Add forever and flush methods to memory driver.

Signed-off-by: Taylor Otwell <taylorotwell@gmail.com>

laravel/cache/drivers/memory.php

@@ -52,6 +52,18 @@ class Memory extends Driver {
 		$this->storage[$key] = $value;
 	}
 
+	/**
+	 * Write an item to the cache that lasts forever.
+	 *
+	 * @param  string  $key
+	 * @param  mixed   $value
+	 * @return void
+	 */
+	public function forever($key, $value)
+	{
+		$this->put($key, $value, 0);
+	}
+
 	/**
 	 * Delete an item from the cache.
 	 *
@@ -63,4 +75,14 @@ class Memory extends Driver {
 		unset($this->storage[$key]);
 	}
 
+	/**
+	 * Flush the entire cache.
+	 *
+	 * @return void
+	 */
+	public function flush()
+	{
+		$this->stroage = array();
+	}
+
 }
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