handles.h revision 3100271588b61cbc1dc472a3f2f105d2eed8497f
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 33namespace v8 { 34namespace 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 42template<class T> 43class 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. 108class 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 190void NormalizeProperties(Handle<JSObject> object, 191 PropertyNormalizationMode mode, 192 int expected_additional_properties); 193void NormalizeElements(Handle<JSObject> object); 194void TransformToFastProperties(Handle<JSObject> object, 195 int unused_property_fields); 196void FlattenString(Handle<String> str); 197 198Handle<Object> SetProperty(Handle<JSObject> object, 199 Handle<String> key, 200 Handle<Object> value, 201 PropertyAttributes attributes); 202 203Handle<Object> SetProperty(Handle<Object> object, 204 Handle<Object> key, 205 Handle<Object> value, 206 PropertyAttributes attributes); 207 208Handle<Object> ForceSetProperty(Handle<JSObject> object, 209 Handle<Object> key, 210 Handle<Object> value, 211 PropertyAttributes attributes); 212 213Handle<Object> SetNormalizedProperty(Handle<JSObject> object, 214 Handle<String> key, 215 Handle<Object> value, 216 PropertyDetails details); 217 218Handle<Object> ForceDeleteProperty(Handle<JSObject> object, 219 Handle<Object> key); 220 221Handle<Object> IgnoreAttributesAndSetLocalProperty(Handle<JSObject> object, 222 Handle<String> key, 223 Handle<Object> value, 224 PropertyAttributes attributes); 225 226Handle<Object> SetPropertyWithInterceptor(Handle<JSObject> object, 227 Handle<String> key, 228 Handle<Object> value, 229 PropertyAttributes attributes); 230 231Handle<Object> SetElement(Handle<JSObject> object, 232 uint32_t index, 233 Handle<Object> value); 234 235Handle<Object> GetProperty(Handle<JSObject> obj, 236 const char* name); 237 238Handle<Object> GetProperty(Handle<Object> obj, 239 Handle<Object> key); 240 241Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver, 242 Handle<JSObject> holder, 243 Handle<String> name, 244 PropertyAttributes* attributes); 245 246Handle<Object> GetPrototype(Handle<Object> obj); 247 248// Return the object's hidden properties object. If the object has no hidden 249// properties and create_if_needed is true, then a new hidden property object 250// will be allocated. Otherwise the Heap::undefined_value is returned. 251Handle<Object> GetHiddenProperties(Handle<JSObject> obj, bool create_if_needed); 252 253Handle<Object> DeleteElement(Handle<JSObject> obj, uint32_t index); 254Handle<Object> DeleteProperty(Handle<JSObject> obj, Handle<String> prop); 255 256Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index); 257 258Handle<JSObject> Copy(Handle<JSObject> obj); 259 260Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray>, 261 Handle<JSArray> array); 262 263// Get the JS object corresponding to the given script; create it 264// if none exists. 265Handle<JSValue> GetScriptWrapper(Handle<Script> script); 266 267// Script line number computations. 268void InitScriptLineEnds(Handle<Script> script); 269int GetScriptLineNumber(Handle<Script> script, int code_position); 270 271// Computes the enumerable keys from interceptors. Used for debug mirrors and 272// by GetKeysInFixedArrayFor below. 273v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSObject> receiver, 274 Handle<JSObject> object); 275v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSObject> receiver, 276 Handle<JSObject> object); 277 278enum KeyCollectionType { LOCAL_ONLY, INCLUDE_PROTOS }; 279 280// Computes the enumerable keys for a JSObject. Used for implementing 281// "for (n in object) { }". 282Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSObject> object, 283 KeyCollectionType type); 284Handle<JSArray> GetKeysFor(Handle<JSObject> object); 285Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object, 286 bool cache_result); 287 288// Computes the union of keys and return the result. 289// Used for implementing "for (n in object) { }" 290Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first, 291 Handle<FixedArray> second); 292 293Handle<String> SubString(Handle<String> str, int start, int end); 294 295 296// Sets the expected number of properties for the function's instances. 297void SetExpectedNofProperties(Handle<JSFunction> func, int nof); 298 299// Sets the prototype property for a function instance. 300void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value); 301 302// Sets the expected number of properties based on estimate from compiler. 303void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared, 304 int estimate); 305void SetExpectedNofPropertiesFromEstimate(Handle<JSFunction> func, 306 int estimate); 307 308 309Handle<JSGlobalProxy> ReinitializeJSGlobalProxy( 310 Handle<JSFunction> constructor, 311 Handle<JSGlobalProxy> global); 312 313Handle<Object> SetPrototype(Handle<JSFunction> function, 314 Handle<Object> prototype); 315 316 317// Does lazy compilation of the given function. Returns true on success and 318// false if the compilation resulted in a stack overflow. 319enum ClearExceptionFlag { KEEP_EXCEPTION, CLEAR_EXCEPTION }; 320 321bool EnsureCompiled(Handle<SharedFunctionInfo> shared, 322 ClearExceptionFlag flag); 323 324bool CompileLazyShared(Handle<SharedFunctionInfo> shared, 325 ClearExceptionFlag flag); 326 327bool CompileLazy(Handle<JSFunction> function, 328 Handle<Object> receiver, 329 ClearExceptionFlag flag); 330 331bool CompileLazyInLoop(Handle<JSFunction> function, 332 Handle<Object> receiver, 333 ClearExceptionFlag flag); 334 335// Returns the lazy compilation stub for argc arguments. 336Handle<Code> ComputeLazyCompile(int argc); 337 338class NoHandleAllocation BASE_EMBEDDED { 339 public: 340#ifndef DEBUG 341 NoHandleAllocation() {} 342 ~NoHandleAllocation() {} 343#else 344 inline NoHandleAllocation(); 345 inline ~NoHandleAllocation(); 346 private: 347 int extensions_; 348#endif 349}; 350 351 352// ---------------------------------------------------------------------------- 353 354 355// Stack allocated wrapper call for optimizing adding multiple 356// properties to an object. 357class OptimizedObjectForAddingMultipleProperties BASE_EMBEDDED { 358 public: 359 OptimizedObjectForAddingMultipleProperties(Handle<JSObject> object, 360 int expected_property_count, 361 bool condition = true); 362 ~OptimizedObjectForAddingMultipleProperties(); 363 private: 364 bool has_been_transformed_; // Tells whether the object has been transformed. 365 int unused_property_fields_; // Captures the unused number of field. 366 Handle<JSObject> object_; // The object being optimized. 367}; 368 369 370} } // namespace v8::internal 371 372#endif // V8_HANDLES_H_ 373