| // Copyright 2006-2008 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef V8_CONTEXTS_H_ |
| #define V8_CONTEXTS_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 |
| }; |
| |
| |
| // 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. |
| |
| // Comment for special_function_table: |
| // Table for providing optimized/specialized functions. |
| // The array contains triplets [object, general_function, optimized_function]. |
| // Primarily added to support built-in optimized variants of |
| // Array.prototype.{push,pop}. |
| |
| #define GLOBAL_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(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \ |
| V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \ |
| 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(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_BOOLEAN_FUN_INDEX, JSFunction, to_boolean_fun) \ |
| V(INSTANTIATE_FUN_INDEX, JSFunction, instantiate_fun) \ |
| V(CONFIGURE_INSTANCE_FUN_INDEX, JSFunction, configure_instance_fun) \ |
| V(FUNCTION_MAP_INDEX, Map, function_map) \ |
| V(FUNCTION_INSTANCE_MAP_INDEX, Map, function_instance_map) \ |
| V(JS_ARRAY_MAP_INDEX, Map, js_array_map)\ |
| V(SPECIAL_FUNCTION_TABLE_INDEX, FixedArray, special_function_table) \ |
| V(ARGUMENTS_BOILERPLATE_INDEX, JSObject, arguments_boilerplate) \ |
| 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, JSObject, function_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(EMPTY_SCRIPT_INDEX, Script, empty_script) \ |
| V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function) \ |
| V(CONTEXT_EXTENSION_FUNCTION_INDEX, JSFunction, context_extension_function) \ |
| V(OUT_OF_MEMORY_INDEX, Object, out_of_memory) \ |
| V(MAP_CACHE_INDEX, Object, map_cache) \ |
| V(CONTEXT_DATA_INDEX, Object, data) |
| |
| // 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'. |
| // |
| // [ fcontext ] A pointer to the innermost enclosing function context. |
| // It is the same for all contexts *allocated* inside a |
| // function, and the function context's fcontext points |
| // to itself. It is only needed for fast access of the |
| // function context (used for declarations, and static |
| // context slot access). |
| // |
| // [ 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. |
| // |
| // [ global ] 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). |
| // Finally, the global context contains additional slots for fast access to |
| // global properties. |
| // |
| // We may be able to simplify the implementation: |
| // |
| // - We may be able to get rid of 'fcontext': We can always use the fact that |
| // previous == NULL for function contexts and so we can search for them. They |
| // are only needed when doing dynamic declarations, and the context chains |
| // tend to be very very short (depth of nesting of 'with' statements). At |
| // the moment we also use it in generated code for context slot accesses - |
| // and there we don't want a loop because of code bloat - but we may not |
| // need it there after all (see comment in codegen_*.cc). |
| // |
| // - If we cannot get rid of fcontext, consider making 'previous' never NULL |
| // except for the global context. This could simplify Context::Lookup. |
| |
| class Context: public FixedArray { |
| public: |
| // Conversions. |
| static Context* cast(Object* context) { |
| ASSERT(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, |
| FCONTEXT_INDEX, |
| PREVIOUS_INDEX, |
| EXTENSION_INDEX, |
| GLOBAL_INDEX, |
| MIN_CONTEXT_SLOTS, |
| |
| // These slots are only in global contexts. |
| GLOBAL_PROXY_INDEX = MIN_CONTEXT_SLOTS, |
| SECURITY_TOKEN_INDEX, |
| ARGUMENTS_BOILERPLATE_INDEX, |
| JS_ARRAY_MAP_INDEX, |
| FUNCTION_MAP_INDEX, |
| FUNCTION_INSTANCE_MAP_INDEX, |
| INITIAL_OBJECT_PROTOTYPE_INDEX, |
| BOOLEAN_FUNCTION_INDEX, |
| NUMBER_FUNCTION_INDEX, |
| STRING_FUNCTION_INDEX, |
| OBJECT_FUNCTION_INDEX, |
| ARRAY_FUNCTION_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, |
| INSTANTIATE_FUN_INDEX, |
| CONFIGURE_INSTANCE_FUN_INDEX, |
| SPECIAL_FUNCTION_TABLE_INDEX, |
| MESSAGE_LISTENERS_INDEX, |
| MAKE_MESSAGE_FUN_INDEX, |
| GET_STACK_TRACE_LINE_INDEX, |
| CONFIGURE_GLOBAL_INDEX, |
| FUNCTION_CACHE_INDEX, |
| RUNTIME_CONTEXT_INDEX, |
| CALL_AS_FUNCTION_DELEGATE_INDEX, |
| CALL_AS_CONSTRUCTOR_DELEGATE_INDEX, |
| EMPTY_SCRIPT_INDEX, |
| SCRIPT_FUNCTION_INDEX, |
| CONTEXT_EXTENSION_FUNCTION_INDEX, |
| OUT_OF_MEMORY_INDEX, |
| MAP_CACHE_INDEX, |
| CONTEXT_DATA_INDEX, |
| GLOBAL_CONTEXT_SLOTS |
| }; |
| |
| // Direct slot access. |
| JSFunction* closure() { return JSFunction::cast(get(CLOSURE_INDEX)); } |
| void set_closure(JSFunction* closure) { set(CLOSURE_INDEX, closure); } |
| |
| Context* fcontext() { return Context::cast(get(FCONTEXT_INDEX)); } |
| void set_fcontext(Context* context) { set(FCONTEXT_INDEX, context); } |
| |
| Context* previous() { |
| Object* result = unchecked_previous(); |
| ASSERT(IsBootstrappingOrContext(result)); |
| return reinterpret_cast<Context*>(result); |
| } |
| void set_previous(Context* context) { set(PREVIOUS_INDEX, context); } |
| |
| bool has_extension() { return unchecked_extension() != NULL; } |
| JSObject* extension() { return JSObject::cast(unchecked_extension()); } |
| void set_extension(JSObject* object) { set(EXTENSION_INDEX, object); } |
| |
| GlobalObject* global() { |
| Object* result = get(GLOBAL_INDEX); |
| ASSERT(IsBootstrappingOrGlobalObject(result)); |
| return reinterpret_cast<GlobalObject*>(result); |
| } |
| void set_global(GlobalObject* global) { set(GLOBAL_INDEX, global); } |
| |
| // Returns a JSGlobalProxy object or null. |
| JSObject* global_proxy(); |
| void set_global_proxy(JSObject* global); |
| |
| // The builtins object. |
| JSBuiltinsObject* builtins(); |
| |
| // Compute the global context by traversing the context chain. |
| Context* global_context(); |
| |
| // Tells if this is a function context (as opposed to a 'with' context). |
| bool is_function_context() { return unchecked_previous() == NULL; } |
| |
| // Tells whether the global context is marked with out of memory. |
| bool has_out_of_memory() { |
| return global_context()->out_of_memory() == Heap::true_value(); |
| } |
| |
| // Mark the global context with out of memory. |
| void mark_out_of_memory() { |
| global_context()->set_out_of_memory(Heap::true_value()); |
| } |
| |
| // The exception holder is the object used as a with object in |
| // the implementation of a catch block. |
| bool is_exception_holder(Object* object) { |
| return IsCatchContext() && extension() == object; |
| } |
| |
| #define GLOBAL_CONTEXT_FIELD_ACCESSORS(index, type, name) \ |
| void set_##name(type* value) { \ |
| ASSERT(IsGlobalContext()); \ |
| set(index, value); \ |
| } \ |
| type* name() { \ |
| ASSERT(IsGlobalContext()); \ |
| return type::cast(get(index)); \ |
| } |
| GLOBAL_CONTEXT_FIELDS(GLOBAL_CONTEXT_FIELD_ACCESSORS) |
| #undef GLOBAL_CONTEXT_FIELD_ACCESSORS |
| |
| // Lookup the the slot called name, starting with the current context. |
| // There are 4 possible outcomes: |
| // |
| // 1) index_ >= 0 && result->IsContext(): |
| // most common case, the result is a Context, and index is the |
| // context slot index, and the slot exists. |
| // attributes == READ_ONLY for the function name variable, NONE otherwise. |
| // |
| // 2) index_ >= 0 && result->IsJSObject(): |
| // the result is the JSObject arguments object, the index is the parameter |
| // index, i.e., key into the arguments object, and the property exists. |
| // attributes != ABSENT. |
| // |
| // 3) index_ < 0 && result->IsJSObject(): |
| // the result is the JSObject extension context or the global object, |
| // and the name is the property name, and the property exists. |
| // attributes != ABSENT. |
| // |
| // 4) index_ < 0 && result.is_null(): |
| // there was no context found with the corresponding property. |
| // attributes == ABSENT. |
| Handle<Object> Lookup(Handle<String> name, ContextLookupFlags flags, |
| int* index_, PropertyAttributes* attributes); |
| |
| // Determine if a local variable with the given name exists in a |
| // context. Do not consider context extension objects. This is |
| // used for compiling code using eval. If the context surrounding |
| // the eval call does not have a local variable with this name and |
| // does not contain a with statement the property is global unless |
| // it is shadowed by a property in an extension object introduced by |
| // eval. |
| bool GlobalIfNotShadowedByEval(Handle<String> name); |
| |
| // Code generation support. |
| static int SlotOffset(int index) { |
| return kHeaderSize + index * kPointerSize - kHeapObjectTag; |
| } |
| |
| private: |
| // Unchecked access to the slots. |
| Object* unchecked_previous() { return get(PREVIOUS_INDEX); } |
| Object* unchecked_extension() { return get(EXTENSION_INDEX); } |
| |
| #ifdef DEBUG |
| // Bootstrapping-aware type checks. |
| static bool IsBootstrappingOrContext(Object* object); |
| static bool IsBootstrappingOrGlobalObject(Object* object); |
| #endif |
| }; |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_CONTEXTS_H_ |