cpp/common/include/rapidjson/internal/stack.h
// 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_