Revert "remove do expressions"

This reverts commit 420492388b06ff295a638adbea0f34c726056607.

CHANGELOG.md

@@ -13,10 +13,6 @@ _Note: Gaps between patch versions are faulty, broken or test releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
-## 5.6.19
-
- * Removed do expressions.
-
 ## 5.6.17
 
  * **Bug Fix**

src/acorn/src/expression.js

@@ -281,6 +281,20 @@ pp.parseExprAtom = function(refShorthandDefaultPos) {
   case tt._yield:
     if (this.inGenerator) this.unexpected()
 
+  case tt._do:
+    if (this.options.features["es7.doExpressions"]) {
+      let node = this.startNode()
+      this.next()
+      var oldInFunction = this.inFunction
+      var oldLabels = this.labels
+      this.labels = []
+      this.inFunction = false
+      node.body = this.parseBlock()
+      this.inFunction = oldInFunction
+      this.labels = oldLabels
+      return this.finishNode(node, "DoExpression")
+    }
+
   case tt.name:
     let start = this.markPosition()
     node = this.startNode()

src/babel/transformation/transformers/es7/do-expressions.js

@@ -0,0 +1,26 @@
+import * as t from "../../../types";
+
+export var metadata = {
+  optional: true,
+  stage: 0
+};
+
+/**
+ * [Please add a description.]
+ */
+
+export var visitor = {
+
+  /**
+   * [Please add a description.]
+   */
+
+  DoExpression(node) {
+    var body = node.body.body;
+    if (body.length) {
+      return body;
+    } else {
+      return t.identifier("undefined");
+    }
+  }
+};

src/babel/transformation/transformers/index.js

@@ -48,6 +48,7 @@ export default {
   "es6.constants":                         require("./es6/constants"),
   "es7.exportExtensions":                  require("./es7/export-extensions"),
   "spec.protoToAssign":                    require("babel-plugin-proto-to-assign"),
+  "es7.doExpressions":                     require("./es7/do-expressions"),
   "es6.spec.symbols":                      require("./es6/spec.symbols"),
   "es7.functionBind":                      require("./es7/function-bind"),
   "spec.undefinedToVoid":                  require("babel-plugin-undefined-to-void"),

src/babel/types/alias-keys.json

@@ -64,6 +64,7 @@
   "CallExpression":            ["Expression"],
   "ComprehensionExpression":   ["Expression", "Scopable"],
   "ConditionalExpression":     ["Expression"],
+  "DoExpression":              ["Expression"],
   "Identifier":                ["Expression"],
   "Literal":                   ["Expression", "Pure"],
   "MemberExpression":          ["Expression"],

src/babel/types/visitor-keys.json

@@ -21,6 +21,7 @@
   "Decorator":                 ["expression"],
   "DebuggerStatement":         [],
   "DoWhileStatement":          ["body", "test"],
+  "DoExpression":              ["body"],
   "EmptyStatement":            [],
   "ExpressionStatement":       ["expression"],
   "File":                      ["program"],

test/core/fixtures/transformation/es7.do-expressions/do-while.js

@@ -0,0 +1,5 @@
+assert.equal(do {
+  var i = 5;
+  do { i--; } while(i > 3);
+  i;
+}, 3);

test/core/fixtures/transformation/es7.do-expressions/empty.js

@@ -0,0 +1 @@
+assert.equal(do {}, undefined);

test/core/fixtures/transformation/es7.do-expressions/for-in.js

@@ -0,0 +1,6 @@
+assert.equal(do {
+  var obj = { foo: "bar", bar: "foo" };
+  for (var key in obj) {
+    obj[key];
+  }
+}, "foo");

test/core/fixtures/transformation/es7.do-expressions/for.js

@@ -0,0 +1,5 @@
+assert.equal(do {
+  for (var i = 0; i < 5; i++) {
+    i;
+  }
+}, 4);

test/core/fixtures/transformation/es7.do-expressions/if-else-if.js

@@ -0,0 +1,7 @@
+assert.equal(do {
+  if (false) {
+    "foo";
+  } else if (true) {
+    "bar";
+  }
+}, "bar");

test/core/fixtures/transformation/es7.do-expressions/if-else.js

@@ -0,0 +1,7 @@
+assert.equal(do {
+  if (false) {
+    "foo";
+  } else {
+    "bar";
+  }
+}, "bar");

test/core/fixtures/transformation/es7.do-expressions/if.js

@@ -0,0 +1,5 @@
+assert.equal(do {
+  if (true) {
+    "bar";
+  }
+}, "bar");

test/core/fixtures/transformation/es7.do-expressions/options.json

@@ -0,0 +1,3 @@
+{
+  "optional": ["es7.doExpressions"]
+}

test/core/fixtures/transformation/es7.do-expressions/single-expression.js

@@ -0,0 +1,3 @@
+assert.equal(do {
+  "foo";
+}, "foo");

test/core/fixtures/transformation/es7.do-expressions/variable-declaration-end.js

@@ -0,0 +1,3 @@
+assert.equal(do {
+  var bar = "foo";
+}, undefined);

test/core/fixtures/transformation/es7.do-expressions/variable-declaration-start.js

@@ -0,0 +1,4 @@
+assert.equal(do {
+  var bar = "foo";
+  bar;
+}, "foo");

test/core/fixtures/transformation/es7.do-expressions/while.js

@@ -0,0 +1,5 @@
+assert.equal(do {
+  var i = 5;
+  while (i > 3) i--;
+  i;
+}, 3);