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

diff --git a/lib/more_collections.nit b/lib/more_collections.nit
index ac2c8d1..3062d5e 100644
--- a/lib/more_collections.nit
+++ b/lib/more_collections.nit
@@ -13,7 +13,9 @@
 # limitations under the License.
 
 # Highly specific, but useful, collections-related classes.
-module more_collections
+module more_collections is serialize
+
+import serialization
 
 # Simple way to store an `HashMap[K, Array[V]]`
 #
@@ -61,6 +63,7 @@ end
 # 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`.
@@ -94,6 +97,13 @@ class HashMap2[K1, K2, V]
 		level2.keys.remove(k2)
 	end
 
+	# Is there a value at `k1, k2`?
+	fun has(k1: K1, k2: K2): Bool
+	do
+		if not level1.keys.has(k1) then return false
+		return level1[k1].keys.has(k2)
+	end
+
 	# Remove all items
 	fun clear do level1.clear
 end
@@ -108,6 +118,7 @@ end
 # 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`.
@@ -141,6 +152,13 @@ class HashMap3[K1, K2, K3, V]
 		level2.remove_at(k2, k3)
 	end
 
+	# Is there a value at `k1, k2, k3`?
+	fun has(k1: K1, k2: K2, k3: K3): Bool
+	do
+		if not level1.keys.has(k1) then return false
+		return level1[k1].has(k2, k3)
+	end
+
 	# Remove all items
 	fun clear do level1.clear
 end
@@ -522,3 +540,44 @@ private class UnrolledIterator[E]
 		end
 	end
 end
+
+# Keep track of the best elements according to a distance value.
+#
+# ~~~
+# var bests = new BestDistance[String](5)
+# bests.update(10, "Too big")
+# assert bests.best_items.is_empty
+# bests.update(5, "Just fine")
+# bests.update(5, "Another one")
+# assert bests.best_items.has_exactly(["Just fine", "Another one"])
+# bests.update(2, "A better one")
+# bests.update(4, "Not good enough")
+# assert bests.best_distance == 2
+# assert bests.best_items.has_exactly(["A better one"])
+# ~~~
+class BestDistance[E]
+	# Current smallest distance
+	var best_distance: Int is writable
+
+	# Known elements with the smallest distance
+	var best_items = new Set[E] is writable
+
+	# Register a `candidate` with a `distance`
+	#
+	# * To high, it is ignored.
+	# * Equal to the current best, it is added
+	# * Better that them, is is the new best element
+	#
+	# Return `true` if the candidate is kept (alone or with other)
+	# returns `false` if the candidate is ignored.
+	fun update(distance: Int, candidate: E): Bool
+	do
+		if distance > best_distance then return false
+		if distance < best_distance then
+			best_distance = distance
+			best_items.clear
+		end
+		best_items.add candidate
+		return true
+	end
+end