// Copyright 2012 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_ELEMENTS_H_ #define V8_ELEMENTS_H_ #include "elements-kind.h" #include "objects.h" #include "heap.h" #include "isolate.h" namespace v8 { namespace internal { // Abstract base class for handles that can operate on objects with differing // ElementsKinds. class ElementsAccessor { public: explicit ElementsAccessor(const char* name) : name_(name) { } virtual ~ElementsAccessor() { } virtual ElementsKind kind() const = 0; const char* name() const { return name_; } // Checks the elements of an object for consistency, asserting when a problem // is found. virtual void Validate(JSObject* obj) = 0; // Returns true if a holder contains an element with the specified key // without iterating up the prototype chain. The caller can optionally pass // in the backing store to use for the check, which must be compatible with // the ElementsKind of the ElementsAccessor. If backing_store is NULL, the // holder->elements() is used as the backing store. virtual bool HasElement(Object* receiver, JSObject* holder, uint32_t key, FixedArrayBase* backing_store = NULL) = 0; // Returns the element with the specified key or undefined if there is no such // element. This method doesn't iterate up the prototype chain. The caller // can optionally pass in the backing store to use for the check, which must // be compatible with the ElementsKind of the ElementsAccessor. If // backing_store is NULL, the holder->elements() is used as the backing store. MUST_USE_RESULT virtual MaybeObject* Get( Object* receiver, JSObject* holder, uint32_t key, FixedArrayBase* backing_store = NULL) = 0; // Modifies the length data property as specified for JSArrays and resizes the // underlying backing store accordingly. The method honors the semantics of // changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that // have non-deletable elements can only be shrunk to the size of highest // element that is non-deletable. MUST_USE_RESULT virtual MaybeObject* SetLength(JSArray* holder, Object* new_length) = 0; // Modifies both the length and capacity of a JSArray, resizing the underlying // backing store as necessary. This method does NOT honor the semantics of // EcmaScript 5.1 15.4.5.2, arrays can be shrunk beyond non-deletable // elements. This method should only be called for array expansion OR by // runtime JavaScript code that use InternalArrays and don't care about // EcmaScript 5.1 semantics. MUST_USE_RESULT virtual MaybeObject* SetCapacityAndLength(JSArray* array, int capacity, int length) = 0; // Deletes an element in an object, returning a new elements backing store. MUST_USE_RESULT virtual MaybeObject* Delete(JSObject* holder, uint32_t key, JSReceiver::DeleteMode mode) = 0; // If kCopyToEnd is specified as the copy_size to CopyElements, it copies all // of elements from source after source_start to the destination array. static const int kCopyToEnd = -1; // If kCopyToEndAndInitializeToHole is specified as the copy_size to // CopyElements, it copies all of elements from source after source_start to // destination array, padding any remaining uninitialized elements in the // destination array with the hole. static const int kCopyToEndAndInitializeToHole = -2; // Copy elements from one backing store to another. Typically, callers specify // the source JSObject or JSArray in source_holder. If the holder's backing // store is available, it can be passed in source and source_holder is // ignored. MUST_USE_RESULT virtual MaybeObject* CopyElements( JSObject* source_holder, uint32_t source_start, FixedArrayBase* destination, ElementsKind destination_kind, uint32_t destination_start, int copy_size, FixedArrayBase* source = NULL) = 0; MUST_USE_RESULT MaybeObject* CopyElements(JSObject* from_holder, FixedArrayBase* to, ElementsKind to_kind, FixedArrayBase* from = NULL) { return CopyElements(from_holder, 0, to, to_kind, 0, kCopyToEndAndInitializeToHole, from); } MUST_USE_RESULT virtual MaybeObject* AddElementsToFixedArray( Object* receiver, JSObject* holder, FixedArray* to, FixedArrayBase* from = NULL) = 0; // Returns a shared ElementsAccessor for the specified ElementsKind. static ElementsAccessor* ForKind(ElementsKind elements_kind) { ASSERT(elements_kind < kElementsKindCount); return elements_accessors_[elements_kind]; } static ElementsAccessor* ForArray(FixedArrayBase* array); static void InitializeOncePerProcess(); static void TearDown(); protected: friend class NonStrictArgumentsElementsAccessor; virtual uint32_t GetCapacity(FixedArrayBase* backing_store) = 0; // Element handlers distinguish between indexes and keys when they manipulate // elements. Indexes refer to elements in terms of their location in the // underlying storage's backing store representation, and are between 0 and // GetCapacity. Keys refer to elements in terms of the value that would be // specified in JavaScript to access the element. In most implementations, // keys are equivalent to indexes, and GetKeyForIndex returns the same value // it is passed. In the NumberDictionary ElementsAccessor, GetKeyForIndex maps // the index to a key using the KeyAt method on the NumberDictionary. virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store, uint32_t index) = 0; private: static ElementsAccessor** elements_accessors_; const char* name_; DISALLOW_COPY_AND_ASSIGN(ElementsAccessor); }; void CopyObjectToObjectElements(FixedArray* from_obj, ElementsKind from_kind, uint32_t from_start, FixedArray* to_obj, ElementsKind to_kind, uint32_t to_start, int copy_size); } } // namespace v8::internal #endif // V8_ELEMENTS_H_