functional

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_FUNCTIONAL
#define _LIBCPP_FUNCTIONAL

/*
    functional synopsis

namespace std
{

template <class Arg, class Result>
struct unary_function
{
    typedef Arg    argument_type;
    typedef Result result_type;
};

template <class Arg1, class Arg2, class Result>
struct binary_function
{
    typedef Arg1   first_argument_type;
    typedef Arg2   second_argument_type;
    typedef Result result_type;
};

template <class T>
class reference_wrapper
    : public unary_function<T1, R> // if wrapping a unary functor
    : public binary_function<T1, T2, R> // if wrapping a binary functor
{
public:
    // types
    typedef T type;
    typedef see below result_type; // Not always defined

    // construct/copy/destroy
    template<class U>
      constexpr reference_wrapper(U&&);                                   // constexpr since C++20
    constexpr reference_wrapper(const reference_wrapper<T>& x) noexcept;  // constexpr since C++20

    // assignment
    constexpr reference_wrapper&
    operator=(const reference_wrapper<T>& x) noexcept;                    // constexpr since C++20

    // access
    constexpr operator T& () const noexcept;                              // constexpr since C++20
    constexpr T& get() const noexcept;                                    // constexpr since C++20

    // invoke
    template <class... ArgTypes>
      constexpr typename result_of<T&(ArgTypes&&...)>::type               // constexpr since C++20
          operator() (ArgTypes&&...) const
              noexcept(is_nothrow_invocable_v<T&, ArgTypes...>);          // noexcept since C++17
};

template <class T>
  reference_wrapper(T&) -> reference_wrapper<T>;

template <class T> reference_wrapper<T> ref(T& t) noexcept;
template <class T> void ref(const T&& t) = delete;
template <class T> reference_wrapper<T> ref(reference_wrapper<T>t) noexcept;

template <class T> reference_wrapper<const T> cref(const T& t) noexcept;
template <class T> void cref(const T&& t) = delete;
template <class T> reference_wrapper<const T> cref(reference_wrapper<T> t) noexcept;

template <class T> struct unwrap_reference;                                       // since C++20
template <class T> struct unwrap_ref_decay : unwrap_reference<decay_t<T>> { };    // since C++20
template <class T> using unwrap_reference_t = typename unwrap_reference<T>::type; // since C++20
template <class T> using unwrap_ref_decay_t = typename unwrap_ref_decay<T>::type; // since C++20

// [refwrap.comparisons], comparisons
friend constexpr bool operator==(reference_wrapper, reference_wrapper);           // Since C++26
friend constexpr bool operator==(reference_wrapper, const T&);                    // Since C++26
friend constexpr bool operator==(reference_wrapper, reference_wrapper<const T>);  // Since C++26

friend constexpr auto operator<=>(reference_wrapper, reference_wrapper);          // Since C++26
friend constexpr auto operator<=>(reference_wrapper, const T&);                   // Since C++26
friend constexpr auto operator<=>(reference_wrapper, reference_wrapper<const T>); // Since C++26

template <class T> // <class T=void> in C++14
struct plus {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct minus {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct multiplies {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct divides {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct modulus {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct negate {
    T operator()(const T& x) const;
};

template <class T> // <class T=void> in C++14
struct equal_to {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct not_equal_to {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct greater {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct less {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct greater_equal {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct less_equal {
    bool operator()(const T& x, const T& y) const;
};

// [comparisons.three.way], class compare_three_way
struct compare_three_way;

template <class T> // <class T=void> in C++14
struct logical_and {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct logical_or {
    bool operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct logical_not {
    bool operator()(const T& x) const;
};

template <class T> // <class T=void> in C++14
struct bit_and {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct bit_or {
    T operator()(const T& x, const T& y) const;
};

template <class T> // <class T=void> in C++14
struct bit_xor {
    T operator()(const T& x, const T& y) const;
};

template <class T=void> // C++14
struct bit_not {
    T operator()(const T& x) const;
};

struct identity; // C++20

template <class Predicate>
class unary_negate // deprecated in C++17, removed in C++20
    : public unary_function<typename Predicate::argument_type, bool>
{
public:
    explicit unary_negate(const Predicate& pred);
    bool operator()(const typename Predicate::argument_type& x) const;
};

template <class Predicate> // deprecated in C++17, removed in C++20
unary_negate<Predicate> not1(const Predicate& pred);

template <class Predicate>
class binary_negate // deprecated in C++17, removed in C++20
    : public binary_function<typename Predicate::first_argument_type,
                             typename Predicate::second_argument_type,
                             bool>
{
public:
    explicit binary_negate(const Predicate& pred);
    bool operator()(const typename Predicate::first_argument_type& x,
                    const typename Predicate::second_argument_type& y) const;
};

template <class Predicate> // deprecated in C++17, removed in C++20
binary_negate<Predicate> not2(const Predicate& pred);

template <class F>
  constexpr unspecified not_fn(F&& f);     // C++17, constexpr in C++20
template <auto f>
  constexpr unspecified not_fn() noexcept; // C++26

// [func.bind.partial], function templates bind_front and bind_back
template<class F, class... Args>
  constexpr unspecified bind_front(F&&, Args&&...); // C++20
template<class F, class... Args>
  constexpr unspecified bind_back(F&&, Args&&...);  // C++23

template<class T> struct is_bind_expression;
template<class T> struct is_placeholder;

    // See C++14 20.9.9, Function object binders
template <class T> inline constexpr bool is_bind_expression_v
  = is_bind_expression<T>::value; // C++17
template <class T> inline constexpr int is_placeholder_v
  = is_placeholder<T>::value; // C++17


template<class Fn, class... BoundArgs>
  constexpr unspecified bind(Fn&&, BoundArgs&&...);  // constexpr in C++20
template<class R, class Fn, class... BoundArgs>
  constexpr unspecified bind(Fn&&, BoundArgs&&...);  // constexpr in C++20

// [func.invoke]
template<class F, class... Args>
 constexpr // constexpr in C++20
 invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) // C++17
    noexcept(is_nothrow_invocable_v<F, Args...>);

template<class R, class F, class... Args>
  constexpr R invoke_r(F&& f, Args&&... args)              // C++23
    noexcept(is_nothrow_invocable_r_v<R, F, Args...>);

namespace placeholders {
  // M is the implementation-defined number of placeholders
  extern unspecified _1;
  extern unspecified _2;
  .
  .
  .
  extern unspecified _Mp;
}

template <class Operation>
class binder1st     // deprecated in C++11, removed in C++17
    : public unary_function<typename Operation::second_argument_type,
                            typename Operation::result_type>
{
protected:
    Operation                               op;
    typename Operation::first_argument_type value;
public:
    binder1st(const Operation& x, const typename Operation::first_argument_type y);
    typename Operation::result_type operator()(      typename Operation::second_argument_type& x) const;
    typename Operation::result_type operator()(const typename Operation::second_argument_type& x) const;
};

template <class Operation, class T>
binder1st<Operation> bind1st(const Operation& op, const T& x);                  // deprecated in C++11, removed in C++17

template <class Operation>
class binder2nd                                                                 // deprecated in C++11, removed in C++17
    : public unary_function<typename Operation::first_argument_type,
                            typename Operation::result_type>
{
protected:
    Operation                                op;
    typename Operation::second_argument_type value;
public:
    binder2nd(const Operation& x, const typename Operation::second_argument_type y);
    typename Operation::result_type operator()(      typename Operation::first_argument_type& x) const;
    typename Operation::result_type operator()(const typename Operation::first_argument_type& x) const;
};

template <class Operation, class T>
binder2nd<Operation> bind2nd(const Operation& op, const T& x);                  // deprecated in C++11, removed in C++17

template <class Arg, class Result>                                              // deprecated in C++11, removed in C++17
class pointer_to_unary_function : public unary_function<Arg, Result>
{
public:
    explicit pointer_to_unary_function(Result (*f)(Arg));
    Result operator()(Arg x) const;
};

template <class Arg, class Result>
pointer_to_unary_function<Arg,Result> ptr_fun(Result (*f)(Arg));                // deprecated in C++11, removed in C++17

template <class Arg1, class Arg2, class Result>                                 // deprecated in C++11, removed in C++17
class pointer_to_binary_function : public binary_function<Arg1, Arg2, Result>
{
public:
    explicit pointer_to_binary_function(Result (*f)(Arg1, Arg2));
    Result operator()(Arg1 x, Arg2 y) const;
};

template <class Arg1, class Arg2, class Result>
pointer_to_binary_function<Arg1,Arg2,Result> ptr_fun(Result (*f)(Arg1,Arg2));   // deprecated in C++11, removed in C++17

template<class S, class T>                                                      // deprecated in C++11, removed in C++17
class mem_fun_t : public unary_function<T*, S>
{
public:
    explicit mem_fun_t(S (T::*p)());
    S operator()(T* p) const;
};

template<class S, class T, class A>
class mem_fun1_t : public binary_function<T*, A, S>                             // deprecated in C++11, removed in C++17
{
public:
    explicit mem_fun1_t(S (T::*p)(A));
    S operator()(T* p, A x) const;
};

template<class S, class T>          mem_fun_t<S,T>    mem_fun(S (T::*f)());     // deprecated in C++11, removed in C++17
template<class S, class T, class A> mem_fun1_t<S,T,A> mem_fun(S (T::*f)(A));    // deprecated in C++11, removed in C++17

template<class S, class T>
class mem_fun_ref_t : public unary_function<T, S>                               // deprecated in C++11, removed in C++17
{
public:
    explicit mem_fun_ref_t(S (T::*p)());
    S operator()(T& p) const;
};

template<class S, class T, class A>
class mem_fun1_ref_t : public binary_function<T, A, S>                          // deprecated in C++11, removed in C++17
{
public:
    explicit mem_fun1_ref_t(S (T::*p)(A));
    S operator()(T& p, A x) const;
};

template<class S, class T>
mem_fun_ref_t<S,T>    mem_fun_ref(S (T::*f)());                                 // deprecated in C++11, removed in C++17
template<class S, class T, class A>
mem_fun1_ref_t<S,T,A> mem_fun_ref(S (T::*f)(A));                                // deprecated in C++11, removed in C++17

template <class S, class T>
class const_mem_fun_t : public unary_function<const T*, S>                      // deprecated in C++11, removed in C++17
{
public:
    explicit const_mem_fun_t(S (T::*p)() const);
    S operator()(const T* p) const;
};

template <class S, class T, class A>
class const_mem_fun1_t : public binary_function<const T*, A, S>                 // deprecated in C++11, removed in C++17
{
public:
    explicit const_mem_fun1_t(S (T::*p)(A) const);
    S operator()(const T* p, A x) const;
};

template <class S, class T>
const_mem_fun_t<S,T>    mem_fun(S (T::*f)() const);                             // deprecated in C++11, removed in C++17
template <class S, class T, class A>
const_mem_fun1_t<S,T,A> mem_fun(S (T::*f)(A) const);                            // deprecated in C++11, removed in C++17

template <class S, class T>
class const_mem_fun_ref_t : public unary_function<T, S>                         // deprecated in C++11, removed in C++17
{
public:
    explicit const_mem_fun_ref_t(S (T::*p)() const);
    S operator()(const T& p) const;
};

template <class S, class T, class A>
class const_mem_fun1_ref_t : public binary_function<T, A, S>                    // deprecated in C++11, removed in C++17
{
public:
    explicit const_mem_fun1_ref_t(S (T::*p)(A) const);
    S operator()(const T& p, A x) const;
};

template <class S, class T>
const_mem_fun_ref_t<S,T>    mem_fun_ref(S (T::*f)() const);                     // deprecated in C++11, removed in C++17
template <class S, class T, class A>
const_mem_fun1_ref_t<S,T,A> mem_fun_ref(S (T::*f)(A) const);                    // deprecated in C++11, removed in C++17

template<class R, class T> constexpr unspecified mem_fn(R T::*) noexcept;       // constexpr in C++20

class bad_function_call
    : public exception
{
};

template<class> class function; // undefined

template<class R, class... ArgTypes>
class function<R(ArgTypes...)>
  : public unary_function<T1, R>      // iff sizeof...(ArgTypes) == 1 and
                                      // ArgTypes contains T1
  : public binary_function<T1, T2, R> // iff sizeof...(ArgTypes) == 2 and
                                      // ArgTypes contains T1 and T2
{
public:
    typedef R result_type;

    // construct/copy/destroy:
    function() noexcept;
    function(nullptr_t) noexcept;
    function(const function&);
    function(function&&) noexcept;
    template<class F>
      function(F);
    template<Allocator Alloc>
      function(allocator_arg_t, const Alloc&) noexcept;            // removed in C++17
    template<Allocator Alloc>
      function(allocator_arg_t, const Alloc&, nullptr_t) noexcept; // removed in C++17
    template<Allocator Alloc>
      function(allocator_arg_t, const Alloc&, const function&);    // removed in C++17
    template<Allocator Alloc>
      function(allocator_arg_t, const Alloc&, function&&);         // removed in C++17
    template<class F, Allocator Alloc>
      function(allocator_arg_t, const Alloc&, F);                  // removed in C++17

    function& operator=(const function&);
    function& operator=(function&&) noexcept;
    function& operator=(nullptr_t) noexcept;
    template<class F>
      function& operator=(F&&);
    template<class F>
      function& operator=(reference_wrapper<F>) noexcept;

    ~function();

    // function modifiers:
    void swap(function&) noexcept;
    template<class F, class Alloc>
      void assign(F&&, const Alloc&);                 // Removed in C++17

    // function capacity:
    explicit operator bool() const noexcept;

    // function invocation:
    R operator()(ArgTypes...) const;

    // function target access:
    const std::type_info& target_type() const noexcept;
    template <typename T>       T* target() noexcept;
    template <typename T> const T* target() const noexcept;
};

// Deduction guides
template<class R, class ...Args>
function(R(*)(Args...)) -> function<R(Args...)>; // since C++17

template<class F>
function(F) -> function<see-below>; // since C++17

// Null pointer comparisons:
template <class R, class ... ArgTypes>
  bool operator==(const function<R(ArgTypes...)>&, nullptr_t) noexcept;

template <class R, class ... ArgTypes>
  bool operator==(nullptr_t, const function<R(ArgTypes...)>&) noexcept; // removed in C++20

template <class R, class ... ArgTypes>
  bool operator!=(const function<R(ArgTypes...)>&, nullptr_t) noexcept; // removed in C++20

template <class  R, class ... ArgTypes>
  bool operator!=(nullptr_t, const function<R(ArgTypes...)>&) noexcept; // removed in C++20

// specialized algorithms:
template <class  R, class ... ArgTypes>
  void swap(function<R(ArgTypes...)>&, function<R(ArgTypes...)>&) noexcept;

template <class T> struct hash;

template <> struct hash<bool>;
template <> struct hash<char>;
template <> struct hash<signed char>;
template <> struct hash<unsigned char>;
template <> struct hash<char8_t>; // since C++20
template <> struct hash<char16_t>;
template <> struct hash<char32_t>;
template <> struct hash<wchar_t>;
template <> struct hash<short>;
template <> struct hash<unsigned short>;
template <> struct hash<int>;
template <> struct hash<unsigned int>;
template <> struct hash<long>;
template <> struct hash<long long>;
template <> struct hash<unsigned long>;
template <> struct hash<unsigned long long>;

template <> struct hash<float>;
template <> struct hash<double>;
template <> struct hash<long double>;

template<class T> struct hash<T*>;
template <> struct hash<nullptr_t>;  // C++17

namespace ranges {
  // [range.cmp], concept-constrained comparisons
  struct equal_to;
  struct not_equal_to;
  struct greater;
  struct less;
  struct greater_equal;
  struct less_equal;
}

}  // std

POLICY:  For non-variadic implementations, the number of arguments is limited
         to 3.  It is hoped that the need for non-variadic implementations
         will be minimal.

*/

#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
#  include <__cxx03/functional>
#else
#  include <__config>

#  include <__functional/binary_function.h>
#  include <__functional/binary_negate.h>
#  include <__functional/bind.h>
#  include <__functional/binder1st.h>
#  include <__functional/binder2nd.h>
#  include <__functional/hash.h>
#  include <__functional/mem_fn.h> // TODO: deprecate
#  include <__functional/mem_fun_ref.h>
#  include <__functional/operations.h>
#  include <__functional/pointer_to_binary_function.h>
#  include <__functional/pointer_to_unary_function.h>
#  include <__functional/reference_wrapper.h>
#  include <__functional/unary_function.h>
#  include <__functional/unary_negate.h>

#  ifndef _LIBCPP_CXX03_LANG
#    include <__functional/function.h>
#  endif

#  if _LIBCPP_STD_VER >= 17
#    include <__functional/boyer_moore_searcher.h>
#    include <__functional/default_searcher.h>
#    include <__functional/invoke.h>
#    include <__functional/not_fn.h>
#  endif

#  if _LIBCPP_STD_VER >= 20
#    include <__functional/bind_back.h>
#    include <__functional/bind_front.h>
#    include <__functional/identity.h>
#    include <__functional/ranges_operations.h>
#    include <__type_traits/unwrap_ref.h>
#  endif

#  include <version>

#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#    pragma GCC system_header
#  endif

#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && defined(_LIBCPP_CXX03_LANG)
#    include <limits>
#    include <new>
#  endif

#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 14
#    include <array>
#    include <initializer_list>
#    include <unordered_map>
#  endif

#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
#    include <atomic>
#    include <concepts>
#    include <cstdlib>
#    include <exception>
#    include <iosfwd>
#    include <memory>
#    include <stdexcept>
#    include <tuple>
#    include <type_traits>
#    include <typeinfo>
#    include <utility>
#    include <vector>
#  endif
#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)

#endif // _LIBCPP_FUNCTIONAL