source: doc/papers/OOPSLA17/evaluation/cpp-stack.hpp@ 3f1d9b5

#pragma once
#include <utility>

template<typename T> class stack {
        struct node {
                T value;
                node* next;

                node( const T& v, node* n = nullptr ) : value(v), next(n) {}
        };
        node* head;

        void copy(const stack<T>& o) {
                node** crnt = &head;
                for ( node* next = o.head; next; next = next->next ) {
                        *crnt = new node{ next->value }; /***/
                        crnt = &(*crnt)->next;
                }
                *crnt = nullptr;
        }
public:
        void clear() {
            for ( node* next = head; next; ) {
                        node* crnt = next;
                        next = crnt->next;
                        delete crnt;
                }
                head = nullptr;
        }

        stack() : head(nullptr) {}
        stack(const stack<T>& o) { copy(o); }
        stack(stack<T>&& o) : head(o.head) { o.head = nullptr; }
        ~stack() { clear(); }

        stack& operator= (const stack<T>& o) {
                if ( this == &o ) return *this;
                clear();
                copy(o);
                return *this;
        }

        stack& operator= (stack<T>&& o) {
                if ( this == &o ) return *this;
                head = o.head;
                o.head = nullptr;
                return *this;
        }

        bool empty() const { return head == nullptr; }

        void push(const T& value) { head = new node{ value, head };  /***/ }

        T pop() {
                node* n = head;
                head = n->next;
                T x = std::move(n->value);
                delete n;
                return x;
        }
};