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1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 //     * Redistributions of source code must retain the above copyright
7 //       notice, this list of conditions and the following disclaimer.
8 //     * Redistributions in binary form must reproduce the above
9 //       copyright notice, this list of conditions and the following
10 //       disclaimer in the documentation and/or other materials provided
11 //       with the distribution.
12 //     * Neither the name of Google Inc. nor the names of its
13 //       contributors may be used to endorse or promote products derived
14 //       from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 
28 #ifndef V8_HANDLES_H_
29 #define V8_HANDLES_H_
30 
31 #include "allocation.h"
32 #include "apiutils.h"
33 
34 namespace v8 {
35 namespace internal {
36 
37 // ----------------------------------------------------------------------------
38 // A Handle provides a reference to an object that survives relocation by
39 // the garbage collector.
40 // Handles are only valid within a HandleScope.
41 // When a handle is created for an object a cell is allocated in the heap.
42 
43 template<typename T>
44 class Handle {
45  public:
INLINE(explicit Handle (T ** location))46   INLINE(explicit Handle(T** location)) { location_ = location; }
47   INLINE(explicit Handle(T* obj));
48   INLINE(Handle(T* obj, Isolate* isolate));
49 
INLINE(Handle ())50   INLINE(Handle()) : location_(NULL) {}
51 
52   // Constructor for handling automatic up casting.
53   // Ex. Handle<JSFunction> can be passed when Handle<Object> is expected.
Handle(Handle<S> handle)54   template <class S> Handle(Handle<S> handle) {
55 #ifdef DEBUG
56     T* a = NULL;
57     S* b = NULL;
58     a = b;  // Fake assignment to enforce type checks.
59     USE(a);
60 #endif
61     location_ = reinterpret_cast<T**>(handle.location());
62   }
63 
64   INLINE(T* operator ->() const) { return operator*(); }
65 
66   // Check if this handle refers to the exact same object as the other handle.
is_identical_to(const Handle<T> other)67   bool is_identical_to(const Handle<T> other) const {
68     return operator*() == *other;
69   }
70 
71   // Provides the C++ dereference operator.
72   INLINE(T* operator*() const);
73 
74   // Returns the address to where the raw pointer is stored.
location()75   T** location() const {
76     ASSERT(location_ == NULL ||
77            reinterpret_cast<Address>(*location_) != kZapValue);
78     return location_;
79   }
80 
cast(Handle<S> that)81   template <class S> static Handle<T> cast(Handle<S> that) {
82     T::cast(*that);
83     return Handle<T>(reinterpret_cast<T**>(that.location()));
84   }
85 
null()86   static Handle<T> null() { return Handle<T>(); }
is_null()87   bool is_null() const { return location_ == NULL; }
88 
89   // Closes the given scope, but lets this handle escape. See
90   // implementation in api.h.
91   inline Handle<T> EscapeFrom(v8::HandleScope* scope);
92 
93  private:
94   T** location_;
95 };
96 
97 
98 // A stack-allocated class that governs a number of local handles.
99 // After a handle scope has been created, all local handles will be
100 // allocated within that handle scope until either the handle scope is
101 // deleted or another handle scope is created.  If there is already a
102 // handle scope and a new one is created, all allocations will take
103 // place in the new handle scope until it is deleted.  After that,
104 // new handles will again be allocated in the original handle scope.
105 //
106 // After the handle scope of a local handle has been deleted the
107 // garbage collector will no longer track the object stored in the
108 // handle and may deallocate it.  The behavior of accessing a handle
109 // for which the handle scope has been deleted is undefined.
110 class HandleScope {
111  public:
112   inline HandleScope();
113   explicit inline HandleScope(Isolate* isolate);
114 
115   inline ~HandleScope();
116 
117   // Counts the number of allocated handles.
118   static int NumberOfHandles();
119 
120   // Creates a new handle with the given value.
121   template <typename T>
122   static inline T** CreateHandle(T* value, Isolate* isolate);
123 
124   // Deallocates any extensions used by the current scope.
125   static void DeleteExtensions(Isolate* isolate);
126 
127   static Address current_next_address();
128   static Address current_limit_address();
129   static Address current_level_address();
130 
131   // Closes the HandleScope (invalidating all handles
132   // created in the scope of the HandleScope) and returns
133   // a Handle backed by the parent scope holding the
134   // value of the argument handle.
135   template <typename T>
136   Handle<T> CloseAndEscape(Handle<T> handle_value);
137 
isolate()138   Isolate* isolate() { return isolate_; }
139 
140  private:
141   // Prevent heap allocation or illegal handle scopes.
142   HandleScope(const HandleScope&);
143   void operator=(const HandleScope&);
144   void* operator new(size_t size);
145   void operator delete(void* size_t);
146 
147   inline void CloseScope();
148 
149   Isolate* isolate_;
150   Object** prev_next_;
151   Object** prev_limit_;
152 
153   // Extend the handle scope making room for more handles.
154   static internal::Object** Extend();
155 
156   // Zaps the handles in the half-open interval [start, end).
157   static void ZapRange(internal::Object** start, internal::Object** end);
158 
159   friend class v8::HandleScope;
160   friend class v8::ImplementationUtilities;
161 };
162 
163 
164 // ----------------------------------------------------------------------------
165 // Handle operations.
166 // They might invoke garbage collection. The result is an handle to
167 // an object of expected type, or the handle is an error if running out
168 // of space or encountering an internal error.
169 
170 // Flattens a string.
171 void FlattenString(Handle<String> str);
172 
173 // Flattens a string and returns the underlying external or sequential
174 // string.
175 Handle<String> FlattenGetString(Handle<String> str);
176 
177 int Utf8Length(Handle<String> str);
178 
179 Handle<Object> SetProperty(Handle<Object> object,
180                            Handle<Object> key,
181                            Handle<Object> value,
182                            PropertyAttributes attributes,
183                            StrictModeFlag strict_mode);
184 
185 Handle<Object> ForceSetProperty(Handle<JSObject> object,
186                                 Handle<Object> key,
187                                 Handle<Object> value,
188                                 PropertyAttributes attributes);
189 
190 Handle<Object> ForceDeleteProperty(Handle<JSObject> object,
191                                    Handle<Object> key);
192 
193 Handle<Object> GetProperty(Handle<JSReceiver> obj,
194                            const char* name);
195 
196 Handle<Object> GetProperty(Handle<Object> obj,
197                            Handle<Object> key);
198 
199 Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver,
200                                           Handle<JSObject> holder,
201                                           Handle<String> name,
202                                           PropertyAttributes* attributes);
203 
204 Handle<Object> SetPrototype(Handle<JSObject> obj, Handle<Object> value);
205 
206 Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index);
207 
208 Handle<JSObject> Copy(Handle<JSObject> obj);
209 
210 Handle<Object> SetAccessor(Handle<JSObject> obj, Handle<AccessorInfo> info);
211 
212 Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray>,
213                                       Handle<JSArray> array);
214 
215 // Get the JS object corresponding to the given script; create it
216 // if none exists.
217 Handle<JSValue> GetScriptWrapper(Handle<Script> script);
218 
219 // Script line number computations.
220 void InitScriptLineEnds(Handle<Script> script);
221 // For string calculates an array of line end positions. If the string
222 // does not end with a new line character, this character may optionally be
223 // imagined.
224 Handle<FixedArray> CalculateLineEnds(Handle<String> string,
225                                      bool with_imaginary_last_new_line);
226 int GetScriptLineNumber(Handle<Script> script, int code_position);
227 // The safe version does not make heap allocations but may work much slower.
228 int GetScriptLineNumberSafe(Handle<Script> script, int code_position);
229 int GetScriptColumnNumber(Handle<Script> script, int code_position);
230 
231 // Computes the enumerable keys from interceptors. Used for debug mirrors and
232 // by GetKeysInFixedArrayFor below.
233 v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSReceiver> receiver,
234                                                  Handle<JSObject> object);
235 v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSReceiver> receiver,
236                                                    Handle<JSObject> object);
237 
238 enum KeyCollectionType { LOCAL_ONLY, INCLUDE_PROTOS };
239 
240 // Computes the enumerable keys for a JSObject. Used for implementing
241 // "for (n in object) { }".
242 Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSReceiver> object,
243                                           KeyCollectionType type,
244                                           bool* threw);
245 Handle<JSArray> GetKeysFor(Handle<JSReceiver> object, bool* threw);
246 Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
247                                        bool cache_result);
248 
249 // Computes the union of keys and return the result.
250 // Used for implementing "for (n in object) { }"
251 Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first,
252                                Handle<FixedArray> second);
253 
254 Handle<String> SubString(Handle<String> str,
255                          int start,
256                          int end,
257                          PretenureFlag pretenure = NOT_TENURED);
258 
259 // Sets the expected number of properties for the function's instances.
260 void SetExpectedNofProperties(Handle<JSFunction> func, int nof);
261 
262 // Sets the prototype property for a function instance.
263 void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value);
264 
265 // Sets the expected number of properties based on estimate from compiler.
266 void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared,
267                                           int estimate);
268 
269 
270 Handle<JSGlobalProxy> ReinitializeJSGlobalProxy(
271     Handle<JSFunction> constructor,
272     Handle<JSGlobalProxy> global);
273 
274 Handle<Object> SetPrototype(Handle<JSFunction> function,
275                             Handle<Object> prototype);
276 
277 Handle<ObjectHashSet> ObjectHashSetAdd(Handle<ObjectHashSet> table,
278                                        Handle<Object> key);
279 
280 Handle<ObjectHashSet> ObjectHashSetRemove(Handle<ObjectHashSet> table,
281                                           Handle<Object> key);
282 
283 Handle<ObjectHashTable> PutIntoObjectHashTable(Handle<ObjectHashTable> table,
284                                                Handle<Object> key,
285                                                Handle<Object> value);
286 
287 class NoHandleAllocation BASE_EMBEDDED {
288  public:
289 #ifndef DEBUG
NoHandleAllocation()290   NoHandleAllocation() {}
~NoHandleAllocation()291   ~NoHandleAllocation() {}
292 #else
293   inline NoHandleAllocation();
294   inline ~NoHandleAllocation();
295  private:
296   int level_;
297 #endif
298 };
299 
300 } }  // namespace v8::internal
301 
302 #endif  // V8_HANDLES_H_
303