Return base collections for some methods

Author: markusjwetzel

src/Collection.php

@@ -36,6 +36,122 @@ public function __construct($items = [])
 
         parent::__construct($items);
     }
+
+    /**
+     * Run a map over each of the items.
+     *
+     * @param  callable  $callback
+     * @return \Illuminate\Support\Collection|static
+     */
+    public function map(callable $callback)
+    {
+        $result = $this->toBase()->map($callback);
+
+        $class = $this->getTypeClass();
+
+        return $result->contains(function ($item) use ($class) {
+            return ! $item instanceof $class;
+        }) ? $result : new static($result->all());
+    }
+
+    /**
+     * Run an associative map over each of the items.
+     *
+     * The callback should return an associative array with a single key / value pair.
+     *
+     * @param  callable  $callback
+     * @return \Illuminate\Support\Collection|static
+     */
+    public function mapWithKeys(callable $callback)
+    {
+        $result = $this->toBase()->mapWithKeys($callback);
+
+        $class = $this->getTypeClass();
+
+        return $result->contains(function ($item) use ($class) {
+            return ! $item instanceof $class;
+        }) ? $result : new static($result->all());
+    }
+
+    /**
+     * The following methods are intercepted to always return base collections.
+     */
+
+    /**
+     * Get an array with the values of a given key.
+     *
+     * @param  string|array  $value
+     * @param  string|null  $key
+     * @return \Illuminate\Support\Collection
+     */
+    public function pluck($value, $key = null)
+    {
+        return $this->toBase()->pluck($value, $key);
+    }
+
+    /**
+     * Get the keys of the collection items.
+     *
+     * @return \Illuminate\Support\Collection
+     */
+    public function keys()
+    {
+        return $this->toBase()->keys();
+    }
+
+    /**
+     * Zip the collection together with one or more arrays.
+     *
+     * @param  mixed  ...$items
+     * @return \Illuminate\Support\Collection
+     */
+    public function zip($items)
+    {
+        return $this->toBase()->zip(...func_get_args());
+    }
+
+    /**
+     * Collapse the collection of items into a single array.
+     *
+     * @return \Illuminate\Support\Collection
+     */
+    public function collapse()
+    {
+        return $this->toBase()->collapse();
+    }
+
+    /**
+     * Get a flattened array of the items in the collection.
+     *
+     * @param  int  $depth
+     * @return \Illuminate\Support\Collection
+     */
+    public function flatten($depth = INF)
+    {
+        return $this->toBase()->flatten($depth);
+    }
+
+    /**
+     * Flip the items in the collection.
+     *
+     * @return \Illuminate\Support\Collection
+     */
+    public function flip()
+    {
+        return $this->toBase()->flip();
+    }
+
+    /**
+     * Pad collection to the specified length with a value.
+     *
+     * @param  int  $size
+     * @param  mixed  $value
+     * @return \Illuminate\Support\Collection
+     */
+    public function pad($size, $value)
+    {
+        return $this->toBase()->pad($size, $value);
+    }
 
     /**
      * Get the class name of the items.