add computed property names support

lib/6to5/transformers/computed-property-names.js

@@ -0,0 +1,32 @@
+var util = require("../util");
+var _    = require("lodash");
+
+exports.ObjectExpression = function (node) {
+  var hasComputed = false;
+  var computed = [];
+
+  node.properties = node.properties.filter(function (prop) {
+    if (prop.computed) {
+      hasComputed = true;
+      computed.unshift(prop);
+      return false;
+    } else {
+      return true;
+    }
+  });
+
+  if (!hasComputed) return;
+
+  var container = util.template("function-return-obj", {
+    OBJECT: node
+  });
+
+  _.each(computed, function (prop) {
+    container.callee.body.body.unshift(util.template("obj-key-set", {
+      KEY: prop.key,
+      VALUE: prop.value
+    }, true));
+  });
+
+  return container;
+};

test/fixtures/computed-property-names/mixed/actual.js

@@ -0,0 +1,6 @@
+var obj = {
+  ["x" + foo]: "heh",
+  ["y" + bar]: "noo",
+  foo: "foo",
+  bar: "bar"
+};

test/fixtures/computed-property-names/mixed/expected.js

@@ -0,0 +1,8 @@
+var obj = function (obj) {
+  obj["x" + foo] = "heh";
+  obj["y" + bar] = "noo";
+  return obj;
+}({
+  foo: "foo",
+  bar: "bar"
+});

test/fixtures/computed-property-names/multiple/actual.js

@@ -0,0 +1,4 @@
+var obj = {
+  ["x" + foo]: "heh",
+  ["y" + bar]: "noo"
+};

test/fixtures/computed-property-names/multiple/expected.js

@@ -0,0 +1,5 @@
+var obj = function (obj) {
+  obj["x" + foo] = "heh";
+  obj["y" + bar] = "noo";
+  return obj;
+}({});

test/fixtures/computed-property-names/single/actual.js

@@ -0,0 +1,3 @@
+var obj = {
+  ["x" + foo]: "heh"
+};

test/fixtures/computed-property-names/single/expected.js

@@ -0,0 +1,4 @@
+var obj = function (obj) {
+  obj["x" + foo] = "heh";
+  return obj;
+}({});