--- /dev/null
+<?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 MIT license. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\ORM\Internal;
+
+/**
+ * The CommitOrderCalculator is used by the UnitOfWork to sort out the
+ * correct order in which changes to entities need to be persisted.
+ *
+ * @since 2.0
+ * @author Roman Borschel <roman@code-factory.org>
+ * @author Guilherme Blanco <guilhermeblanco@hotmail.com>
+ */
+class CommitOrderCalculator
+{
+ const NOT_VISITED = 1;
+ const IN_PROGRESS = 2;
+ const VISITED = 3;
+
+ private $_nodeStates = array();
+ private $_classes = array(); // The nodes to sort
+ private $_relatedClasses = array();
+ private $_sorted = array();
+
+ /**
+ * Clears the current graph.
+ *
+ * @return void
+ */
+ public function clear()
+ {
+ $this->_classes =
+ $this->_relatedClasses = array();
+ }
+
+ /**
+ * Gets a valid commit order for all current nodes.
+ *
+ * Uses a depth-first search (DFS) to traverse the graph.
+ * The desired topological sorting is the reverse postorder of these searches.
+ *
+ * @return array The list of ordered classes.
+ */
+ public function getCommitOrder()
+ {
+ // Check whether we need to do anything. 0 or 1 node is easy.
+ $nodeCount = count($this->_classes);
+
+ if ($nodeCount <= 1) {
+ return ($nodeCount == 1) ? array_values($this->_classes) : array();
+ }
+
+ // Init
+ foreach ($this->_classes as $node) {
+ $this->_nodeStates[$node->name] = self::NOT_VISITED;
+ }
+
+ // Go
+ foreach ($this->_classes as $node) {
+ if ($this->_nodeStates[$node->name] == self::NOT_VISITED) {
+ $this->_visitNode($node);
+ }
+ }
+
+ $sorted = array_reverse($this->_sorted);
+
+ $this->_sorted = $this->_nodeStates = array();
+
+ return $sorted;
+ }
+
+ private function _visitNode($node)
+ {
+ $this->_nodeStates[$node->name] = self::IN_PROGRESS;
+
+ if (isset($this->_relatedClasses[$node->name])) {
+ foreach ($this->_relatedClasses[$node->name] as $relatedNode) {
+ if ($this->_nodeStates[$relatedNode->name] == self::NOT_VISITED) {
+ $this->_visitNode($relatedNode);
+ }
+ }
+ }
+
+ $this->_nodeStates[$node->name] = self::VISITED;
+ $this->_sorted[] = $node;
+ }
+
+ public function addDependency($fromClass, $toClass)
+ {
+ $this->_relatedClasses[$fromClass->name][] = $toClass;
+ }
+
+ public function hasClass($className)
+ {
+ return isset($this->_classes[$className]);
+ }
+
+ public function addClass($class)
+ {
+ $this->_classes[$class->name] = $class;
+ }
+}