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

diff --git a/lib/standard/collection/abstract_collection.nit b/lib/standard/collection/abstract_collection.nit
index bb17064..2f7e454 100644
--- a/lib/standard/collection/abstract_collection.nit
+++ b/lib/standard/collection/abstract_collection.nit
@@ -66,6 +66,14 @@ interface Collection[E]
 	#     assert [1..1[.is_empty   == true
 	fun is_empty: Bool do return length == 0
 
+	# Alias for `not is_empty`.
+	#
+	# Some people prefer to have conditions grammatically easier to read.
+	#
+	#     assert [1,2,3].not_empty  == true
+	#     assert [1..1[.not_empty   == false
+	fun not_empty: Bool do return not self.is_empty
+
 	# Number of items in the collection.
 	#
 	#     assert [10,20,30].length == 3
@@ -171,8 +179,9 @@ interface Collection[E]
 	end
 end
 
-# Instances of the Iterator class generates a series of elements, one at a time.
-# They are mainly used with collections.
+# Iterators generate a series of elements, one at a time.
+#
+# They are mainly used with collections and obtained from `Collection::iterator`.
 interface Iterator[E]
 	# The current item.
 	# Require `is_ok`.
@@ -203,7 +212,7 @@ end
 #
 # Used to pass arguments by reference.
 #
-# Also used when one want to give asingle element when a full
+# Also used when one want to give a single element when a full
 # collection is expected
 class Container[E]
 	super Collection[E]
@@ -305,7 +314,7 @@ end
 #      # ...
 #      s.add(a)
 #      assert s.has(b)      ==  true
-interface Set[E: Object]
+interface Set[E]
 	super SimpleCollection[E]
 
 	redef fun has_only(item)
@@ -416,7 +425,14 @@ interface MapRead[K, V]
 		return default
 	end
 
-	# Alias for `keys.has`
+	# Is there an item associated with `key`?
+	#
+	#     var x = new HashMap[String, Int]
+	#     x["four"] = 4
+	#     assert x.has_key("four") == true
+	#     assert x.has_key("five") == false
+	#
+	# By default it is a synonymous to `keys.has` but could be redefined with a direct implementation.
 	fun has_key(key: K): Bool do return self.keys.has(key)
 
 	# Get a new iterator on the map.
@@ -466,6 +482,49 @@ interface MapRead[K, V]
 	# Note: the value is returned *as is*, implementations may want to store the value in the map before returning it
 	# @toimplement
 	protected fun provide_default_value(key: K): V do abort
+
+	# Does `self` and `other` have the same keys associated with the same values?
+	#
+	# ~~~
+	# var a = new HashMap[String, Int]
+	# var b = new ArrayMap[Object, Numeric]
+	# assert a == b
+	# a["one"] = 1
+	# assert a != b
+	# b["one"] = 1
+	# assert a == b
+	# b["one"] = 2
+	# assert a != b
+	# ~~~
+	redef fun ==(other)
+	do
+		if not other isa MapRead[nullable Object, nullable Object] then return false
+		if other.length != self.length then return false
+		for k, v in self do
+			if not other.has_key(k) then return false
+			if other[k] != v then return false
+		end
+		return true
+	end
+
+	# A hashcode based on the hashcode of the keys and the values.
+	#
+	# ~~~
+	# var a = new HashMap[String, Int]
+	# var b = new ArrayMap[Object, Numeric]
+	# a["one"] = 1
+	# b["one"] = 1
+	# assert a.hash == b.hash
+	# ~~~
+	redef fun hash
+	do
+		var res = length
+		for k, v in self do
+			if k != null then res += k.hash * 7
+			if v != null then res += v.hash * 11
+		end
+		return res
+	end
 end
 
 # Maps are associative collections: `key` -> `item`.
@@ -963,6 +1022,8 @@ interface CoupleMap[K, V]
 			return c.second
 		end
 	end
+
+	redef fun has_key(key) do return couple_at(key) != null
 end
 
 # Iterator on CoupleMap