Extracted all identifier quoting logic into a separate object

Cake/Database/Dialect/PostgresDialectTrait.php

@@ -27,10 +27,7 @@
  */
 trait PostgresDialectTrait {
 
-	use SqlDialectTrait {
-		_expressionTranslators as private _quotingTranslators;
-	}
-
+	use SqlDialectTrait;
 /**
  *  String used to start a database identifier quoting to make it safe
  *
@@ -77,7 +74,7 @@ protected function _insertQueryTranslator($query) {
  */
 	protected function _expressionTranslators() {
 		$namespace = 'Cake\Database\Expression';
-		return $this->_quotingTranslators() + [
+		return [
 			$namespace . '\FunctionExpression' => '_transformFunctionExpression'
 		];
 	}

Cake/Database/Dialect/SqliteDialectTrait.php

@@ -23,9 +23,7 @@
 
 trait SqliteDialectTrait {
 
-	use SqlDialectTrait {
-		_expressionTranslators as private _quotingTranslators;
-	}
+	use SqlDialectTrait;
 
 /**
  *  String used to start a database identifier quoting to make it safe
@@ -49,7 +47,7 @@ trait SqliteDialectTrait {
  */
 	protected function _expressionTranslators() {
 		$namespace = 'Cake\Database\Expression';
-		return $this->_quotingTranslators() + [
+		return [
 			$namespace . '\FunctionExpression' => '_transformFunctionExpression'
 		];
 	}

Cake/Database/IdentifierQuoter.php

@@ -0,0 +1,210 @@
+<?php
+/**
+ * PHP Version 5.4
+ *
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         CakePHP(tm) v 3.0.0
+ * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
+ */
+namespace Cake\Database;
+
+use Cake\Database\Expression\Comparison;
+use Cake\Database\Expression\OrderByExpression;
+use Cake\Database\Expression\IdentifierExpression;
+
+/**
+ * Contains all the logic related to quoting identifiers in a Query object
+ *
+ */
+class IdentifierQuoter {
+
+/**
+ * The driver instance used to do the identifier quoting
+ *
+ * @var Cake\Database\Driver
+ */
+	protected $_driver;
+
+/**
+ * Constructor
+ *
+ * @param Cake\Database\Driver The driver instance used to do the identifier quoting
+ * @return void
+ */
+	public function __construct(Driver $driver) {
+		$this->_driver = $driver;
+	}
+
+/**
+ * Iterates over each of the clauses in a query looking for identifiers and
+ * quotes them
+ *
+ * @param Query $query The query to have its identifiers quoted
+ * @return Query
+ */
+	public function quote(Query $query) {
+		$binder = $query->valueBinder();
+		$query->valueBinder(false);
+
+		if ($query->type() === 'insert') {
+			$this->_quoteInsert($query);
+		} else {
+			$this->_qouteParts($query);
+		}
+
+		$query->traverseExpressions(function($expression) {
+			if ($expression instanceof Comparison) {
+				$this->_quoteComparison($expression);
+				return;
+			}
+
+			if ($expression instanceof OrderByExpression) {
+				$this->_quoteOrderBy($expression);
+				return;
+			}
+
+			if ($expression instanceof IdentifierExpression) {
+				$this->_quoteIndetifierExpression($expression);
+				return;
+			}
+		});
+
+		$query->valueBinder($binder);
+		return $query;
+	}
+
+/**
+ * Quotes all identifiers in each of the clauses of a query
+ *
+ * @param Query
+ * @return void
+ */
+	protected function _qouteParts($query) {
+		foreach (['distinct', 'select', 'from', 'group'] as $part) {
+			$contents = $query->clause($part);
+
+			if (!is_array($contents)) {
+				continue;
+			}
+
+			$result = $this->_basicQuoter($contents);
+			if ($result) {
+				$query->{$part}($result, true);
+			}
+		}
+
+		$joins = $query->clause('join');
+		if ($joins) {
+			$joins = $this->_quoteJoins($joins);
+			$query->join($joins, [], true);
+		}
+	}
+
+/**
+ * A generic identifier quoting function used for various parts of the query
+ *
+ * @param array $part the part of the query to quote
+ * @return array
+ */
+	protected function _basicQuoter($part) {
+		$result = [];
+		foreach ((array)$part as $alias => $value) {
+			$value = !is_string($value) ? $value : $this->_driver->quoteIdentifier($value);
+			$alias = is_numeric($alias) ? $alias : $this->_driver->quoteIdentifier($alias);
+			$result[$alias] = $value;
+		}
+		return $result;
+	}
+
+/**
+ * Quotes both the table and alias fot an array of joins as stored in a Query
+ * object
+ *
+ * @param array $joins
+ * @return array
+ */
+	protected function _quoteJoins($joins) {
+		$result = [];
+		foreach ($joins as $value) {
+			$alias = null;
+			if (!empty($value['alias'])) {
+				$alias = $this->_driver->quoteIdentifier($value['alias']);
+				$value['alias'] = $alias;
+			}
+
+			if (is_string($value['table'])) {
+				$value['table'] = $this->_driver->quoteIdentifier($value['table']);
+			}
+
+			$result[$alias] = $value;
+		}
+
+		return $result;
+	}
+
+/**
+ * Quotes the table name and columns for an insert query
+ *
+ * @param Query $query
+ * @return Query
+ */
+	protected function _quoteInsert($query) {
+		list($table, $columns) = $query->clause('insert');
+		$table = $this->_driver->quoteIdentifier($table);
+		foreach ($columns as &$column) {
+			if (is_string($column)) {
+				$column = $this->_driver->quoteIdentifier($column);
+			}
+		}
+		$query->insert($table, $columns);
+	}
+
+/**
+ * Quotes identifiers in comparison expression objects
+ *
+ * @param \Cake\Database\Expression\Comparison $expression
+ * @return void
+ */
+	protected function _quoteComparison(Comparison $expression) {
+		$field = $expression->getField();
+		if (is_string($field)) {
+			$expression->field($this->_driver->quoteIdentifier($field));
+		}
+	}
+
+/**
+ * Quotes identifiers in "order by" expression objects
+ *
+ * @param \Cake\Database\Expression\OrderByExpression $expression
+ * @return void
+ */
+	protected function _quoteOrderBy(OrderByExpression $expression) {
+		$expression->iterateParts(function($part, &$field) {
+			if (is_string($field)) {
+				$field = $this->_driver->quoteIdentifier($field);
+			}
+			return $part;
+		});
+	}
+
+/**
+ * Quotes identifiers in "order by" expression objects
+ *
+ * @param \Cake\Database\Expression\IdentifierExpression $expression
+ * @return void
+ */
+	protected function _quoteIndetifierExpression(IdentifierExpression $expression) {
+		$expression->setIdentifier(
+			$this->_driver->quoteIdentifier($expression->getIdentifier())
+		);
+	}
+
+}