// Tencent is pleased to support the open source community by making RapidJSON available. // // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. // // Licensed under the MIT License (the "License"); you may not use this file except // in compliance with the License. You may obtain a copy of the License at // // http://opensource.org/licenses/MIT // // Unless required by applicable law or agreed to in writing, software distributed // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR // CONDITIONS OF ANY KIND, either express or implied. See the License for the // specific language governing permissions and limitations under the License. #ifndef RAPIDJSON_INTERNAL_STACK_H_ #define RAPIDJSON_INTERNAL_STACK_H_ #include "../allocators.h" #include "swap.h" #include <cstddef> #if defined(__clang__) RAPIDJSON_DIAG_PUSH RAPIDJSON_DIAG_OFF(c++98-compat) #endif RAPIDJSON_NAMESPACE_BEGIN namespace internal { /////////////////////////////////////////////////////////////////////////////// // Stack //! A type-unsafe stack for storing different types of data. /*! \tparam Allocator Allocator for allocating stack memory. */ template <typename Allocator> class Stack { public: // Optimization note: Do not allocate memory for stack_ in constructor. // Do it lazily when first Push() -> Expand() -> Resize(). Stack(Allocator* allocator, size_t stackCapacity) : allocator_(allocator), ownAllocator_(0), stack_(0), stackTop_(0), stackEnd_(0), initialCapacity_(stackCapacity) { } #if RAPIDJSON_HAS_CXX11_RVALUE_REFS Stack(Stack&& rhs) : allocator_(rhs.allocator_), ownAllocator_(rhs.ownAllocator_), stack_(rhs.stack_), stackTop_(rhs.stackTop_), stackEnd_(rhs.stackEnd_), initialCapacity_(rhs.initialCapacity_) { rhs.allocator_ = 0; rhs.ownAllocator_ = 0; rhs.stack_ = 0; rhs.stackTop_ = 0; rhs.stackEnd_ = 0; rhs.initialCapacity_ = 0; } #endif ~Stack() { Destroy(); } #if RAPIDJSON_HAS_CXX11_RVALUE_REFS Stack& operator=(Stack&& rhs) { if (&rhs != this) { Destroy(); allocator_ = rhs.allocator_; ownAllocator_ = rhs.ownAllocator_; stack_ = rhs.stack_; stackTop_ = rhs.stackTop_; stackEnd_ = rhs.stackEnd_; initialCapacity_ = rhs.initialCapacity_; rhs.allocator_ = 0; rhs.ownAllocator_ = 0; rhs.stack_ = 0; rhs.stackTop_ = 0; rhs.stackEnd_ = 0; rhs.initialCapacity_ = 0; } return *this; } #endif void Swap(Stack& rhs) RAPIDJSON_NOEXCEPT { internal::Swap(allocator_, rhs.allocator_); internal::Swap(ownAllocator_, rhs.ownAllocator_); internal::Swap(stack_, rhs.stack_); internal::Swap(stackTop_, rhs.stackTop_); internal::Swap(stackEnd_, rhs.stackEnd_); internal::Swap(initialCapacity_, rhs.initialCapacity_); } void Clear() { stackTop_ = stack_; } void ShrinkToFit() { if (Empty()) { // If the stack is empty, completely deallocate the memory. Allocator::Free(stack_); // NOLINT (+clang-analyzer-unix.Malloc) stack_ = 0; stackTop_ = 0; stackEnd_ = 0; } else Resize(GetSize()); } // Optimization note: try to minimize the size of this function for force inline. // Expansion is run very infrequently, so it is moved to another (probably non-inline) function. template<typename T> RAPIDJSON_FORCEINLINE void Reserve(size_t count = 1) { // Expand the stack if needed if (RAPIDJSON_UNLIKELY(static_cast<std::ptrdiff_t>(sizeof(T) * count) > (stackEnd_ - stackTop_))) Expand<T>(count); } template<typename T> RAPIDJSON_FORCEINLINE T* Push(size_t count = 1) { Reserve<T>(count); return PushUnsafe<T>(count); } template<typename T> RAPIDJSON_FORCEINLINE T* PushUnsafe(size_t count = 1) { RAPIDJSON_ASSERT(stackTop_); RAPIDJSON_ASSERT(static_cast<std::ptrdiff_t>(sizeof(T) * count) <= (stackEnd_ - stackTop_)); T* ret = reinterpret_cast<T*>(stackTop_); stackTop_ += sizeof(T) * count; return ret; } template<typename T> T* Pop(size_t count) { RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T)); stackTop_ -= count * sizeof(T); return reinterpret_cast<T*>(stackTop_); } template<typename T> T* Top() { RAPIDJSON_ASSERT(GetSize() >= sizeof(T)); return reinterpret_cast<T*>(stackTop_ - sizeof(T)); } template<typename T> const T* Top() const { RAPIDJSON_ASSERT(GetSize() >= sizeof(T)); return reinterpret_cast<T*>(stackTop_ - sizeof(T)); } template<typename T> T* End() { return reinterpret_cast<T*>(stackTop_); } template<typename T> const T* End() const { return reinterpret_cast<T*>(stackTop_); } template<typename T> T* Bottom() { return reinterpret_cast<T*>(stack_); } template<typename T> const T* Bottom() const { return reinterpret_cast<T*>(stack_); } bool HasAllocator() const { return allocator_ != 0; } Allocator& GetAllocator() { RAPIDJSON_ASSERT(allocator_); return *allocator_; } bool Empty() const { return stackTop_ == stack_; } size_t GetSize() const { return static_cast<size_t>(stackTop_ - stack_); } size_t GetCapacity() const { return static_cast<size_t>(stackEnd_ - stack_); } private: template<typename T> void Expand(size_t count) { // Only expand the capacity if the current stack exists. Otherwise just create a stack with initial capacity. size_t newCapacity; if (stack_ == 0) { if (!allocator_) ownAllocator_ = allocator_ = RAPIDJSON_NEW(Allocator)(); newCapacity = initialCapacity_; } else { newCapacity = GetCapacity(); newCapacity += (newCapacity + 1) / 2; } size_t newSize = GetSize() + sizeof(T) * count; if (newCapacity < newSize) newCapacity = newSize; Resize(newCapacity); } void Resize(size_t newCapacity) { const size_t size = GetSize(); // Backup the current size stack_ = static_cast<char*>(allocator_->Realloc(stack_, GetCapacity(), newCapacity)); stackTop_ = stack_ + size; stackEnd_ = stack_ + newCapacity; } void Destroy() { Allocator::Free(stack_); RAPIDJSON_DELETE(ownAllocator_); // Only delete if it is owned by the stack } // Prohibit copy constructor & assignment operator. Stack(const Stack&); Stack& operator=(const Stack&); Allocator* allocator_; Allocator* ownAllocator_; char *stack_; char *stackTop_; char *stackEnd_; size_t initialCapacity_; }; } // namespace internal RAPIDJSON_NAMESPACE_END #if defined(__clang__) RAPIDJSON_DIAG_POP #endif #endif // RAPIDJSON_STACK_H_