support `for [await]...of` statements (#4627)

1 files changed, 19 insertions, 8 deletions

diff --git a/lib/parse.js b/lib/parse.js
index d5098ff5..c8f63d80 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -1039,6 +1039,7 @@ function parse($TEXT, options) {
     }
 
     function for_() {
+        var await = is("name", "await") && next();
         expect("(");
         var init = null;
         if (!is("punc", ";")) {
@@ -1049,16 +1050,26 @@ function parse($TEXT, options) {
                 : is("keyword", "var")
                 ? (next(), var_(true))
                 : expression(true);
-            if (is("operator", "in")) {
+            var ctor;
+            if (await) {
+                expect_token("name", "of");
+                ctor = AST_ForAwaitOf;
+            } else if (is("operator", "in")) {
+                next();
+                ctor = AST_ForIn;
+            } else if (is("name", "of")) {
+                next();
+                ctor = AST_ForOf;
+            }
+            if (ctor) {
                 if (init instanceof AST_Definitions) {
                     if (init.definitions.length > 1) {
-                        token_error(init.start, "Only one variable declaration allowed in for..in loop");
+                        token_error(init.start, "Only one variable declaration allowed in for..in/of loop");
                     }
                 } else if (!(is_assignable(init) || (init = to_destructured(init)) instanceof AST_Destructured)) {
-                    token_error(init.start, "Invalid left-hand side in for..in loop");
+                    token_error(init.start, "Invalid left-hand side in for..in/of loop");
                 }
-                next();
-                return for_in(init);
+                return for_enum(ctor, init);
             }
         }
         return regular_for(init);
@@ -1078,10 +1089,10 @@ function parse($TEXT, options) {
         });
     }
 
-    function for_in(init) {
+    function for_enum(ctor, init) {
         var obj = expression();
         expect(")");
-        return new AST_ForIn({
+        return new ctor({
             init   : init,
             object : obj,
             body   : in_loop(statement)
@@ -1523,7 +1534,7 @@ function parse($TEXT, options) {
                     func.end = prev();
                     return subscripts(func, allow_calls);
                 }
-                if (is("name")) {
+                if (is("name") && is_token(peek(), "punc", "=>")) {
                     start = S.token;
                     sym = _make_symbol(AST_SymbolRef, start);
                     next();