1 // Copyright 2012 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_CONTEXTS_H_ 29 #define V8_CONTEXTS_H_ 30 31 #include "heap.h" 32 #include "objects.h" 33 34 namespace v8 { 35 namespace internal { 36 37 38 enum ContextLookupFlags { 39 FOLLOW_CONTEXT_CHAIN = 1, 40 FOLLOW_PROTOTYPE_CHAIN = 2, 41 42 DONT_FOLLOW_CHAINS = 0, 43 FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN 44 }; 45 46 47 // ES5 10.2 defines lexical environments with mutable and immutable bindings. 48 // Immutable bindings have two states, initialized and uninitialized, and 49 // their state is changed by the InitializeImmutableBinding method. The 50 // BindingFlags enum represents information if a binding has definitely been 51 // initialized. A mutable binding does not need to be checked and thus has 52 // the BindingFlag MUTABLE_IS_INITIALIZED. 53 // 54 // There are two possibilities for immutable bindings 55 // * 'const' declared variables. They are initialized when evaluating the 56 // corresponding declaration statement. They need to be checked for being 57 // initialized and thus get the flag IMMUTABLE_CHECK_INITIALIZED. 58 // * The function name of a named function literal. The binding is immediately 59 // initialized when entering the function and thus does not need to be 60 // checked. it gets the BindingFlag IMMUTABLE_IS_INITIALIZED. 61 // Accessing an uninitialized binding produces the undefined value. 62 // 63 // The harmony proposal for block scoped bindings also introduces the 64 // uninitialized state for mutable bindings. 65 // * A 'let' declared variable. They are initialized when evaluating the 66 // corresponding declaration statement. They need to be checked for being 67 // initialized and thus get the flag MUTABLE_CHECK_INITIALIZED. 68 // * A 'var' declared variable. It is initialized immediately upon creation 69 // and thus doesn't need to be checked. It gets the flag 70 // MUTABLE_IS_INITIALIZED. 71 // * Catch bound variables, function parameters and variables introduced by 72 // function declarations are initialized immediately and do not need to be 73 // checked. Thus they get the flag MUTABLE_IS_INITIALIZED. 74 // Immutable bindings in harmony mode get the _HARMONY flag variants. Accessing 75 // an uninitialized binding produces a reference error. 76 // 77 // In V8 uninitialized bindings are set to the hole value upon creation and set 78 // to a different value upon initialization. 79 enum BindingFlags { 80 MUTABLE_IS_INITIALIZED, 81 MUTABLE_CHECK_INITIALIZED, 82 IMMUTABLE_IS_INITIALIZED, 83 IMMUTABLE_CHECK_INITIALIZED, 84 IMMUTABLE_IS_INITIALIZED_HARMONY, 85 IMMUTABLE_CHECK_INITIALIZED_HARMONY, 86 MISSING_BINDING 87 }; 88 89 90 // Heap-allocated activation contexts. 91 // 92 // Contexts are implemented as FixedArray objects; the Context 93 // class is a convenience interface casted on a FixedArray object. 94 // 95 // Note: Context must have no virtual functions and Context objects 96 // must always be allocated via Heap::AllocateContext() or 97 // Factory::NewContext. 98 99 #define NATIVE_CONTEXT_FIELDS(V) \ 100 V(GLOBAL_PROXY_INDEX, JSObject, global_proxy_object) \ 101 V(SECURITY_TOKEN_INDEX, Object, security_token) \ 102 V(BOOLEAN_FUNCTION_INDEX, JSFunction, boolean_function) \ 103 V(NUMBER_FUNCTION_INDEX, JSFunction, number_function) \ 104 V(STRING_FUNCTION_INDEX, JSFunction, string_function) \ 105 V(STRING_FUNCTION_PROTOTYPE_MAP_INDEX, Map, string_function_prototype_map) \ 106 V(SYMBOL_FUNCTION_INDEX, JSFunction, symbol_function) \ 107 V(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \ 108 V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function) \ 109 V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \ 110 V(JS_ARRAY_MAPS_INDEX, Object, js_array_maps) \ 111 V(DATE_FUNCTION_INDEX, JSFunction, date_function) \ 112 V(JSON_OBJECT_INDEX, JSObject, json_object) \ 113 V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function) \ 114 V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype) \ 115 V(INITIAL_ARRAY_PROTOTYPE_INDEX, JSObject, initial_array_prototype) \ 116 V(CREATE_DATE_FUN_INDEX, JSFunction, create_date_fun) \ 117 V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun) \ 118 V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun) \ 119 V(TO_DETAIL_STRING_FUN_INDEX, JSFunction, to_detail_string_fun) \ 120 V(TO_OBJECT_FUN_INDEX, JSFunction, to_object_fun) \ 121 V(TO_INTEGER_FUN_INDEX, JSFunction, to_integer_fun) \ 122 V(TO_UINT32_FUN_INDEX, JSFunction, to_uint32_fun) \ 123 V(TO_INT32_FUN_INDEX, JSFunction, to_int32_fun) \ 124 V(GLOBAL_EVAL_FUN_INDEX, JSFunction, global_eval_fun) \ 125 V(INSTANTIATE_FUN_INDEX, JSFunction, instantiate_fun) \ 126 V(CONFIGURE_INSTANCE_FUN_INDEX, JSFunction, configure_instance_fun) \ 127 V(ARRAY_BUFFER_FUN_INDEX, JSFunction, array_buffer_fun) \ 128 V(UINT8_ARRAY_FUN_INDEX, JSFunction, uint8_array_fun) \ 129 V(INT8_ARRAY_FUN_INDEX, JSFunction, int8_array_fun) \ 130 V(UINT16_ARRAY_FUN_INDEX, JSFunction, uint16_array_fun) \ 131 V(INT16_ARRAY_FUN_INDEX, JSFunction, int16_array_fun) \ 132 V(UINT32_ARRAY_FUN_INDEX, JSFunction, uint32_array_fun) \ 133 V(INT32_ARRAY_FUN_INDEX, JSFunction, int32_array_fun) \ 134 V(FLOAT_ARRAY_FUN_INDEX, JSFunction, float_array_fun) \ 135 V(DOUBLE_ARRAY_FUN_INDEX, JSFunction, double_array_fun) \ 136 V(UINT8C_ARRAY_FUN_INDEX, JSFunction, uint8c_array_fun) \ 137 V(DATA_VIEW_FUN_INDEX, JSFunction, data_view_fun) \ 138 V(FUNCTION_MAP_INDEX, Map, function_map) \ 139 V(STRICT_MODE_FUNCTION_MAP_INDEX, Map, strict_mode_function_map) \ 140 V(FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, function_without_prototype_map) \ 141 V(STRICT_MODE_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \ 142 strict_mode_function_without_prototype_map) \ 143 V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map)\ 144 V(ARGUMENTS_BOILERPLATE_INDEX, JSObject, arguments_boilerplate) \ 145 V(ALIASED_ARGUMENTS_BOILERPLATE_INDEX, JSObject, \ 146 aliased_arguments_boilerplate) \ 147 V(STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX, JSObject, \ 148 strict_mode_arguments_boilerplate) \ 149 V(MESSAGE_LISTENERS_INDEX, JSObject, message_listeners) \ 150 V(MAKE_MESSAGE_FUN_INDEX, JSFunction, make_message_fun) \ 151 V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun) \ 152 V(CONFIGURE_GLOBAL_INDEX, JSFunction, configure_global_fun) \ 153 V(FUNCTION_CACHE_INDEX, JSObject, function_cache) \ 154 V(JSFUNCTION_RESULT_CACHES_INDEX, FixedArray, jsfunction_result_caches) \ 155 V(NORMALIZED_MAP_CACHE_INDEX, NormalizedMapCache, normalized_map_cache) \ 156 V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \ 157 V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \ 158 V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction, \ 159 call_as_constructor_delegate) \ 160 V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \ 161 V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \ 162 V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \ 163 V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \ 164 V(MAP_CACHE_INDEX, Object, map_cache) \ 165 V(EMBEDDER_DATA_INDEX, FixedArray, embedder_data) \ 166 V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \ 167 V(ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX, Object, \ 168 error_message_for_code_gen_from_strings) \ 169 V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \ 170 to_complete_property_descriptor) \ 171 V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \ 172 V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \ 173 V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) \ 174 V(PROXY_ENUMERATE_INDEX, JSFunction, proxy_enumerate) \ 175 V(OBSERVERS_NOTIFY_CHANGE_INDEX, JSFunction, observers_notify_change) \ 176 V(OBSERVERS_ENQUEUE_SPLICE_INDEX, JSFunction, observers_enqueue_splice) \ 177 V(OBSERVERS_BEGIN_SPLICE_INDEX, JSFunction, \ 178 observers_begin_perform_splice) \ 179 V(OBSERVERS_END_SPLICE_INDEX, JSFunction, \ 180 observers_end_perform_splice) \ 181 V(OBSERVERS_DELIVER_CHANGES_INDEX, JSFunction, observers_deliver_changes) \ 182 V(GENERATOR_FUNCTION_MAP_INDEX, Map, generator_function_map) \ 183 V(STRICT_MODE_GENERATOR_FUNCTION_MAP_INDEX, Map, \ 184 strict_mode_generator_function_map) \ 185 V(GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX, Map, \ 186 generator_object_prototype_map) \ 187 V(GENERATOR_RESULT_MAP_INDEX, Map, generator_result_map) \ 188 V(RANDOM_SEED_INDEX, ByteArray, random_seed) 189 190 // JSFunctions are pairs (context, function code), sometimes also called 191 // closures. A Context object is used to represent function contexts and 192 // dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak). 193 // 194 // At runtime, the contexts build a stack in parallel to the execution 195 // stack, with the top-most context being the current context. All contexts 196 // have the following slots: 197 // 198 // [ closure ] This is the current function. It is the same for all 199 // contexts inside a function. It provides access to the 200 // incoming context (i.e., the outer context, which may 201 // or may not become the current function's context), and 202 // it provides access to the functions code and thus it's 203 // scope information, which in turn contains the names of 204 // statically allocated context slots. The names are needed 205 // for dynamic lookups in the presence of 'with' or 'eval'. 206 // 207 // [ previous ] A pointer to the previous context. It is NULL for 208 // function contexts, and non-NULL for 'with' contexts. 209 // Used to implement the 'with' statement. 210 // 211 // [ extension ] A pointer to an extension JSObject, or NULL. Used to 212 // implement 'with' statements and dynamic declarations 213 // (through 'eval'). The object in a 'with' statement is 214 // stored in the extension slot of a 'with' context. 215 // Dynamically declared variables/functions are also added 216 // to lazily allocated extension object. Context::Lookup 217 // searches the extension object for properties. 218 // For global and block contexts, contains the respective 219 // ScopeInfo. 220 // For module contexts, points back to the respective JSModule. 221 // 222 // [ global_object ] A pointer to the global object. Provided for quick 223 // access to the global object from inside the code (since 224 // we always have a context pointer). 225 // 226 // In addition, function contexts may have statically allocated context slots 227 // to store local variables/functions that are accessed from inner functions 228 // (via static context addresses) or through 'eval' (dynamic context lookups). 229 // Finally, the native context contains additional slots for fast access to 230 // native properties. 231 232 class Context: public FixedArray { 233 public: 234 // Conversions. 235 static Context* cast(Object* context) { 236 ASSERT(context->IsContext()); 237 return reinterpret_cast<Context*>(context); 238 } 239 240 // The default context slot layout; indices are FixedArray slot indices. 241 enum { 242 // These slots are in all contexts. 243 CLOSURE_INDEX, 244 PREVIOUS_INDEX, 245 // The extension slot is used for either the global object (in global 246 // contexts), eval extension object (function contexts), subject of with 247 // (with contexts), or the variable name (catch contexts), the serialized 248 // scope info (block contexts), or the module instance (module contexts). 249 EXTENSION_INDEX, 250 GLOBAL_OBJECT_INDEX, 251 MIN_CONTEXT_SLOTS, 252 253 // This slot holds the thrown value in catch contexts. 254 THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS, 255 256 // These slots are only in native contexts. 257 GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS, 258 SECURITY_TOKEN_INDEX, 259 ARGUMENTS_BOILERPLATE_INDEX, 260 ALIASED_ARGUMENTS_BOILERPLATE_INDEX, 261 STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX, 262 REGEXP_RESULT_MAP_INDEX, 263 FUNCTION_MAP_INDEX, 264 STRICT_MODE_FUNCTION_MAP_INDEX, 265 FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, 266 STRICT_MODE_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, 267 INITIAL_OBJECT_PROTOTYPE_INDEX, 268 INITIAL_ARRAY_PROTOTYPE_INDEX, 269 BOOLEAN_FUNCTION_INDEX, 270 NUMBER_FUNCTION_INDEX, 271 STRING_FUNCTION_INDEX, 272 STRING_FUNCTION_PROTOTYPE_MAP_INDEX, 273 SYMBOL_FUNCTION_INDEX, 274 OBJECT_FUNCTION_INDEX, 275 INTERNAL_ARRAY_FUNCTION_INDEX, 276 ARRAY_FUNCTION_INDEX, 277 JS_ARRAY_MAPS_INDEX, 278 DATE_FUNCTION_INDEX, 279 JSON_OBJECT_INDEX, 280 REGEXP_FUNCTION_INDEX, 281 CREATE_DATE_FUN_INDEX, 282 TO_NUMBER_FUN_INDEX, 283 TO_STRING_FUN_INDEX, 284 TO_DETAIL_STRING_FUN_INDEX, 285 TO_OBJECT_FUN_INDEX, 286 TO_INTEGER_FUN_INDEX, 287 TO_UINT32_FUN_INDEX, 288 TO_INT32_FUN_INDEX, 289 TO_BOOLEAN_FUN_INDEX, 290 GLOBAL_EVAL_FUN_INDEX, 291 INSTANTIATE_FUN_INDEX, 292 CONFIGURE_INSTANCE_FUN_INDEX, 293 ARRAY_BUFFER_FUN_INDEX, 294 UINT8_ARRAY_FUN_INDEX, 295 INT8_ARRAY_FUN_INDEX, 296 UINT16_ARRAY_FUN_INDEX, 297 INT16_ARRAY_FUN_INDEX, 298 UINT32_ARRAY_FUN_INDEX, 299 INT32_ARRAY_FUN_INDEX, 300 FLOAT_ARRAY_FUN_INDEX, 301 DOUBLE_ARRAY_FUN_INDEX, 302 UINT8C_ARRAY_FUN_INDEX, 303 DATA_VIEW_FUN_INDEX, 304 MESSAGE_LISTENERS_INDEX, 305 MAKE_MESSAGE_FUN_INDEX, 306 GET_STACK_TRACE_LINE_INDEX, 307 CONFIGURE_GLOBAL_INDEX, 308 FUNCTION_CACHE_INDEX, 309 JSFUNCTION_RESULT_CACHES_INDEX, 310 NORMALIZED_MAP_CACHE_INDEX, 311 RUNTIME_CONTEXT_INDEX, 312 CALL_AS_FUNCTION_DELEGATE_INDEX, 313 CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, 314 SCRIPT_FUNCTION_INDEX, 315 OPAQUE_REFERENCE_FUNCTION_INDEX, 316 CONTEXT_EXTENSION_FUNCTION_INDEX, 317 OUT_OF_MEMORY_INDEX, 318 EMBEDDER_DATA_INDEX, 319 ALLOW_CODE_GEN_FROM_STRINGS_INDEX, 320 ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX, 321 TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, 322 DERIVED_HAS_TRAP_INDEX, 323 DERIVED_GET_TRAP_INDEX, 324 DERIVED_SET_TRAP_INDEX, 325 PROXY_ENUMERATE_INDEX, 326 OBSERVERS_NOTIFY_CHANGE_INDEX, 327 OBSERVERS_ENQUEUE_SPLICE_INDEX, 328 OBSERVERS_BEGIN_SPLICE_INDEX, 329 OBSERVERS_END_SPLICE_INDEX, 330 OBSERVERS_DELIVER_CHANGES_INDEX, 331 GENERATOR_FUNCTION_MAP_INDEX, 332 STRICT_MODE_GENERATOR_FUNCTION_MAP_INDEX, 333 GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX, 334 GENERATOR_RESULT_MAP_INDEX, 335 RANDOM_SEED_INDEX, 336 337 // Properties from here are treated as weak references by the full GC. 338 // Scavenge treats them as strong references. 339 OPTIMIZED_FUNCTIONS_LIST, // Weak. 340 MAP_CACHE_INDEX, // Weak. 341 NEXT_CONTEXT_LINK, // Weak. 342 343 // Total number of slots. 344 NATIVE_CONTEXT_SLOTS, 345 346 FIRST_WEAK_SLOT = OPTIMIZED_FUNCTIONS_LIST 347 }; 348 349 // Direct slot access. 350 JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); } 351 void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); } 352 353 Context* previous() { 354 Object* result = unchecked_previous(); 355 ASSERT(IsBootstrappingOrValidParentContext(result, this)); 356 return reinterpret_cast<Context*>(result); 357 } 358 void set_previous(Context* context) { set(PREVIOUS_INDEX, context); } 359 360 bool has_extension() { return extension() != NULL; } 361 Object* extension() { return get(EXTENSION_INDEX); } 362 void set_extension(Object* object) { set(EXTENSION_INDEX, object); } 363 364 JSModule* module() { return JSModule::cast(get(EXTENSION_INDEX)); } 365 void set_module(JSModule* module) { set(EXTENSION_INDEX, module); } 366 367 // Get the context where var declarations will be hoisted to, which 368 // may be the context itself. 369 Context* declaration_context(); 370 371 GlobalObject* global_object() { 372 Object* result = get(GLOBAL_OBJECT_INDEX); 373 ASSERT(IsBootstrappingOrGlobalObject(result)); 374 return reinterpret_cast<GlobalObject*>(result); 375 } 376 void set_global_object(GlobalObject* object) { 377 set(GLOBAL_OBJECT_INDEX, object); 378 } 379 380 // Returns a JSGlobalProxy object or null. 381 JSObject* global_proxy(); 382 void set_global_proxy(JSObject* global); 383 384 // The builtins object. 385 JSBuiltinsObject* builtins(); 386 387 // Get the innermost global context by traversing the context chain. 388 Context* global_context(); 389 390 // Compute the native context by traversing the context chain. 391 Context* native_context(); 392 393 // Predicates for context types. IsNativeContext is also defined on Object 394 // because we frequently have to know if arbitrary objects are natives 395 // contexts. 396 bool IsNativeContext() { 397 Map* map = this->map(); 398 return map == map->GetHeap()->native_context_map(); 399 } 400 bool IsFunctionContext() { 401 Map* map = this->map(); 402 return map == map->GetHeap()->function_context_map(); 403 } 404 bool IsCatchContext() { 405 Map* map = this->map(); 406 return map == map->GetHeap()->catch_context_map(); 407 } 408 bool IsWithContext() { 409 Map* map = this->map(); 410 return map == map->GetHeap()->with_context_map(); 411 } 412 bool IsBlockContext() { 413 Map* map = this->map(); 414 return map == map->GetHeap()->block_context_map(); 415 } 416 bool IsModuleContext() { 417 Map* map = this->map(); 418 return map == map->GetHeap()->module_context_map(); 419 } 420 bool IsGlobalContext() { 421 Map* map = this->map(); 422 return map == map->GetHeap()->global_context_map(); 423 } 424 425 // Tells whether the native context is marked with out of memory. 426 inline bool has_out_of_memory(); 427 428 // Mark the native context with out of memory. 429 inline void mark_out_of_memory(); 430 431 // A native context hold a list of all functions which have been optimized. 432 void AddOptimizedFunction(JSFunction* function); 433 void RemoveOptimizedFunction(JSFunction* function); 434 Object* OptimizedFunctionsListHead(); 435 void ClearOptimizedFunctions(); 436 437 Handle<Object> ErrorMessageForCodeGenerationFromStrings(); 438 439 #define NATIVE_CONTEXT_FIELD_ACCESSORS(index, type, name) \ 440 void set_##name(type* value) { \ 441 ASSERT(IsNativeContext()); \ 442 set(index, value); \ 443 } \ 444 bool is_##name(type* value) { \ 445 ASSERT(IsNativeContext()); \ 446 return type::cast(get(index)) == value; \ 447 } \ 448 type* name() { \ 449 ASSERT(IsNativeContext()); \ 450 return type::cast(get(index)); \ 451 } 452 NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_FIELD_ACCESSORS) 453 #undef NATIVE_CONTEXT_FIELD_ACCESSORS 454 455 // Lookup the slot called name, starting with the current context. 456 // There are three possibilities: 457 // 458 // 1) result->IsContext(): 459 // The binding was found in a context. *index is always the 460 // non-negative slot index. *attributes is NONE for var and let 461 // declarations, READ_ONLY for const declarations (never ABSENT). 462 // 463 // 2) result->IsJSObject(): 464 // The binding was found as a named property in a context extension 465 // object (i.e., was introduced via eval), as a property on the subject 466 // of with, or as a property of the global object. *index is -1 and 467 // *attributes is not ABSENT. 468 // 469 // 3) result.is_null(): 470 // There was no binding found, *index is always -1 and *attributes is 471 // always ABSENT. 472 Handle<Object> Lookup(Handle<String> name, 473 ContextLookupFlags flags, 474 int* index, 475 PropertyAttributes* attributes, 476 BindingFlags* binding_flags); 477 478 // Code generation support. 479 static int SlotOffset(int index) { 480 return kHeaderSize + index * kPointerSize - kHeapObjectTag; 481 } 482 483 static int FunctionMapIndex(LanguageMode language_mode, bool is_generator) { 484 return is_generator 485 ? (language_mode == CLASSIC_MODE 486 ? GENERATOR_FUNCTION_MAP_INDEX 487 : STRICT_MODE_GENERATOR_FUNCTION_MAP_INDEX) 488 : (language_mode == CLASSIC_MODE 489 ? FUNCTION_MAP_INDEX 490 : STRICT_MODE_FUNCTION_MAP_INDEX); 491 } 492 493 static const int kSize = kHeaderSize + NATIVE_CONTEXT_SLOTS * kPointerSize; 494 495 // GC support. 496 typedef FixedBodyDescriptor< 497 kHeaderSize, kSize, kSize> ScavengeBodyDescriptor; 498 499 typedef FixedBodyDescriptor< 500 kHeaderSize, 501 kHeaderSize + FIRST_WEAK_SLOT * kPointerSize, 502 kSize> MarkCompactBodyDescriptor; 503 504 private: 505 // Unchecked access to the slots. 506 Object* unchecked_previous() { return get(PREVIOUS_INDEX); } 507 508 #ifdef DEBUG 509 // Bootstrapping-aware type checks. 510 static bool IsBootstrappingOrValidParentContext(Object* object, Context* kid); 511 static bool IsBootstrappingOrGlobalObject(Object* object); 512 #endif 513 514 STATIC_CHECK(kHeaderSize == Internals::kContextHeaderSize); 515 STATIC_CHECK(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex); 516 }; 517 518 } } // namespace v8::internal 519 520 #endif // V8_CONTEXTS_H_ 521
