diff --git a/include/rapidjson/internal/stack.h b/include/rapidjson/internal/stack.h index 966893b3fc01ecf5a80752926a4b6b621e694ca6..89558d0daa4158caca95d9a73cf5eb922ece79ac 100644 --- a/include/rapidjson/internal/stack.h +++ b/include/rapidjson/internal/stack.h @@ -1,7 +1,29 @@ +// 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_ -namespace rapidjson { +#include "../allocators.h" +#include "swap.h" + +#if defined(__clang__) +RAPIDJSON_DIAG_PUSH +RAPIDJSON_DIAG_OFF(c++98-compat) +#endif + +RAPIDJSON_NAMESPACE_BEGIN namespace internal { /////////////////////////////////////////////////////////////////////////////// @@ -13,70 +35,197 @@ namespace internal { template class Stack { public: - Stack(Allocator* allocator, size_t stack_capacity) : allocator_(allocator), own_allocator_(0), stack_(0), stack_top_(0), stack_end_(0), stack_capacity_(stack_capacity) { - RAPIDJSON_ASSERT(stack_capacity_ > 0); - if (!allocator_) - own_allocator_ = allocator_ = new Allocator(); - stack_top_ = stack_ = (char*)allocator_->Malloc(stack_capacity_); - stack_end_ = stack_ + stack_capacity_; - } - - ~Stack() { - Allocator::Free(stack_); - delete own_allocator_; // Only delete if it is owned by the stack - } - - void Clear() { /*stack_top_ = 0;*/ stack_top_ = stack_; } - - template - T* Push(size_t count = 1) { - // Expand the stack if needed - if (stack_top_ + sizeof(T) * count >= stack_end_) { - size_t new_capacity = stack_capacity_ * 2; - size_t size = GetSize(); - size_t new_size = GetSize() + sizeof(T) * count; - if (new_capacity < new_size) - new_capacity = new_size; - stack_ = (char*)allocator_->Realloc(stack_, stack_capacity_, new_capacity); - stack_capacity_ = new_capacity; - stack_top_ = stack_ + size; - stack_end_ = stack_ + stack_capacity_; - } - T* ret = (T*)stack_top_; - stack_top_ += sizeof(T) * count; - return ret; - } - - template - T* Pop(size_t count) { - RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T)); - stack_top_ -= count * sizeof(T); - return (T*)stack_top_; - } - - template - T* Top() { - RAPIDJSON_ASSERT(GetSize() >= sizeof(T)); - return (T*)(stack_top_ - sizeof(T)); - } - - template - T* Bottom() { return (T*)stack_; } - - Allocator& GetAllocator() { return *allocator_; } - size_t GetSize() const { return stack_top_ - stack_; } - size_t GetCapacity() const { return stack_capacity_; } + // 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 + RAPIDJSON_FORCEINLINE void Reserve(size_t count = 1) { + // Expand the stack if needed + if (RAPIDJSON_UNLIKELY(stackTop_ + sizeof(T) * count > stackEnd_)) + Expand(count); + } + + template + RAPIDJSON_FORCEINLINE T* Push(size_t count = 1) { + Reserve(count); + return PushUnsafe(count); + } + + template + RAPIDJSON_FORCEINLINE T* PushUnsafe(size_t count = 1) { + RAPIDJSON_ASSERT(stackTop_); + RAPIDJSON_ASSERT(stackTop_ + sizeof(T) * count <= stackEnd_); + T* ret = reinterpret_cast(stackTop_); + stackTop_ += sizeof(T) * count; + return ret; + } + + template + T* Pop(size_t count) { + RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T)); + stackTop_ -= count * sizeof(T); + return reinterpret_cast(stackTop_); + } + + template + T* Top() { + RAPIDJSON_ASSERT(GetSize() >= sizeof(T)); + return reinterpret_cast(stackTop_ - sizeof(T)); + } + + template + const T* Top() const { + RAPIDJSON_ASSERT(GetSize() >= sizeof(T)); + return reinterpret_cast(stackTop_ - sizeof(T)); + } + + template + T* End() { return reinterpret_cast(stackTop_); } + + template + const T* End() const { return reinterpret_cast(stackTop_); } + + template + T* Bottom() { return reinterpret_cast(stack_); } + + template + const T* Bottom() const { return reinterpret_cast(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(stackTop_ - stack_); } + size_t GetCapacity() const { return static_cast(stackEnd_ - stack_); } private: - Allocator* allocator_; - Allocator* own_allocator_; - char *stack_; - char *stack_top_; - char *stack_end_; - size_t stack_capacity_; + template + 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(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 -} // namespace rapidjson +RAPIDJSON_NAMESPACE_END + +#if defined(__clang__) +RAPIDJSON_DIAG_POP +#endif #endif // RAPIDJSON_STACK_H_