additional argument to map, filter, and forEach; will be passed as `t…

…his` to the callback
balpha · Jun 20, 2011 · 894e650 · 894e650
1 parent 299f890
commit 894e650
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Showing 2 changed files with 33 additions and 6 deletions.
diff --git a/lyfe.js b/lyfe.js
@@ -32,10 +32,10 @@
     };
 
     var makeForEach_fromFunction = function (f) {
-        return function (g) {
+        return function (g, thisObj) {
             var index = 0,
                 gen = {
-                    yield: function (val) { var send = g(val, index, stopIteration); index++; return send; },
+                    yield: function (val) { var send = g.call(thisObj, val, index, stopIteration); index++; return send; },
                     yieldMany: function (source) { source.forEach(function (val) { gen.yield(val); }) },
                     stop: stopIteration
                 };
@@ -70,12 +70,12 @@
             this.forEach(function (val) { result.push(val); });
             return result;
         },
-        filter: function (pred) {
+        filter: function (pred, thisObj) {
             var source = this;
             return new Generator(function () {
                 var gen = this;
                 source.forEach(function (val) {
-                    if (pred(val))
+                    if (pred.call(thisObj, val))
                         gen.yield(val);
                 });
             });
@@ -101,12 +101,12 @@
                 });
             });
         },
-        map: function (f) {
+        map: function (f, thisObj) {
             var source = this;
             return new Generator(function () {
                 var gen = this;
                 source.forEach(function (val) {
-                    gen.yield(f(val));
+                    gen.yield(f.call(thisObj, val));
                 });
             });
         },

diff --git a/test.html b/test.html
@@ -336,6 +336,33 @@
         var doubled = squares.and(squares).toArray()
         return arrEqual(doubled, [1, 9, 25, 1, 9, 25]) && called == 3;
     });
+
+    test("thisObj argument to filter", function () {
+        var good1, good2;
+        var obj = { foo: 123 };
+        var gen = Generator([42]);
+        gen.filter(function (x) { good1 = this === window; return true; }).toArray();
+        gen.filter(function (x) { good2 = this === obj; return true; }, obj).toArray();
+        return good1 && good2;
+    });
+
+    test("thisObj argument to map", function () {
+        var good1, good2;
+        var obj = { foo: 123 };
+        var gen = Generator([42]);
+        gen.map(function (x) { good1 = this === window; return 43; }).toArray();
+        gen.map(function (x) { good2 = this === obj; return 43; }, obj).toArray();
+        return good1 && good2;
+    });
+
+    test("thisObj argument to forEach", function () {
+        var good1, good2;
+        var obj = { foo: 123 };
+        var gen = Generator([42]);
+        gen.forEach(function (x) { good1 = this === window; });
+        gen.forEach(function (x) { good2 = this === obj; }, obj);
+        return good1 && good2;
+    });
 
 </script>