--- /dev/null
+<?php
+
+/*
+ * This file is part of the Behat.
+ * (c) Konstantin Kudryashov <ever.zet@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Behat\Behat\Context\Reader;
+
+use Behat\Behat\Context\Environment\ContextEnvironment;
+
+/**
+ * Proxies call to another reader and caches context callees for a length of an entire exercise.
+ *
+ * @author Konstantin Kudryashov <ever.zet@gmail.com>
+ */
+final class ContextReaderCachedPerContext implements ContextReader
+{
+ /**
+ * @var ContextReader
+ */
+ private $childReader;
+ /**
+ * @var array[]
+ */
+ private $cachedCallees = array();
+
+ /**
+ * Initializes reader.
+ *
+ * @param ContextReader $childReader
+ */
+ public function __construct(ContextReader $childReader)
+ {
+ $this->childReader = $childReader;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function readContextCallees(ContextEnvironment $environment, $contextClass)
+ {
+ if (isset($this->cachedCallees[$contextClass])) {
+ return $this->cachedCallees[$contextClass];
+ }
+
+ return $this->cachedCallees[$contextClass] = $this->childReader->readContextCallees(
+ $environment, $contextClass
+ );
+ }
+}