[libgee] Add highier-order functions to MapIterator

[Maciej Marcin Piechotka <mpiechotka src gnome org>]

commit ba8fa57b20c2790f33438ec3f1e43e552bc2d69f
Author: Maciej Piechotka <uzytkownik2 gmail com>
Date:   Tue Jan 4 15:23:14 2011 +0100

    Add highier-order functions to MapIterator

 gee/mapiterator.vala |   36 ++++++++++++++++++++++++++++++++++++
 tests/testmap.vala   |   34 ++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 0 deletions(-)
---
diff --git a/gee/mapiterator.vala b/gee/mapiterator.vala
index 30df860..5479e0c 100644
--- a/gee/mapiterator.vala
+++ b/gee/mapiterator.vala
@@ -21,6 +21,11 @@
  * 	Didier 'Ptitjes Villevalois <ptitjes free fr>
  */
 
+namespace Gee {
+	public delegate A FoldMapFunc<A, K, V> (K k, V v, owned A a);
+	public delegate void ForallMapFunc<K, V> (K k, V v);
+}
+
 /**
  * An iterator over a map.
  *
@@ -97,5 +102,36 @@ public interface Gee.MapIterator<K,V> : Object {
 	 * of iterator may cache it.
 	 */
 	public abstract bool read_only { get; }
+	
+	/**
+	 * Standard aggragation function.
+	 *
+	 * It takes a function, seed and first element, returns the new seed and
+	 * progress to next element when the operation repeats.
+	 *
+	 * Operation moves the iterator to last element in iteration. If iterator
+	 * points at some element it will be included in iteration.
+	 */
+	public virtual A fold<A> (FoldMapFunc<A, K, V> f, owned A seed)
+	{
+		if (valid)
+			seed = f (get_key (), get_value (), (owned) seed);
+		while (next ())
+			seed = f (get_key (), get_value (), (owned) seed);
+		return (owned) seed;
+	}
+	
+	/**
+	 * Apply function to each element returned by iterator. 
+	 *
+	 * Operation moves the iterator to last element in iteration. If iterator
+	 * points at some element it will be included in iteration.
+	 */
+	public new virtual void foreach (ForallMapFunc<K, V> f) {
+		if (valid)
+			f (get_key (), get_value ());
+		while (next ())
+			f (get_key (), get_value ());
+	}
 }
 
diff --git a/tests/testmap.vala b/tests/testmap.vala
index df7aa54..8ae85a2 100644
--- a/tests/testmap.vala
+++ b/tests/testmap.vala
@@ -39,6 +39,8 @@ public abstract class MapTests : Gee.TestCase {
 		add_test ("[Map] unset all", test_unset_all);
 		add_test ("[Map] has all", test_has_all);
 		add_test ("[Map] GObject properties", test_gobject_properties);
+		add_test ("[Map] fold", test_fold);
+		add_test ("[Map] foreach", test_foreach);
 	}
 
 	protected Map<string, string> test_map;
@@ -527,6 +529,38 @@ public abstract class MapTests : Gee.TestCase {
 		assert (value.get_int () == test_map.size);
 		value.unset ();
 	}
+	
+	public void test_fold () {
+		test_map.set ("one", "one");
+		test_map.set ("two", "two");
+		test_map.set ("three", "three");
+		
+		int count;
+		
+		count = test_map.map_iterator ().fold<int> ((x, y, z) => {return z + 1;}, 0);
+		assert (count == 3);
+		
+		var iter = test_map.map_iterator ();
+		assert (iter.next ());
+		count = iter.fold<int> ((x, y, z) => {return z + 1;}, 0);
+		assert (count == 3);
+	}
+	
+	public void test_foreach () {
+		test_map.set ("one", "one");
+		test_map.set ("two", "two");
+		test_map.set ("three", "three");
+		
+		int count = 0;
+		
+		test_map.map_iterator ().foreach ((x, y) => {count++;});
+		assert (count == 3);
+		
+		var iter = test_map.map_iterator ();
+		assert (iter.next ());
+		iter.foreach ((x, y) => {count++;});
+		assert (count == 6);
+	}