Add support for flatmap

src/list.js

@@ -275,6 +275,25 @@ class TypedList extends BaseTypeInferedList {
  }
  }
  }
+ flatMap(mapper, context) {
+ if (this.size === 0) {
+ return this
+ } else {
+ const result = TypeInferedList.from(this).flatMap(mapper, context)
+ if (this[$store] === result[$store]) {
+ return this
+ }
+ if (result[$type] === this[$type]) {
+ const list = construct(this)
+ list[$store] = result[$store]
+ list.size = result.size
+ return list
+ } else {
+ return result
+ }
+ }
+ }
+
 }
 
 export const List = function(descriptor, label) {

src/test/list.js

@@ -985,3 +985,22 @@ test('empty list optimization', assert => {
  assert.equal(Points([Point({x: 1})]).clear(),
  Points([Point({x: 1}), Point({y: 2})]).clear())
 })
+
+test('flatMap', assert => {
+ var numbers = NumberList.of(97, 98, 99);
+ var letters = numbers.flatMap(v => Immutable.fromJS([
+ String.fromCharCode(v),
+ String.fromCharCode(v).toUpperCase(),
+ ]))
+
+ assert.deepEqual(letters.toArray(), ['a','A','b','B','c','C'])
+
+ var letters = numbers.flatMap(v => [
+ String.fromCharCode(v),
+ String.fromCharCode(v).toUpperCase(),
+ ])
+
+ assert.deepEqual(letters.toArray(), ['a','A','b','B','c','C'])
+
+})
+