Спринт 14. Реализация метода EmplaceBack.

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vector.h
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#pragma once
#include <cassert>
#include <memory>
#include <algorithm>
#include <cstdlib>
#include <new>
#include <utility>

template <typename T>
class RawMemory {
public:
    RawMemory() = default;

    explicit RawMemory(size_t capacity) : buffer_(Allocate(capacity))
                                        , capacity_(capacity) {}

    ~RawMemory() {Deallocate(buffer_);}

    RawMemory(const RawMemory&) = delete;
    RawMemory& operator=(const RawMemory& rhs) = delete;

    RawMemory(RawMemory&& other) noexcept : buffer_(std::exchange(other.buffer_, nullptr))
                                          , capacity_(std::exchange(other.capacity_, 0)) {}

    RawMemory& operator=(RawMemory&& rhs) noexcept {

        if (this != &rhs) {
            buffer_ = std::move(rhs.buffer_);
            capacity_ = std::move(rhs.capacity_);
            rhs.buffer_ = nullptr;
            rhs.capacity_ = 0;
        }

        return *this;
    }

    T* operator+(size_t offset) noexcept {assert(offset <= capacity_); return buffer_ + offset;}
    const T* operator+(size_t offset) const noexcept {return const_cast<RawMemory&>(*this) + offset;}

    const T& operator[](size_t index) const noexcept {return const_cast<RawMemory&>(*this)[index];}
    T& operator[](size_t index) noexcept {assert(index < capacity_); return buffer_[index];}

    void Swap(RawMemory& other) noexcept {std::swap(buffer_, other.buffer_); std::swap(capacity_, other.capacity_);}

    const T* GetAddress() const noexcept {return buffer_;}
    T* GetAddress() noexcept {return buffer_;}
    size_t Capacity() const {return capacity_;}

private:
    T* buffer_ = nullptr;
    size_t capacity_ = 0;

    static T* Allocate(size_t n) {return n != 0 ? static_cast<T*>(operator new(n * sizeof(T))) : nullptr;}
    static void Deallocate(T* buf) noexcept {operator delete(buf);}
};

template <typename T>
class Vector {
public:

    Vector() = default;

    explicit Vector(size_t size) : data_(size)
                                 , size_(size) {std::uninitialized_value_construct_n(data_.GetAddress(), size);}

    Vector(const Vector& other) : data_(other.size_)
                                , size_(other.size_) {std::uninitialized_copy_n(other.data_.GetAddress(), size_, data_.GetAddress());}

    Vector(Vector&& other) noexcept : data_(std::move(other.data_))
                                    , size_(std::exchange(other.size_, 0)) {}

    ~Vector() {std::destroy_n(data_.GetAddress(), size_);}

    size_t Size() const noexcept {return size_;}
    size_t Capacity() const noexcept {return data_.Capacity();}
    void Swap(Vector& other) noexcept {data_.Swap(other.data_), std::swap(size_, other.size_);}

    void Reserve(size_t new_capacity) {

        if (new_capacity <= data_.Capacity()) {
            return;
        }

        RawMemory<T> new_data(new_capacity);

        if constexpr (std::is_nothrow_move_constructible_v<T> || !std::is_copy_constructible_v<T>) {
            std::uninitialized_move_n(data_.GetAddress(), size_, new_data.GetAddress());
        } else {
            std::uninitialized_copy_n(data_.GetAddress(), size_, new_data.GetAddress());
        }

        std::destroy_n(data_.GetAddress(), size_);
        data_.Swap(new_data);
    }

    void Resize(size_t new_size) {

        if (new_size < size_) {
            std::destroy_n(data_.GetAddress() + new_size, size_ - new_size);

        } else {

            if (new_size > data_.Capacity()) {
                const size_t new_capacity = std::max(data_.Capacity() * 2, new_size);

                Reserve(new_capacity);
            }

            std::uninitialized_value_construct_n(data_.GetAddress() + size_, new_size - size_);
        }

        size_ = new_size;
    }

    template <typename Type>
    void PushBack(Type&& value);

    template <typename... Args>
    T& EmplaceBack(Args&&... args);

    void PopBack() {
        assert(size_);
        std::destroy_at(data_.GetAddress() + size_ - 1);
        --size_;
    }

    Vector& operator=(const Vector& other) {

        if (this != &other) {

            if (other.size_ <= data_.Capacity()) {

                if (size_ <= other.size_) {

                    std::copy(other.data_.GetAddress(),
                              other.data_.GetAddress() + size_,
                              data_.GetAddress());

                    std::uninitialized_copy_n(other.data_.GetAddress() + size_,
                                              other.size_ - size_,
                                              data_.GetAddress() + size_);
                } else {

                    std::copy(other.data_.GetAddress(),
                              other.data_.GetAddress() + other.size_,
                              data_.GetAddress());

                    std::destroy_n(data_.GetAddress() + other.size_,
                                   size_ - other.size_);
                }

                size_ = other.size_;

            } else {
                Vector other_copy(other);
                Swap(other_copy);
            }
        }

        return *this;
    }

    Vector& operator=(Vector&& other) noexcept {Swap(other); return *this;}

    const T& operator[](size_t index) const noexcept {return const_cast<Vector&>(*this)[index];}
    T& operator[](size_t index) noexcept {assert(index < size_); return data_[index];}

private:
    RawMemory<T> data_;
    size_t size_ = 0;
};

template <typename T>
template <typename Type>
void Vector<T>::PushBack(Type&& value) {

    if (data_.Capacity() <= size_) {

        RawMemory<T> new_data(size_ == 0 ? 1 : size_ * 2);

        new (new_data.GetAddress() + size_) T(std::forward<Type>(value));

        if constexpr (std::is_nothrow_move_constructible_v<T> || !std::is_copy_constructible_v<T>) {
            std::uninitialized_move_n(data_.GetAddress(), size_, new_data.GetAddress());
        } else {
            std::uninitialized_copy_n(data_.GetAddress(), size_, new_data.GetAddress());
        }

        std::destroy_n(data_.GetAddress(), size_);
        data_.Swap(new_data);

    } else {
        new (data_.GetAddress() + size_) T(std::forward<Type>(value));
    }

    size_++;
}

template <typename T>
template <typename... Args>
T& Vector<T>::EmplaceBack(Args&&... args) {

    if (data_.Capacity() <= size_) {

        RawMemory<T> new_data(size_ == 0 ? 1 : size_ * 2);

        new (new_data.GetAddress() + size_) T(std::forward<Args>(args)...);

        if constexpr (std::is_nothrow_move_constructible_v<T> || !std::is_copy_constructible_v<T>) {
            std::uninitialized_move_n(data_.GetAddress(), size_, new_data.GetAddress());
        } else {
            std::uninitialized_copy_n(data_.GetAddress(), size_, new_data.GetAddress());
        }

        std::destroy_n(data_.GetAddress(), size_);
        data_.Swap(new_data);

    } else {
        new (data_.GetAddress() + size_) T(std::forward<Args>(args)...);
    }

    return data_[size_++];
}
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main.cpp
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#include "vector.h"

#include <iostream>
#include <stdexcept>
#include <string>

namespace {

inline const uint32_t DEFAULT_COOKIE = 0xdeadbeef;

struct TestObj {

    TestObj() = default;
    TestObj(const TestObj& other) = default;
    TestObj& operator=(const TestObj& other) = default;
    TestObj(TestObj&& other) = default;
    TestObj& operator=(TestObj&& other) = default;

    ~TestObj() {cookie = 0;}

    [[nodiscard]] bool IsAlive() const noexcept {return cookie == DEFAULT_COOKIE;}

    uint32_t cookie = DEFAULT_COOKIE;
};

struct Obj {

    Obj() {

        if (default_construction_throw_countdown > 0) {

            if (--default_construction_throw_countdown == 0) {
                throw std::runtime_error("Oops");
            }
        }

        ++num_default_constructed;
    }

    explicit Obj(int id) : id(id) {++num_constructed_with_id;}

    Obj(int id, std::string name) : id(id)
                                  , name(std::move(name)) {++num_constructed_with_id_and_name;}

    Obj(const Obj& other) : id(other.id) {

        if (other.throw_on_copy) {
            throw std::runtime_error("Oops");
        }

        ++num_copied;
    }

    Obj(Obj&& other) noexcept : id(other.id) {++num_moved;}

    Obj& operator=(const Obj& other) = default;
    Obj& operator=(Obj&& other) = default;

    ~Obj() {++num_destroyed; id = 0;}

    static int GetAliveObjectCount() {

        return num_default_constructed
               + num_copied
               + num_moved
               + num_constructed_with_id
               + num_constructed_with_id_and_name
               - num_destroyed;
    }

    static void ResetCounters() {
        default_construction_throw_countdown = 0;
        num_default_constructed = 0;
        num_copied = 0;
        num_moved = 0;
        num_destroyed = 0;
        num_constructed_with_id = 0;
        num_constructed_with_id_and_name = 0;
    }

    bool throw_on_copy = false;
    int id = 0;
    std::string name;

    static inline int default_construction_throw_countdown = 0;
    static inline int num_default_constructed = 0;
    static inline int num_constructed_with_id = 0;
    static inline int num_constructed_with_id_and_name = 0;
    static inline int num_copied = 0;
    static inline int num_moved = 0;
    static inline int num_destroyed = 0;
};

}//end namespace

void Test1() {

    Obj::ResetCounters();

    const size_t SIZE = 100500;
    const size_t INDEX = 10;
    const int MAGIC = 42;

    {
        Vector<int> v;

        assert(v.Capacity() == 0);
        assert(v.Size() == 0);

        v.Reserve(SIZE);

        assert(v.Capacity() == SIZE);
        assert(v.Size() == 0);
    }

    {
        Vector<int> v(SIZE);

        const auto& cv(v);
        assert(v.Capacity() == SIZE);
        assert(v.Size() == SIZE);
        assert(v[0] == 0);
        assert(&v[0] == &cv[0]);

        v[INDEX] = MAGIC;

        assert(v[INDEX] == MAGIC);
        assert(&v[100] - &v[0] == 100);

        v.Reserve(SIZE * 2);

        assert(v.Size() == SIZE);
        assert(v.Capacity() == SIZE * 2);
        assert(v[INDEX] == MAGIC);
    }

    {
        Vector<int> v(SIZE);

        v[INDEX] = MAGIC;

        const auto v_copy(v);
        assert(&v[INDEX] != &v_copy[INDEX]);
        assert(v[INDEX] == v_copy[INDEX]);
    }

    {
        Vector<Obj> v;

        v.Reserve(SIZE);

        assert(Obj::GetAliveObjectCount() == 0);
    }

    {
        Vector<Obj> v(SIZE);

        assert(Obj::GetAliveObjectCount() == SIZE);

        const int old_copy_count = Obj::num_copied;
        const int old_move_count = Obj::num_moved;

        v.Reserve(SIZE * 2);

        assert(Obj::GetAliveObjectCount() == SIZE);
        assert(Obj::num_copied == old_copy_count);
        assert(Obj::num_moved == old_move_count + static_cast<int>(SIZE));
    }

    assert(Obj::GetAliveObjectCount() == 0);
}

void Test2() {
    const size_t SIZE = 100;

    Obj::ResetCounters();

    {
        Obj::default_construction_throw_countdown = SIZE / 2;
        try {
            Vector<Obj> v(SIZE);
            assert(false && "Exception is expected");

        } catch (const std::runtime_error&) {

        } catch (...) {
            assert(false && "Unexpected exception");
        }

        assert(Obj::num_default_constructed == SIZE / 2 - 1);
        assert(Obj::GetAliveObjectCount() == 0);
    }

    Obj::ResetCounters();

    {
        Vector<Obj> v(SIZE);

        try {
            v[SIZE / 2].throw_on_copy = true;
            Vector<Obj> v_copy(v);
            assert(false && "Exception is expected");

        } catch (const std::runtime_error&) {
            assert(Obj::num_copied == SIZE / 2);

        } catch (...) {
            assert(false && "Unexpected exception");
        }

        assert(Obj::GetAliveObjectCount() == SIZE);
    }

    Obj::ResetCounters();

    {
        Vector<Obj> v(SIZE);

        try {
            v[SIZE - 1].throw_on_copy = true;
            v.Reserve(SIZE * 2);

        } catch (...) {
            assert(false && "Unexpected exception");
        }

        assert(v.Capacity() == SIZE * 2);
        assert(v.Size() == SIZE);
        assert(Obj::GetAliveObjectCount() == SIZE);
    }
}

void Test3() {
    const size_t MEDIUM_SIZE = 100;
    const size_t LARGE_SIZE = 250;
    const int ID = 42;

    {
        Obj::ResetCounters();

        Vector<int> v(MEDIUM_SIZE);

        {
            auto v_copy(std::move(v));

            assert(v_copy.Size() == MEDIUM_SIZE);
            assert(v_copy.Capacity() == MEDIUM_SIZE);
        }

        assert(Obj::GetAliveObjectCount() == 0);
    }

    {
        Obj::ResetCounters();

        {
            Vector<Obj> v(MEDIUM_SIZE);

            v[MEDIUM_SIZE / 2].id = ID;

            assert(Obj::num_default_constructed == MEDIUM_SIZE);

            Vector<Obj> moved_from_v(std::move(v));

            assert(moved_from_v.Size() == MEDIUM_SIZE);
            assert(moved_from_v[MEDIUM_SIZE / 2].id == ID);
        }

        assert(Obj::GetAliveObjectCount() == 0);

        assert(Obj::num_moved == 0);
        assert(Obj::num_copied == 0);
        assert(Obj::num_default_constructed == MEDIUM_SIZE);
    }

    {
        Obj::ResetCounters();

        Vector<Obj> v_medium(MEDIUM_SIZE);

        v_medium[MEDIUM_SIZE / 2].id = ID;

        Vector<Obj> v_large(LARGE_SIZE);

        v_large = v_medium;

        assert(v_large.Size() == MEDIUM_SIZE);
        assert(v_large.Capacity() == LARGE_SIZE);
        assert(v_large[MEDIUM_SIZE / 2].id == ID);
        assert(Obj::GetAliveObjectCount() == MEDIUM_SIZE + MEDIUM_SIZE);
    }

    {
        Obj::ResetCounters();

        Vector<Obj> v(MEDIUM_SIZE);

        {
            Vector<Obj> v_large(LARGE_SIZE);

            v_large[LARGE_SIZE - 1].id = ID;
            v = v_large;

            assert(v.Size() == LARGE_SIZE);
            assert(v_large.Capacity() == LARGE_SIZE);
            assert(v_large[LARGE_SIZE - 1].id == ID);
            assert(Obj::GetAliveObjectCount() == LARGE_SIZE + LARGE_SIZE);
        }

        assert(Obj::GetAliveObjectCount() == LARGE_SIZE);
    }

    assert(Obj::GetAliveObjectCount() == 0);

    {
        Obj::ResetCounters();

        Vector<Obj> v(MEDIUM_SIZE);

        v[MEDIUM_SIZE - 1].id = ID;

        Vector<Obj> v_small(MEDIUM_SIZE / 2);
        v_small.Reserve(MEDIUM_SIZE + 1);

        const size_t num_copies = Obj::num_copied;
        v_small = v;

        assert(v_small.Size() == v.Size());
        assert(v_small.Capacity() == MEDIUM_SIZE + 1);

        v_small[MEDIUM_SIZE - 1].id = ID;

        assert(Obj::num_copied - num_copies == MEDIUM_SIZE - (MEDIUM_SIZE / 2));
    }
}

void Test4() {
    const size_t ID = 42;
    const size_t SIZE = 100'500;

    {
        Obj::ResetCounters();

        Vector<Obj> v;

        v.Resize(SIZE);

        assert(v.Size() == SIZE);
        assert(v.Capacity() == SIZE);
        assert(Obj::num_default_constructed == SIZE);
    }

    assert(Obj::GetAliveObjectCount() == 0);

    {
        const size_t NEW_SIZE = 10'000;

        Obj::ResetCounters();

        Vector<Obj> v(SIZE);

        v.Resize(NEW_SIZE);

        assert(v.Size() == NEW_SIZE);
        assert(v.Capacity() == SIZE);
        assert(Obj::num_destroyed == SIZE - NEW_SIZE);
    }

    assert(Obj::GetAliveObjectCount() == 0);

    {
        Obj::ResetCounters();

        Vector<Obj> v(SIZE);

        Obj o{ID};

        v.PushBack(o);

        assert(v.Size() == SIZE + 1);
        assert(v.Capacity() == SIZE * 2);
        assert(v[SIZE].id == ID);
        assert(Obj::num_default_constructed == SIZE);
        assert(Obj::num_copied == 1);
        assert(Obj::num_constructed_with_id == 1);
        assert(Obj::num_moved == SIZE);
    }

    assert(Obj::GetAliveObjectCount() == 0);

    {
        Obj::ResetCounters();

        Vector<Obj> v(SIZE);

        v.PushBack(Obj{ID});

        assert(v.Size() == SIZE + 1);
        assert(v.Capacity() == SIZE * 2);
        assert(v[SIZE].id == ID);
        assert(Obj::num_default_constructed == SIZE);
        assert(Obj::num_copied == 0);
        assert(Obj::num_constructed_with_id == 1);
        assert(Obj::num_moved == SIZE + 1);
    }

    {
        Obj::ResetCounters();

        Vector<Obj> v;

        v.PushBack(Obj{ID});

        v.PopBack();

        assert(v.Size() == 0);
        assert(v.Capacity() == 1);
        assert(Obj::GetAliveObjectCount() == 0);
    }

    {
        Vector<TestObj> v(1);

        assert(v.Size() == v.Capacity());

        v.PushBack(v[0]);
        assert(v[0].IsAlive());
        assert(v[1].IsAlive());
    }
    {
        Vector<TestObj> v(1);

        assert(v.Size() == v.Capacity());

        v.PushBack(std::move(v[0]));
        assert(v[0].IsAlive());
        assert(v[1].IsAlive());
    }
}

void Test5() {
    const int ID = 42;
    using namespace std::literals;

    {
        Obj::ResetCounters();

        Vector<Obj> v;

        auto& elem = v.EmplaceBack(ID, "Ivan"s);

        assert(v.Capacity() == 1);
        assert(v.Size() == 1);
        assert(&elem == &v[0]);
        assert(v[0].id == ID);
        assert(v[0].name == "Ivan"s);
        assert(Obj::num_constructed_with_id_and_name == 1);
        assert(Obj::GetAliveObjectCount() == 1);
    }

    assert(Obj::GetAliveObjectCount() == 0);

    {
        Vector<TestObj> v(1);

        assert(v.Size() == v.Capacity());

        v.EmplaceBack(v[0]);
        assert(v[0].IsAlive());
        assert(v[1].IsAlive());
    }
}

int main() {
    try {
        Test1();
        Test2();
        Test3();
        Test4();
        Test5();

    } catch (const std::exception& e) {
        std::cerr << e.what() << std::endl;
    }
}