mirror of
https://github.com/boostorg/hof.git
synced 2026-01-31 20:22:11 +00:00
328 lines
9.3 KiB
C++
328 lines
9.3 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2014 Paul Fultz II
|
|
placeholders.h
|
|
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
|
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
==============================================================================*/
|
|
|
|
#ifndef FIT_GUARD_FUNCTION_PLACEHOLDERS_H
|
|
#define FIT_GUARD_FUNCTION_PLACEHOLDERS_H
|
|
|
|
/// placeholders
|
|
/// ============
|
|
///
|
|
/// Description
|
|
/// -----------
|
|
///
|
|
/// The placeholders provide `std::bind` compatible placeholders that
|
|
/// additionally provide basic C++ operators that creates bind expressions.
|
|
/// Each bind expression supports `constexpr` function evaluation.
|
|
///
|
|
/// Synopsis
|
|
/// --------
|
|
///
|
|
/// placeholder<1> _1 = {};
|
|
/// placeholder<2> _2 = {};
|
|
/// placeholder<3> _3 = {};
|
|
/// placeholder<4> _4 = {};
|
|
/// placeholder<5> _5 = {};
|
|
/// placeholder<6> _6 = {};
|
|
/// placeholder<7> _7 = {};
|
|
/// placeholder<8> _8 = {};
|
|
/// placeholder<9> _9 = {};
|
|
///
|
|
/// Operators
|
|
/// ---------
|
|
///
|
|
/// * Binary operators: +,-,*,/,%,>>,<<,>,<,<=,>=,==,!=,&,^,|,&&,||
|
|
/// * Assign operators: +=,-=,*=,/=,%=,>>=,<<=,&=,|=,^=
|
|
/// * Unary operators: !,~,+,-,*,++,--
|
|
///
|
|
///
|
|
/// Example
|
|
/// -------
|
|
///
|
|
/// auto sum = _1 + _2;
|
|
/// assert(3 == sum(1, 2));
|
|
///
|
|
///
|
|
/// unamed placeholder
|
|
/// ==================
|
|
///
|
|
/// Description
|
|
/// -----------
|
|
///
|
|
/// The unamed placeholder can be used to build simple functions from C++
|
|
/// operators.
|
|
///
|
|
/// Note: The function produced by the unamed placeholder is not a bind expression.
|
|
///
|
|
/// Synopsis
|
|
/// --------
|
|
///
|
|
/// /* unspecified */ _ = {};
|
|
///
|
|
/// Example
|
|
/// -------
|
|
///
|
|
/// auto sum = _ + _;
|
|
/// assert(3 == sum(1, 2));
|
|
///
|
|
|
|
#include <fit/lazy.hpp>
|
|
#include <fit/protect.hpp>
|
|
|
|
namespace fit { namespace detail {
|
|
template<int N>
|
|
struct simple_placeholder
|
|
{};
|
|
}} // namespace fit
|
|
|
|
namespace std {
|
|
template<int N>
|
|
struct is_placeholder<fit::detail::simple_placeholder<N>>
|
|
: std::integral_constant<int, N>
|
|
{};
|
|
}
|
|
|
|
|
|
namespace fit {
|
|
|
|
#define FIT_FOREACH_BINARY_OP(m) \
|
|
m(+, add) \
|
|
m(-, subtract) \
|
|
m(*, multiply) \
|
|
m(/, divide) \
|
|
m(%, remainder) \
|
|
m(>>, shift_right) \
|
|
m(<<, shift_left) \
|
|
m(>, greater_than) \
|
|
m(<, less_than) \
|
|
m(<=, less_than_equal) \
|
|
m(>=, greater_than_equal) \
|
|
m(==, equal) \
|
|
m(!=, not_equal) \
|
|
m(&, bit_and) \
|
|
m(^, xor_) \
|
|
m(|, bit_or) \
|
|
m(&&, and_) \
|
|
m(||, or_)
|
|
|
|
#define FIT_FOREACH_ASSIGN_OP(m) \
|
|
m(+=, assign_add) \
|
|
m(-=, assign_subtract) \
|
|
m(*=, assign_multiply) \
|
|
m(/=, assign_divide) \
|
|
m(%=, assign_remainder) \
|
|
m(>>=, assign_right_shift) \
|
|
m(<<=, assign_left_shift) \
|
|
m(&=, assign_bit_and) \
|
|
m(|=, assign_bit_or) \
|
|
m(^=, assign_xor)
|
|
|
|
#ifndef _MSC_VER
|
|
#define FIT_FOREACH_UNARY_OP(m) \
|
|
m(!, not_) \
|
|
m(~, compl_) \
|
|
m(+, unary_plus) \
|
|
m(-, unary_subtract) \
|
|
m(*, dereference) \
|
|
m(++, increment) \
|
|
m(--, decrement)
|
|
#else
|
|
#define FIT_FOREACH_UNARY_OP(m) \
|
|
m(!, not_) \
|
|
m(~, compl_) \
|
|
m(+, unary_plus) \
|
|
m(-, unary_subtract) \
|
|
m(*, dereference)
|
|
#endif
|
|
|
|
namespace operators {
|
|
|
|
struct call
|
|
{
|
|
template<class F, class... Ts>
|
|
constexpr auto operator()(F&& f, Ts&&... xs) const FIT_RETURNS
|
|
(f(FIT_FORWARD(Ts)(xs)...));
|
|
};
|
|
|
|
#define FIT_BINARY_OP(op, name) \
|
|
struct name \
|
|
{ \
|
|
template<class T, class U> \
|
|
constexpr auto operator()(T&& x, U&& y) const FIT_RETURNS \
|
|
(FIT_FORWARD(T)(x) op FIT_FORWARD(U)(y)); \
|
|
};
|
|
|
|
FIT_FOREACH_BINARY_OP(FIT_BINARY_OP)
|
|
FIT_FOREACH_ASSIGN_OP(FIT_BINARY_OP)
|
|
|
|
#define FIT_UNARY_OP(op, name) \
|
|
struct name \
|
|
{ \
|
|
template<class T> \
|
|
constexpr auto operator()(T&& x) const FIT_RETURNS \
|
|
(op(FIT_FORWARD(T)(x))); \
|
|
};
|
|
|
|
|
|
FIT_FOREACH_UNARY_OP(FIT_UNARY_OP)
|
|
|
|
}
|
|
|
|
template<int N>
|
|
struct placeholder
|
|
{
|
|
#if FIT_HAS_MANGLE_OVERLOAD
|
|
template<class... Ts>
|
|
constexpr auto operator()(Ts&&... xs) const FIT_RETURNS
|
|
( fit::lazy(operators::call())(detail::simple_placeholder<N>(), FIT_FORWARD(Ts)(xs)...) );
|
|
#else
|
|
template<class... Ts>
|
|
struct result_call
|
|
{ typedef decltype(fit::lazy(operators::call())(detail::simple_placeholder<N>(), std::declval<Ts>()...)) type; };
|
|
template<class... Ts>
|
|
constexpr typename result_call<Ts...>::type operator()(Ts&&... xs) const
|
|
{ return fit::lazy(operators::call())(detail::simple_placeholder<N>(), FIT_FORWARD(Ts)(xs)...); };
|
|
|
|
#endif
|
|
|
|
#define FIT_PLACEHOLDER_UNARY_OP(op, name) \
|
|
constexpr auto operator op () const FIT_RETURNS \
|
|
( fit::lazy(operators::name())(detail::simple_placeholder<N>()) );
|
|
|
|
FIT_FOREACH_UNARY_OP(FIT_PLACEHOLDER_UNARY_OP)
|
|
|
|
#define FIT_PLACEHOLDER_ASSIGN_OP(op, name) \
|
|
template<class T> \
|
|
constexpr auto operator op (T&& x) const FIT_RETURNS \
|
|
( fit::lazy(operators::name())(detail::simple_placeholder<N>(), FIT_FORWARD(T)(x)) );
|
|
|
|
FIT_FOREACH_ASSIGN_OP(FIT_PLACEHOLDER_ASSIGN_OP)
|
|
|
|
};
|
|
|
|
#if FIT_HAS_MANGLE_OVERLOAD
|
|
|
|
#define FIT_PLACEHOLDER_BINARY_OP(op, name) \
|
|
template<class T, int N> \
|
|
constexpr inline auto operator op (const placeholder<N>&, T&& x) FIT_RETURNS \
|
|
( fit::lazy(operators::name())(detail::simple_placeholder<N>(), FIT_FORWARD(T)(x)) ); \
|
|
template<class T, int N> \
|
|
constexpr inline auto operator op (T&& x, const placeholder<N>&) FIT_RETURNS \
|
|
( fit::lazy(operators::name())(FIT_FORWARD(T)(x), detail::simple_placeholder<N>()) ); \
|
|
template<int N, int M> \
|
|
constexpr inline auto operator op (const placeholder<N>&, const placeholder<M>&) FIT_RETURNS \
|
|
( fit::lazy(operators::name())(detail::simple_placeholder<N>(), detail::simple_placeholder<M>()) );
|
|
|
|
#else
|
|
|
|
#define FIT_PLACEHOLDER_BINARY_OP(op, name) \
|
|
template<class T, class U> \
|
|
struct result_ ## name \
|
|
{ typedef decltype(fit::lazy(operators::name())(std::declval<T>(), std::declval<U>())) type; }; \
|
|
template<class T, int N> \
|
|
constexpr inline typename result_ ## name<detail::simple_placeholder<N>, T>::type operator op (const placeholder<N>&, T&& x) \
|
|
{ return fit::lazy(operators::name())(detail::simple_placeholder<N>(), FIT_FORWARD(T)(x)); } \
|
|
template<class T, int N> \
|
|
constexpr inline typename result_ ## name<T, detail::simple_placeholder<N>>::type operator op (T&& x, const placeholder<N>&) \
|
|
{ return fit::lazy(operators::name())(FIT_FORWARD(T)(x), detail::simple_placeholder<N>()); } \
|
|
template<int N, int M> \
|
|
constexpr inline typename result_ ## name<detail::simple_placeholder<N>, detail::simple_placeholder<M>>::type operator op (const placeholder<N>&, const placeholder<M>&) \
|
|
{ return fit::lazy(operators::name())(detail::simple_placeholder<N>(), detail::simple_placeholder<M>()); }
|
|
|
|
#endif
|
|
|
|
FIT_FOREACH_BINARY_OP(FIT_PLACEHOLDER_BINARY_OP)
|
|
|
|
FIT_DECLARE_STATIC_VAR(_1, placeholder<1>);
|
|
FIT_DECLARE_STATIC_VAR(_2, placeholder<2>);
|
|
FIT_DECLARE_STATIC_VAR(_3, placeholder<3>);
|
|
FIT_DECLARE_STATIC_VAR(_4, placeholder<4>);
|
|
FIT_DECLARE_STATIC_VAR(_5, placeholder<5>);
|
|
FIT_DECLARE_STATIC_VAR(_6, placeholder<6>);
|
|
FIT_DECLARE_STATIC_VAR(_7, placeholder<7>);
|
|
FIT_DECLARE_STATIC_VAR(_8, placeholder<8>);
|
|
FIT_DECLARE_STATIC_VAR(_9, placeholder<9>);
|
|
|
|
|
|
namespace detail {
|
|
|
|
|
|
|
|
struct unamed_placeholder
|
|
{
|
|
template<class T, class Invoker>
|
|
struct partial_ap
|
|
{
|
|
T val;
|
|
|
|
FIT_INHERIT_DEFAULT_EMPTY(partial_ap, T)
|
|
|
|
template<class X, class... Xs, FIT_ENABLE_IF_CONSTRUCTIBLE(T, X&&, Xs&&...)>
|
|
constexpr partial_ap(X&& x, Xs&&... xs) : val(FIT_FORWARD(X)(x), FIT_FORWARD(Xs)(xs)...)
|
|
{}
|
|
|
|
FIT_RETURNS_CLASS(partial_ap);
|
|
|
|
template<class X>
|
|
constexpr auto operator()(X&& x) const FIT_RETURNS
|
|
(Invoker()(FIT_CONST_THIS->val, FIT_FORWARD(X)(x)));
|
|
};
|
|
|
|
template<class Op>
|
|
struct left
|
|
{
|
|
template<class T, class X>
|
|
constexpr auto operator()(const T& val, X&& x) const FIT_RETURNS
|
|
(Op()(val, FIT_FORWARD(X)(x)));
|
|
};
|
|
|
|
template<class Op>
|
|
struct right
|
|
{
|
|
template<class T, class X>
|
|
constexpr auto operator()(const T& val, X&& x) const FIT_RETURNS
|
|
(Op()(FIT_FORWARD(X)(x), val));
|
|
};
|
|
|
|
#define FIT_UNAMED_PLACEHOLDER_UNARY_OP(op, name) \
|
|
constexpr auto operator op () const FIT_RETURNS \
|
|
( operators::name() );
|
|
|
|
FIT_FOREACH_UNARY_OP(FIT_UNAMED_PLACEHOLDER_UNARY_OP)
|
|
|
|
#define FIT_UNAMED_PLACEHOLDER_ASSIGN_OP(op, name) \
|
|
template<class T> \
|
|
constexpr auto operator op (const T& x) const FIT_RETURNS \
|
|
( partial_ap<T, left<operators::name>>(x) );
|
|
|
|
FIT_FOREACH_ASSIGN_OP(FIT_UNAMED_PLACEHOLDER_ASSIGN_OP)
|
|
};
|
|
#define FIT_UNAMED_PLACEHOLDER_BINARY_OP(op, name) \
|
|
template<class T> \
|
|
constexpr inline auto operator op (const unamed_placeholder&, const T& x) FIT_RETURNS \
|
|
( unamed_placeholder::partial_ap<T, unamed_placeholder::right<operators::name>>(x) ); \
|
|
template<class T> \
|
|
constexpr inline auto operator op (const T& x, const unamed_placeholder&) FIT_RETURNS \
|
|
( unamed_placeholder::partial_ap<T, unamed_placeholder::left<operators::name>>(x) ); \
|
|
constexpr inline auto operator op (const unamed_placeholder&, const unamed_placeholder&) FIT_RETURNS \
|
|
( operators::name() );
|
|
|
|
FIT_FOREACH_BINARY_OP(FIT_UNAMED_PLACEHOLDER_BINARY_OP)
|
|
}
|
|
|
|
FIT_DECLARE_STATIC_VAR(_, detail::unamed_placeholder);
|
|
|
|
} // namespace fit
|
|
|
|
namespace std {
|
|
template<int N>
|
|
struct is_placeholder<fit::placeholder<N>>
|
|
: std::integral_constant<int, N>
|
|
{};
|
|
}
|
|
|
|
#endif
|