add support for break and continue in block binding

lib/6to5/transformers/block-binding.js

@@ -3,6 +3,8 @@ var util     = require("../util");
 var b        = require("ast-types").builders;
 var _        = require("lodash");
 
+var funcTypes = ["FunctionDeclaration", "FunctionExpression"];
+
 var isLet = function (node) {
   if (node && node.type === "VariableDeclaration" && node.kind === "let") {
     node.kind = "var";
@@ -22,9 +24,7 @@ var hasLet = function (nodes) {
 };
 
 exports.Program = function (node) {
-  if (hasLet(node.body)) {
-    node.body = buildNode(node.body);
-  }
+  if (hasLet(node.body)) node.body = buildNode(node.body);
 };
 
 exports.BlockStatement = function (node, parent) {
@@ -33,7 +33,31 @@ exports.BlockStatement = function (node, parent) {
   // ignore if we're the body of a closure already
   if (parent.type === "FunctionExpression") return;
 
-  node.body = buildNode(node.body);
+  var body = node.body;
+  node.body = buildNode(node.body, true);
+
+  var container = _.last(node.body);
+  traverse.replace(container, function (node) {
+    if (node.type === "ContinueStatement") {
+      return b.returnStatement(null);
+    }
+  }, funcTypes);
+
+  if (traverse.hasType(body, "BreakStatement", funcTypes)) {
+    var id = b.identifier("_break");
+
+    node.body.unshift(b.variableDeclaration("var", [
+      b.variableDeclarator(id, b.literal(false))
+    ]));
+
+    traverse.replace(container, function (node) {
+      if (node.type === "BreakStatement") {
+        return b.returnStatement(b.assignmentExpression("=", id, b.literal(true)));
+      }
+    }, funcTypes);
+
+    node.body.push(b.ifStatement(id, b.breakStatement()));
+  }
 };
 
 exports.ForOfStatement =
@@ -45,7 +69,7 @@ exports.ForStatement = function (node) {
   if (isLet(node.init)) return buildNode(node);
 };
 
-var buildNode = function (node) {
+var buildNode = function (node, isBlock) {
   var nodes = [];
 
   // hoist normal variable declarations
@@ -55,9 +79,11 @@ var buildNode = function (node) {
     if (node._ignoreBlockBindingHoist) return node;
 
     if (node.type === "VariableDeclaration" && node.kind === "var") {
-      nodes.push(b.variableDeclaration("var", node.declarations.map(function (declar) {
+      var declars = node.declarations.map(function (declar) {
         return b.variableDeclarator(declar.id, null);
-      })));
+      });
+
+      nodes.push(b.variableDeclaration("var", declars));
 
       return node.declarations.map(function (declar) {
         return util.template("assign", {
@@ -80,7 +106,8 @@ var buildNode = function (node) {
 
   var block = b.blockStatement([]);
   block.body = node;
-  var func = b.functionExpression(null, [], block, false)
+
+  var func = b.functionExpression(null, [], block, false);
 
   var templateName = "function-call";
   if (traverse.hasType(node, "ThisExpression")) {

lib/6to5/traverse/index.js

@@ -1,15 +1,17 @@
 var VISITOR_KEYS = require("./visitor-keys");
 var _            = require("lodash");
 
-var traverse = module.exports = function (parent, callback) {
+var traverse = module.exports = function (parent, callback, blacklistTypes) {
+
   if (_.isArray(parent)) {
     _.each(parent, function (node) {
-      traverse(node, callback);
+      traverse(node, callback, blacklistTypes);
     });
     return;
   }
 
   var keys = VISITOR_KEYS[parent.type] || [];
+  blacklistTypes = blacklistTypes || [];
 
   _.each(keys, function (key) {
     var nodes = parent[key];
@@ -20,6 +22,7 @@ var traverse = module.exports = function (parent, callback) {
 
       // strict references in case the callback modified/replaced the node
 
+      if (blacklistTypes.indexOf(obj[key].type) >= 0) return;
       var result = callback(obj[key], parent, obj, key);
       if (result === false) return;
 
@@ -47,12 +50,15 @@ var traverse = module.exports = function (parent, callback) {
 
 traverse.Delete = {};
 
-traverse.hasType = function (tree, type) {
+traverse.hasType = function (tree, type, blacklistTypes) {
+  if (tree.type === type) return true;
+
   var has = false;
+  blacklistTypes = blacklistTypes || []
 
   if (_.isArray(tree)) {
     return !!_.find(tree, function (node) {
-      return traverse.hasType(node, type);
+      return traverse.hasType(node, type, blacklistTypes);
     });
   } else {
     traverse(tree, function (node) {
@@ -60,7 +66,7 @@ traverse.hasType = function (tree, type) {
         has = true;
         return false;
       }
-    });
+    }, blacklistTypes);
   }
 
   return has;
@@ -69,6 +75,7 @@ traverse.hasType = function (tree, type) {
 traverse.replace = function (node, callback) {
   traverse(node, function (node, parent, obj, key) {
     var result = callback(node, parent);
+    if (result === false) return false;
     if (result != null) obj[key] = result;
   });
 };

test/fixtures/block-binding/for-in-block-wrap-break/actual.js

@@ -0,0 +1,6 @@
+var arr = [1, 2, 3];
+for (let i in arr) {
+  let val = arr[i];
+  console.log(val * 2);
+  break;
+}

test/fixtures/block-binding/for-in-block-wrap-break/expected.js

@@ -0,0 +1,16 @@
+var arr = [
+  1,
+  2,
+  3
+];
+(function () {
+  for (var i in arr) {
+    var _break = false;
+    (function () {
+      var val = arr[i];
+      console.log(val * 2);
+      return _break = true;
+    }());
+    if (_break) break;
+  }
+}());

test/fixtures/block-binding/for-in-block-wrap-continue/actual.js

@@ -0,0 +1,6 @@
+var arr = [1, 2, 3];
+for (let i in arr) {
+  let val = arr[i];
+  console.log(val * 2);
+  continue;
+}

test/fixtures/block-binding/for-in-block-wrap-continue/expected.js

@@ -0,0 +1,14 @@
+var arr = [
+  1,
+  2,
+  3
+];
+(function () {
+  for (var i in arr) {
+    (function () {
+      var val = arr[i];
+      console.log(val * 2);
+      return;
+    }());
+  }
+}());