Added walk() method

README.md

@@ -168,6 +168,7 @@ will return:
 * [unshift()](#unshift) : Adds an element at the beginning
 * [usort()](#usort) : Sorts elements using callback
 * [values()](#values) : Returns all elements with new keys
+* [walk()](#walk) : Applies the given callback to all elements
 
 
 ## Method documentation
@@ -2248,6 +2249,57 @@ Map::from( ['x' => 'b', 2 => 'a', 'c'] )->values();
 A new map with `[0 => 'b', 1 => 'a', 2 => 'c']` as content
 
 
+### walk()
+
+Applies the given callback to all elements.
+
+To change the values of the Map, specify the value parameter as reference
+(&$value). You can only change the values but not the keys nor the array
+structure.
+
+```php
+public function walk( callable $callback, $data = null, bool $recursive = true ) : self
+```
+
+* @param callable $callback Function with (item, key, data) parameters
+* @param mixed $data Arbitrary data that will be passed to the callback as third parameter
+* @param bool $recursive TRUE to traverse sub-arrays recursively (default), FALSE to iterate Map elements only
+* @return self Map for fluid interface
+
+**Examples:**
+
+```php
+Map::from( ['a', 'B', ['c', 'd'], 'e'] )->walk( function( &$value ) {
+    $value = strtoupper( $value );
+} );
+Map::from( [66 => 'B', 97 => 'a'] )->walk( function( $value, $key ) {
+    echo 'ASCII ' . $key . ' is ' . $value . "\n";
+} );
+Map::from( [1, 2, 3] )->walk( function( &$value, $key, $data ) {
+    $value = $data[$value] ?? $value;
+}, [1 => 'one', 2 => 'two'] );
+```
+
+**Results:**
+
+The first example will change the Map elements to:
+```php
+   ['A', 'B', ['C', 'D'], 'E']
+```
+The output of the second one will be:
+```
+  ASCII 66 is B
+  ASCII 97 is a
+```
+The last example changes the Map elements to:
+```php
+  ['one', 'two', 3]
+```
+
+By default, Map elements which are arrays will be traversed recursively.
+To iterate over the Map elements only, pass FALSE as third parameter.
+
+
 
 ## Custom methods
 

src/Map.php

@@ -1906,6 +1906,53 @@ public function values() : self
 	}
 
 
+	/**
+	 * Applies the given callback to all elements.
+	 *
+	 * To change the values of the Map, specify the value parameter as reference
+	 * (&$value). You can only change the values but not the keys nor the array
+	 * structure.
+	 *
+	 * Examples:
+	 *  Map::from( ['a', 'B', ['c', 'd'], 'e'] )->walk( function( &$value ) {
+	 *    $value = strtoupper( $value );
+	 *  } );
+	 *  Map::from( [66 => 'B', 97 => 'a'] )->walk( function( $value, $key ) {
+	 *    echo 'ASCII ' . $key . ' is ' . $value . "\n";
+	 *  } );
+	 *  Map::from( [1, 2, 3] )->walk( function( &$value, $key, $data ) {
+	 *    $value = $data[$value] ?? $value;
+	 *  }, [1 => 'one', 2 => 'two'] );
+	 *
+	 * Results:
+	 * The first example will change the Map elements to:
+	 *   ['A', 'B', ['C', 'D'], 'E']
+	 * The output of the second one will be:
+	 *  ASCII 66 is B
+	 *  ASCII 97 is a
+	 * The last example changes the Map elements to:
+	 *  ['one', 'two', 3]
+	 *
+	 * By default, Map elements which are arrays will be traversed recursively.
+	 * To iterate over the Map elements only, pass FALSE as third parameter.
+	 *
+	 * @param callable $callback Function with (item, key, data) parameters
+	 * @param mixed $data Arbitrary data that will be passed to the callback as third parameter
+	 * @param bool $recursive TRUE to traverse sub-arrays recursively (default), FALSE to iterate Map elements only
+	 * @return self Map for fluid interface
+	 */
+	public function walk( callable $callback, $data = null, bool $recursive = true ) : self
+	{
+		if( $recursive ) {
+			array_walk_recursive( $this->list, $callback, $data );
+		} else {
+			array_walk( $this->list, $callback, $data );
+		}
+
+		return $this;
+	}
+
+
 	/**
 	 * Returns a plain array of the given elements.
 	 *

tests/MapTest.php

@@ -1477,6 +1477,42 @@ public function testValues()
 		$this->assertInstanceOf( Map::class, $r );
 		$this->assertEquals( [1, 'Hello'], $r->toArray() );
 	}
+
+
+	public function testWalk()
+	{
+		$m = new Map( ['a', 'B', ['c', 'd'], 'e'] );
+		$r = $m->walk( function( &$value ) {
+			$value = strtoupper( $value );
+		} );
+
+		$this->assertInstanceOf( Map::class, $r );
+		$this->assertEquals( ['A', 'B', ['C', 'D'], 'E'], $r->toArray() );
+	}
+
+
+	public function testWalkNonRecursive()
+	{
+		$m = new Map( ['a', 'B', ['c', 'd'], 'e'] );
+		$r = $m->walk( function( &$value ) {
+			$value = ( !is_array( $value ) ? strtoupper( $value ) : $value );
+		}, null, false );
+
+		$this->assertInstanceOf( Map::class, $r );
+		$this->assertEquals( ['A', 'B', ['c', 'd'], 'E'], $r->toArray() );
+	}
+
+
+	public function testWalkData()
+	{
+		$m = new Map( [1, 2, 3] );
+		$r = $m->walk( function( &$value, $key, $data ) {
+			$value = $data[$value] ?? $value;
+		}, [1 => 'one', 2 => 'two'] );
+
+		$this->assertInstanceOf( Map::class, $r );
+		$this->assertEquals( ['one', 'two', 3], $r->toArray() );
+	}
 }