| /* |
| * Copyright (C) 2011 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 RefCountedArray_h |
| #define RefCountedArray_h |
| |
| #include <wtf/FastMalloc.h> |
| #include <wtf/StdLibExtras.h> |
| #include <wtf/Vector.h> |
| |
| // This implements a reference counted array for POD** values, which is optimized for: |
| // - An empty array only uses one word. |
| // - A copy of the array only uses one word (i.e. assignment means aliasing). |
| // - The vector can't grow beyond 2^32-1 elements. |
| // - In all other regards this has similar space usage to a Vector. |
| // |
| // ** This could be modified to support non-POD values quite easily. It just |
| // hasn't been, so far, because there has been no need. Moreover, even now, |
| // it's used for things that aren't quite POD according to the official |
| // defintion, such as JSC::Instruction. |
| |
| namespace WTF { |
| |
| template<typename T> |
| class RefCountedArray { |
| public: |
| RefCountedArray() |
| : m_data(0) |
| { |
| } |
| |
| RefCountedArray(const RefCountedArray& other) |
| : m_data(other.m_data) |
| { |
| if (m_data) |
| Header::fromPayload(m_data)->refCount++; |
| } |
| |
| explicit RefCountedArray(const Vector<T>& other) |
| { |
| if (other.isEmpty()) { |
| m_data = 0; |
| return; |
| } |
| |
| m_data = (static_cast<Header*>(fastMalloc(Header::size() + sizeof(T) * other.size())))->payload(); |
| Header::fromPayload(m_data)->refCount = 1; |
| Header::fromPayload(m_data)->length = other.size(); |
| ASSERT(Header::fromPayload(m_data)->length == other.size()); |
| memcpy(m_data, other.begin(), sizeof(T) * other.size()); |
| } |
| |
| RefCountedArray& operator=(const RefCountedArray& other) |
| { |
| T* oldData = m_data; |
| m_data = other.m_data; |
| if (m_data) |
| Header::fromPayload(m_data)->refCount++; |
| |
| if (!oldData) |
| return *this; |
| if (--Header::fromPayload(oldData)->refCount) |
| return *this; |
| fastFree(Header::fromPayload(oldData)); |
| return *this; |
| } |
| |
| ~RefCountedArray() |
| { |
| if (!m_data) |
| return; |
| if (--Header::fromPayload(m_data)->refCount) |
| return; |
| fastFree(Header::fromPayload(m_data)); |
| } |
| |
| size_t size() const |
| { |
| if (!m_data) |
| return 0; |
| return Header::fromPayload(m_data)->length; |
| } |
| |
| T* data() { return m_data; } |
| T* begin() { return m_data; } |
| T* end() |
| { |
| if (!m_data) |
| return 0; |
| return m_data + Header::fromPayload(m_data)->length; |
| } |
| |
| const T* data() const { return m_data; } |
| const T* begin() const { return m_data; } |
| const T* end() const { return const_cast<RefCountedArray*>(this)->end(); } |
| |
| T& at(size_t i) |
| { |
| ASSERT(i < size()); |
| return begin()[i]; |
| } |
| |
| const T& at(size_t i) const |
| { |
| ASSERT(i < size()); |
| return begin()[i]; |
| } |
| |
| T& operator[](size_t i) { return at(i); } |
| const T& operator[](size_t i) const { return at(i); } |
| |
| private: |
| struct Header { |
| unsigned refCount; |
| unsigned length; |
| |
| static size_t size() |
| { |
| return (sizeof(Header) + 7) & ~7; |
| } |
| |
| T* payload() |
| { |
| char* result = reinterpret_cast<char*>(this) + size(); |
| ASSERT(!(bitwise_cast<uintptr_t>(result) & 7)); |
| return reinterpret_cast_ptr<T*>(result); |
| } |
| |
| static Header* fromPayload(T* payload) |
| { |
| return reinterpret_cast_ptr<Header*>(reinterpret_cast<char*>(payload) - size()); |
| } |
| }; |
| |
| T* m_data; |
| }; |
| |
| } // namespace WTF |
| |
| using WTF::RefCountedArray; |
| |
| #endif // RefCountedArray_h |
| |