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

diff --git a/lib/more_collections.nit b/lib/more_collections.nit
index 50117cf..f9b55af 100644
--- a/lib/more_collections.nit
+++ b/lib/more_collections.nit
@@ -29,15 +29,16 @@ module more_collections
 #     assert m.has_key("four")
 #     assert m["four"] == ['i', 'i', 'i', 'i']
 #     assert m["zzz"] == new Array[Char]
-class MultiHashMap[K: Object, V]
+class MultiHashMap[K, V]
 	super HashMap[K, Array[V]]
 
 	# Add `v` to the array associated with `k`.
 	# If there is no array associated, then create it.
 	fun add_one(k: K, v: V)
 	do
-		if self.has_key(k) then
-			self[k].add(v)
+		var x = self.get_or_null(k)
+		if x != null then
+			x.add(v)
 		else
 			self[k] = [v]
 		end
@@ -48,51 +49,74 @@ class MultiHashMap[K: Object, V]
 		self[key] = res
 		return res
 	end
-
-	init do end
 end
 
 # Simple way to store an `HashMap[K1, HashMap[K2, V]]`
-class HashMap2[K1: Object, K2: Object, V]
-	private var level1: HashMap[K1, HashMap[K2, V]] = new HashMap[K1, HashMap[K2, V]]
+#
+# ~~~~
+# var hm2 = new HashMap2[Int, String, Float]
+# hm2[1, "one"] = 1.0
+# hm2[2, "two"] = 2.0
+# assert hm2[1, "one"] == 1.0
+# assert hm2[2, "not-two"] == null
+# ~~~~
+class HashMap2[K1, K2, V]
+	private var level1 = new HashMap[K1, HashMap[K2, V]]
 
 	# Return the value associated to the keys `k1` and `k2`.
 	# Return `null` if no such a value.
 	fun [](k1: K1, k2: K2): nullable V
 	do
 		var level1 = self.level1
-		if not level1.has_key(k1) then return null
-		var level2 = level1[k1]
-		if not level2.has_key(k2) then return null
-		return level2[k2]
+		var level2 = level1.get_or_null(k1)
+		if level2 == null then return null
+		return level2.get_or_null(k2)
 	end
 
 	# Set `v` the value associated to the keys `k1` and `k2`.
 	fun []=(k1: K1, k2: K2, v: V)
 	do
 		var level1 = self.level1
-		var level2: HashMap[K2, V]
-		if not level1.has_key(k1) then
+		var level2 = level1.get_or_null(k1)
+		if level2 == null then
 			level2 = new HashMap[K2, V]
 			level1[k1] = level2
-		else
-			level2 = level1[k1]
 		end
 		level2[k2] = v
 	end
+
+	# Remove the item at `k1` and `k2`
+	fun remove_at(k1: K1, k2: K2)
+	do
+		var level1 = self.level1
+		var level2 = level1.get_or_null(k1)
+		if level2 == null then return
+		level2.keys.remove(k2)
+	end
+
+	# Remove all items
+	fun clear do level1.clear
 end
 
 # Simple way to store an `HashMap[K1, HashMap[K2, HashMap[K3, V]]]`
-class HashMap3[K1: Object, K2: Object, K3: Object, V]
-	private var level1: HashMap[K1, HashMap2[K2, K3, V]] = new HashMap[K1, HashMap2[K2, K3, V]]
+#
+# ~~~~
+# var hm3 = new HashMap3[Int, String, Int, Float]
+# hm3[1, "one", 11] = 1.0
+# hm3[2, "two", 22] = 2.0
+# assert hm3[1, "one", 11] == 1.0
+# assert hm3[2, "not-two", 22] == null
+# ~~~~
+class HashMap3[K1, K2, K3, V]
+	private var level1 = new HashMap[K1, HashMap2[K2, K3, V]]
 
 	# Return the value associated to the keys `k1`, `k2`, and `k3`.
 	# Return `null` if no such a value.
 	fun [](k1: K1, k2: K2, k3: K3): nullable V
 	do
 		var level1 = self.level1
-		if not level1.has_key(k1) then return null
-		var level2 = level1[k1]
+		var level2 = level1.get_or_null(k1)
+		if level2 == null then return null
 		return level2[k2, k3]
 	end
 
@@ -100,13 +124,72 @@ class HashMap3[K1: Object, K2: Object, K3: Object, V]
 	fun []=(k1: K1, k2: K2, k3: K3, v: V)
 	do
 		var level1 = self.level1
-		var level2: HashMap2[K2, K3, V]
-		if not level1.has_key(k1) then
+		var level2 = level1.get_or_null(k1)
+		if level2 == null then
 			level2 = new HashMap2[K2, K3, V]
 			level1[k1] = level2
-		else
-			level2 = level1[k1]
 		end
 		level2[k2, k3] = v
 	end
+
+	# Remove the item at `k1`, `k2` and `k3`
+	fun remove_at(k1: K1, k2: K2, k3: K3)
+	do
+		var level1 = self.level1
+		var level2 = level1.get_or_null(k1)
+		if level2 == null then return
+		level2.remove_at(k2, k3)
+	end
+
+	# Remove all items
+	fun clear do level1.clear
+end
+
+# A map with a default value.
+#
+# ~~~~
+# var dm = new DefaultMap[String, Int](10)
+# assert dm["a"] == 10
+# ~~~~
+#
+# The default value is used when the key is not present.
+# And getting a default value does not register the key.
+#
+# ~~~~
+# assert dm["a"] == 10
+# assert dm.length == 0
+# assert dm.has_key("a") == false
+# ~~~~
+#
+# It also means that removed key retrieve the default value.
+#
+# ~~~~
+# dm["a"] = 2
+# assert dm["a"] == 2
+# dm.keys.remove("a")
+# assert dm["a"] == 10
+# ~~~~
+#
+# Warning: the default value is used as is, so using mutable object might
+# cause side-effects.
+#
+# ~~~~
+# var dma = new DefaultMap[String, Array[Int]](new Array[Int])
+#
+# dma["a"].add(65)
+# assert dma["a"] == [65]
+# assert dma.default == [65]
+# assert dma["c"] == [65]
+#
+# dma["b"] += [66]
+# assert dma["b"] == [65, 66]
+# assert dma.default == [65]
+# ~~~~
+class DefaultMap[K, V]
+	super HashMap[K, V]
+
+	# The default value.
+	var default: V
+
+	redef fun provide_default_value(key) do return default
 end