1/*
2 * Copyright (C) 2010 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#ifndef Local_h
27#define Local_h
28
29#include "Handle.h"
30#include "VM.h"
31
32/*
33 A strongly referenced handle whose lifetime is temporary, limited to a given
34 LocalScope. Use Locals for local values on the stack. It is an error to
35 create a Local outside of any LocalScope.
36*/
37
38namespace JSC {
39
40template <typename T> class Local : public Handle<T> {
41 friend class LocalScope;
42 using Handle<T>::slot;
43
44public:
45 typedef typename Handle<T>::ExternalType ExternalType;
46
47 Local(VM&, ExternalType = ExternalType());
48 Local(VM&, Handle<T>);
49 Local(const Local<T>&); // Adopting constructor. Used to return a Local to a calling function.
50
51 Local& operator=(ExternalType);
52 Local& operator=(Handle<T>);
53
54private:
55 Local(HandleSlot, ExternalType); // Used by LocalScope::release() to move a Local to a containing scope.
56 void set(ExternalType);
57};
58
59template <typename T> inline Local<T>::Local(VM& vm, ExternalType value)
60 : Handle<T>(vm.heap.handleStack()->push())
61{
62 set(value);
63}
64
65template <typename T> inline Local<T>::Local(VM& vm, Handle<T> other)
66 : Handle<T>(vm.heap.handleStack()->push())
67{
68 set(other.get());
69}
70
71template <typename T> inline Local<T>::Local(const Local<T>& other)
72 : Handle<T>(other.slot())
73{
74 const_cast<Local<T>&>(other).setSlot(0); // Prevent accidental sharing.
75}
76
77template <typename T> inline Local<T>::Local(HandleSlot slot, ExternalType value)
78 : Handle<T>(slot, value)
79{
80}
81
82template <typename T> inline Local<T>& Local<T>::operator=(ExternalType value)
83{
84 set(value);
85 return *this;
86}
87
88template <typename T> inline Local<T>& Local<T>::operator=(Handle<T> other)
89{
90 set(other.get());
91 return *this;
92}
93
94template <typename T> inline void Local<T>::set(ExternalType externalType)
95{
96 ASSERT(slot());
97 *slot() = externalType;
98}
99
100
101template <typename T, unsigned inlineCapacity = 0> class LocalStack {
102 typedef typename Handle<T>::ExternalType ExternalType;
103public:
104 LocalStack(VM& vm)
105 : m_vm(vm)
106 , m_count(0)
107 {
108 }
109
110 ExternalType peek() const
111 {
112 ASSERT(m_count > 0);
113 return m_stack[m_count - 1].get();
114 }
115
116 ExternalType pop()
117 {
118 ASSERT(m_count > 0);
119 return m_stack[--m_count].get();
120 }
121
122 void push(ExternalType value)
123 {
124 if (m_count == m_stack.size())
125 m_stack.append(Local<T>(m_vm, value));
126 else
127 m_stack[m_count] = value;
128 m_count++;
129 }
130
131 bool isEmpty() const { return !m_count; }
132 unsigned size() const { return m_count; }
133
134private:
135 VM& m_vm;
136 Vector<Local<T>, inlineCapacity> m_stack;
137 unsigned m_count;
138};
139
140}
141
142namespace WTF {
143
144template<typename T> struct VectorTraits<JSC::Local<T>> : SimpleClassVectorTraits {
145 static const bool needsDestruction = false;
146 static const bool canInitializeWithMemset = false;
147 static const bool canCompareWithMemcmp = false;
148};
149
150}
151
152#endif
153