# 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]]`
#
# 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`.
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
# 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`.
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
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