handles.h revision b0fe1620dcb4135ac3ab2d66ff93072373911299
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(explicit 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() : prev_next_(current_.next), prev_limit_(current_.limit) { 111 current_.level++; 112 } 113 114 ~HandleScope() { 115 current_.next = prev_next_; 116 current_.level--; 117 if (current_.limit != prev_limit_) { 118 current_.limit = prev_limit_; 119 DeleteExtensions(); 120 } 121#ifdef DEBUG 122 ZapRange(prev_next_, prev_limit_); 123#endif 124 } 125 126 // Counts the number of allocated handles. 127 static int NumberOfHandles(); 128 129 // Creates a new handle with the given value. 130 template <typename T> 131 static inline T** CreateHandle(T* value) { 132 internal::Object** cur = current_.next; 133 if (cur == current_.limit) cur = Extend(); 134 // Update the current next field, set the value in the created 135 // handle, and return the result. 136 ASSERT(cur < current_.limit); 137 current_.next = cur + 1; 138 139 T** result = reinterpret_cast<T**>(cur); 140 *result = value; 141 return result; 142 } 143 144 // Deallocates any extensions used by the current scope. 145 static void DeleteExtensions(); 146 147 static Address current_next_address(); 148 static Address current_limit_address(); 149 static Address current_level_address(); 150 151 private: 152 // Prevent heap allocation or illegal handle scopes. 153 HandleScope(const HandleScope&); 154 void operator=(const HandleScope&); 155 void* operator new(size_t size); 156 void operator delete(void* size_t); 157 158 static v8::ImplementationUtilities::HandleScopeData current_; 159 Object** const prev_next_; 160 Object** const prev_limit_; 161 162 // Extend the handle scope making room for more handles. 163 static internal::Object** Extend(); 164 165 // Zaps the handles in the half-open interval [start, end). 166 static void ZapRange(internal::Object** start, internal::Object** end); 167 168 friend class v8::HandleScope; 169 friend class v8::ImplementationUtilities; 170}; 171 172 173// ---------------------------------------------------------------------------- 174// Handle operations. 175// They might invoke garbage collection. The result is an handle to 176// an object of expected type, or the handle is an error if running out 177// of space or encountering an internal error. 178 179void NormalizeProperties(Handle<JSObject> object, 180 PropertyNormalizationMode mode, 181 int expected_additional_properties); 182void NormalizeElements(Handle<JSObject> object); 183void TransformToFastProperties(Handle<JSObject> object, 184 int unused_property_fields); 185void NumberDictionarySet(Handle<NumberDictionary> dictionary, 186 uint32_t index, 187 Handle<Object> value, 188 PropertyDetails details); 189 190// Flattens a string. 191void FlattenString(Handle<String> str); 192 193// Flattens a string and returns the underlying external or sequential 194// string. 195Handle<String> FlattenGetString(Handle<String> str); 196 197Handle<Object> SetProperty(Handle<JSObject> object, 198 Handle<String> key, 199 Handle<Object> value, 200 PropertyAttributes attributes); 201 202Handle<Object> SetProperty(Handle<Object> object, 203 Handle<Object> key, 204 Handle<Object> value, 205 PropertyAttributes attributes); 206 207Handle<Object> ForceSetProperty(Handle<JSObject> object, 208 Handle<Object> key, 209 Handle<Object> value, 210 PropertyAttributes attributes); 211 212Handle<Object> SetNormalizedProperty(Handle<JSObject> object, 213 Handle<String> key, 214 Handle<Object> value, 215 PropertyDetails details); 216 217Handle<Object> ForceDeleteProperty(Handle<JSObject> object, 218 Handle<Object> key); 219 220Handle<Object> IgnoreAttributesAndSetLocalProperty(Handle<JSObject> object, 221 Handle<String> key, 222 Handle<Object> value, 223 PropertyAttributes attributes); 224 225Handle<Object> SetPropertyWithInterceptor(Handle<JSObject> object, 226 Handle<String> key, 227 Handle<Object> value, 228 PropertyAttributes attributes); 229 230Handle<Object> SetElement(Handle<JSObject> object, 231 uint32_t index, 232 Handle<Object> value); 233 234Handle<Object> GetProperty(Handle<JSObject> obj, 235 const char* name); 236 237Handle<Object> GetProperty(Handle<Object> obj, 238 Handle<Object> key); 239 240Handle<Object> GetElement(Handle<Object> obj, 241 uint32_t index); 242 243Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver, 244 Handle<JSObject> holder, 245 Handle<String> name, 246 PropertyAttributes* attributes); 247 248Handle<Object> GetPrototype(Handle<Object> obj); 249 250Handle<Object> SetPrototype(Handle<JSObject> obj, Handle<Object> value); 251 252// Return the object's hidden properties object. If the object has no hidden 253// properties and create_if_needed is true, then a new hidden property object 254// will be allocated. Otherwise the Heap::undefined_value is returned. 255Handle<Object> GetHiddenProperties(Handle<JSObject> obj, bool create_if_needed); 256 257Handle<Object> DeleteElement(Handle<JSObject> obj, uint32_t index); 258Handle<Object> DeleteProperty(Handle<JSObject> obj, Handle<String> prop); 259 260Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index); 261 262Handle<JSObject> Copy(Handle<JSObject> obj); 263 264Handle<Object> SetAccessor(Handle<JSObject> obj, Handle<AccessorInfo> info); 265 266Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray>, 267 Handle<JSArray> array); 268 269// Get the JS object corresponding to the given script; create it 270// if none exists. 271Handle<JSValue> GetScriptWrapper(Handle<Script> script); 272 273// Script line number computations. 274void InitScriptLineEnds(Handle<Script> script); 275// For string calculates an array of line end positions. If the string 276// does not end with a new line character, this character may optionally be 277// imagined. 278Handle<FixedArray> CalculateLineEnds(Handle<String> string, 279 bool with_imaginary_last_new_line); 280int GetScriptLineNumber(Handle<Script> script, int code_position); 281// The safe version does not make heap allocations but may work much slower. 282int GetScriptLineNumberSafe(Handle<Script> script, int code_position); 283 284// Computes the enumerable keys from interceptors. Used for debug mirrors and 285// by GetKeysInFixedArrayFor below. 286v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSObject> receiver, 287 Handle<JSObject> object); 288v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSObject> receiver, 289 Handle<JSObject> object); 290 291enum KeyCollectionType { LOCAL_ONLY, INCLUDE_PROTOS }; 292 293// Computes the enumerable keys for a JSObject. Used for implementing 294// "for (n in object) { }". 295Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSObject> object, 296 KeyCollectionType type); 297Handle<JSArray> GetKeysFor(Handle<JSObject> object); 298Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object, 299 bool cache_result); 300 301// Computes the union of keys and return the result. 302// Used for implementing "for (n in object) { }" 303Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first, 304 Handle<FixedArray> second); 305 306Handle<String> SubString(Handle<String> str, 307 int start, 308 int end, 309 PretenureFlag pretenure = NOT_TENURED); 310 311 312// Sets the expected number of properties for the function's instances. 313void SetExpectedNofProperties(Handle<JSFunction> func, int nof); 314 315// Sets the prototype property for a function instance. 316void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value); 317 318// Sets the expected number of properties based on estimate from compiler. 319void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared, 320 int estimate); 321 322 323Handle<JSGlobalProxy> ReinitializeJSGlobalProxy( 324 Handle<JSFunction> constructor, 325 Handle<JSGlobalProxy> global); 326 327Handle<Object> SetPrototype(Handle<JSFunction> function, 328 Handle<Object> prototype); 329 330 331// Does lazy compilation of the given function. Returns true on success and 332// false if the compilation resulted in a stack overflow. 333enum ClearExceptionFlag { KEEP_EXCEPTION, CLEAR_EXCEPTION }; 334 335bool EnsureCompiled(Handle<SharedFunctionInfo> shared, 336 ClearExceptionFlag flag); 337 338bool CompileLazyShared(Handle<SharedFunctionInfo> shared, 339 ClearExceptionFlag flag); 340 341bool CompileLazy(Handle<JSFunction> function, ClearExceptionFlag flag); 342 343bool CompileLazyInLoop(Handle<JSFunction> function, ClearExceptionFlag flag); 344 345bool CompileOptimized(Handle<JSFunction> function, int osr_ast_id); 346 347class NoHandleAllocation BASE_EMBEDDED { 348 public: 349#ifndef DEBUG 350 NoHandleAllocation() {} 351 ~NoHandleAllocation() {} 352#else 353 inline NoHandleAllocation(); 354 inline ~NoHandleAllocation(); 355 private: 356 int level_; 357#endif 358}; 359 360 361// ---------------------------------------------------------------------------- 362 363 364// Stack allocated wrapper call for optimizing adding multiple 365// properties to an object. 366class OptimizedObjectForAddingMultipleProperties BASE_EMBEDDED { 367 public: 368 OptimizedObjectForAddingMultipleProperties(Handle<JSObject> object, 369 int expected_property_count, 370 bool condition = true); 371 ~OptimizedObjectForAddingMultipleProperties(); 372 private: 373 bool has_been_transformed_; // Tells whether the object has been transformed. 374 int unused_property_fields_; // Captures the unused number of field. 375 Handle<JSObject> object_; // The object being optimized. 376}; 377 378 379} } // namespace v8::internal 380 381#endif // V8_HANDLES_H_ 382