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Diffstat (limited to 'include/rapidjson/internal/stack.h')
| -rw-r--r-- | include/rapidjson/internal/stack.h | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/include/rapidjson/internal/stack.h b/include/rapidjson/internal/stack.h new file mode 100644 index 00000000..022c9aab --- /dev/null +++ b/include/rapidjson/internal/stack.h @@ -0,0 +1,230 @@ +// 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. All rights reserved. +// +// 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" + +#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_); + 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(stackTop_ + sizeof(T) * count > stackEnd_)) + 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_ + sizeof(T) * count <= stackEnd_); + 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_ |