Changed CollectionMapper to map any expression type instead of just M…

…appings.

src/CollectionMapper.php

@@ -1,29 +1,31 @@
 <?php
 namespace ScriptFUSION\Mapper;
 
+use ScriptFUSION\Mapper\Strategy\Strategy;
+
 /**
  * Maps collections of records.
  */
 class CollectionMapper extends Mapper
 {
     /**
      * @param \Iterator $collection
-     * @param Mapping|null $mapping
+     * @param Strategy|Mapping|array|mixed $expression Expression.
      * @param mixed $context
      *
      * @return \Generator
      *
      * @throws InvalidRecordException A record in the specified collection was not an array type.
      */
-    public function mapCollection(\Iterator $collection, Mapping $mapping = null, $context = null)
+    public function mapCollection(\Iterator $collection, $expression = null, $context = null)
     {
         foreach ($collection as $key => $record) {
             if (!is_array($record)) {
                 throw new InvalidRecordException('Record must be an array.');
             }
 
-            yield $key => $mapping
-                ? $this->mapMapping($record, $mapping, $context, $key)
+            yield $key => $expression !== null
+                ? $this->mapMapping($record, $expression, $context, $key)
                 : $record;
         }
     }