexer::T_DISTINCT)) {
+                $this->match(Lexer::T_DISTINCT);
+                $isDistinct = true;
+            }
+
+            $pathExp = $this->SingleValuedPathExpression();
+            $this->match(Lexer::T_CLOSE_PARENTHESIS);
+        } else {
+            if ($this->_lexer->isNextToken(Lexer::T_AVG)) {
+                $this->match(Lexer::T_AVG);
+            } else if ($this->_lexer->isNextToken(Lexer::T_MAX)) {
+                $this->match(Lexer::T_MAX);
+            } else if ($this->_lexer->isNextToken(Lexer::T_MIN)) {
+                $this->match(Lexer::T_MIN);
+            } else if ($this->_lexer->isNextToken(Lexer::T_SUM)) {
+                $this->match(Lexer::T_SUM);
+            } else {
+                $this->syntaxError('One of: MAX, MIN, AVG, SUM, COUNT');
+            }
+
+            $functionName = $this->_lexer->token['value'];
+            $this->match(Lexer::T_OPEN_PARENTHESIS);
+            $pathExp = $this->SimpleArithmeticExpression();
+            $this->match(Lexer::T_CLOSE_PARENTHESIS);
+        }
+
+        return new AST\AggregateExpression($functionName, $pathExp, $isDistinct);
+    }
+
+    /**
+     * QuantifiedExpression ::= ("ALL" | "ANY" | "SOME") "(" Subselect ")"
+     *
+     * @return \Doctrine\ORM\Query\AST\QuantifiedExpression
+     */
+    public function QuantifiedExpression()
+    {
+        $type = '';
+
+        if ($this->_lexer->isNextToken(Lexer::T_ALL)) {
+            $this->match(Lexer::T_ALL);
+            $type = 'ALL';
+        } else if ($this->_lexer->isNextToken(Lexer::T_ANY)) {
+            $this->match(Lexer::T_ANY);
+             $type = 'ANY';
+        } else if ($this->_lexer->isNextToken(Lexer::T_SOME)) {
+            $this->match(Lexer::T_SOME);
+             $type = 'SOME';
+        } else {
+            $this->syntaxError('ALL, ANY or SOME');
+        }
+
+        $this->match(Lexer::T_OPEN_PARENTHESIS);
+        $qExpr = new AST\QuantifiedExpression($this->Subselect());
+        $qExpr->type = $type;
+        $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+        return $qExpr;
+    }
+
+    /**
+     * BetweenExpression ::= ArithmeticExpression ["NOT"] "BETWEEN" ArithmeticExpression "AND" ArithmeticExpression
+     *
+     * @return \Doctrine\ORM\Query\AST\BetweenExpression
+     */
+    public function BetweenExpression()
+    {
+        $not = false;
+        $arithExpr1 = $this->ArithmeticExpression();
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $not = true;
+        }
+
+        $this->match(Lexer::T_BETWEEN);
+        $arithExpr2 = $this->ArithmeticExpression();
+        $this->match(Lexer::T_AND);
+        $arithExpr3 = $this->ArithmeticExpression();
+
+        $betweenExpr = new AST\BetweenExpression($arithExpr1, $arithExpr2, $arithExpr3);
+        $betweenExpr->not = $not;
+
+        return $betweenExpr;
+    }
+
+    /**
+     * ComparisonExpression ::= ArithmeticExpression ComparisonOperator ( QuantifiedExpression | ArithmeticExpression )
+     *
+     * @return \Doctrine\ORM\Query\AST\ComparisonExpression
+     */
+    public function ComparisonExpression()
+    {
+        $peek = $this->_lexer->glimpse();
+
+        $leftExpr = $this->ArithmeticExpression();
+        $operator = $this->ComparisonOperator();
+
+        if ($this->_isNextAllAnySome()) {
+            $rightExpr = $this->QuantifiedExpression();
+        } else {
+            $rightExpr = $this->ArithmeticExpression();
+        }
+
+        return new AST\ComparisonExpression($leftExpr, $operator, $rightExpr);
+    }
+
+    /**
+     * InExpression ::= SingleValuedPathExpression ["NOT"] "IN" "(" (InParameter {"," InParameter}* | Subselect) ")"
+     *
+     * @return \Doctrine\ORM\Query\AST\InExpression
+     */
+    public function InExpression()
+    {
+        $inExpression = new AST\InExpression($this->SingleValuedPathExpression());
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $inExpression->not = true;
+        }
+
+        $this->match(Lexer::T_IN);
+        $this->match(Lexer::T_OPEN_PARENTHESIS);
+
+        if ($this->_lexer->isNextToken(Lexer::T_SELECT)) {
+            $inExpression->subselect = $this->Subselect();
+        } else {
+            $literals = array();
+            $literals[] = $this->InParameter();
+
+            while ($this->_lexer->isNextToken(Lexer::T_COMMA)) {
+                $this->match(Lexer::T_COMMA);
+                $literals[] = $this->InParameter();
+            }
+
+            $inExpression->literals = $literals;
+        }
+
+        $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+        return $inExpression;
+    }
+
+    /**
+     * InstanceOfExpression ::= IdentificationVariable ["NOT"] "INSTANCE" ["OF"] (AbstractSchemaName | InputParameter)
+     *
+     * @return \Doctrine\ORM\Query\AST\InstanceOfExpression
+     */
+    public function InstanceOfExpression()
+    {
+        $instanceOfExpression = new AST\InstanceOfExpression($this->IdentificationVariable());
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $instanceOfExpression->not = true;
+        }
+
+        $this->match(Lexer::T_INSTANCE);
+
+        if ($this->_lexer->isNextToken(Lexer::T_OF)) {
+            $this->match(Lexer::T_OF);
+        }
+
+        if ($this->_lexer->isNextToken(Lexer::T_INPUT_PARAMETER)) {
+            $this->match(Lexer::T_INPUT_PARAMETER);
+            $exprValue = new AST\InputParameter($this->_lexer->token['value']);
+        } else {
+            $exprValue = $this->AliasIdentificationVariable();
+        }
+
+        $instanceOfExpression->value = $exprValue;
+        
+        return $instanceOfExpression;
+    }
+
+    /**
+     * LikeExpression ::= StringExpression ["NOT"] "LIKE" (string | input_parameter) ["ESCAPE" char]
+     *
+     * @return \Doctrine\ORM\Query\AST\LikeExpression
+     */
+    public function LikeExpression()
+    {
+        $stringExpr = $this->StringExpression();
+        $not = false;
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $not = true;
+        }
+
+        $this->match(Lexer::T_LIKE);
+
+        if ($this->_lexer->isNextToken(Lexer::T_INPUT_PARAMETER)) {
+            $this->match(Lexer::T_INPUT_PARAMETER);
+            $stringPattern = new AST\InputParameter($this->_lexer->token['value']);
+        } else {
+            $this->match(Lexer::T_STRING);
+            $stringPattern = $this->_lexer->token['value'];
+        }
+
+        $escapeChar = null;
+
+        if ($this->_lexer->lookahead['type'] === Lexer::T_ESCAPE) {
+            $this->match(Lexer::T_ESCAPE);
+            $this->match(Lexer::T_STRING);
+            $escapeChar = $this->_lexer->token['value'];
+        }
+
+        $likeExpr = new AST\LikeExpression($stringExpr, $stringPattern, $escapeChar);
+        $likeExpr->not = $not;
+
+        return $likeExpr;
+    }
+
+    /**
+     * NullComparisonExpression ::= (SingleValuedPathExpression | InputParameter) "IS" ["NOT"] "NULL"
+     *
+     * @return \Doctrine\ORM\Query\AST\NullComparisonExpression
+     */
+    public function NullComparisonExpression()
+    {
+        if ($this->_lexer->isNextToken(Lexer::T_INPUT_PARAMETER)) {
+            $this->match(Lexer::T_INPUT_PARAMETER);
+            $expr = new AST\InputParameter($this->_lexer->token['value']);
+        } else {
+            $expr = $this->SingleValuedPathExpression();
+        }
+
+        $nullCompExpr = new AST\NullComparisonExpression($expr);
+        $this->match(Lexer::T_IS);
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $nullCompExpr->not = true;
+        }
+
+        $this->match(Lexer::T_NULL);
+
+        return $nullCompExpr;
+    }
+
+    /**
+     * ExistsExpression ::= ["NOT"] "EXISTS" "(" Subselect ")"
+     *
+     * @return \Doctrine\ORM\Query\AST\ExistsExpression
+     */
+    public function ExistsExpression()
+    {
+        $not = false;
+
+        if ($this->_lexer->isNextToken(Lexer::T_NOT)) {
+            $this->match(Lexer::T_NOT);
+            $not = true;
+        }
+
+        $this->match(Lexer::T_EXISTS);
+        $this->match(Lexer::T_OPEN_PARENTHESIS);
+        $existsExpression = new AST\ExistsExpression($this->Subselect());
+        $existsExpression->not = $not;
+        $this->match(Lexer::T_CLOSE_PARENTHESIS);
+
+        return $existsExpression;
+    }
+
+    /**
+     * ComparisonOperator ::= "=" | "<" | "<=" | "<>" | ">" | ">=" | "!="
+     *
+     * @return string
+     */
+    public function ComparisonOperator()
+    {
+        switch ($this->_lexer->lookahead['value']) {
+            case '=':
+                $this->match(Lexer::T_EQUALS);
+
+                return '=';
+
+            case '<':
+                $this->match(Lexer::T_LOWER_THAN);
+                $operator = '<';
+
+                if ($this->_lexer->isNextToken(Lexer::T_EQUALS)) {
+                    $this->match(Lexer::T_EQUALS);
+                    $operator .= '=';
+                } else if ($this->_lexer->isNextToken(Lexer::T_GREATER_THAN)) {
+                    $this->match(Lexer::T_GREATER_THAN);
+                    $operator .= '>';
+                }
+
+                return $operator;
+
+            case '>':
+                $this->match(Lexer::T_GREATER_THAN);
+                $operator = '>';
+
+                if ($this->_lexer->isNextToken(Lexer::T_EQUALS)) {
+                    $this->match(Lexer::T_EQUALS);
+                    $operator .= '=';
+                }
+
+                return $operator;
+
+            case '!':
+                $this->match(Lexer::T_NEGATE);
+                $this->match(Lexer::T_EQUALS);
+
+                return '<>';
+
+            default:
+                $this->syntaxError('=, <, <=, <>, >, >=, !=');
+        }
+    }
+
+    /**
+     * FunctionDeclaration ::= FunctionsReturningStrings | FunctionsReturningNumerics | FunctionsReturningDatetime
+     */
+    public function FunctionDeclaration()
+    {
+        $token = $this->_lexer->lookahead;
+        $funcName = strtolower($token['value']);
+
+        // Check for built-in functions first!
+        if (isset(self::$_STRING_FUNCTIONS[$funcName])) {
+            return $this->FunctionsReturningStrings();
+        } else if (isset(self::$_NUMERIC_FUNCTIONS[$funcName])) {
+            return $this->FunctionsReturningNumerics();
+        } else if (isset(self::$_DATETIME_FUNCTIONS[$funcName])) {
+            return $this->FunctionsReturningDatetime();
+        }
+
+        // Check for custom functions afterwards
+        $config = $this->_em->getConfiguration();
+
+        if ($config->getCustomStringFunction($funcName) !== null) {
+            return $this->CustomFunctionsReturningStrings();
+        } else if ($config->getCustomNumericFunction($funcName) !== null) {
+            return $this->CustomFunctionsReturningNumerics();
+        } else if ($config->getCustomDatetimeFunction($funcName) !== null) {
+            return $this->CustomFunctionsReturningDatetime();
+        }
+
+        $this->syntaxError('known function', $token);
+    }
+
+    /**
+     * FunctionsReturningNumerics ::=
+     *      "LENGTH" "(" StringPrimary ")" |
+     *      "LOCATE" "(" StringPrimary "," StringPrimary ["," SimpleArithmeticExpression]")" |
+     *      "ABS" "(" SimpleArithmeticExpression ")" |
+     *      "SQRT" "(" SimpleArithmeticExpression ")" |
+     *      "MOD" "(" SimpleArithmeticExpression "," SimpleArithmeticExpression ")" |
+     *      "SIZE" "(" CollectionValuedPathExpression ")"
+     */
+    public function FunctionsReturningNumerics()
+    {
+        $funcNameLower = strtolower($this->_lexer->lookahead['value']);
+        $funcClass = self::$_NUMERIC_FUNCTIONS[$funcNameLower];
+        $function = new $funcClass($funcNameLower);
+        $function->parse($this);
+
+        return $function;
+    }
+
+    public function CustomFunctionsReturningNumerics()
+    {
+        $funcName = strtolower($this->_lexer->lookahead['value']);
+        // getCustomNumericFunction is case-insensitive
+        $funcClass = $this->_em->getConfiguration()->getCustomNumericFunction($funcName);
+        $function = new $funcClass($funcName);
+        $function->parse($this);
+
+        return $function;
+    }
+
+    /**
+     * FunctionsReturningDateTime ::= "CURRENT_DATE" | "CURRENT_TIME" | "CURRENT_TIMESTAMP"
+     */
+    public function FunctionsReturningDatetime()
+    {
+        $funcNameLower = strtolower($this->_lexer->lookahead['value']);
+        $funcClass = self::$_DATETIME_FUNCTIONS[$funcNameLower];
+        $function = new $funcClass($funcNameLower);
+        $function->parse($this);
+
+        return $function;
+    }
+
+    public function CustomFunctionsReturningDatetime()
+    {
+        $funcName = $this->_lexer->lookahead['value'];
+        // getCustomDatetimeFunction is case-insensitive
+        $funcClass = $this->_em->getConfiguration()->getCustomDatetimeFunction($funcName);
+        $function = new $funcClass($funcName);
+        $function->parse($this);
+
+        return $function;
+    }
+
+    /**
+     * FunctionsReturningStrings ::=
+     *   "CONCAT" "(" StringPrimary "," StringPrimary ")" |
+     *   "SUBSTRING" "(" StringPrimary "," SimpleArithmeticExpression "," SimpleArithmeticExpression ")" |
+     *   "TRIM" "(" [["LEADING" | "TRAILING" | "BOTH"] [char] "FROM"] StringPrimary ")" |
+     *   "LOWER" "(" StringPrimary ")" |
+     *   "UPPER" "(" StringPrimary ")"
+     */
+    public function FunctionsReturningStrings()
+    {
+        $funcNameLower = strtolower($this->_lexer->lookahead['value']);
+        $funcClass = self::$_STRING_FUNCTIONS[$funcNameLower];
+        $function = new $funcClass($funcNameLower);
+        $function->parse($this);
+
+        return $function;
+    }
+
+    public function CustomFunctionsReturningStrings()
+    {
+        $funcName = $this->_lexer->lookahead['value'];
+        // getCustomStringFunction is case-insensitive
+        $funcClass = $this->_em->getConfiguration()->getCustomStringFunction($funcName);
+        $function = new $funcClass($funcName);
+        $function->parse($this);
+
+        return $function;
+    }
+}