super HashMap[K, Array[V]]
# Add `v` to the array associated with `k`.
+ #
# If there is no array associated, then create it.
+ #
+ # For the inverse operation, see `remove_one`.
+ #
+ # ```
+ # var m = new MultiHashMap[String, Char]
+ # m.add_one("four", 'i')
+ # m.add_one("four", 'i')
+ # m.add_one("four", 'i')
+ # m.add_one("four", 'i')
+ # assert m.has_key("four")
+ # assert m["four"] == ['i', 'i', 'i', 'i']
+ # ```
fun add_one(k: K, v: V)
do
var x = self.get_or_null(k)
self[key] = res
return res
end
+
+ # Remove an occurrence of `v` from the array associated with `k`.
+ #
+ # If the associated array does not contain `v`, do nothing. If the
+ # associated array only contain one element and this element is `v`, remove
+ # the key `k`.
+ #
+ # In a nutshell, does the inverse operation of `add_one`.
+ #
+ # ```
+ # var m = new MultiHashMap[String, Char]
+ # m["four"] = ['4', 'i', 'i', 'i', 'i']
+ # m.remove_one("four", 'i')
+ # assert m["four"] == ['4', 'i', 'i', 'i']
+ #
+ # m = new MultiHashMap[String, Char]
+ # m.add_one("one", '1')
+ # m.remove_one("one", '?')
+ # assert m["one"] == ['1']
+ # m.remove_one("one", '1')
+ # assert not m.has_key("one")
+ # assert m["one"] == new Array[Char]
+ #
+ # m = new MultiHashMap[String, Char]
+ # m.add_one("one", '1')
+ # m.remove_one("two", '2')
+ # assert not m.has_key("two")
+ # assert m["one"] == ['1']
+ # assert m["two"] == new Array[Char]
+ # ```
+ fun remove_one(k: K, v: V)
+ do
+ var x = get_or_null(k)
+ if x != null then
+ x.remove(v)
+ if x.is_empty then keys.remove(k)
+ end
+ end
end
# Simple way to store an `HashMap[K1, HashMap[K2, V]]`
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