Differential D793 Diff 2592 extern/rapidjson/include/rapidjson/internal/stack.h

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extern/rapidjson/include/rapidjson/internal/stack.h

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				// Copyright (C) 2011 Milo Yip
				//
				// Permission is hereby granted, free of charge, to any person obtaining a copy
				// of this software and associated documentation files (the "Software"), to deal
				// in the Software without restriction, including without limitation the rights
				// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
				// copies of the Software, and to permit persons to whom the Software is
				// furnished to do so, subject to the following conditions:
				//
				// The above copyright notice and this permission notice shall be included in
				// all copies or substantial portions of the Software.
				//
				// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
				// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
				// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
				// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
				// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
				// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
				// THE SOFTWARE.

				#ifndef RAPIDJSON_INTERNAL_STACK_H_
				#define RAPIDJSON_INTERNAL_STACK_H_

				namespace rapidjson {
				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) {
				RAPIDJSON_ASSERT(stackCapacity > 0);
				if (!allocator_)
				ownAllocator = allocator_ = new Allocator();
				}

				~Stack() {
				Allocator::Free(stack_);
				delete ownAllocator; // Only delete if it is owned by the stack
				}

				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 T* Push(size_t count = 1) {
				// Expand the stack if needed
				if (stackTop_ + sizeof(T) * count >= stackEnd_)
				Expand<T>(count);

				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>
				T* Bottom() { return (T*)stack_; }

				Allocator& GetAllocator() { 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)
				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_ = (char*)allocator_->Realloc(stack_, GetCapacity(), newCapacity);
				stackTop_ = stack_ + size;
				stackEnd_ = stack_ + newCapacity;
				}

				// 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
				} // namespace rapidjson

				#endif // RAPIDJSON_STACK_H_