Provide a PSR-16 decorator for storage adapters

This patch builds on both the approach made in zendframework#126 as well as a comment
to that patch made by @marc-mabe (zendframework#126 (comment))
in order to provide a decorator for zend-cache storage adapters that
fulfills the PSR-16 `SimpleCacheInterface`.

Usage is as follows:

```php
// $adapter is an instance of StorageInterface
$cache = new SimpleCacheDecorator($adapter);
```

From there, you can then use `$cache` anywhere you would normally use a
PSR-16 instance.

composer.json

@@ -18,6 +18,7 @@
     "require": {
         "php": "^5.6 || ^7.0",
         "psr/cache": "^1.0",
+        "psr/simple-cache": "^1.0",
         "zendframework/zend-eventmanager": "^2.6.3 || ^3.2",
         "zendframework/zend-servicemanager": "^2.7.8 || ^3.3",
         "zendframework/zend-stdlib": "^2.7.7 || ^3.1"

src/Psr/SimpleCacheDecorator.php

@@ -0,0 +1,187 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-cache for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-cache/blob/master/LICENSE.md New BSD License
+ */
+
+namespace Zend\Cache\Psr;
+
+use Exception;
+use Psr\SimpleCache\CacheInterface as SimpleCacheInterface;
+use Throwable;
+use Zend\Cache\Exception\InvalidArgumentException as ZendCacheInvalidArgumentException;
+use Zend\Cache\Storage\FlushableInterface;
+use Zend\Cache\Storage\StorageInterface;
+
+/**
+ * Decoreate a zend-cache storage adapter for usage as a PSR-16 implementation.
+ */
+class SimpleCacheDecorator implements SimpleCacheInterface
+{
+    /**
+     * @var StorageInterface
+     */
+    private $storage;
+
+    /**
+     * Reference used by storage when calling getItem() to indicate status of
+     * operation.
+     *
+     * @var null|bool
+     */
+    private $success;
+
+    public function __construct(StorageInterface $storage)
+    {
+        $this->storage = $storage;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function get($key, $default = null)
+    {
+        $this->success = null;
+        try {
+            $result = $this->storage->getItem($key, $this->success);
+            $result = $result === null ? $default : $result;
+            return $this->success ? $result : $default;
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function set($key, $value, $ttl = null)
+    {
+        $options = $this->storage->getOptions();
+        $previousTtl = $options->getTtl();
+        $options->setTtl($ttl);
+
+        try {
+            $result = $this->storage->setItem($key, $value);
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+
+        $options->setTtl($previousTtl);
+        return $result;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function delete($key)
+    {
+        try {
+            return $this->storage->removeItem($key);
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function clear()
+    {
+        if (! $this->storage instanceof FlushableInterface) {
+            return false;
+        }
+        return $this->storage->flush();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getMultiple($keys, $default = null)
+    {
+        try {
+            $results = $this->storage->getItems($keys);
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+
+        foreach ($keys as $key) {
+            if (! isset($results[$key]) && null !== $default) {
+                $results[$key] = $default;
+            }
+        }
+
+        return $results;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function setMultiple($values, $ttl = null)
+    {
+        $options = $this->storage->getOptions();
+        $previousTtl = $options->getTtl();
+        $options->setTtl($ttl);
+
+        try {
+            $result = $this->storage->setItems($values);
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+
+        $options->setTtl($previousTtl);
+        return $result;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function deleteMultiple($keys)
+    {
+        try {
+            $result = $this->storage->removeItems($keys);
+            return empty($result);
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function has($key)
+    {
+        try {
+            return $this->storage->hasItem($key);
+        } catch (Throwable $e) {
+            throw static::translateException($e);
+        } catch (Exception $e) {
+            throw static::translateException($e);
+        }
+    }
+
+    /**
+     * @param Throwable|Exception $e
+     * @return SimpleCacheException
+     */
+    private static function translateException($e)
+    {
+        $exceptionClass = $e instanceof ZendCacheInvalidArgumentException
+            ? SimpleCacheInvalidArgumentException::class
+            : SimpleCacheException::class;
+
+        return new $exceptionClass($e->getMessage(), $e->getCode(), $e);
+    }
+}

src/Psr/SimpleCacheException.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-cache for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-cache/blob/master/LICENSE.md New BSD License
+ */
+
+namespace Zend\Cache\Psr;
+
+use Psr\SimpleCache\CacheException as PsrCacheException;
+use RuntimeException;
+
+class SimpleCacheException extends RuntimeException implements PsrCacheException
+{
+}

src/Psr/SimpleCacheInvalidArgumentException.php

@@ -0,0 +1,14 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-cache for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-cache/blob/master/LICENSE.md New BSD License
+ */
+
+namespace Zend\Cache\Psr;
+
+use Psr\SimpleCache\InvalidArgumentException as PsrInvalidArgumentException;
+
+class SimpleCacheInvalidArgumentException extends \InvalidArgumentException implements PsrInvalidArgumentException
+{
+}