1/*
2 * Copyright (C) 2006, 2007, 2008, 2009 Google Inc. 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 are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef V8NodeFilterCondition_h
32#define V8NodeFilterCondition_h
33
34#include "bindings/core/v8/ScopedPersistent.h"
35#include "bindings/core/v8/ScriptState.h"
36#include "core/dom/NodeFilterCondition.h"
37#include "platform/heap/Handle.h"
38#include "wtf/PassRefPtr.h"
39#include <v8.h>
40
41namespace blink {
42
43class Node;
44class ExceptionState;
45
46// V8NodeFilterCondition maintains a Javascript implemented callback for
47// filtering Node returned by NodeIterator/TreeWalker.
48// A NodeFilterCondition is referenced by a NodeFilter, and A NodeFilter is
49// referenced by a NodeIterator/TreeWalker. As V8NodeFilterCondition maintains
50// a Javascript callback which may reference Document, we need to avoid circular
51// reference spanning V8/Blink object space.
52// To address this issue, V8NodeFilterCondition holds a weak reference to
53// |m_filter|, the Javascript value, and the whole reference is exposed to V8 to
54// let V8 GC handle collection of |m_filter|.
55// (DOM)
56// NodeIterator  ----RefPtr----> NodeFilter ----RefPtr----> NodeFilterCondition
57//   |   ^                        |   ^                        |
58//  weak |                       weak |                ScopedPersistent(weak)
59//   | RefPtr                     | RefPtr                     |
60//   v   |                        v   |                        v
61// NodeIterator  --HiddenValue--> NodeFilter --HiddenValue--> JS Callback
62// (V8)
63class V8NodeFilterCondition FINAL : public NodeFilterCondition {
64public:
65    static PassRefPtrWillBeRawPtr<V8NodeFilterCondition> create(v8::Handle<v8::Value> filter, v8::Handle<v8::Object> owner, ScriptState* scriptState)
66    {
67        return adoptRefWillBeNoop(new V8NodeFilterCondition(filter, owner, scriptState));
68    }
69
70    virtual ~V8NodeFilterCondition();
71
72    virtual short acceptNode(Node*, ExceptionState&) const OVERRIDE;
73
74private:
75    // As the value |filter| is maintained by V8GC, the |owner| which references
76    // V8NodeFilterCondition, usually a wrapper of NodeFilter, is specified here
77    // to hold a strong reference to |filter|.
78    V8NodeFilterCondition(v8::Handle<v8::Value> filter, v8::Handle<v8::Object> owner, ScriptState*);
79
80    static void setWeakCallback(const v8::WeakCallbackData<v8::Value, V8NodeFilterCondition>&);
81
82    RefPtr<ScriptState> m_scriptState;
83    ScopedPersistent<v8::Value> m_filter;
84};
85
86} // namespace blink
87
88#endif // V8NodeFilterCondition_h
89