1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
/*
* Copyright (C) 2003, 2008, 2009 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef ScopeChain_h
#define ScopeChain_h
#include <wtf/FastAllocBase.h>
namespace JSC {
class JSGlobalData;
class JSGlobalObject;
class JSObject;
class MarkStack;
class ScopeChainIterator;
class ScopeChainNode {
WTF_MAKE_FAST_ALLOCATED;
public:
ScopeChainNode(ScopeChainNode* next, JSObject* object, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis)
: next(next)
, object(object)
, globalData(globalData)
, globalObject(globalObject)
, globalThis(globalThis)
, refCount(1)
{
ASSERT(globalData);
ASSERT(globalObject);
}
#ifndef NDEBUG
// Due to the number of subtle and timing dependent bugs that have occurred due
// to deleted but still "valid" ScopeChainNodes we now deliberately clobber the
// contents in debug builds.
~ScopeChainNode()
{
next = 0;
object = 0;
globalData = 0;
globalObject = 0;
globalThis = 0;
}
#endif
ScopeChainNode* next;
JSObject* object;
JSGlobalData* globalData;
JSGlobalObject* globalObject;
JSObject* globalThis;
int refCount;
void deref() { ASSERT(refCount); if (--refCount == 0) { release();} }
void ref() { ASSERT(refCount); ++refCount; }
void release();
// Before calling "push" on a bare ScopeChainNode, a client should
// logically "copy" the node. Later, the client can "deref" the head
// of its chain of ScopeChainNodes to reclaim all the nodes it added
// after the logical copy, leaving nodes added before the logical copy
// (nodes shared with other clients) untouched.
ScopeChainNode* copy()
{
ref();
return this;
}
ScopeChainNode* push(JSObject*);
ScopeChainNode* pop();
ScopeChainIterator begin() const;
ScopeChainIterator end() const;
#ifndef NDEBUG
void print() const;
#endif
};
inline ScopeChainNode* ScopeChainNode::push(JSObject* o)
{
ASSERT(o);
return new ScopeChainNode(this, o, globalData, globalObject, globalThis);
}
inline ScopeChainNode* ScopeChainNode::pop()
{
ASSERT(next);
ScopeChainNode* result = next;
if (--refCount != 0)
++result->refCount;
else
delete this;
return result;
}
inline void ScopeChainNode::release()
{
// This function is only called by deref(),
// Deref ensures these conditions are true.
ASSERT(refCount == 0);
ScopeChainNode* n = this;
do {
ScopeChainNode* next = n->next;
delete n;
n = next;
} while (n && --n->refCount == 0);
}
class ScopeChainIterator {
public:
ScopeChainIterator(const ScopeChainNode* node)
: m_node(node)
{
}
JSObject* const & operator*() const { return m_node->object; }
JSObject* const * operator->() const { return &(operator*()); }
ScopeChainIterator& operator++() { m_node = m_node->next; return *this; }
// postfix ++ intentionally omitted
bool operator==(const ScopeChainIterator& other) const { return m_node == other.m_node; }
bool operator!=(const ScopeChainIterator& other) const { return m_node != other.m_node; }
private:
const ScopeChainNode* m_node;
};
inline ScopeChainIterator ScopeChainNode::begin() const
{
return ScopeChainIterator(this);
}
inline ScopeChainIterator ScopeChainNode::end() const
{
return ScopeChainIterator(0);
}
class NoScopeChain {};
class ScopeChain {
friend class JIT;
public:
ScopeChain(NoScopeChain)
: m_node(0)
{
}
ScopeChain(JSObject* o, JSGlobalData* globalData, JSGlobalObject* globalObject, JSObject* globalThis)
: m_node(new ScopeChainNode(0, o, globalData, globalObject, globalThis))
{
}
ScopeChain(const ScopeChain& c)
: m_node(c.m_node->copy())
{
}
ScopeChain& operator=(const ScopeChain& c);
explicit ScopeChain(ScopeChainNode* node)
: m_node(node->copy())
{
}
~ScopeChain()
{
if (m_node)
m_node->deref();
#ifndef NDEBUG
m_node = 0;
#endif
}
void swap(ScopeChain&);
ScopeChainNode* node() const { return m_node; }
JSObject* top() const { return m_node->object; }
ScopeChainIterator begin() const { return m_node->begin(); }
ScopeChainIterator end() const { return m_node->end(); }
void push(JSObject* o) { m_node = m_node->push(o); }
void pop() { m_node = m_node->pop(); }
void clear() { m_node->deref(); m_node = 0; }
JSGlobalObject* globalObject() const { return m_node->globalObject; }
void markAggregate(MarkStack&) const;
// Caution: this should only be used if the codeblock this is being used
// with needs a full scope chain, otherwise this returns the depth of
// the preceeding call frame
//
// Returns the depth of the current call frame's scope chain
int localDepth() const;
#ifndef NDEBUG
void print() const { m_node->print(); }
#endif
private:
ScopeChainNode* m_node;
};
inline void ScopeChain::swap(ScopeChain& o)
{
ScopeChainNode* tmp = m_node;
m_node = o.m_node;
o.m_node = tmp;
}
inline ScopeChain& ScopeChain::operator=(const ScopeChain& c)
{
ScopeChain tmp(c);
swap(tmp);
return *this;
}
} // namespace JSC
#endif // ScopeChain_h
|
