feat: use iterable object directly (#113)

linq.d.ts

@@ -20,6 +20,7 @@ declare namespace Enumerable {
   export function from(obj: string): IEnumerable<string>;
   export function from<T>(obj: T[]): IEnumerable<T>;
   export function from<T>(obj: Iterator<T>): IEnumerable<T>;
+  export function from<T>(obj: Iterable<T>): IEnumerable<T>;
   export function from<T>(obj: { length: number;[x: number]: T; }): IEnumerable<T>;
   export function from<K extends PropertyKey, T>(obj: Record<K, T>): IEnumerable<{ key: K; value: T }>;
   export function make<T>(element: T): IEnumerable<T>;

linq.js

@@ -323,6 +323,20 @@ Enumerable.from = function (obj) {
         }
 
         // iterable object
+        if (typeof Symbol !== 'undefined' && typeof obj[Symbol.iterator] !== 'undefined') {
+            let iterator;
+            return new Enumerable(function () {
+                return new IEnumerator(
+                    function () { iterator = obj[Symbol.iterator]()},
+                    function () {
+                        var next = iterator.next();
+                        return (next.done ? false : (this.yieldReturn(next.value)));
+                    },
+                    Functions.Blank);
+            });
+        }
+
+        // iterator object
         if (typeof Symbol !== 'undefined' && typeof obj.next !== 'undefined') {
             return new Enumerable(function () {
                 return new IEnumerator(

test/iterator.js

@@ -11,20 +11,17 @@ test("for..of", function () {
     deepEqual(actual, [1, 2, 3]);
 });
 
-test("Symbol.iterator", function () {
-    let actual = [1, 2, 3, 4];
+test("Symbol.iterator", function ()
+{
+    let actual = [1,2,3,4];
     let expected = Array.from(Enumerable.from(actual));
     deepEqual(actual, expected);
-    let actual2 = actual.map(function (x) {
-        return x * 2
-    }); // [2,4,6,8];
-    expected = Enumerable.from(actual).select(function (x) {
-        return x * 2
-    });
+    let actual2 = actual.map(function(x) { return x * 2 }); // [2,4,6,8];
+    expected = Enumerable.from(actual).select(function(x) { return x * 2 });
     deepEqual(actual2, Array.from(expected));
 });
 
-test("from Iterable", function () {
+test("from Generator", function () {
     function* words() {
         yield "abc";
         yield "def";
@@ -39,7 +36,27 @@ test("from Iterable", function () {
     deepEqual(actual, ["abc", "def"]);
 });
 
-test("from Symbol.iterator", function () {
+test("from Iterable object", function () {
+    const map = new Map();
+
+    map.set(1, 2);
+    map.set(2, 4);
+
+    deepEqual(Enumerable
+            .from(map)
+            .select(item => ({key: item[0], value: item[1]}))
+            .select(item=>item.key)
+            .toArray(),
+        [1, 2]);
+
+    let actual = [];
+    for (var a of map) {
+        actual.push(a[0]);
+    }
+    deepEqual(actual, [1, 2]);
+});
+
+test("from Iterator object", function () {
     const n = {
         // This is just a simple replacement for the data structure that needs to be traversed.
         // It may actually be a tree or other data structure implemented by a custom traversal.