8191819: String.prototype.match should follow ES6 specification

Reviewed-by: sundar

src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/objects/NativeString.java

@@ -689,19 +689,17 @@ public final class NativeString extends ScriptObject implements OptimisticBuilti
 
         nativeRegExp.setLastIndex(0);
 
-        int previousLastIndex = 0;
         final List<Object> matches = new ArrayList<>();
 
         Object result;
+        // We follow ECMAScript 6 spec here (checking for empty string instead of previous index)
+        // as the ES5 specification is buggy and causes empty strings to be matched twice.
         while ((result = nativeRegExp.exec(str)) != null) {
-            final int thisIndex = nativeRegExp.getLastIndex();
-            if (thisIndex == previousLastIndex) {
-                nativeRegExp.setLastIndex(thisIndex + 1);
-                previousLastIndex = thisIndex + 1;
-            } else {
-                previousLastIndex = thisIndex;
+            final String matchStr = JSType.toString(((ScriptObject)result).get(0));
+            if (matchStr.isEmpty()) {
+                nativeRegExp.setLastIndex(nativeRegExp.getLastIndex() + 1);
             }
-            matches.add(((ScriptObject)result).get(0));
+            matches.add(matchStr);
         }
 
         if (matches.isEmpty()) {

test/nashorn/script/basic/JDK-8191819.js

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * 
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ * 
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ * 
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * JDK-8191819: String.prototype.match should follow ES6 specification
+ *
+ * @test
+ * @run
+ */
+
+Assert.assertEquals("a\nb\rc\n\rd\r\ne".match(/^(.*)/gm).join("*"), "a*b*c**d**e");
+
+