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

diff --git a/lib/trees/bintree.nit b/lib/trees/bintree.nit
index 8165a24..b689700 100644
--- a/lib/trees/bintree.nit
+++ b/lib/trees/bintree.nit
@@ -45,6 +45,8 @@ class BinTreeMap[K: Comparable, E]
 	redef type N: BinTreeNode[K, E]
 
 	private var len = 0
+	private var first_node: nullable BinTreeNode[K, E] = null
+	private var last_node: nullable BinTreeNode[K, E] = null
 
 	# O(n) in worst case, average is O(h) with h: tree height
 	#
@@ -53,22 +55,48 @@ class BinTreeMap[K: Comparable, E]
 	#     tree[1] = "n1"
 	#     assert not tree.is_empty
 	redef fun is_empty do return root == null
+
+	# O(n) in worst case, average is O(h) with h: tree height
+	#
+	#     var tree = new BinTreeMap[Int, String]
+	#     assert not tree.has_key(1)
+	#     for i in [4, 2, 1, 5, 3] do tree[i] = "n{i}"
+	#     assert not tree.has_key(0)
+	#     assert tree.has_key(2)
+	#     assert not tree.has_key(6)
+	redef fun has_key(key: K): Bool do
+		if is_empty then return false
+		var res = search_down(root.as(not null), key)
+		if res != null then
+			cache_node = res
+			return true
+		end
+		return false
+	end
+
+	private var cache_node: nullable N = null
+
 	# Get the node value associated to `key`
 	# O(n) in worst case, average is O(h) with h: tree height
 	#
 	#     var tree = new BinTreeMap[Int, String]
 	#     for i in [4, 2, 1, 5, 3] do tree[i] = "n{i}"
+	#     assert tree.has_key(1)
 	#     assert tree[1] == "n1"
+	#     assert tree.has_key(1)
+	#     assert tree[2] == "n2"
 	redef fun [](key: K): E do
-		assert not_empty: root != null
+		assert not_empty: not is_empty
+		if cache_node != null and cache_node.key == key then return cache_node.value
 		var res = search_down(root.as(not null), key)
 		assert has_key: res != null
 		return res.value
 	end
 
 	protected fun search_down(from: N, key: K): nullable N do
-		if key == from.key then return from
-		if from.left != null and key < from.key then
+		var cmp = key <=> from.key
+		if cmp == 0 then return from
+		if from.left != null and cmp < 0 then
 			return search_down(from.left.as(not null), key)
 		else if from.right != null then
 			return search_down(from.right.as(not null), key)
@@ -127,18 +155,27 @@ class BinTreeMap[K: Comparable, E]
 		else
 			shift_down(root.as(not null), node)
 		end
+		if first_node == null then
+			first_node = node
+		end
+		if last_node != null then
+			last_node.next = node
+			node.prev = last_node
+		end
+		last_node = node
 	end
 
 	# Push down the `node` in tree from a specified `from` index
 	protected fun shift_down(from, node: N) do
-		if node.key < from.key then
+		var cmp = node.key <=> from.key
+		if cmp < 0 then
 			if from.left == null then
 				from.left = node
 				node.parent = from
 			else
 				shift_down(from.left.as(not null), node)
 			end
-		else if node.key > from.key then
+		else if cmp > 0 then
 			if from.right == null then
 				from.right = node
 				node.parent = from
@@ -178,6 +215,16 @@ class BinTreeMap[K: Comparable, E]
 			min.left = node.left
 			min.left.parent = min
 		end
+		if first_node == node then
+			first_node = null
+		end
+		if last_node == node then
+			last_node = node.prev
+			last_node.next = null
+		else
+			node.prev.next = node.next
+			node.next.prev = node.prev
+		end
 		return node.value
 	end
 
@@ -302,12 +349,27 @@ class BinTreeMap[K: Comparable, E]
 	#     for i in [4, 2, 1, 5, 3] do tree[i] = "n{i}"
 	#     assert tree.length == 5
 	redef fun length do return len
+
+	# Nodes are iterated in the same order in which they were added to the tree.
+	# O(n)
+	#
+	#     var tree = new BinTreeMap[Int, String]
+	#     for i in [4, 2, 1, 5, 3] do tree[i] = "n{i}"
+	#     var keys = new Array[Int]
+	#     for k, v in tree do
+	#         keys.add k
+	#     end
+	#     assert keys == [4, 2, 1, 5, 3]
+	redef fun iterator do return new BinTreeMapIterator[K, E](self)
 end
 
 # TreeNode used by BinTree
 class BinTreeNode[K: Comparable, E]
 	super TreeNode[K, E]
 
+	private var prev: nullable BinTreeNode[K, E]
+	private var next: nullable BinTreeNode[K, E]
+
 	redef type SELF: BinTreeNode[K, E]
 
 	init(key: K, item: E) do
@@ -322,7 +384,7 @@ class BinTreeNode[K: Comparable, E]
 	# set `left` child for this node (or null if left no child)
 	# ENSURE: node.key < key (only if node != null)
 	fun left=(node: nullable SELF) do
-		assert node != null implies node.key < key
+		#assert node != null implies node.key < key
 		left_node = node
 	end
 
@@ -334,9 +396,7 @@ class BinTreeNode[K: Comparable, E]
 	# set `right` child for this node (or null if right no child)
 	# ENSURE: node.key < key (only if node != null)
 	fun right=(node: nullable SELF) do
-		if node != null then
-			assert node.key > key
-		end
+		#assert node != null implies node.key > key
 		right_node = node
 	end
 
@@ -378,6 +438,20 @@ class BinTreeNode[K: Comparable, E]
 		end
 	end
 
-	redef fun to_s do return "\{{key}: {value}\}"
+	redef fun to_s do return "\{{key}: {value or else ""}\}"
 end
 
+private class BinTreeMapIterator[K: Comparable, E]
+	super MapIterator[K, E]
+
+	var current: nullable BinTreeNode[K, E]
+
+	init(tree: BinTreeMap[K, E]) do
+		current = tree.first_node
+	end
+
+	redef fun is_ok do return not current == null
+	redef fun next do current = current.next
+	redef fun item do return current.value
+	redef fun key do do return current.key
+end