C++17 Linked List Implementation

LinkedList.h

/**
 * @class LinkedList
 * @brief A simple linked list.
 *
 * A linked list is a data structure represented by a series of nodes wherein
 * each node maintains a record of its stored value and a pointer to another
 * node.
 *
 * This implementation is intended to provide very basic functionality,
 * including insertion, deletion, and size.
 *
 * @author  Chris Engelsma <chris.engelsma@gmail.com>
 * @date    Oct 7, 2019
 */

#pragma once

#include <iostream>
#include <sstream>

template<typename T>
struct Node
{
    T data;
    Node* next;
};


template<typename T>
class LinkedList
{
public:
    // The head node.
    Node<T>* m_head{nullptr};

    /**
     * @brief Constructs an empty linked list.
     */
    constexpr LinkedList() = default;

    /**
     * @brief Destructs this linked list.
     */
    ~LinkedList();

    /**
     * @brief Returns this linked list as a space-delimited std::string.
     * @return a std::string representation of this list.
     */
    [[nodiscard]] std::string toString() const;

    /**
     * @brief Inserts a value at the beginning of this list.
     * @param value a node value to insert.
     */
    template<typename K>
    constexpr void insertFirst(const K& value);
    void insertFirst(const T& value);

    /**
     * @brief Inserts a value at the end of this list.
     * @param value a node value to insert.
     */
    template<typename K>
    constexpr void insertLast(const K& value);
    void insertLast(const T& value);

    /**
     * @brief Removes the first value from this list.
     */
    void removeFirst();

    /**
     * @brief Determines if this linked list is empty.
     * @return true, if empty; false, otherwise.
     */
    [[nodiscard]] bool isEmpty() const { return m_head == nullptr; };

    /**
     * @brief Removes the last value from this list.
     */
    void removeLast();

    /**
     * @brief Gets the number of nodes in this list.
     * @return the number of nodes in this list.
     */
    [[nodiscard]] size_t size() const;

    friend std::ostream& operator<<(std::ostream& stream, const LinkedList& list)
    {
        stream << list.toString();
        return stream;
    }

};

using LinkedListf  = LinkedList<float>;
using LinkedListd  = LinkedList<double>;
using LinkedListi  = LinkedList<int32_t>;
using LinkedListui = LinkedList<uint32_t>;

#include "LinkedList.inl"

LinkedList.inl

#include "LinkedList.h"

template<typename T>
LinkedList<T>::~LinkedList()
{
    if (m_head != nullptr)
    {
        auto node = m_head->next;
        while (node != nullptr)
        {
            auto next = node->next;
            delete node;
            node = next;
        }

        m_head = nullptr;
    }
}

template<typename T>
template<typename K>
constexpr void LinkedList<T>::insertFirst(const K& value)
{
    (*this)->insertFirst(static_cast<T>(value));
}


template<typename T>
template<typename K>
constexpr void LinkedList<T>::insertLast(const K& value)
{
    (*this)->insertLast(static_cast<T>(value));
}


template<typename T>
void LinkedList<T>::insertFirst(const T& value)
{
    auto node = new Node<T>();
    node->data = value;

    if (m_head == nullptr)
    {
        m_head = node;
        m_head->next = nullptr;
    }
    else
    {
        auto temp = m_head;
        m_head = node;
        m_head->next = temp;
    }
}

template<typename T>
void LinkedList<T>::insertLast(const T& value)
{
    auto node = new Node<T>();
    node->data = value;
    node->next = nullptr;

    if (m_head == nullptr)
    {
        m_head = node;
        return;
    }

    auto temp = m_head;
    while (temp->next != nullptr)
    {
        temp = temp->next;
    }

    node->next = nullptr;
    temp->next = node;
}

template<typename T>
void LinkedList<T>::removeFirst()
{
    if (m_head == nullptr)
    {
        return;
    }

    m_head = m_head->next;
}

template<typename T>
void LinkedList<T>::removeLast()
{
    if (m_head == nullptr)
    {
        return;
    }

    if (m_head->next == nullptr)
    {
        delete m_head;
        return;
    }
    auto node = m_head;

    while (node->next->next != nullptr)
    {
        node = node->next;
    }

    delete node->next;
    node->next = nullptr;
}

template<typename T>
size_t LinkedList<T>::size() const
{
    auto   node    = m_head;
    size_t counter = 0;

    while (node != nullptr)
    {
        counter++;
        node = node->next;
    }

    return counter;
}

template<typename T>
std::string LinkedList<T>::toString() const
{
    std::stringstream stream;
    auto              node = m_head;
    if (node != nullptr)
    {
        while (node != nullptr)
        {
            stream << node->data << " -> ";
            node = node->next;
        }

    }
    stream << "NULL";
    return stream.str();
}

main.cpp

#include "LinkedList.h"
#include <ctime>
#include <iostream>
#include <cstdlib>

/**
 * Demos LinkedList by randomly inserting 10 integers.
 */
int main()
{
    auto list = new LinkedListi();

    srand(time(nullptr));
    int min = 0;   // Min integer
    int max = 100; // Max integer
    int n   = 10;  // Insert 10 random integers.
    int i   = 0;

    do
    {
        int value = rand() % max + min;
        std::cout << "Value to insert: " << value << std::endl;

        list->insertLast(value);

        std::cout << *list << std::endl;

        i++;
    } while (i<n);

    do
    {
        std::cout << "Removing first value" << std::endl;
        list->removeFirst();
        std::cout << *list << std::endl;
    } while (list->size() > 0);

    delete list; list = nullptr;

    exit(0);
}