customisation_point.hpp File Reference

Helper utilities for defining customisation point objects (CPOs). More...

#include <seqan3/core/platform.hpp>

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Namespaces
	seqan3
	The main SeqAn3 namespace.

Macros
#define	SEQAN3_CPO_IMPL(PRIO, TERM)
	A macro that helps defining the overload set of a customisation point. More...
#define	SEQAN3_CPO_OVERLOAD(...)
	A macro that helps to define a seqan3::detail::customisation_point_object. More...
#define	SEQAN3_CPO_OVERLOAD_BODY(...)   noexcept(auto) { return __VA_ARGS__; }
	A macro helper for SEQAN3_CPO_OVERLOAD. More...

Detailed Description

Helper utilities for defining customisation point objects (CPOs).

Author

Hannes Hauswedell <hannes.hauswedell AT fu-berlin.de>

Macro Definition Documentation

SEQAN3_CPO_IMPL

#define SEQAN3_CPO_IMPL	(		PRIO,
			TERM
	)

Value:

                                                                          \
template <typename t, typename ...arg_ts>                                                                            \
static constexpr decltype(auto) impl(seqan3::detail::priority_tag<PRIO>,                                             \
                                     [[maybe_unused]] t && v,                                                        \
                                     [[maybe_unused]] arg_ts && ... args)                                            \
    noexcept(noexcept(TERM))                                                                                         \
    requires requires (seqan3::detail::priority_tag<PRIO> const &/*<- need for doxygen*/, t && v, arg_ts && ... args)\
    { { TERM }; }                                                                                                    \
{                                                                                                                    \
    return TERM;                                                                                                     \
}

A macro that helps defining the overload set of a customisation point.

Deprecated:

Please use SEQAN3_CPO_OVERLOAD to define seqan3::detail::customisation_point_object instead.

SEQAN3_CPO_OVERLOAD

#define SEQAN3_CPO_OVERLOAD

(

...

)

Value:

    cpo_overload(__VA_ARGS__) \
    SEQAN3_CPO_OVERLOAD_BODY

A macro that helps to define a seqan3::detail::customisation_point_object.

Expands to a function definition with the name cpo_overload.

It puts the given expression via SEQAN3_CPO_OVERLOAD_BODY as a single return statement in the function body, the noexcept declaration and requires declaration.

    template <typename range_t>
        requires true // further constraints
    static constexpr auto SEQAN3_CPO_OVERLOAD(seqan3::detail::priority_tag<1>, range_t && range)
    (
        /*return*/ std::forward<range_t>(range).begin() /*;*/
    );

expands to something similar to

template <typename range_t>
    requires true // further constraints
static constexpr auto cpo_overload(seqan3::detail::priority_tag<1>, range_t && range)
 
    noexcept(noexcept(std::forward<range_t>(range).begin()))
 
    requires requires()
    {
        {std::forward<range_t>(range).begin()};
    }
 
{
    return std::forward<range_t>(range).begin();
}

SEQAN3_CPO_OVERLOAD_BODY

#define SEQAN3_CPO_OVERLOAD_BODY

(

...

)

noexcept(auto) { return __VA_ARGS__; }

A macro helper for SEQAN3_CPO_OVERLOAD.

Please note that in order to allow a semicolon at the end when using this macro, i.e.

SEQAN3_CPO_OVERLOAD_BODY
(
    ...
);

we need some expression at the end of the macro that can have a semicolon appended. We chose static_assert(true) for that reason.