1 // Copyright 2017 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_OBJECTS_DATA_HANDLER_H_ 6 #define V8_OBJECTS_DATA_HANDLER_H_ 7 8 #include "src/objects.h" 9 10 // Has to be the last include (doesn't have include guards): 11 #include "src/objects/object-macros.h" 12 13 namespace v8 { 14 namespace internal { 15 16 // DataHandler is a base class for load and store handlers that can't be 17 // encoded in one Smi. Kind of a handler can be deduced from instance type. 18 class DataHandler : public Struct { 19 public: 20 // [smi_handler]: A Smi which encodes a handler or Code object (we still 21 // use code handlers for accessing lexical environment variables, but soon 22 // only smi handlers will remain). See LoadHandler and StoreHandler for 23 // details about encoding. 24 DECL_ACCESSORS(smi_handler, Object) 25 26 // [validity_cell]: A validity Cell that guards prototype chain modifications. 27 DECL_ACCESSORS(validity_cell, Object) 28 29 // Returns number of optional data fields available in the object. 30 inline int data_field_count() const; 31 32 // [data1-3]: These are optional general-purpose fields whose content and 33 // presence depends on the handler kind. 34 DECL_ACCESSORS(data1, MaybeObject) 35 DECL_ACCESSORS(data2, MaybeObject) 36 DECL_ACCESSORS(data3, MaybeObject) 37 38 // Layout description. 39 #define DATA_HANDLER_FIELDS(V) \ 40 V(kSmiHandlerOffset, kPointerSize) \ 41 V(kValidityCellOffset, kPointerSize) \ 42 V(kSizeWithData0, 0) \ 43 V(kData1Offset, kPointerSize) \ 44 V(kSizeWithData1, 0) \ 45 V(kData2Offset, kPointerSize) \ 46 V(kSizeWithData2, 0) \ 47 V(kData3Offset, kPointerSize) \ 48 V(kSizeWithData3, 0) 49 50 DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, DATA_HANDLER_FIELDS) 51 #undef DATA_HANDLER_FIELDS 52 53 DECL_CAST(DataHandler) 54 55 DECL_VERIFIER(DataHandler) 56 57 class BodyDescriptor; 58 }; 59 60 } // namespace internal 61 } // namespace v8 62 63 #include "src/objects/object-macros-undef.h" 64 65 #endif // V8_OBJECTS_DATA_HANDLER_H_ 66