1 // Copyright 2006-2008 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 "apiutils.h" 32 33 namespace v8 { 34 namespace internal { 35 36 // ---------------------------------------------------------------------------- 37 // A Handle provides a reference to an object that survives relocation by 38 // the garbage collector. 39 // Handles are only valid within a HandleScope. 40 // When a handle is created for an object a cell is allocated in the heap. 41 42 template<class T> 43 class Handle { 44 public: 45 INLINE(Handle(T** location)) { location_ = location; } 46 INLINE(explicit Handle(T* obj)); 47 48 INLINE(Handle()) : location_(NULL) {} 49 50 // Constructor for handling automatic up casting. 51 // Ex. Handle<JSFunction> can be passed when Handle<Object> is expected. 52 template <class S> Handle(Handle<S> handle) { 53 #ifdef DEBUG 54 T* a = NULL; 55 S* b = NULL; 56 a = b; // Fake assignment to enforce type checks. 57 USE(a); 58 #endif 59 location_ = reinterpret_cast<T**>(handle.location()); 60 } 61 62 INLINE(T* operator ->() const) { return operator*(); } 63 64 // Check if this handle refers to the exact same object as the other handle. 65 bool is_identical_to(const Handle<T> other) const { 66 return operator*() == *other; 67 } 68 69 // Provides the C++ dereference operator. 70 INLINE(T* operator*() const); 71 72 // Returns the address to where the raw pointer is stored. 73 T** location() const { 74 ASSERT(location_ == NULL || 75 reinterpret_cast<Address>(*location_) != kZapValue); 76 return location_; 77 } 78 79 template <class S> static Handle<T> cast(Handle<S> that) { 80 T::cast(*that); 81 return Handle<T>(reinterpret_cast<T**>(that.location())); 82 } 83 84 static Handle<T> null() { return Handle<T>(); } 85 bool is_null() { return location_ == NULL; } 86 87 // Closes the given scope, but lets this handle escape. See 88 // implementation in api.h. 89 inline Handle<T> EscapeFrom(v8::HandleScope* scope); 90 91 private: 92 T** location_; 93 }; 94 95 96 // A stack-allocated class that governs a number of local handles. 97 // After a handle scope has been created, all local handles will be 98 // allocated within that handle scope until either the handle scope is 99 // deleted or another handle scope is created. If there is already a 100 // handle scope and a new one is created, all allocations will take 101 // place in the new handle scope until it is deleted. After that, 102 // new handles will again be allocated in the original handle scope. 103 // 104 // After the handle scope of a local handle has been deleted the 105 // garbage collector will no longer track the object stored in the 106 // handle and may deallocate it. The behavior of accessing a handle 107 // for which the handle scope has been deleted is undefined. 108 class HandleScope { 109 public: 110 HandleScope() : previous_(current_) { 111 current_.extensions = 0; 112 } 113 114 ~HandleScope() { 115 Leave(&previous_); 116 } 117 118 // Counts the number of allocated handles. 119 static int NumberOfHandles(); 120 121 // Creates a new handle with the given value. 122 template <typename T> 123 static inline T** CreateHandle(T* value) { 124 internal::Object** cur = current_.next; 125 if (cur == current_.limit) cur = Extend(); 126 // Update the current next field, set the value in the created 127 // handle, and return the result. 128 ASSERT(cur < current_.limit); 129 current_.next = cur + 1; 130 131 T** result = reinterpret_cast<T**>(cur); 132 *result = value; 133 return result; 134 } 135 136 // Deallocates any extensions used by the current scope. 137 static void DeleteExtensions(); 138 139 static Address current_extensions_address(); 140 static Address current_next_address(); 141 static Address current_limit_address(); 142 143 private: 144 // Prevent heap allocation or illegal handle scopes. 145 HandleScope(const HandleScope&); 146 void operator=(const HandleScope&); 147 void* operator new(size_t size); 148 void operator delete(void* size_t); 149 150 static v8::ImplementationUtilities::HandleScopeData current_; 151 const v8::ImplementationUtilities::HandleScopeData previous_; 152 153 // Pushes a fresh handle scope to be used when allocating new handles. 154 static void Enter( 155 v8::ImplementationUtilities::HandleScopeData* previous) { 156 *previous = current_; 157 current_.extensions = 0; 158 } 159 160 // Re-establishes the previous scope state. Should be called only 161 // once, and only for the current scope. 162 static void Leave( 163 const v8::ImplementationUtilities::HandleScopeData* previous) { 164 if (current_.extensions > 0) { 165 DeleteExtensions(); 166 } 167 current_ = *previous; 168 #ifdef DEBUG 169 ZapRange(current_.next, current_.limit); 170 #endif 171 } 172 173 // Extend the handle scope making room for more handles. 174 static internal::Object** Extend(); 175 176 // Zaps the handles in the half-open interval [start, end). 177 static void ZapRange(internal::Object** start, internal::Object** end); 178 179 friend class v8::HandleScope; 180 friend class v8::ImplementationUtilities; 181 }; 182 183 184 // ---------------------------------------------------------------------------- 185 // Handle operations. 186 // They might invoke garbage collection. The result is an handle to 187 // an object of expected type, or the handle is an error if running out 188 // of space or encountering an internal error. 189 190 void NormalizeProperties(Handle<JSObject> object, 191 PropertyNormalizationMode mode, 192 int expected_additional_properties); 193 void NormalizeElements(Handle<JSObject> object); 194 void TransformToFastProperties(Handle<JSObject> object, 195 int unused_property_fields); 196 void FlattenString(Handle<String> str); 197 198 Handle<Object> SetProperty(Handle<JSObject> object, 199 Handle<String> key, 200 Handle<Object> value, 201 PropertyAttributes attributes); 202 203 Handle<Object> SetProperty(Handle<Object> object, 204 Handle<Object> key, 205 Handle<Object> value, 206 PropertyAttributes attributes); 207 208 Handle<Object> ForceSetProperty(Handle<JSObject> object, 209 Handle<Object> key, 210 Handle<Object> value, 211 PropertyAttributes attributes); 212 213 Handle<Object> SetNormalizedProperty(Handle<JSObject> object, 214 Handle<String> key, 215 Handle<Object> value, 216 PropertyDetails details); 217 218 Handle<Object> ForceDeleteProperty(Handle<JSObject> object, 219 Handle<Object> key); 220 221 Handle<Object> IgnoreAttributesAndSetLocalProperty(Handle<JSObject> object, 222 Handle<String> key, 223 Handle<Object> value, 224 PropertyAttributes attributes); 225 226 Handle<Object> SetPropertyWithInterceptor(Handle<JSObject> object, 227 Handle<String> key, 228 Handle<Object> value, 229 PropertyAttributes attributes); 230 231 Handle<Object> SetElement(Handle<JSObject> object, 232 uint32_t index, 233 Handle<Object> value); 234 235 Handle<Object> GetProperty(Handle<JSObject> obj, 236 const char* name); 237 238 Handle<Object> GetProperty(Handle<Object> obj, 239 Handle<Object> key); 240 241 Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver, 242 Handle<JSObject> holder, 243 Handle<String> name, 244 PropertyAttributes* attributes); 245 246 Handle<Object> GetPrototype(Handle<Object> obj); 247 248 Handle<Object> SetPrototype(Handle<JSObject> obj, Handle<Object> value); 249 250 // Return the object's hidden properties object. If the object has no hidden 251 // properties and create_if_needed is true, then a new hidden property object 252 // will be allocated. Otherwise the Heap::undefined_value is returned. 253 Handle<Object> GetHiddenProperties(Handle<JSObject> obj, bool create_if_needed); 254 255 Handle<Object> DeleteElement(Handle<JSObject> obj, uint32_t index); 256 Handle<Object> DeleteProperty(Handle<JSObject> obj, Handle<String> prop); 257 258 Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index); 259 260 Handle<JSObject> Copy(Handle<JSObject> obj); 261 262 Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray>, 263 Handle<JSArray> array); 264 265 // Get the JS object corresponding to the given script; create it 266 // if none exists. 267 Handle<JSValue> GetScriptWrapper(Handle<Script> script); 268 269 // Script line number computations. 270 void InitScriptLineEnds(Handle<Script> script); 271 int GetScriptLineNumber(Handle<Script> script, int code_position); 272 273 // Computes the enumerable keys from interceptors. Used for debug mirrors and 274 // by GetKeysInFixedArrayFor below. 275 v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSObject> receiver, 276 Handle<JSObject> object); 277 v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSObject> receiver, 278 Handle<JSObject> object); 279 280 enum KeyCollectionType { LOCAL_ONLY, INCLUDE_PROTOS }; 281 282 // Computes the enumerable keys for a JSObject. Used for implementing 283 // "for (n in object) { }". 284 Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSObject> object, 285 KeyCollectionType type); 286 Handle<JSArray> GetKeysFor(Handle<JSObject> object); 287 Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object, 288 bool cache_result); 289 290 // Computes the union of keys and return the result. 291 // Used for implementing "for (n in object) { }" 292 Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first, 293 Handle<FixedArray> second); 294 295 Handle<String> SubString(Handle<String> str, int start, int end); 296 297 298 // Sets the expected number of properties for the function's instances. 299 void SetExpectedNofProperties(Handle<JSFunction> func, int nof); 300 301 // Sets the prototype property for a function instance. 302 void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value); 303 304 // Sets the expected number of properties based on estimate from compiler. 305 void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared, 306 int estimate); 307 void SetExpectedNofPropertiesFromEstimate(Handle<JSFunction> func, 308 int estimate); 309 310 311 Handle<JSGlobalProxy> ReinitializeJSGlobalProxy( 312 Handle<JSFunction> constructor, 313 Handle<JSGlobalProxy> global); 314 315 Handle<Object> SetPrototype(Handle<JSFunction> function, 316 Handle<Object> prototype); 317 318 319 // Does lazy compilation of the given function. Returns true on success and 320 // false if the compilation resulted in a stack overflow. 321 enum ClearExceptionFlag { KEEP_EXCEPTION, CLEAR_EXCEPTION }; 322 323 bool EnsureCompiled(Handle<SharedFunctionInfo> shared, 324 ClearExceptionFlag flag); 325 326 bool CompileLazyShared(Handle<SharedFunctionInfo> shared, 327 ClearExceptionFlag flag); 328 329 bool CompileLazy(Handle<JSFunction> function, 330 Handle<Object> receiver, 331 ClearExceptionFlag flag); 332 333 bool CompileLazyInLoop(Handle<JSFunction> function, 334 Handle<Object> receiver, 335 ClearExceptionFlag flag); 336 337 // Returns the lazy compilation stub for argc arguments. 338 Handle<Code> ComputeLazyCompile(int argc); 339 340 class NoHandleAllocation BASE_EMBEDDED { 341 public: 342 #ifndef DEBUG 343 NoHandleAllocation() {} 344 ~NoHandleAllocation() {} 345 #else 346 inline NoHandleAllocation(); 347 inline ~NoHandleAllocation(); 348 private: 349 int extensions_; 350 #endif 351 }; 352 353 354 // ---------------------------------------------------------------------------- 355 356 357 // Stack allocated wrapper call for optimizing adding multiple 358 // properties to an object. 359 class OptimizedObjectForAddingMultipleProperties BASE_EMBEDDED { 360 public: 361 OptimizedObjectForAddingMultipleProperties(Handle<JSObject> object, 362 int expected_property_count, 363 bool condition = true); 364 ~OptimizedObjectForAddingMultipleProperties(); 365 private: 366 bool has_been_transformed_; // Tells whether the object has been transformed. 367 int unused_property_fields_; // Captures the unused number of field. 368 Handle<JSObject> object_; // The object being optimized. 369 }; 370 371 372 } } // namespace v8::internal 373 374 #endif // V8_HANDLES_H_ 375
