1 /*

     2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package jdk.nashorn.api.scripting;

    27 

    28 import jdk.nashorn.internal.runtime.JSType;

    29 

    30 /**

    31  * Default implementation of {@link JSObject#getDefaultValue(Class)}. Isolated into a separate class mostly so

    32  * that we can have private static instances of function name arrays, something we couldn't declare without it

    33  * being visible in {@link JSObject} interface.

    34  */

    35 class DefaultValueImpl {

    36     private static final String[] DEFAULT_VALUE_FNS_NUMBER = new String[] { "valueOf", "toString" };

    37     private static final String[] DEFAULT_VALUE_FNS_STRING = new String[] { "toString", "valueOf" };

    38 

    39     static Object getDefaultValue(final JSObject jsobj, final Class<?> hint) throws UnsupportedOperationException {

    40         final boolean isNumber = hint == null || hint == Number.class;

    41         for(final String methodName: isNumber ? DEFAULT_VALUE_FNS_NUMBER : DEFAULT_VALUE_FNS_STRING) {

    42             final Object objMember = jsobj.getMember(methodName);

    43             if (objMember instanceof JSObject) {

    44                 final JSObject member = (JSObject)objMember;

    45                 if (member.isFunction()) {

    46                     final Object value = member.call(jsobj);

    47                     if (JSType.isPrimitive(value)) {

    48                         return value;

    49                     }

    50                 }

    51             }

    52         }

    53         throw new UnsupportedOperationException(isNumber ? "cannot.get.default.number" : "cannot.get.default.string");

    54     }

    55 }