22 Containers library [containers]

22.6 Container adaptors [container.adaptors]

22.6.6 Class template stack [stack]

22.6.6.1 General [stack.general]

Any sequence container supporting operations back(), push_­back() and pop_­back() can be used to instantiate stack.
In particular, vector, list and deque can be used.

22.6.6.2 Definition [stack.defn]

namespace std { template<class T, class Container = deque<T>> class stack { public: using value_type = typename Container::value_type; using reference = typename Container::reference; using const_reference = typename Container::const_reference; using size_type = typename Container::size_type; using container_type = Container; protected: Container c; public: stack() : stack(Container()) {} explicit stack(const Container&); explicit stack(Container&&); template<class InputIterator> stack(InputIterator first, InputIterator last); template<class Alloc> explicit stack(const Alloc&); template<class Alloc> stack(const Container&, const Alloc&); template<class Alloc> stack(Container&&, const Alloc&); template<class Alloc> stack(const stack&, const Alloc&); template<class Alloc> stack(stack&&, const Alloc&); template<class InputIterator, class Alloc> stack(InputIterator first, InputIterator last, const Alloc&); [[nodiscard]] bool empty() const { return c.empty(); } size_type size() const { return c.size(); } reference top() { return c.back(); } const_reference top() const { return c.back(); } void push(const value_type& x) { c.push_back(x); } void push(value_type&& x) { c.push_back(std::move(x)); } template<class... Args> decltype(auto) emplace(Args&&... args) { return c.emplace_back(std::forward<Args>(args)...); } void pop() { c.pop_back(); } void swap(stack& s) noexcept(is_nothrow_swappable_v<Container>) { using std::swap; swap(c, s.c); } }; template<class Container> stack(Container) -> stack<typename Container::value_type, Container>; template<class InputIterator> stack(InputIterator, InputIterator) -> stack<iter-value-type<InputIterator>>; template<class Container, class Allocator> stack(Container, Allocator) -> stack<typename Container::value_type, Container>; template<class InputIterator, class Allocator> stack(InputIterator, InputIterator, Allocator) -> stack<iter-value-type<InputIterator>, deque<iter-value-type<InputIterator>, Allocator>>; template<class T, class Container, class Alloc> struct uses_allocator<stack<T, Container>, Alloc> : uses_allocator<Container, Alloc>::type { }; }

22.6.6.3 Constructors [stack.cons]

explicit stack(const Container& cont);
Effects: Initializes c with cont.
explicit stack(Container&& cont);
Effects: Initializes c with std​::​move(cont).
template<class InputIterator> stack(InputIterator first, InputIterator last);
Effects: Initializes c with first as the first argument and last as the second argument.

22.6.6.4 Constructors with allocators [stack.cons.alloc]

If uses_­allocator_­v<container_­type, Alloc> is false the constructors in this subclause shall not participate in overload resolution.
template<class Alloc> explicit stack(const Alloc& a);
Effects: Initializes c with a.
template<class Alloc> stack(const container_type& cont, const Alloc& a);
Effects: Initializes c with cont as the first argument and a as the second argument.
template<class Alloc> stack(container_type&& cont, const Alloc& a);
Effects: Initializes c with std​::​move(cont) as the first argument and a as the second argument.
template<class Alloc> stack(const stack& s, const Alloc& a);
Effects: Initializes c with s.c as the first argument and a as the second argument.
template<class Alloc> stack(stack&& s, const Alloc& a);
Effects: Initializes c with std​::​move(s.c) as the first argument and a as the second argument.
template<class InputIterator, class Alloc> stack(InputIterator first, InputIterator last, const Alloc& alloc);
Effects: Initializes c with first as the first argument, last as the second argument, and alloc as the third argument.

22.6.6.5 Operators [stack.ops]

template<class T, class Container> bool operator==(const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c == y.c.
template<class T, class Container> bool operator!=(const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c != y.c.
template<class T, class Container> bool operator< (const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c < y.c.
template<class T, class Container> bool operator> (const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c > y.c.
template<class T, class Container> bool operator<=(const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c <= y.c.
template<class T, class Container> bool operator>=(const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c >= y.c.
template<class T, three_­way_­comparable Container> compare_three_way_result_t<Container> operator<=>(const stack<T, Container>& x, const stack<T, Container>& y);
Returns: x.c <=> y.c.

22.6.6.6 Specialized algorithms [stack.special]

template<class T, class Container> void swap(stack<T, Container>& x, stack<T, Container>& y) noexcept(noexcept(x.swap(y)));
Constraints: is_­swappable_­v<Container> is true.
Effects: As if by x.swap(y).