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/*
* Copyright 2003 - 2016, The libsigc++ Development Team
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef SIGC_ADAPTORS_COMPOSE_H
#define SIGC_ADAPTORS_COMPOSE_H
#include <sigc++/adaptors/adapts.h>
#include <functional>
namespace sigc
{
/** @defgroup compose compose()
* sigc::compose() combines two or three arbitrary functors.
* On invocation, parameters are passed on to one or two getter functor(s).
* The return value(s) are then passed on to the setter function.
*
* @par Examples:
* @code
* float square_root(float a) { return sqrtf(a); }
* float sum(float a, float b) { return a+b; }
* std::cout << sigc::compose(&square_root, &sum)(9, 16); // calls square_root(sum(3,6))
* std::cout << sigc::compose(&sum, &square_root, &square_root)(9); // calls sum(square_root(9),
* square_root(9))
* @endcode
*
* The functor sigc::compose() returns can be passed directly into
* sigc::signal::connect().
*
* @par Example:
* @code
* sigc::signal(float(float, float)> some_signal;
* some_signal.connect(sigc::compose(&square_root, &sum));
* @endcode
*
* @ingroup adaptors
*/
/** Adaptor that combines two functors.
* Use the convenience function sigc::compose() to create an instance of sigc::compose1_functor.
*
* The following template arguments are used:
* - @e T_setter Type of the setter functor to wrap.
* - @e T_getter Type of the getter functor to wrap.
*
* @ingroup compose
*/
template<typename T_setter, typename T_getter>
struct compose1_functor : public adapts<T_setter>
{
template<typename... T_arg>
decltype(auto) operator()(T_arg&&... a)
{
return std::invoke(this->functor_, get_(std::forward<T_arg>(a)...));
}
/** Constructs a compose1_functor object that combines the passed functors.
* @param setter Functor that receives the return values of the invocation of @e getter1 and
* @e getter2.
* @param getter Functor to invoke from operator()().
*/
compose1_functor(const T_setter& setter, const T_getter& getter)
: adapts<T_setter>(setter), get_(getter)
{
}
T_getter get_; // public, so that visit_each() can access it
};
/** Adaptor that combines three functors.
* Use the convenience function sigc::compose() to create an instance of sigc::compose2_functor.
*
* The following template arguments are used:
* - @e T_setter Type of the setter functor to wrap.
* - @e T_getter1 Type of the first getter functor to wrap.
* - @e T_getter2 Type of the second getter functor to wrap.
*
* @ingroup compose
*/
template<typename T_setter, typename T_getter1, typename T_getter2>
struct compose2_functor : public adapts<T_setter>
{
template<typename... T_arg>
decltype(auto) operator()(T_arg... a)
{
return std::invoke(this->functor_, get1_(a...), get2_(a...));
}
/** Constructs a compose2_functor object that combines the passed functors.
* @param setter Functor that receives the return values of the invocation of @e getter1 and
* @e getter2.
* @param getter1 Functor to invoke from operator()().
* @param getter2 Functor to invoke from operator()().
*/
compose2_functor(const T_setter& setter, const T_getter1& getter1, const T_getter2& getter2)
: adapts<T_setter>(setter), get1_(getter1), get2_(getter2)
{
}
T_getter1 get1_; // public, so that visit_each() can access it
T_getter2 get2_; // public, so that visit_each() can access it
};
#ifndef DOXYGEN_SHOULD_SKIP_THIS
// template specialization of visitor<>::do_visit_each<>(action, functor):
/** Performs a functor on each of the targets of a functor.
* The function overload for sigc::compose1_functor performs a functor on the
* functors stored in the sigc::compose1_functor object.
*
* @ingroup compose
*/
template<typename T_setter, typename T_getter>
struct visitor<compose1_functor<T_setter, T_getter>>
{
template<typename T_action>
static void do_visit_each(const T_action& action,
const compose1_functor<T_setter, T_getter>& target)
{
sigc::visit_each(action, target.functor_);
sigc::visit_each(action, target.get_);
}
};
// template specialization of visitor<>::do_visit_each<>(action, functor):
/** Performs a functor on each of the targets of a functor.
* The function overload for sigc::compose2_functor performs a functor on the
* functors stored in the sigc::compose2_functor object.
*
* @ingroup compose
*/
template<typename T_setter, typename T_getter1, typename T_getter2>
struct visitor<compose2_functor<T_setter, T_getter1, T_getter2>>
{
template<typename T_action>
static void do_visit_each(const T_action& action,
const compose2_functor<T_setter, T_getter1, T_getter2>& target)
{
sigc::visit_each(action, target.functor_);
sigc::visit_each(action, target.get1_);
sigc::visit_each(action, target.get2_);
}
};
#endif // DOXYGEN_SHOULD_SKIP_THIS
/** Creates an adaptor of type sigc::compose1_functor which combines two functors.
*
* @param setter Functor that receives the return value of the invocation of @e getter.
* @param getter Functor to invoke from operator()().
* @return Adaptor that executes @e setter with the value returned from invocation of @e
* getter.
*
* @ingroup compose
*/
template<typename T_setter, typename T_getter>
inline compose1_functor<T_setter, T_getter>
compose(const T_setter& setter, const T_getter& getter)
{
return compose1_functor<T_setter, T_getter>(setter, getter);
}
/** Creates an adaptor of type sigc::compose2_functor which combines three functors.
*
* @param setter Functor that receives the return values of the invocation of @e getter1 and
* @e getter2.
* @param getter1 Functor to invoke from operator()().
* @param getter2 Functor to invoke from operator()().
* @return Adaptor that executes @e setter with the values return from invocation of @e
* getter1 and @e getter2.
*
* @ingroup compose
*/
template<typename T_setter, typename T_getter1, typename T_getter2>
inline compose2_functor<T_setter, T_getter1, T_getter2>
compose(const T_setter& setter, const T_getter1& getter1, const T_getter2& getter2)
{
return compose2_functor<T_setter, T_getter1, T_getter2>(setter, getter1, getter2);
}
} /* namespace sigc */
#endif /* SIGC_ADAPTORS_COMPOSE_H */
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