[jvm] add native Int64Map implementation

std/jvm/_std/haxe/ds/Int64Map.hx

@@ -0,0 +1,73 @@
+package haxe.ds;
+
+@:coreApi
+class Int64Map<T> implements haxe.Constraints.IMap<haxe.Int64, T> {
+	var hashMap:java.util.HashMap<haxe.Int64, T>;
+
+	@:overload
+	public function new():Void {
+		hashMap = new java.util.HashMap();
+	}
+
+	@:overload
+	function new(hashMap:java.util.HashMap<haxe.Int64, T>):Void {
+		this.hashMap = hashMap;
+	}
+
+	public function set(key:haxe.Int64, value:T):Void {
+		hashMap.put(key, value);
+	}
+
+	public function get(key:haxe.Int64):Null<T> {
+		return hashMap.get(key);
+	}
+
+	public function exists(key:haxe.Int64):Bool {
+		return hashMap.containsKey(key);
+	}
+
+	public function remove(key:haxe.Int64):Bool {
+		var has = exists(key);
+		hashMap.remove(key);
+		return has;
+	}
+
+	public inline function keys():Iterator<haxe.Int64> {
+		return hashMap.keySet().iterator();
+	}
+
+	@:runtime public inline function keyValueIterator():KeyValueIterator<haxe.Int64, T> {
+		return new haxe.iterators.MapKeyValueIterator(this);
+	}
+
+	public inline function iterator():Iterator<T> {
+		return hashMap.values().iterator();
+	}
+
+	public function copy():Int64Map<T> {
+		return new Int64Map(hashMap.clone());
+	}
+
+	public function toString():String {
+		var s = new StringBuf();
+		s.add("[");
+		var it = keys();
+		for (i in it) {
+			s.add(i.toString());
+			s.add(" => ");
+			s.add(Std.string(get(i)));
+			if (it.hasNext())
+				s.add(", ");
+		}
+		s.add("]");
+		return s.toString();
+	}
+
+	public function clear():Void {
+		hashMap.clear();
+	}
+
+	public function size():Int {
+		return hashMap.size();
+	}
+}