--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\BrowserKit;
+
+/**
+ * History.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class History
+{
+ protected $stack = array();
+ protected $position = -1;
+
+ /**
+ * Clears the history.
+ */
+ public function clear()
+ {
+ $this->stack = array();
+ $this->position = -1;
+ }
+
+ /**
+ * Adds a Request to the history.
+ *
+ * @param Request $request A Request instance
+ */
+ public function add(Request $request)
+ {
+ $this->stack = array_slice($this->stack, 0, $this->position + 1);
+ $this->stack[] = clone $request;
+ $this->position = count($this->stack) - 1;
+ }
+
+ /**
+ * Returns true if the history is empty.
+ *
+ * @return bool true if the history is empty, false otherwise
+ */
+ public function isEmpty()
+ {
+ return count($this->stack) == 0;
+ }
+
+ /**
+ * Goes back in the history.
+ *
+ * @return Request A Request instance
+ *
+ * @throws \LogicException if the stack is already on the first page
+ */
+ public function back()
+ {
+ if ($this->position < 1) {
+ throw new \LogicException('You are already on the first page.');
+ }
+
+ return clone $this->stack[--$this->position];
+ }
+
+ /**
+ * Goes forward in the history.
+ *
+ * @return Request A Request instance
+ *
+ * @throws \LogicException if the stack is already on the last page
+ */
+ public function forward()
+ {
+ if ($this->position > count($this->stack) - 2) {
+ throw new \LogicException('You are already on the last page.');
+ }
+
+ return clone $this->stack[++$this->position];
+ }
+
+ /**
+ * Returns the current element in the history.
+ *
+ * @return Request A Request instance
+ *
+ * @throws \LogicException if the stack is empty
+ */
+ public function current()
+ {
+ if (-1 == $this->position) {
+ throw new \LogicException('The page history is empty.');
+ }
+
+ return clone $this->stack[$this->position];
+ }
+}