X-Git-Url: http://nitlanguage.org

diff --git a/lib/standard/collection/array.nit b/lib/standard/collection/array.nit
index 1fb8581..3cc0b57 100644
--- a/lib/standard/collection/array.nit
+++ b/lib/standard/collection/array.nit
@@ -13,7 +13,9 @@
 
 # This module introduces the standard array structure.
 # It also implements two other abstract collections : ArrayMap and ArraySet
-module array
+module array is
+	no_warning "useless-type-test" # to avoid warning with nitc while compiling with c_src
+end
 
 import abstract_collection
 
@@ -130,7 +132,20 @@ abstract class AbstractArrayRead[E]
 		end
 	end
 
-	redef fun iterator: ArrayIterator[E] do return new ArrayIterator[E](self)
+	redef fun iterator: ArrayIterator[E] do
+		var res = _free_iterator
+		if res == null then return new ArrayIterator[E](self)
+		res._index = 0
+		_free_iterator = null
+		return res
+	end
+
+	# An old iterator, free to reuse.
+	# Once an iterator is `finish`, it become reusable.
+	# Since some arrays are iterated a lot, this avoid most of the
+	# continuous allocation/garbage-collection of the needed iterators.
+	private var free_iterator: nullable ArrayIterator[E] = null
+
 	redef fun reverse_iterator do return new ArrayReverseIterator[E](self)
 end
 
@@ -477,6 +492,8 @@ private class ArrayIterator[E]
 	redef var index = 0
 
 	var array: AbstractArrayRead[E]
+
+	redef fun finish do _array._free_iterator = self
 end
 
 private class ArrayReverseIterator[E]
@@ -618,8 +635,8 @@ class ArrayMap[K, E]
 		end
 	end
 
-	redef var keys: RemovableCollection[K] = new ArrayMapKeys[K, E](self)
-	redef var values: RemovableCollection[E] = new ArrayMapValues[K, E](self)
+	redef var keys: RemovableCollection[K] = new ArrayMapKeys[K, E](self) is lazy
+	redef var values: RemovableCollection[E] = new ArrayMapValues[K, E](self) is lazy
 
 	# O(1)
 	redef fun length do return _items.length