temporary

Author: Constellation

escodegen.js

@@ -1268,13 +1268,55 @@
         ExpressionStatement: function (stmt, flags) {
             var result, fragment;
 
+            function isClassPrefixed(fragment) {
+                var code;
+                if (fragment.slice(0, 5) !== 'class') {
+                    return false;
+                }
+                code = fragment.charCodeAt(5);
+                return code === 0x7B  /* '{' */ || esutils.code.isWhiteSpace(code) || esutils.code.isLineTerminator(code);
+            }
+
+            function isFunctionPrefixed(fragment) {
+                var code;
+                if (fragment.slice(0, 8) !== 'function') {
+                    return false;
+                }
+                code = fragment.charCodeAt(8);
+                return code === 0x28 /* '(' */ || esutils.code.isWhiteSpace(code) || code === 0x2A  /* '*' */ || esutils.code.isLineTerminator(code);
+            }
+
+            function isAsyncPrefixed(fragment) {
+                var code, i, iz;
+                if (fragment.slice(0, 5) !== 'async') {
+                    return false;
+                }
+                if (!esutils.code.isWhiteSpace(fragment.charCodeAt(5))) {
+                    return false;
+                }
+                for (i = 6, iz = fragment.length; i < iz; ++i) {
+                    if (!esutils.code.isWhiteSpace(fragment.charCodeAt(i))) {
+                        break;
+                    }
+                }
+                if (i === iz) {
+                    return false;
+                }
+                if (fragment.slice(i, i + 8) !== 'function') {
+                    return false;
+                }
+                code = fragment.charCodeAt(i + 8);
+                return code === 0x28 /* '(' */ || esutils.code.isWhiteSpace(code) || code === 0x2A  /* '*' */ || esutils.code.isLineTerminator(code);
+            }
+
             result = [this.generateExpression(stmt.expression, Precedence.Sequence, E_TTT)];
             // 12.4 '{', 'function', 'class' is not allowed in this position.
             // wrap expression with parentheses
             fragment = toSourceNodeWhenNeeded(result).toString();
-            if (fragment.charAt(0) === '{' ||  // ObjectExpression
-                    (fragment.slice(0, 5) === 'class' && ' {'.indexOf(fragment.charAt(5)) >= 0) ||  // class
-                    (fragment.slice(0, 8) === 'function' && '* ('.indexOf(fragment.charAt(8)) >= 0) ||  // function or generator
+            if (fragment.charCodeAt(0) === 0x7B  /* '{' */ ||  // ObjectExpression
+                    isClassPrefixed(fragment) ||
+                    isFunctionPrefixed(fragment) ||
+                    isAsyncPrefixed(fragment) ||
                     (directive && (flags & F_DIRECTIVE_CTX) && stmt.expression.type === Syntax.Literal && typeof stmt.expression.value === 'string')) {
                 result = ['(', result, ')' + this.semicolon(flags)];
             } else {