BufferArray.java revision 1040:cc3000241e57 
1/*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 *   - Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 *
11 *   - Redistributions in binary form must reproduce the above copyright
12 *     notice, this list of conditions and the following disclaimer in the
13 *     documentation and/or other materials provided with the distribution.
14 *
15 *   - Neither the name of Oracle nor the names of its
16 *     contributors may be used to endorse or promote products derived
17 *     from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
20 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32import java.nio.DoubleBuffer;
33import jdk.nashorn.api.scripting.AbstractJSObject;
34
35/**
36 * Simple class demonstrating pluggable script object
37 * implementation. By implementing jdk.nashorn.api.scripting.JSObject
38 * (or extending AbstractJSObject which implements it), you
39 * can supply a friendly script object. Nashorn will call
40 * 'magic' methods on such a class on 'obj.foo, obj.foo = 33,
41 * obj.bar()' etc. from script.
42 *
43 * In this example, Java nio DoubleBuffer object is wrapped
44 * as a friendly script object that provides indexed acces
45 * to buffer content and also support array-like "length"
46 * readonly property to retrieve buffer's capacity. This class
47 * also demonstrates a function valued property called "buf".
48 * On 'buf' method, we return the underlying nio buffer object
49 * that is being wrapped.
50 */
51public class BufferArray extends AbstractJSObject {
52    // underlying nio buffer
53    private final DoubleBuffer buf;
54
55    /**
56     * Constructor
57     * @param size initial size
58     */
59    public BufferArray(final int size) {
60        buf = DoubleBuffer.allocate(size);
61    }
62
63    /**
64     * Constructur
65     * @param buf {@link DoubleBuffer} to link to
66     */
67    public BufferArray(final DoubleBuffer buf) {
68        this.buf = buf;
69    }
70
71    // called to check if indexed property exists
72    @Override
73    public boolean hasSlot(final int index) {
74        return index > 0 && index < buf.capacity();
75    }
76
77    // get the value from that index
78    @Override
79    public Object getSlot(final int index) {
80       return buf.get(index);
81    }
82
83    // set the value at that index
84    @Override
85    public void setSlot(final int index, final Object value) {
86       buf.put(index, ((Number)value).doubleValue());
87    }
88
89    // do you have a property of that given name?
90    @Override
91    public boolean hasMember(final String name) {
92       return "length".equals(name) || "buf".equals(name);
93    }
94
95    // get the value of that named property
96    @Override
97    public Object getMember(final String name) {
98       switch (name) {
99          case "length":
100              return buf.capacity();
101          case "buf":
102              // return a 'function' value for this property
103              return new AbstractJSObject() {
104                  @Override
105                  public Object call(final Object thiz, final Object... args) {
106                      return BufferArray.this.buf;
107                  }
108
109                  // yes, I'm a function !
110                  @Override
111                  public boolean isFunction() {
112                      return true;
113                  }
114              };
115          default:
116              break;
117       }
118       return null;
119    }
120}
121