customisation_point.hpp File Reference

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

#include <seqan3/core/platform.hpp>

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Namespaces
namespace	seqan3
	The main SeqAn3 namespace.

Macros
#define	SEQAN3_CPO_OVERLOAD(...)   cpo_overload(__VA_ARGS__) SEQAN3_CPO_OVERLOAD_BODY
	A macro that helps to define a seqan3::detail::customisation_point_object. More...
#define	SEQAN3_CPO_OVERLOAD_BODY(...)
	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_OVERLOAD

#define SEQAN3_CPO_OVERLOAD

(

...

)

cpo_overload(__VA_ARGS__) SEQAN3_CPO_OVERLOAD_BODY

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

DEV

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

(

...

)

Value:

        noexcept(auto)                                                                                                 \
        {                                                                                                              \
            return __VA_ARGS__;                                                                                        \
        }

A macro helper for SEQAN3_CPO_OVERLOAD.

DEV

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.