// Copyright 2012 the V8 project authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file.

#ifndef V8_CONTEXTS_H_

#define V8_CONTEXTS_H_

#include "src/heap/heap.h"

#include "src/objects.h"

namespace v8 {

namespace internal {

enum ContextLookupFlags {

FOLLOW_CONTEXT_CHAIN = 1,

FOLLOW_PROTOTYPE_CHAIN = 2,

DONT_FOLLOW_CHAINS = 0,

FOLLOW_CHAINS = FOLLOW_CONTEXT_CHAIN | FOLLOW_PROTOTYPE_CHAIN

};

// ES5 10.2 defines lexical environments with mutable and immutable bindings.

// Immutable bindings have two states, initialized and uninitialized, and

// their state is changed by the InitializeImmutableBinding method. The

// BindingFlags enum represents information if a binding has definitely been

// initialized. A mutable binding does not need to be checked and thus has

// the BindingFlag MUTABLE_IS_INITIALIZED.

//

// There are two possibilities for immutable bindings

// * 'const' declared variables. They are initialized when evaluating the

// corresponding declaration statement. They need to be checked for being

// initialized and thus get the flag IMMUTABLE_CHECK_INITIALIZED.

// * The function name of a named function literal. The binding is immediately

// initialized when entering the function and thus does not need to be

// checked. it gets the BindingFlag IMMUTABLE_IS_INITIALIZED.

// Accessing an uninitialized binding produces the undefined value.

//

// The harmony proposal for block scoped bindings also introduces the

// uninitialized state for mutable bindings.

// * A 'let' declared variable. They are initialized when evaluating the

// corresponding declaration statement. They need to be checked for being

// initialized and thus get the flag MUTABLE_CHECK_INITIALIZED.

// * A 'var' declared variable. It is initialized immediately upon creation

// and thus doesn't need to be checked. It gets the flag

// MUTABLE_IS_INITIALIZED.

// * Catch bound variables, function parameters and variables introduced by

// function declarations are initialized immediately and do not need to be

// checked. Thus they get the flag MUTABLE_IS_INITIALIZED.

// Immutable bindings in harmony mode get the _HARMONY flag variants. Accessing

// an uninitialized binding produces a reference error.

//

// In V8 uninitialized bindings are set to the hole value upon creation and set

// to a different value upon initialization.

enum BindingFlags {

MUTABLE_IS_INITIALIZED,

MUTABLE_CHECK_INITIALIZED,

IMMUTABLE_IS_INITIALIZED,

IMMUTABLE_CHECK_INITIALIZED,

IMMUTABLE_IS_INITIALIZED_HARMONY,

IMMUTABLE_CHECK_INITIALIZED_HARMONY,

MISSING_BINDING

};

// Heap-allocated activation contexts.

//

// Contexts are implemented as FixedArray objects; the Context

// class is a convenience interface casted on a FixedArray object.

//

// Note: Context must have no virtual functions and Context objects

// must always be allocated via Heap::AllocateContext() or

// Factory::NewContext.

#define NATIVE_CONTEXT_FIELDS(V) \

V(GLOBAL_PROXY_INDEX, JSObject, global_proxy_object) \

V(SECURITY_TOKEN_INDEX, Object, security_token) \

V(BOOLEAN_FUNCTION_INDEX, JSFunction, boolean_function) \

V(NUMBER_FUNCTION_INDEX, JSFunction, number_function) \

V(STRING_FUNCTION_INDEX, JSFunction, string_function) \

V(STRING_FUNCTION_PROTOTYPE_MAP_INDEX, Map, string_function_prototype_map) \

V(SYMBOL_FUNCTION_INDEX, JSFunction, symbol_function) \

V(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \

V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function) \

V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \

V(JS_ARRAY_MAPS_INDEX, Object, js_array_maps) \

V(DATE_FUNCTION_INDEX, JSFunction, date_function) \

V(JSON_OBJECT_INDEX, JSObject, json_object) \

V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function) \

V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype) \

V(INITIAL_ARRAY_PROTOTYPE_INDEX, JSObject, initial_array_prototype) \

V(CREATE_DATE_FUN_INDEX, JSFunction, create_date_fun) \

V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun) \

V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun) \

V(TO_DETAIL_STRING_FUN_INDEX, JSFunction, to_detail_string_fun) \

V(TO_OBJECT_FUN_INDEX, JSFunction, to_object_fun) \

V(TO_INTEGER_FUN_INDEX, JSFunction, to_integer_fun) \

V(TO_UINT32_FUN_INDEX, JSFunction, to_uint32_fun) \

V(TO_INT32_FUN_INDEX, JSFunction, to_int32_fun) \

V(TO_LENGTH_FUN_INDEX, JSFunction, to_length_fun) \

V(GLOBAL_EVAL_FUN_INDEX, JSFunction, global_eval_fun) \

V(ARRAY_BUFFER_FUN_INDEX, JSFunction, array_buffer_fun) \

V(UINT8_ARRAY_FUN_INDEX, JSFunction, uint8_array_fun) \

V(INT8_ARRAY_FUN_INDEX, JSFunction, int8_array_fun) \

V(UINT16_ARRAY_FUN_INDEX, JSFunction, uint16_array_fun) \

V(INT16_ARRAY_FUN_INDEX, JSFunction, int16_array_fun) \

V(UINT32_ARRAY_FUN_INDEX, JSFunction, uint32_array_fun) \

V(INT32_ARRAY_FUN_INDEX, JSFunction, int32_array_fun) \

V(FLOAT32_ARRAY_FUN_INDEX, JSFunction, float32_array_fun) \

V(FLOAT64_ARRAY_FUN_INDEX, JSFunction, float64_array_fun) \

V(UINT8_CLAMPED_ARRAY_FUN_INDEX, JSFunction, uint8_clamped_array_fun) \

V(INT8_ARRAY_EXTERNAL_MAP_INDEX, Map, int8_array_external_map) \

V(UINT8_ARRAY_EXTERNAL_MAP_INDEX, Map, uint8_array_external_map) \

V(INT16_ARRAY_EXTERNAL_MAP_INDEX, Map, int16_array_external_map) \

V(UINT16_ARRAY_EXTERNAL_MAP_INDEX, Map, uint16_array_external_map) \

V(INT32_ARRAY_EXTERNAL_MAP_INDEX, Map, int32_array_external_map) \

V(UINT32_ARRAY_EXTERNAL_MAP_INDEX, Map, uint32_array_external_map) \

V(FLOAT32_ARRAY_EXTERNAL_MAP_INDEX, Map, float32_array_external_map) \

V(FLOAT64_ARRAY_EXTERNAL_MAP_INDEX, Map, float64_array_external_map) \

V(UINT8_CLAMPED_ARRAY_EXTERNAL_MAP_INDEX, Map, \

uint8_clamped_array_external_map) \

V(DATA_VIEW_FUN_INDEX, JSFunction, data_view_fun) \

V(SLOPPY_FUNCTION_MAP_INDEX, Map, sloppy_function_map) \

V(SLOPPY_FUNCTION_WITH_READONLY_PROTOTYPE_MAP_INDEX, Map, \

sloppy_function_with_readonly_prototype_map) \

V(STRICT_FUNCTION_MAP_INDEX, Map, strict_function_map) \

V(SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \

sloppy_function_without_prototype_map) \

V(STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map, \

strict_function_without_prototype_map) \

V(BOUND_FUNCTION_MAP_INDEX, Map, bound_function_map) \

V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map) \

V(SLOPPY_ARGUMENTS_MAP_INDEX, Map, sloppy_arguments_map) \

V(ALIASED_ARGUMENTS_MAP_INDEX, Map, aliased_arguments_map) \

V(STRICT_ARGUMENTS_MAP_INDEX, Map, strict_arguments_map) \

V(MESSAGE_LISTENERS_INDEX, JSObject, message_listeners) \

V(MAKE_MESSAGE_FUN_INDEX, JSFunction, make_message_fun) \

V(GET_STACK_TRACE_LINE_INDEX, JSFunction, get_stack_trace_line_fun) \

V(CONFIGURE_GLOBAL_INDEX, JSFunction, configure_global_fun) \

V(FUNCTION_CACHE_INDEX, ObjectHashTable, function_cache) \

V(JSFUNCTION_RESULT_CACHES_INDEX, FixedArray, jsfunction_result_caches) \

V(NORMALIZED_MAP_CACHE_INDEX, Object, normalized_map_cache) \

V(RUNTIME_CONTEXT_INDEX, Context, runtime_context) \

V(CALL_AS_FUNCTION_DELEGATE_INDEX, JSFunction, call_as_function_delegate) \

V(CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, JSFunction, \

call_as_constructor_delegate) \

V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \

V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function) \

V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \

V(MAP_CACHE_INDEX, Object, map_cache) \

V(EMBEDDER_DATA_INDEX, FixedArray, embedder_data) \

V(ALLOW_CODE_GEN_FROM_STRINGS_INDEX, Object, allow_code_gen_from_strings) \

V(ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX, Object, \

error_message_for_code_gen_from_strings) \

V(IS_PROMISE_INDEX, JSFunction, is_promise) \

V(PROMISE_CREATE_INDEX, JSFunction, promise_create) \

V(PROMISE_RESOLVE_INDEX, JSFunction, promise_resolve) \

V(PROMISE_REJECT_INDEX, JSFunction, promise_reject) \

V(PROMISE_CHAIN_INDEX, JSFunction, promise_chain) \

V(PROMISE_CATCH_INDEX, JSFunction, promise_catch) \

V(PROMISE_THEN_INDEX, JSFunction, promise_then) \

V(TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX, JSFunction, \

to_complete_property_descriptor) \

V(DERIVED_HAS_TRAP_INDEX, JSFunction, derived_has_trap) \

V(DERIVED_GET_TRAP_INDEX, JSFunction, derived_get_trap) \

V(DERIVED_SET_TRAP_INDEX, JSFunction, derived_set_trap) \

V(PROXY_ENUMERATE_INDEX, JSFunction, proxy_enumerate) \

V(OBSERVERS_NOTIFY_CHANGE_INDEX, JSFunction, observers_notify_change) \

V(OBSERVERS_ENQUEUE_SPLICE_INDEX, JSFunction, observers_enqueue_splice) \

V(OBSERVERS_BEGIN_SPLICE_INDEX, JSFunction, observers_begin_perform_splice) \

V(OBSERVERS_END_SPLICE_INDEX, JSFunction, observers_end_perform_splice) \

V(NATIVE_OBJECT_OBSERVE_INDEX, JSFunction, native_object_observe) \

V(NATIVE_OBJECT_GET_NOTIFIER_INDEX, JSFunction, native_object_get_notifier) \

V(NATIVE_OBJECT_NOTIFIER_PERFORM_CHANGE, JSFunction, \

native_object_notifier_perform_change) \

V(SLOPPY_GENERATOR_FUNCTION_MAP_INDEX, Map, sloppy_generator_function_map) \

V(STRICT_GENERATOR_FUNCTION_MAP_INDEX, Map, strict_generator_function_map) \

V(GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX, Map, generator_object_prototype_map) \

V(ITERATOR_RESULT_MAP_INDEX, Map, iterator_result_map) \

V(MAP_ITERATOR_MAP_INDEX, Map, map_iterator_map) \

V(SET_ITERATOR_MAP_INDEX, Map, set_iterator_map) \

V(ARRAY_VALUES_ITERATOR_INDEX, JSFunction, array_values_iterator) \

V(SCRIPT_CONTEXT_TABLE_INDEX, ScriptContextTable, script_context_table)

// A table of all script contexts. Every loaded top-level script with top-level

// lexical declarations contributes its ScriptContext into this table.

//

// The table is a fixed array, its first slot is the current used count and

// the subsequent slots 1..used contain ScriptContexts.

class ScriptContextTable : public FixedArray {

public:

// Conversions.

static ScriptContextTable* cast(Object* context) {

DCHECK(context->IsScriptContextTable());

return reinterpret_cast<ScriptContextTable*>(context);

}

struct LookupResult {

int context_index;

int slot_index;

VariableMode mode;

InitializationFlag init_flag;

MaybeAssignedFlag maybe_assigned_flag;

};

int used() const { return Smi::cast(get(kUsedSlot))->value(); }

void set_used(int used) { set(kUsedSlot, Smi::FromInt(used)); }

static Handle<Context> GetContext(Handle<ScriptContextTable> table, int i) {

DCHECK(i < table->used());

return Handle<Context>::cast(FixedArray::get(table, i + 1));

}

// Lookup a variable `name` in a ScriptContextTable.

// If it returns true, the variable is found and `result` contains

// valid information about its location.

// If it returns false, `result` is untouched.

MUST_USE_RESULT

static bool Lookup(Handle<ScriptContextTable> table, Handle<String> name,

LookupResult* result);

MUST_USE_RESULT

static Handle<ScriptContextTable> Extend(Handle<ScriptContextTable> table,

Handle<Context> script_context);

static int GetContextOffset(int context_index) {

return kFirstContextOffset + context_index * kPointerSize;

}

private:

static const int kUsedSlot = 0;

static const int kFirstContextOffset =

FixedArray::kHeaderSize + (kUsedSlot + 1) * kPointerSize;

DISALLOW_IMPLICIT_CONSTRUCTORS(ScriptContextTable);

};

// JSFunctions are pairs (context, function code), sometimes also called

// closures. A Context object is used to represent function contexts and

// dynamically pushed 'with' contexts (or 'scopes' in ECMA-262 speak).

//

// At runtime, the contexts build a stack in parallel to the execution

// stack, with the top-most context being the current context. All contexts

// have the following slots:

//

// [ closure ] This is the current function. It is the same for all

// contexts inside a function. It provides access to the

// incoming context (i.e., the outer context, which may

// or may not become the current function's context), and

// it provides access to the functions code and thus it's

// scope information, which in turn contains the names of

// statically allocated context slots. The names are needed

// for dynamic lookups in the presence of 'with' or 'eval'.

//

// [ previous ] A pointer to the previous context. It is NULL for

// function contexts, and non-NULL for 'with' contexts.

// Used to implement the 'with' statement.

//

// [ extension ] A pointer to an extension JSObject, or NULL. Used to

// implement 'with' statements and dynamic declarations

// (through 'eval'). The object in a 'with' statement is

// stored in the extension slot of a 'with' context.

// Dynamically declared variables/functions are also added

// to lazily allocated extension object. Context::Lookup

// searches the extension object for properties.

// For global and block contexts, contains the respective

// ScopeInfo.

// For module contexts, points back to the respective JSModule.

//

// [ global_object ] A pointer to the global object. Provided for quick

// access to the global object from inside the code (since

// we always have a context pointer).

//

// In addition, function contexts may have statically allocated context slots

// to store local variables/functions that are accessed from inner functions

// (via static context addresses) or through 'eval' (dynamic context lookups).

// The native context contains additional slots for fast access to native

// properties.

//

// Finally, with Harmony scoping, the JSFunction representing a top level

// script will have the ScriptContext rather than a FunctionContext.

// Script contexts from all top-level scripts are gathered in

// ScriptContextTable.

class Context: public FixedArray {

public:

// Conversions.

static Context* cast(Object* context) {

DCHECK(context->IsContext());

return reinterpret_cast<Context*>(context);

}

// The default context slot layout; indices are FixedArray slot indices.

enum {

// These slots are in all contexts.

CLOSURE_INDEX,

PREVIOUS_INDEX,

// The extension slot is used for either the global object (in global

// contexts), eval extension object (function contexts), subject of with

// (with contexts), or the variable name (catch contexts), the serialized

// scope info (block contexts), or the module instance (module contexts).

EXTENSION_INDEX,

GLOBAL_OBJECT_INDEX,

MIN_CONTEXT_SLOTS,

// This slot holds the thrown value in catch contexts.

THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,

// These slots are only in native contexts.

GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS,

SECURITY_TOKEN_INDEX,

SLOPPY_ARGUMENTS_MAP_INDEX,

ALIASED_ARGUMENTS_MAP_INDEX,

STRICT_ARGUMENTS_MAP_INDEX,

REGEXP_RESULT_MAP_INDEX,

SLOPPY_FUNCTION_MAP_INDEX,

SLOPPY_FUNCTION_WITH_READONLY_PROTOTYPE_MAP_INDEX,

STRICT_FUNCTION_MAP_INDEX,

SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX,

STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX,

BOUND_FUNCTION_MAP_INDEX,

INITIAL_OBJECT_PROTOTYPE_INDEX,

INITIAL_ARRAY_PROTOTYPE_INDEX,

BOOLEAN_FUNCTION_INDEX,

NUMBER_FUNCTION_INDEX,

STRING_FUNCTION_INDEX,

STRING_FUNCTION_PROTOTYPE_MAP_INDEX,

SYMBOL_FUNCTION_INDEX,

OBJECT_FUNCTION_INDEX,

INTERNAL_ARRAY_FUNCTION_INDEX,

ARRAY_FUNCTION_INDEX,

JS_ARRAY_MAPS_INDEX,

DATE_FUNCTION_INDEX,

JSON_OBJECT_INDEX,

REGEXP_FUNCTION_INDEX,

CREATE_DATE_FUN_INDEX,

TO_NUMBER_FUN_INDEX,

TO_STRING_FUN_INDEX,

TO_DETAIL_STRING_FUN_INDEX,

TO_OBJECT_FUN_INDEX,

TO_INTEGER_FUN_INDEX,

TO_UINT32_FUN_INDEX,

TO_INT32_FUN_INDEX,

TO_BOOLEAN_FUN_INDEX,

GLOBAL_EVAL_FUN_INDEX,

ARRAY_BUFFER_FUN_INDEX,

UINT8_ARRAY_FUN_INDEX,

INT8_ARRAY_FUN_INDEX,

UINT16_ARRAY_FUN_INDEX,

INT16_ARRAY_FUN_INDEX,

UINT32_ARRAY_FUN_INDEX,

INT32_ARRAY_FUN_INDEX,

FLOAT32_ARRAY_FUN_INDEX,

FLOAT64_ARRAY_FUN_INDEX,

UINT8_CLAMPED_ARRAY_FUN_INDEX,

INT8_ARRAY_EXTERNAL_MAP_INDEX,

UINT8_ARRAY_EXTERNAL_MAP_INDEX,

INT16_ARRAY_EXTERNAL_MAP_INDEX,

UINT16_ARRAY_EXTERNAL_MAP_INDEX,

INT32_ARRAY_EXTERNAL_MAP_INDEX,

UINT32_ARRAY_EXTERNAL_MAP_INDEX,

FLOAT32_ARRAY_EXTERNAL_MAP_INDEX,

FLOAT64_ARRAY_EXTERNAL_MAP_INDEX,

UINT8_CLAMPED_ARRAY_EXTERNAL_MAP_INDEX,

DATA_VIEW_FUN_INDEX,

MESSAGE_LISTENERS_INDEX,

MAKE_MESSAGE_FUN_INDEX,

GET_STACK_TRACE_LINE_INDEX,

CONFIGURE_GLOBAL_INDEX,

FUNCTION_CACHE_INDEX,

JSFUNCTION_RESULT_CACHES_INDEX,

NORMALIZED_MAP_CACHE_INDEX,

RUNTIME_CONTEXT_INDEX,

CALL_AS_FUNCTION_DELEGATE_INDEX,

CALL_AS_CONSTRUCTOR_DELEGATE_INDEX,

SCRIPT_FUNCTION_INDEX,

OPAQUE_REFERENCE_FUNCTION_INDEX,

CONTEXT_EXTENSION_FUNCTION_INDEX,

OUT_OF_MEMORY_INDEX,

EMBEDDER_DATA_INDEX,

ALLOW_CODE_GEN_FROM_STRINGS_INDEX,

ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX,

RUN_MICROTASKS_INDEX,

ENQUEUE_MICROTASK_INDEX,

IS_PROMISE_INDEX,

PROMISE_CREATE_INDEX,

PROMISE_RESOLVE_INDEX,

PROMISE_REJECT_INDEX,

PROMISE_CHAIN_INDEX,

PROMISE_CATCH_INDEX,

PROMISE_THEN_INDEX,

TO_COMPLETE_PROPERTY_DESCRIPTOR_INDEX,

DERIVED_HAS_TRAP_INDEX,

DERIVED_GET_TRAP_INDEX,

DERIVED_SET_TRAP_INDEX,

PROXY_ENUMERATE_INDEX,

OBSERVERS_NOTIFY_CHANGE_INDEX,

OBSERVERS_ENQUEUE_SPLICE_INDEX,

OBSERVERS_BEGIN_SPLICE_INDEX,

OBSERVERS_END_SPLICE_INDEX,

NATIVE_OBJECT_OBSERVE_INDEX,

NATIVE_OBJECT_GET_NOTIFIER_INDEX,

NATIVE_OBJECT_NOTIFIER_PERFORM_CHANGE,

SLOPPY_GENERATOR_FUNCTION_MAP_INDEX,

STRICT_GENERATOR_FUNCTION_MAP_INDEX,

GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX,

ITERATOR_RESULT_MAP_INDEX,

MAP_ITERATOR_MAP_INDEX,

SET_ITERATOR_MAP_INDEX,

ARRAY_VALUES_ITERATOR_INDEX,

SCRIPT_CONTEXT_TABLE_INDEX,

MAP_CACHE_INDEX,

TO_LENGTH_FUN_INDEX,

// Properties from here are treated as weak references by the full GC.

// Scavenge treats them as strong references.

OPTIMIZED_FUNCTIONS_LIST, // Weak.

OPTIMIZED_CODE_LIST, // Weak.

DEOPTIMIZED_CODE_LIST, // Weak.

NEXT_CONTEXT_LINK, // Weak.

// Total number of slots.

NATIVE_CONTEXT_SLOTS,

FIRST_WEAK_SLOT = OPTIMIZED_FUNCTIONS_LIST

};

// Direct slot access.

JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); }

void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); }

Context* previous() {

Object* result = unchecked_previous();

DCHECK(IsBootstrappingOrValidParentContext(result, this));

return reinterpret_cast<Context*>(result);

}

void set_previous(Context* context) { set(PREVIOUS_INDEX, context); }

bool has_extension() { return extension() != NULL; }

Object* extension() { return get(EXTENSION_INDEX); }

void set_extension(Object* object) { set(EXTENSION_INDEX, object); }

JSModule* module() { return JSModule::cast(get(EXTENSION_INDEX)); }

void set_module(JSModule* module) { set(EXTENSION_INDEX, module); }

// Get the context where var declarations will be hoisted to, which

// may be the context itself.

Context* declaration_context();

GlobalObject* global_object() {

Object* result = get(GLOBAL_OBJECT_INDEX);

DCHECK(IsBootstrappingOrGlobalObject(this->GetIsolate(), result));

return reinterpret_cast<GlobalObject*>(result);

}

void set_global_object(GlobalObject* object) {

set(GLOBAL_OBJECT_INDEX, object);

}

// Returns a JSGlobalProxy object or null.

JSObject* global_proxy();

void set_global_proxy(JSObject* global);

// The builtins object.

JSBuiltinsObject* builtins();

// Get the script context by traversing the context chain.

Context* script_context();

// Compute the native context by traversing the context chain.

Context* native_context();

// Predicates for context types. IsNativeContext is also defined on Object

// because we frequently have to know if arbitrary objects are natives

// contexts.

bool IsNativeContext() {

Map* map = this->map();

return map == map->GetHeap()->native_context_map();

}

bool IsFunctionContext() {

Map* map = this->map();

return map == map->GetHeap()->function_context_map();

}

bool IsCatchContext() {

Map* map = this->map();

return map == map->GetHeap()->catch_context_map();

}

bool IsWithContext() {

Map* map = this->map();

return map == map->GetHeap()->with_context_map();

}

bool IsBlockContext() {

Map* map = this->map();

return map == map->GetHeap()->block_context_map();

}

bool IsModuleContext() {

Map* map = this->map();

return map == map->GetHeap()->module_context_map();

}

bool IsScriptContext() {

Map* map = this->map();

return map == map->GetHeap()->script_context_map();

}

bool HasSameSecurityTokenAs(Context* that) {

return this->global_object()->native_context()->security_token() ==

that->global_object()->native_context()->security_token();

}

// A native context holds a list of all functions with optimized code.

void AddOptimizedFunction(JSFunction* function);

void RemoveOptimizedFunction(JSFunction* function);

void SetOptimizedFunctionsListHead(Object* head);

Object* OptimizedFunctionsListHead();

// The native context also stores a list of all optimized code and a

// list of all deoptimized code, which are needed by the deoptimizer.

void AddOptimizedCode(Code* code);

void SetOptimizedCodeListHead(Object* head);

Object* OptimizedCodeListHead();

void SetDeoptimizedCodeListHead(Object* head);

Object* DeoptimizedCodeListHead();

Handle<Object> ErrorMessageForCodeGenerationFromStrings();

#define NATIVE_CONTEXT_FIELD_ACCESSORS(index, type, name) \

void set_##name(type* value) { \

DCHECK(IsNativeContext()); \

set(index, value); \

} \

bool is_##name(type* value) { \

DCHECK(IsNativeContext()); \

return type::cast(get(index)) == value; \

} \

type* name() { \

DCHECK(IsNativeContext()); \

return type::cast(get(index)); \

}

NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_FIELD_ACCESSORS)

#undef NATIVE_CONTEXT_FIELD_ACCESSORS

// Lookup the slot called name, starting with the current context.

// There are three possibilities:

//

// 1) result->IsContext():

// The binding was found in a context. *index is always the

// non-negative slot index. *attributes is NONE for var and let

// declarations, READ_ONLY for const declarations (never ABSENT).

//

// 2) result->IsJSObject():

// The binding was found as a named property in a context extension

// object (i.e., was introduced via eval), as a property on the subject

// of with, or as a property of the global object. *index is -1 and

// *attributes is not ABSENT.

//

// 3) result.is_null():

// There was no binding found, *index is always -1 and *attributes is

// always ABSENT.

Handle<Object> Lookup(Handle<String> name,

ContextLookupFlags flags,

int* index,

PropertyAttributes* attributes,

BindingFlags* binding_flags);

// Code generation support.

static int SlotOffset(int index) {

return kHeaderSize + index * kPointerSize - kHeapObjectTag;

}

static int FunctionMapIndex(LanguageMode language_mode, FunctionKind kind) {

if (IsGeneratorFunction(kind)) {

return is_strict(language_mode) ? STRICT_GENERATOR_FUNCTION_MAP_INDEX

: SLOPPY_GENERATOR_FUNCTION_MAP_INDEX;

}

if (IsArrowFunction(kind) || IsConciseMethod(kind) ||

IsAccessorFunction(kind)) {

return is_strict(language_mode)

? STRICT_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX

: SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX;

}

return is_strict(language_mode) ? STRICT_FUNCTION_MAP_INDEX

: SLOPPY_FUNCTION_MAP_INDEX;

}

static const int kSize = kHeaderSize + NATIVE_CONTEXT_SLOTS * kPointerSize;

// GC support.

typedef FixedBodyDescriptor<

kHeaderSize, kSize, kSize> ScavengeBodyDescriptor;

typedef FixedBodyDescriptor<

kHeaderSize,

kHeaderSize + FIRST_WEAK_SLOT * kPointerSize,

kSize> MarkCompactBodyDescriptor;

private:

// Unchecked access to the slots.

Object* unchecked_previous() { return get(PREVIOUS_INDEX); }

#ifdef DEBUG

// Bootstrapping-aware type checks.

static bool IsBootstrappingOrValidParentContext(Object* object, Context* kid);

static bool IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object);

#endif

STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);

STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);

};

} } // namespace v8::internal

#endif // V8_CONTEXTS_H_