1/*
2 * Copyright (C) 2011 Apple 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
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include "HandleTypes.h"
29
30namespace JSC {
31
32/*
33 A Handle is a smart pointer that updates automatically when the garbage
34 collector moves the object to which it points.
35
36 The base Handle class represents a temporary reference to a pointer whose
37 lifetime is guaranteed by something else.
38*/
39
40enum class ShouldStrongDestructorGrabLock : bool { No, Yes };
41
42template <class T> class Handle;
43
44// Creating a JSValue Handle is invalid
45template <> class Handle<JSValue>;
46
47class HandleBase {
48 template <typename T> friend class Weak;
49 template <typename T, ShouldStrongDestructorGrabLock shouldStrongDestructorGrabLock> friend class Strong;
50 friend class HandleSet;
51 friend struct JSCallbackObjectData;
52
53public:
54 bool operator!() const { return !m_slot || !*m_slot; }
55
56 explicit operator bool() const { return m_slot && *m_slot; }
57
58 HandleSlot slot() const { return m_slot; }
59
60protected:
61 HandleBase(HandleSlot slot)
62 : m_slot(slot)
63 {
64 }
65
66 void swap(HandleBase& other) { std::swap(m_slot, other.m_slot); }
67
68 void setSlot(HandleSlot slot)
69 {
70 m_slot = slot;
71 }
72
73private:
74 HandleSlot m_slot;
75};
76
77template <typename Base, typename T> struct HandleConverter {
78 T* operator->()
79 {
80 return static_cast<Base*>(this)->get();
81 }
82 const T* operator->() const
83 {
84 return static_cast<const Base*>(this)->get();
85 }
86
87 T* operator*()
88 {
89 return static_cast<Base*>(this)->get();
90 }
91 const T* operator*() const
92 {
93 return static_cast<const Base*>(this)->get();
94 }
95};
96
97template <typename Base> struct HandleConverter<Base, Unknown> {
98 Handle<JSObject> asObject() const;
99 bool isObject() const { return jsValue().isObject(); }
100 bool getNumber(double number) const { return jsValue().getNumber(number); }
101 WTF::String getString(JSGlobalObject*) const;
102 bool isUndefinedOrNull() const { return jsValue().isUndefinedOrNull(); }
103
104private:
105 JSValue jsValue() const
106 {
107 return static_cast<const Base*>(this)->get();
108 }
109};
110
111template <typename T> class Handle : public HandleBase, public HandleConverter<Handle<T>, T> {
112public:
113 template <typename A, typename B> friend struct HandleConverter;
114 typedef typename HandleTypes<T>::ExternalType ExternalType;
115 template <typename U> Handle(Handle<U> o)
116 {
117 typename HandleTypes<T>::template validateUpcast<U>();
118 setSlot(o.slot());
119 }
120
121 void swap(Handle& other) { HandleBase::swap(other); }
122
123 ExternalType get() const { return HandleTypes<T>::getFromSlot(this->slot()); }
124
125protected:
126 Handle(HandleSlot slot = 0)
127 : HandleBase(slot)
128 {
129 }
130
131private:
132 friend class HandleSet;
133 friend class WeakBlock;
134
135 static Handle<T> wrapSlot(HandleSlot slot)
136 {
137 return Handle<T>(slot);
138 }
139};
140
141template <typename Base> Handle<JSObject> HandleConverter<Base, Unknown>::asObject() const
142{
143 return Handle<JSObject>::wrapSlot(static_cast<const Base*>(this)->slot());
144}
145
146template <typename T, typename U> inline bool operator==(const Handle<T>& a, const Handle<U>& b)
147{
148 return a.get() == b.get();
149}
150
151template <typename T, typename U> inline bool operator==(const Handle<T>& a, U* b)
152{
153 return a.get() == b;
154}
155
156template <typename T, typename U> inline bool operator==(T* a, const Handle<U>& b)
157{
158 return a == b.get();
159}
160
161template <typename T, typename U> inline bool operator!=(const Handle<T>& a, const Handle<U>& b)
162{
163 return a.get() != b.get();
164}
165
166template <typename T, typename U> inline bool operator!=(const Handle<T>& a, U* b)
167{
168 return a.get() != b;
169}
170
171template <typename T, typename U> inline bool operator!=(T* a, const Handle<U>& b)
172{
173 return a != b.get();
174}
175
176template <typename T, typename U> inline bool operator!=(const Handle<T>& a, JSValue b)
177{
178 return a.get() != b;
179}
180
181template <typename T, typename U> inline bool operator!=(JSValue a, const Handle<U>& b)
182{
183 return a != b.get();
184}
185
186} // namespace JSC
187