Kylin/DataStructure/LinkedList.h

#ifndef LINKEDLIST_H
#define LINKEDLIST_H

#include "Exception.h"
#include "List.h"
#include <initializer_list>

namespace Kylin {

template <typename T>
class LinkedList : public List<T> {
protected:
    struct Node : public Object {
        T value;
        Node *next = nullptr;
    };

    struct : public Object {
        char reserved[sizeof(T)];
        Node *next = nullptr;
    } mutable m_header;

public:
    class Iterator : public Object {
        friend class LinkedList;

    public:
        Iterator() = default;
        Iterator(Node *pos) : pos(pos) {}
        Iterator &operator++() {
            pos = pos->next;
            return *this;
        }
        Iterator operator++(int) {
            auto old = *this;
            pos = pos->next;
            return old;
        }

        Iterator operator+=(size_t size) {
            for (size_t i = 0; (i < size) && (pos != nullptr); i++) {
                pos = &(*pos)->next;
            }
        }
        T *operator->() const { return &pos->value; }
        T &operator*() const { return pos->value; }
        bool operator!=(const Iterator &iter) { return pos != iter.pos; }
        bool operator==(const Iterator &iter) { return pos == iter.pos; }

    private:
        Node *pos = nullptr;
    };

    LinkedList() { m_last = reinterpret_cast<Node *>(&m_header); }

    LinkedList(std::initializer_list<T> init) {
        m_last = reinterpret_cast<Node *>(&m_header);
        for (auto &value : init) {
            append(value);
        }
    }

    LinkedList(const LinkedList &other) {
        auto sourceNode = other.m_header.next;
        auto targetNode = reinterpret_cast<Node *>(&m_header);
        while (sourceNode != nullptr) {
            auto newNode = create();
            if (newNode == nullptr) THROW_EXCEPTION(NoEnoughMemoryException, "No memory to create node ...");
            newNode->value = sourceNode->value;
            targetNode->next = newNode;
            targetNode = newNode;
            sourceNode = sourceNode->next;
            m_size++;
            targetNode->next = nullptr;
            m_last = targetNode;
        }
    }

    LinkedList(LinkedList &&other) {
        m_size = other.m_size;
        m_header = other.m_header;
        m_last = other.m_last;

        other.m_size = 0;
        other.m_header.next = nullptr;
        other.m_last = reinterpret_cast<Node *>(&other.m_header);
    }

    ~LinkedList() { clear(); }

    void swap(LinkedList &other) {
        if (this == &other) return;
        auto tempSize = other.m_size;
        auto tempHeader = other.m_header;
        auto tempLast = other.m_last;

        other.m_header = m_header;
        other.m_size = m_size;
        other.m_last = m_last;

        m_header = tempHeader;
        m_size = tempSize;
        m_last = tempLast;
    }

    virtual void append(const T &value) {
        auto node = create();
        if (node == nullptr) THROW_EXCEPTION(NoEnoughMemoryException, "No memory to create node ...");
        node->value = value;

        node->next = m_last->next; // for circular linked list
        m_last->next = node;
        m_last = node;
        m_size++;
    }

    virtual void insert(size_t index, const T &value) {
        if (index >= m_size) return append(value);
        Node *prev = position(index);
        Node *node = create();
        if (node == nullptr) THROW_EXCEPTION(NoEnoughMemoryException, "No memory to create node ...");
        node->value = value;
        node->next = prev->next;
        prev->next = node;
        m_size += 1;
    }

    T &last() override {
        if (m_size <= 0) THROW_EXCEPTION(InvalidOperationException, "There is no element in the container.");
        return m_last->value;
    }

    void removeAt(size_t index) override {
        if (index >= m_size) THROW_EXCEPTION(IndexOutOfBoundsException, "The index is out of range.");
        Node *prev = position(index);
        Node *toDel = prev->next;
        prev->next = toDel->next;
        if (index == m_size - 1) m_last = prev;
        m_size--;
        destroy(toDel);
    }

    virtual void clear() {
        while (m_header.next != nullptr) {
            Node *del = m_header.next;
            m_header.next = del->next;
            m_size--;
            destroy(del);
        }
        m_last = reinterpret_cast<Node *>(&m_header);
    }

    virtual size_t size() const noexcept { return m_size; }

    virtual size_t indexOf(const T &value, size_t from = 0) const final {
        auto node = position(from)->next;
        for (size_t i = from; i < m_size; i++, node = node->next) {
            if (node->value == value) return i;
        }
        return LinkedList::npos;
    }

    Iterator begin() { return Iterator(m_header.next); }

    Iterator begin() const { return Iterator(m_header.next); }

    virtual Iterator end() { return Iterator(); }

    virtual Iterator end() const { return Iterator(); }

    T &operator[](size_t index) override {
        if (index >= m_size) THROW_EXCEPTION(IndexOutOfBoundsException, "Index out of bounds...");
        return position(index)->next->value;
    }

protected:
    Node *position(size_t index) const {
        Node *ret = reinterpret_cast<Node *>(&m_header);
        for (size_t i = 0; i < index; i++) {
            ret = ret->next;
        }
        return ret;
    }

    virtual Node *create() { return new Node(); }

    virtual void destroy(Node *p) { delete p; }

    size_t m_size = 0;

    Node *m_last = nullptr;
};
} // namespace Kylin
#endif // LINKEDLIST_H