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

diff --git a/lib/standard/collection/hash_collection.nit b/lib/standard/collection/hash_collection.nit
index 818da57..f3857293 100644
--- a/lib/standard/collection/hash_collection.nit
+++ b/lib/standard/collection/hash_collection.nit
@@ -10,120 +10,142 @@
 # You  are  allowed  to  redistribute it and sell it, alone or is a part of
 # another product.
 
-# Introduce Hashmap and Hashset.
-package hash_collection
+# Introduce `HashMap` and `HashSet`.
+module hash_collection
 
 import array
-import hash
+
+redef class Map[K, V]
+	# Get a `HashMap[K, V]` as default implementation
+	new do return new HashMap[K, V]
+end
 
 # A HashCollection is an array of HashNode[K] indexed by the K hash value
-private class HashCollection[K: Object, N: HashNode[K], E]
-special Collection[E]
-special ArrayCapable[nullable N]
-	var _array: nullable NativeArray[nullable N] = null # Used to store items
-	var _capacity: Int = 0 # Size of _array
-	redef readable var _length: Int = 0 # Number of items in the map
+private abstract class HashCollection[K]
+	type N: HashNode[K]
+
+	var array: nullable NativeArray[nullable N] = null # Used to store items
+	var capacity: Int = 0 # Size of _array
+	var the_length: Int = 0 # Number of items in the map
 
-	readable var _first_item: nullable N = null # First added item (used to visit items in nice order)
-	var _last_item: nullable N = null # Last added item (same)
+	var first_item: nullable N = null # First added item (used to visit items in nice order)
+	var last_item: nullable N = null # Last added item (same)
 
-	# The last index accessed
-	var _last_accessed_index: Int = -1
+	# The last key accessed (used for cache)
+	var last_accessed_key: nullable K = null
 
-	# The last key accessed
-	var _last_accessed_key: nullable K = null
+	# The last node accessed (used for cache)
+	var last_accessed_node: nullable N = null
 
-	# Return the index of the k element
+	# Return the index of the key k
 	fun index_at(k: K): Int
 	do
-		var arr = _array
-
-		# Fisrt step: look in the last indexed elt
-		if k == _last_accessed_key then return _last_accessed_index
-
-		# Compute the base position of the key
-		var base = k.hash % _capacity
-		if base < 0 then base = - base
-
-		# Look for the key in the array
-		var cur = base
-		loop
-			var c = arr[cur]
-			if c == null or c.key == k then # REAL equals
-				_last_accessed_index = cur
-				_last_accessed_key = k
-				return cur
+		if k == null then return 0
+
+		var i = k.hash % _capacity
+		if i < 0 then i = - i
+		return i
+	end
+
+	# Return the node associated with the key
+	fun node_at(k: K): nullable N
+	do
+		# cache: `is` is used instead of `==` because it is a faster filter (even if not exact)
+		if k.is_same_instance(_last_accessed_key) then return _last_accessed_node
+
+		var res = node_at_idx(index_at(k), k)
+		_last_accessed_key = k
+		_last_accessed_node = res
+		return res
+	end
+
+	# Return the node associated with the key (but with the index already known)
+	fun node_at_idx(i: Int, k: K): nullable N
+	do
+		var c = _array[i]
+		while c != null do
+			var ck = c._key
+			if ck.is_same_instance(k) or ck == k then # FIXME prefilter because the compiler is not smart enought yet
+				break
 			end
-			cur -= 1
-			if cur < 0 then cur = _capacity - 1
-			assert no_loop: cur != base
+			c = c._next_in_bucklet
 		end
-		abort
+		return c
 	end
 
-	# Add a new node (should be free)
+	# Add a new node at a given index
 	fun store(index: Int, node: N)
 	do
 		# Store the item in the list
 		if _first_item == null then
 			_first_item = node
 		else
-			_last_item.next_item = node
+			_last_item._next_item = node
 		end
-		node.prev_item = _last_item
-		node.next_item = null
+		node._prev_item = _last_item
+		node._next_item = null
 		_last_item = node
+
 		# Then store it in the array
-		assert _array[index] == null
+		var next = _array[index]
 		_array[index] = node
-		var l = _length
-		_length = l + 1
-		l = (l + 5) * 150 / 100
+		node._next_in_bucklet = next
+		if next != null then next._prev_in_bucklet = node
+
+		_last_accessed_key = node._key
+		_last_accessed_node = node
+
+		# Enlarge if needed
+		var l = _the_length
+		_the_length = l + 1
+
+		# Magic values determined empirically
+		# We do not want to enlarge too much
+		# We also want a odd capacity so that the modulo is more distributive
+		l = (l + 5) * 2 + 1
 		if l >= _capacity then
-			enlarge(l * 2)
+			enlarge(l * 3 / 2 + 1)
 		end
 	end
 
-	fun remove_index(i: Int)
+	# Remove the node assosiated with the key
+	fun remove_node(k: K)
 	do
-		assert correct_index: i >= 0 and i < _capacity
-		var node = _array[i]
-		assert has_couple: node != null
+		var i = index_at(k)
+		var node = node_at_idx(i, k)
+		if node == null then return
+
 		# Remove the item in the list
-		var prev = node.prev_item
-		var next = node.next_item
+		var prev = node._prev_item
+		var next = node._next_item
 		if prev != null then
-			prev.next_item = next
+			prev._next_item = next
 		else
 			_first_item = next
 		end
 		if next != null then
-			next.prev_item = prev
+			next._prev_item = prev
 		else
 			_last_item = prev
 		end
+
 		# Remove the item in the array
-		_array[i] = null
-		_length -= 1
-		# Now replaces things before if needed
-		loop
-			i -= 1
-			if i < 0 then
-				i = _capacity - 1
-			end
-			var n = _array[i]
-			if n == null then
-				return
-			end
-			var i2 = index_at(n.key)
-			if i != i2 then
-				_array[i] = null
-				assert _array[i2] == null
-				_array[i2] = n
-			end
+		_the_length -= 1
+		prev = node._prev_in_bucklet
+		next = node._next_in_bucklet
+		if prev != null then
+			prev._next_in_bucklet = next
+		else
+			_array[i] = next
 		end
+		if next != null then
+			next._prev_in_bucklet = prev
+		end
+
+		_last_accessed_key = null
 	end
 
+	# Clear the whole structure
 	fun raz
 	do
 		var i = _capacity - 1
@@ -131,24 +153,24 @@ special ArrayCapable[nullable N]
 			_array[i] = null
 			i -= 1
 		end
-		_length = 0
+		_the_length = 0
 		_first_item = null
 		_last_item = null
 		_last_accessed_key = null
 	end
 
+	# Force a capacity
 	fun enlarge(cap: Int)
 	do
 		var old_cap = _capacity
 		# get a new capacity
-		# cap = cap * 130 / 100 + 5 + 1000 # /
-		if cap < _length + 1 then cap = _length + 1
+		if cap < _the_length + 1 then cap = _the_length + 1
 		if cap <= _capacity then return
 		_capacity = cap
 		_last_accessed_key = null
 
 		# get a new array
-		var new_array = calloc_array(cap)
+		var new_array = new NativeArray[nullable N](cap)
 		_array = new_array
 
 		# clean the new array
@@ -163,141 +185,194 @@ special ArrayCapable[nullable N]
 		# Reput items in the array
 		var node = _first_item
 		while node != null do
-			var ind = index_at(node.key)
-			assert new_array[ind] == null
-			new_array[ind] = node
-			node = node.next_item
+			var index = index_at(node._key)
+			# Then store it in the array
+			var next = new_array[index]
+			new_array[index] = node
+			node._prev_in_bucklet = null
+			node._next_in_bucklet = next
+			if next != null then next._prev_in_bucklet = node
+			node = node._next_item
 		end
-		_last_accessed_key = null
 	end
 end
 
-private class HashNode[K]
-	fun key: K is abstract
+private abstract class HashNode[K]
+	var key: K
 	type N: HashNode[K]
-	readable writable var _next_item: nullable N = null
-	readable writable var _prev_item: nullable N = null
+	var next_item: nullable N = null
+	var prev_item: nullable N = null
+	var prev_in_bucklet: nullable N = null
+	var next_in_bucklet: nullable N = null
 end
 
+# A `Map` implemented with a hash table.
+#
+# ~~~
+# var map = new HashMap[nullable String, Int]
+# map[null] = 0
+# map["one"] = 1
+# map["two"] = 2
+#
+# assert map[null] == 0
+# assert map["one"] == 1
+# assert map.keys.has("two")
+# assert map.values.length == 3
+# ~~~
 class HashMap[K, V]
-special CoupleMap[K, V]
-special HashCollection[K, HashMapNode[K, V], V]
+	super Map[K, V]
+	super HashCollection[K]
+
+	redef type N: HashMapNode[K, V] is fixed
+
+	redef fun [](key)
+	do
+		var c = node_at(key)
+		if c == null then
+			return provide_default_value(key)
+		else
+			return c._value
+		end
+	end
 
 	redef fun iterator: HashMapIterator[K, V] do return new HashMapIterator[K,V](self)
 
-	redef fun iterate
-		!each(e: V)
+	redef fun length do return _the_length
+
+	redef fun is_empty do return _the_length == 0
+
+	redef fun []=(key, v)
 	do
-		var c = _first_item
-		while c != null do
-			each(c.second)
-			c = c._next_item
+		var i = index_at(key)
+		var c = node_at_idx(i, key)
+		if c != null then
+			c._key = key
+			c._value = v
+		else
+			store(i, new HashMapNode[K, V](key, v))
 		end
 	end
 
-	redef fun first
+	redef fun clear do raz
+
+	init
 	do
-		assert _length > 0
-		return _first_item.second
+		_capacity = 0
+		_the_length = 0
+		enlarge(0)
 	end
 
-	redef fun is_empty do return _length == 0
+	redef var keys: RemovableCollection[K] = new HashMapKeys[K, V](self)
+	redef var values: RemovableCollection[V] = new HashMapValues[K, V](self)
+end
+
+# View of the keys of a HashMap
+private class HashMapKeys[K, V]
+	super RemovableCollection[K]
+	# The original map
+	var map: HashMap[K, V]
+
+	redef fun count(k) do if self.has(k) then return 1 else return 0
+	redef fun first do return self.map._first_item._key
+	redef fun has(k) do return self.map.node_at(k) != null
+	redef fun has_only(k) do return (self.has(k) and self.length == 1) or self.is_empty
+	redef fun is_empty do return self.map.is_empty
+	redef fun length do return self.map.length
+
+	redef fun iterator do return new MapKeysIterator[K, V](self.map.iterator)
+
+	redef fun clear do self.map.clear
+
+	redef fun remove(key) do self.map.remove_node(key)
+	redef fun remove_all(key) do self.map.remove_node(key)
+end
+
+# View of the values of a Map
+private class HashMapValues[K, V]
+	super RemovableCollection[V]
+	# The original map
+	var map: HashMap[K, V]
 
 	redef fun count(item)
 	do
 		var nb = 0
-		var i = 0
-		while i < _capacity do
-			var c = _array[i]
-			if c != null and c.second == item then nb += 1
-			i += 1
+		var c = self.map._first_item
+		while c != null do
+			if c._value == item then nb += 1
+			c = c._next_item
 		end
 		return nb
 	end
+	redef fun first do return self.map._first_item._value
 
 	redef fun has(item)
 	do
-		var i = 0
-		while i < _capacity do
-			var c = _array[i]
-			if c != null and c.second == item then return true
-			i += 1
+		var c = self.map._first_item
+		while c != null do
+			if c._value == item then return true
+			c = c._next_item
 		end
 		return false
 	end
 
 	redef fun has_only(item)
 	do
-		var i = 0
-		while i < _capacity do
-			var c = _array[i]
-			if c != null and c.second != item then return false
-			i += 1
+		var c = self.map._first_item
+		while c != null do
+			if c._value != item then return false
+			c = c._next_item
 		end
 		return true
 	end
 
-	redef fun []=(key, v)
-	do
-		assert key != null
-		var i = index_at(key)
-		var c = _array[i]
-		if c != null then
-			c.first = key
-			c.second = v
-		else
-			store(i, new HashMapNode[K, V](key, v))
-		end
-	end
+	redef fun is_empty do return self.map.is_empty
+	redef fun length do return self.map.length
+
+	redef fun iterator do return new MapValuesIterator[K, V](self.map.iterator)
+
+	redef fun clear do self.map.clear
 
 	redef fun remove(item)
 	do
-		var i = 0
-		while i < _capacity do
-			var c = _array[i]
-			if c != null and c.second == item then
-				remove_index(i)
+		var map = self.map
+		var c = map._first_item
+		while c != null do
+			if c._value == item then
+				map.remove_node(c._key)
 				return
 			end
-			i += 1
+			c = c._next_item
 		end
 	end
 
-	redef fun remove_at(key) do remove_index(index_at(key))
-
-	redef fun clear do raz
-
-	redef fun couple_at(key) do return _array[index_at(key)]
-
-	init
+	redef fun remove_all(item)
 	do
-		_capacity = 0
-		_length = 0
-		enlarge(0)
+		var map = self.map
+		var c = map._first_item
+		while c != null do
+			if c._value == item then
+				map.remove_node(c._key)
+			end
+			c = c._next_item
+		end
 	end
 end
 
-class HashMapNode[K, V]
-special Couple[K, V]
-special HashNode[K]
-	redef fun key do return first
+private class HashMapNode[K, V]
+	super HashNode[K]
 	redef type N: HashMapNode[K, V]
-
-	init(k: K, v: V)
-	do
-		first = k
-		second = v
-	end
+	var value: V
 end
 
+# A `MapIterator` over a `HashMap`.
 class HashMapIterator[K, V]
-special MapIterator[K, V]
+	super MapIterator[K, V]
 	redef fun is_ok do return _node != null
 
 	redef fun item
 	do
 		assert is_ok
-		return _node.second
+		return _node._value
 	end
 
 	#redef fun item=(value)
@@ -309,57 +384,63 @@ special MapIterator[K, V]
 	redef fun key
 	do
 		assert is_ok
-		return _node.first
+		return _node._key
 	end
 
 	redef fun next
 	do
 		assert is_ok
-		_node = _node.next_item
+		_node = _node._next_item
 	end
 
 	# The map to iterate on
-	var _map: HashMap[K, V]
+	private var map: HashMap[K, V]
 
 	# The current node
-	var _node: nullable HashMapNode[K, V]
+	private var node: nullable HashMapNode[K, V] = null
 
-	init(map: HashMap[K, V])
+	init
 	do
 		_map = map
-		_node = map.first_item
+		_node = _map._first_item
 	end
 end
 
-class HashSet[E]
-special Set[E]
-special HashCollection[E, HashSetNode[E], E]
+# A `Set` implemented with a hash table.
+# Keys of such a map cannot be null and require a working `hash` method
+class HashSet[E: Object]
+	super Set[E]
+	super HashCollection[E]
+
+	redef type N: HashSetNode[E] is fixed
+
+	redef fun length do return _the_length
 
-	redef fun is_empty do return _length == 0
+	redef fun is_empty do return _the_length == 0
 
 	redef fun first
 	do
-		assert _length > 0
-		return _first_item.key
+		assert _the_length > 0
+		return _first_item._key
 	end
 
 	redef fun has(item)
 	do
-		return _array[index_at(item)] != null
+		return node_at(item) != null
 	end
 
 	redef fun add(item)
 	do
 		var i = index_at(item)
-		var c = _array[i]
+		var c = node_at_idx(i, item)
 		if c != null then
-			c.key = item
+			c._key = item
 		else
 			store(i,new HashSetNode[E](item))
 		end
 	end
 
-	redef fun remove(item) do remove_index(index_at(item))
+	redef fun remove(item) do remove_node(item)
 
 	redef fun clear do raz
 
@@ -368,49 +449,49 @@ special HashCollection[E, HashSetNode[E], E]
 	init
 	do
 		_capacity = 0
-		_length = 0
+		_the_length = 0
 		enlarge(0)
 	end
-end
 
-class HashSetNode[E]
-special HashNode[E]
-	redef type N: HashSetNode[E]
+	# Build a list filled with the items of `coll`.
+	init from(coll: Collection[E]) do
+		init
+		add_all(coll)
+	end
 
-	redef readable writable var _key: E
+	redef fun new_set do return new HashSet[E]
+end
 
-	init(e: E)
-	do
-		_key = e
-	end
+private class HashSetNode[E: Object]
+	super HashNode[E]
+	redef type N: HashSetNode[E]
 end
 
-class HashSetIterator[E]
-special Iterator[E]
+private class HashSetIterator[E: Object]
+	super Iterator[E]
 	redef fun is_ok do return _node != null
 
 	redef fun item
 	do
 		assert is_ok
-		return _node.key
+		return _node._key
 	end
 
 	redef fun next
 	do
 		assert is_ok
-		_node = _node.next_item
+		_node = _node._next_item
 	end
 
 	# The set to iterate on
-	var _set: HashSet[E]
+	var set: HashSet[E]
 
 	# The position in the internal map storage
-	var _node: nullable HashSetNode[E]
+	var node: nullable HashSetNode[E] = null
 
-	init(set: HashSet[E])
+	init
 	do
-		_set = set
-		_node = set.first_item
+		_node = _set._first_item
 	end
 end