1 /*
2 * Copyright (C) 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
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 V8StringResource_h
27 #define V8StringResource_h
28
29 #include <v8.h>
30 #include "wtf/Threading.h"
31 #include "wtf/text/AtomicString.h"
32 #include "wtf/text/WTFString.h"
33
34 namespace WebCore {
35
36 class ExternalStringVisitor;
37
38 // WebCoreStringResource is a helper class for v8ExternalString. It is used
39 // to manage the life-cycle of the underlying buffer of the external string.
40 class WebCoreStringResourceBase {
41 public:
WebCoreStringResourceBase(const String & string)42 explicit WebCoreStringResourceBase(const String& string)
43 : m_plainString(string)
44 {
45 #ifndef NDEBUG
46 m_threadId = WTF::currentThread();
47 #endif
48 ASSERT(!string.isNull());
49 v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(memoryConsumption(string));
50 }
51
WebCoreStringResourceBase(const AtomicString & string)52 explicit WebCoreStringResourceBase(const AtomicString& string)
53 : m_plainString(string.string())
54 , m_atomicString(string)
55 {
56 #ifndef NDEBUG
57 m_threadId = WTF::currentThread();
58 #endif
59 ASSERT(!string.isNull());
60 v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(memoryConsumption(string));
61 }
62
~WebCoreStringResourceBase()63 virtual ~WebCoreStringResourceBase()
64 {
65 #ifndef NDEBUG
66 ASSERT(m_threadId == WTF::currentThread());
67 #endif
68 int reducedExternalMemory = -memoryConsumption(m_plainString);
69 if (m_plainString.impl() != m_atomicString.impl() && !m_atomicString.isNull())
70 reducedExternalMemory -= memoryConsumption(m_atomicString.string());
71 v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(reducedExternalMemory);
72 }
73
webcoreString()74 const String& webcoreString() { return m_plainString; }
75
atomicString()76 const AtomicString& atomicString()
77 {
78 #ifndef NDEBUG
79 ASSERT(m_threadId == WTF::currentThread());
80 #endif
81 if (m_atomicString.isNull()) {
82 m_atomicString = AtomicString(m_plainString);
83 ASSERT(!m_atomicString.isNull());
84 if (m_plainString.impl() != m_atomicString.impl())
85 v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(memoryConsumption(m_atomicString.string()));
86 }
87 return m_atomicString;
88 }
89
90 protected:
91 // A shallow copy of the string. Keeps the string buffer alive until the V8 engine garbage collects it.
92 String m_plainString;
93 // If this string is atomic or has been made atomic earlier the
94 // atomic string is held here. In the case where the string starts
95 // off non-atomic and becomes atomic later it is necessary to keep
96 // the original string alive because v8 may keep derived pointers
97 // into that string.
98 AtomicString m_atomicString;
99
100 private:
memoryConsumption(const String & string)101 static int memoryConsumption(const String& string)
102 {
103 return string.length() * (string.is8Bit() ? sizeof(LChar) : sizeof(UChar));
104 }
105 #ifndef NDEBUG
106 WTF::ThreadIdentifier m_threadId;
107 #endif
108 };
109
110 class WebCoreStringResource16 FINAL : public WebCoreStringResourceBase, public v8::String::ExternalStringResource {
111 public:
WebCoreStringResource16(const String & string)112 explicit WebCoreStringResource16(const String& string)
113 : WebCoreStringResourceBase(string)
114 {
115 ASSERT(!string.is8Bit());
116 }
117
WebCoreStringResource16(const AtomicString & string)118 explicit WebCoreStringResource16(const AtomicString& string)
119 : WebCoreStringResourceBase(string)
120 {
121 ASSERT(!string.is8Bit());
122 }
123
length()124 virtual size_t length() const OVERRIDE { return m_plainString.impl()->length(); }
data()125 virtual const uint16_t* data() const OVERRIDE
126 {
127 return reinterpret_cast<const uint16_t*>(m_plainString.impl()->characters16());
128 }
129 };
130
131 class WebCoreStringResource8 FINAL : public WebCoreStringResourceBase, public v8::String::ExternalAsciiStringResource {
132 public:
WebCoreStringResource8(const String & string)133 explicit WebCoreStringResource8(const String& string)
134 : WebCoreStringResourceBase(string)
135 {
136 ASSERT(string.is8Bit());
137 }
138
WebCoreStringResource8(const AtomicString & string)139 explicit WebCoreStringResource8(const AtomicString& string)
140 : WebCoreStringResourceBase(string)
141 {
142 ASSERT(string.is8Bit());
143 }
144
length()145 virtual size_t length() const OVERRIDE { return m_plainString.impl()->length(); }
data()146 virtual const char* data() const OVERRIDE
147 {
148 return reinterpret_cast<const char*>(m_plainString.impl()->characters8());
149 }
150 };
151
152 enum ExternalMode {
153 Externalize,
154 DoNotExternalize
155 };
156
157 template <typename StringType>
158 StringType v8StringToWebCoreString(v8::Handle<v8::String>, ExternalMode);
159 String int32ToWebCoreString(int value);
160
161 // V8StringResource is an adapter class that converts V8 values to Strings
162 // or AtomicStrings as appropriate, using multiple typecast operators.
163 enum V8StringResourceMode {
164 DefaultMode,
165 WithNullCheck,
166 WithUndefinedOrNullCheck
167 };
168
169 template <V8StringResourceMode Mode = DefaultMode>
170 class V8StringResource {
171 public:
V8StringResource()172 V8StringResource()
173 : m_mode(Externalize)
174 {
175 }
176
V8StringResource(v8::Handle<v8::Value> object)177 V8StringResource(v8::Handle<v8::Value> object)
178 : m_v8Object(object)
179 , m_mode(Externalize)
180 {
181 }
182
183 void operator=(v8::Handle<v8::Value> object)
184 {
185 m_v8Object = object;
186 }
187
188 void operator=(const String& string)
189 {
190 setString(string);
191 }
192
prepare()193 bool prepare()
194 {
195 if (m_v8Object.IsEmpty())
196 return true;
197
198 if (!isValid()) {
199 setString(String());
200 return true;
201 }
202
203 if (LIKELY(m_v8Object->IsString()))
204 return true;
205
206 if (LIKELY(m_v8Object->IsInt32())) {
207 setString(int32ToWebCoreString(m_v8Object->Int32Value()));
208 return true;
209 }
210
211 m_mode = DoNotExternalize;
212 v8::TryCatch block;
213 m_v8Object = m_v8Object->ToString();
214 // Handle the case where an exception is thrown as part of invoking toString on the object.
215 if (block.HasCaught()) {
216 block.ReThrow();
217 return false;
218 }
219 return true;
220 }
String()221 operator String() const { return toString<String>(); }
AtomicString()222 operator AtomicString() const { return toString<AtomicString>(); }
223
224 private:
225 bool isValid() const;
226
setString(const String & string)227 void setString(const String& string)
228 {
229 m_string = string;
230 m_v8Object.Clear(); // To signal that String is ready.
231 }
232
233 template <class StringType>
toString()234 StringType toString() const
235 {
236 if (LIKELY(!m_v8Object.IsEmpty()))
237 return v8StringToWebCoreString<StringType>(const_cast<v8::Handle<v8::Value>*>(&m_v8Object)->As<v8::String>(), m_mode);
238
239 return StringType(m_string);
240 }
241
242 v8::Handle<v8::Value> m_v8Object;
243 ExternalMode m_mode;
244 String m_string;
245 };
246
isValid()247 template<> inline bool V8StringResource<DefaultMode>::isValid() const
248 {
249 return true;
250 }
251
isValid()252 template<> inline bool V8StringResource<WithNullCheck>::isValid() const
253 {
254 return !m_v8Object->IsNull();
255 }
256
isValid()257 template<> inline bool V8StringResource<WithUndefinedOrNullCheck>::isValid() const
258 {
259 return !m_v8Object->IsNull() && !m_v8Object->IsUndefined();
260 }
261
262 } // namespace WebCore
263
264 #endif // V8StringResource_h
265