add destructuring support

FEATURES.md

@@ -98,7 +98,7 @@ console.log(`${x} + ${y} = ${x + y}`); // "5 + 10 = 15"
 0o767 === 503; // true
 ```
 
-## Iterators
+## For Of
 
 ```javascript
 ```
@@ -134,7 +134,7 @@ function f(x, y) {
 [for (i of [1, 2, 3]) i * i]; // [1, 4, 9]
 ```
 
-## Destructuring assignment
+## Destructuring
 
 ```javascript
 var [a, [b], c, d] = ["hello", [", ", "junk"], ["world"]];

README.md

@@ -45,9 +45,9 @@
 | [Computed property names](FEATURES.md#computed-property-names)       | ✓           |                       |
 | [Constants](FEATURES.md#constants)                                   | ✓           |                       |
 | [Binary and Octal Literals](FEATURES.md#binary-and-octal-literals)   | ✓           |                       |
-| [Iterators](FEATURES.md#iterators)                                   | ✓           | ✓                     |
+| [For of](FEATURES.md#for-of)                                         | ✓           | ✓                     |
 | [Array comprehension](FEATURES.md#array-comprehension)               | ✓           |                       |
-| [Destructuring assignment](FEATURES.md#destructuring-assignment)     |             |                       |
+| [Destructuring](FEATURES.md#destructuring)                           | ✓           |                       |
 | [Generators](FEATURES.md#generators)                                 |             |                       |
 
 ## Installation

lib/6to5/templates/variable-assign.js

@@ -0,0 +1 @@
+var KEY = VALUE;

lib/6to5/transformers/destructuring.js

@@ -0,0 +1,112 @@
+var util = require("../util");
+var _    = require("lodash");
+
+var isPattern = function (id) {
+  return id.type === "ArrayPattern" || id.type === "ObjectPattern";
+};
+
+exports.VariableDeclaration = function (node, parent, opts, generateUid) {
+  var nodes = [];
+
+  var hasPattern = false;
+  _.each(node.declarations, function (declar) {
+    if (isPattern(declar.id)) {
+      hasPattern = true;
+      return false;
+    }
+  });
+  if (!hasPattern) return;
+
+  //
+
+  var buildVariableAssign = function (id, init) {
+    return {
+      type: "VariableDeclaration",
+      kind: node.kind,
+      declarations: [{
+        type: "VariableDeclarator",
+        id: id,
+        init: init
+      }]
+    };
+  };
+
+  var push = function (pattern, parentId) {
+    if (pattern.type === "ObjectPattern") {
+      pushObjectPattern(pattern, parentId);
+    } else if (pattern.type === "ArrayPattern") {
+      pushArrayPattern(pattern, parentId);
+    }
+  };
+
+  var pushObjectPattern = function (pattern, parentId) {
+    _.each(pattern.properties, function (prop) {
+      var id = prop.value;
+
+      var init = {
+        type: "MemberExpression",
+        object: parentId,
+        property: prop.key
+      };
+
+      if (isPattern(id)) {
+        push(id, init);
+      } else {
+        nodes.push(buildVariableAssign(id, init));
+      }
+    });
+  };
+
+  var pushArrayPattern = function (pattern, parentId) {
+    _.each(pattern.elements, function (id, i) {
+      var init = {
+        type: "MemberExpression",
+        computed: true,
+        object: parentId,
+        property: {
+          type: "Literal",
+          value: i
+        }
+      };
+
+      if (id.type === "Identifier") {
+        nodes.push(buildVariableAssign(id, init));
+      } else {
+        push(id, init);
+      }
+    });
+  };
+
+  var pushPattern = function (id, init) {
+    if (init.type !== "MemberExpression" && init.type !== "Identifier") {
+      var key = generateUid("ref");
+
+      nodes.push(util.template("variable-assign", {
+        KEY: key,
+        VALUE: init
+      }, true));
+
+      init = {
+        type: "Identifier",
+        name: key
+      };
+    }
+
+    push(id, init);
+  };
+
+  //
+
+  _.each(node.declarations, function (declar) {
+    var init = declar.init;
+    var id   = declar.id;
+
+    if (isPattern(id)) {
+      pushPattern(id, init);
+    } else {
+      nodes.push(buildVariableAssign(id, init));
+    }
+  });
+
+  return nodes;
+};

test/fixtures/destructuring/array/actual.js

@@ -0,0 +1 @@
+var [a, [b], [c], d] = ["hello", [", ", "junk"], ["world"]];

test/fixtures/destructuring/array/expected.js

@@ -0,0 +1,5 @@
+var _ref = ["hello", [", ", "junk"], ["world"]];
+var a = _ref[0];
+var b = _ref[1][0];
+var c = _ref[2][0];
+var d = _ref[3];

test/fixtures/destructuring/mixed/actual.js

@@ -0,0 +1 @@
+var {topLeft: [x1, y1], bottomRight: [x2, y2] } = rect;

test/fixtures/destructuring/mixed/expected.js

@@ -0,0 +1,4 @@
+var x1 = rect.topLeft[0];
+var y1 = rect.topLeft[1];
+var x2 = rect.bottomRight[0];
+var y2 = rect.bottomRight[1];

test/fixtures/destructuring/multiple/actual.js

@@ -0,0 +1 @@
+var { x, y } = coords, foo = "bar";

test/fixtures/destructuring/multiple/expected.js

@@ -0,0 +1,3 @@
+var x = coords.x;
+var y = coords.y;
+var foo = "bar";

test/fixtures/destructuring/object-advanced/actual.js

@@ -0,0 +1 @@
+var {topLeft: {x: x1, y: y1}, bottomRight: {x: x2, y: y2}} = rect;

test/fixtures/destructuring/object-advanced/expected.js

@@ -0,0 +1,4 @@
+var x1 = rect.topLeft.x;
+var y1 = rect.topLeft.y;
+var x2 = rect.bottomRight.x;
+var y2 = rect.bottomRight.y;

test/fixtures/destructuring/object-basic/actual.js

@@ -0,0 +1 @@
+var { x, y } = coords;

test/fixtures/destructuring/object-basic/expected.js

@@ -0,0 +1,2 @@
+var x = coords.x;
+var y = coords.y;