Adding arrow functions

lib/parse.js

@@ -510,6 +510,16 @@ function tokenizer($TEXT, filename, html5_comments) {
         return S.regex_allowed ? read_regexp("") : read_operator("/");
     };
 
+    function handle_eq_sign() {
+        next();
+        if (peek() === ">") {
+            next();
+            return token("arrow", "=>");
+        } else {
+            return read_operator("=");
+        }
+    };
+
     function handle_dot() {
         next();
         return is_digit(peek().charCodeAt(0))
@@ -559,6 +569,7 @@ function tokenizer($TEXT, filename, html5_comments) {
           case 34: case 39: return read_string(ch);
           case 46: return handle_dot();
           case 47: return handle_slash();
+          case 61: return handle_eq_sign();
         }
         if (is_digit(code)) return read_num();
         if (PUNC_CHARS(ch)) return token("punc", next());
@@ -975,6 +986,41 @@ function parse($TEXT, options) {
         });
     };
 
+    var arrow_function = function(args) {
+        expect_token("arrow", "=>");
+
+        if (args instanceof AST_SymbolRef) {
+            args = [args];
+        } else if (args instanceof AST_Seq) {
+            args = args.to_array();
+        } else if (args instanceof AST_Node) {
+            croak("Invalid syntax", args.start.line, args.start.col);
+        }
+
+        for (var i = 0; i < args.length; i++) {
+            if (!(args[i] instanceof AST_SymbolRef)) {
+                croak("Invalid parameter for an arrow function", args[i].start.line, args[i].start.col);
+            }
+
+            args[i] = new AST_SymbolFunarg({
+                name: args[i].name,
+                start: args[i].start,
+                end: args[i].end
+            })
+        }
+
+        return new AST_Arrow({
+            argnames: args,
+            body: (function(){
+                if (is("punc", "{")) {
+                    return _function_body();
+                } else {
+                    return expression(true);
+                }
+            })()
+        });
+    };
+
     var function_ = function(ctor) {
         var start = S.token
 
@@ -1486,6 +1532,13 @@ function parse($TEXT, options) {
 
     var maybe_assign = function(no_in) {
         var start = S.token;
+
+        if (start.value == "(" && peek().value == ")") {
+            next();  // (
+            next();  // )
+            return arrow_function([]);
+        }
+
         var left = maybe_conditional(no_in), val = S.token.value;
         if (is("operator") && ASSIGNMENT(val)) {
             if (is_assignable(left)) {
@@ -1500,6 +1553,9 @@ function parse($TEXT, options) {
             }
             croak("Invalid assignment");
         }
+        if (is("arrow")) {
+            return arrow_function(left)
+        }
         return left;
     };