blame: source/code/Libs/include/cereal/external/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 CEREAL_RAPIDJSON_INTERNAL_STACK_H_

#define CEREAL_RAPIDJSON_INTERNAL_STACK_H_

#include "../allocators.h"

#include "swap.h"

#if defined(__clang__)

CEREAL_RAPIDJSON_DIAG_PUSH

CEREAL_RAPIDJSON_DIAG_OFF(c++98-compat)

#endif

CEREAL_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 CEREAL_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 CEREAL_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) CEREAL_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>

    CEREAL_RAPIDJSON_FORCEINLINE void Reserve(size_t count = 1) {

         // Expand the stack if needed

        if (CEREAL_RAPIDJSON_UNLIKELY(stackTop_ + sizeof(T) * count > stackEnd_))

            Expand<T>(count);

    }

    template<typename T>

    CEREAL_RAPIDJSON_FORCEINLINE T* Push(size_t count = 1) {

        Reserve<T>(count);

        return PushUnsafe<T>(count);

    }

    template<typename T>

    CEREAL_RAPIDJSON_FORCEINLINE T* PushUnsafe(size_t count = 1) {

        CEREAL_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) {

        CEREAL_RAPIDJSON_ASSERT(GetSize() >= count * sizeof(T));

        stackTop_ -= count * sizeof(T);

        return reinterpret_cast<T*>(stackTop_);

    }

    template<typename T>

    T* Top() { 

        CEREAL_RAPIDJSON_ASSERT(GetSize() >= sizeof(T));

        return reinterpret_cast<T*>(stackTop_ - sizeof(T));

    }

    template<typename T>

    const T* Top() const {

        CEREAL_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() {

        CEREAL_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_ = CEREAL_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_);

        CEREAL_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

CEREAL_RAPIDJSON_NAMESPACE_END

#if defined(__clang__)

CEREAL_RAPIDJSON_DIAG_POP

#endif

#endif // CEREAL_RAPIDJSON_STACK_H_