From 1d6ad30876d1bc8eb30c3087bbce2252155d0864 Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Fri, 4 Apr 2014 11:30:19 -0400
Subject: [PATCH] libs/collection: implements `reverse_iterator` in Array and
 List

Signed-off-by: Jean Privat <jean@pryen.org>
---
 lib/standard/collection/array.nit |   15 +++++++++++++++
 lib/standard/collection/list.nit  |   18 ++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/lib/standard/collection/array.nit b/lib/standard/collection/array.nit
index 36e878b..22da04e 100644
--- a/lib/standard/collection/array.nit
+++ b/lib/standard/collection/array.nit
@@ -131,6 +131,7 @@ abstract class AbstractArrayRead[E]
 	end
 
 	redef fun iterator: ArrayIterator[E] do return new ArrayIterator[E](self)
+	redef fun reverse_iterator do return new ArrayReverseIterator[E](self)
 end
 
 # Resizable one dimension array of objects.
@@ -364,6 +365,20 @@ private class ArrayIterator[E]
 	var _array: AbstractArrayRead[E]
 end
 
+private class ArrayReverseIterator[E]
+	super ArrayIterator[E]
+
+	redef fun is_ok do return _index >= 0
+
+	redef fun next do _index -= 1
+
+	init(a: AbstractArrayRead[E])
+	do
+		_array = a
+		_index = a.length - 1
+	end
+end
+
 # Others collections ##########################################################
 
 # A set implemented with an Array.
diff --git a/lib/standard/collection/list.nit b/lib/standard/collection/list.nit
index c9a7155..0c5ce5f 100644
--- a/lib/standard/collection/list.nit
+++ b/lib/standard/collection/list.nit
@@ -201,6 +201,7 @@ class List[E]
 
 
 	redef fun iterator: ListIterator[E] do return new ListIterator[E](self)
+	redef fun reverse_iterator: ListIterator[E] do return new ListReverseIterator[E](self)
 
 	# Build an empty list.
 	init do end
@@ -315,6 +316,23 @@ class ListIterator[E]
 	end
 end
 
+private class ListReverseIterator[E]
+	super ListIterator[E]
+
+	redef fun next
+	do
+		_node = _node.prev
+		_index -= 1
+	end
+
+	private init(list: List[E])
+	do
+		_list = list
+		_node = list._tail
+		_index = list.length
+	end
+end
+
 # Linked nodes that constitute a linked list.
 private class ListNode[E]
 	super Container[E]
-- 
1.7.9.5