/*
* Copyright 2002, 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_VISIT_EACH_HPP_
#define _SIGC_VISIT_EACH_HPP_
#include <sigc++/type_traits.h>
#include <type_traits>
namespace sigc {
#ifndef DOXYGEN_SHOULD_SKIP_THIS
namespace internal {
//This should really be an inner class of limit_derived_target, without the T_limit template type,
//But the SUN CC 5.7 (not earlier versions) compiler finds it ambiguous when we specify a particular specialization of it.
//and does not seem to allow us to tell it explicitly that it's an inner class.
template <bool I_derived, class T_type, class T_limit>
struct with_type;
//Specialization for I_derived = false
template <class T_type, class T_limit> struct
with_type<false, T_type, T_limit>
{
static void execute_(const T_type&, const T_limit&) {}
};
//Specialization for I_derived = true
template <class T_type, class T_limit>
struct with_type<true, T_type, T_limit>
{
static void execute_(const T_type& _A_type, const T_limit& _A_action)
{ _A_action.action_(_A_type); }
};
/// Helper struct for visit_each_type().
template <class T_target, class T_action>
struct limit_derived_target
{
typedef limit_derived_target<T_target, T_action> T_self;
template <class T_type>
void operator()(const T_type& _A_type) const
{
with_type<std::is_base_of<T_target, T_type>::value || std::is_same<T_target, T_type>::value, T_type, T_self>::execute_(_A_type, *this);
}
limit_derived_target(const T_action& _A_action)
: action_(_A_action)
{}
T_action action_;
};
// Specialization for T_target pointer types, to provide a slightly different execute_() implementation.
template <bool I_derived, class T_type, class T_limit>
struct with_type_pointer;
//Specialization for I_derived = false
template <class T_type, class T_limit>
struct with_type_pointer<false, T_type, T_limit>
{
static void execute_(const T_type&, const T_limit&) {}
};
//Specialization for I_derived = true
template <class T_type, class T_limit>
struct with_type_pointer<true, T_type, T_limit>
{
static void execute_(const T_type& _A_type, const T_limit& _A_action)
{ _A_action.action_(&_A_type); }
};
template <class T_target, class T_action>
struct limit_derived_target<T_target*, T_action>
{
typedef limit_derived_target<T_target*, T_action> T_self;
template <class T_type>
void operator()(const T_type& _A_type) const
{
with_type_pointer<std::is_base_of<T_target, T_type>::value || std::is_same<T_target, T_type>::value, T_type, T_self>::execute_(_A_type, *this);
}
limit_derived_target(const T_action& _A_action)
: action_(_A_action)
{}
T_action action_;
};
} /* namespace internal */
#endif // DOXYGEN_SHOULD_SKIP_THIS
// struct visitor was introduced as a result of https://bugzilla.gnome.org/show_bug.cgi?id=724496
// The advantage of using specializations of a template struct instead of overloads of
// a template function is described by Herb Sutter in http://www.gotw.ca/publications/mill17.htm
// In libsigc++ the main reason for using this technique is that we can avoid using ADL
// (argument-dependent lookup), and therefore there is no risk that a visit_each() overload
// in e.g. Boost is selected by mistake.
/** sigc::visitor<T_functor>::do_visit_each() performs a functor on each of the targets of a functor.
* All unknown types just call @a _A_action on them.
* Add specializations that specialize the @a T_functor argument for your own
* functor types, so that subobjects get visited. This is needed to enable
* auto-disconnection support for your functor types.
*
* @par Example:
* @code
* namespace some_ns
* {
* struct some_functor
* {
* void operator()() {}
* some_possibly_sigc_trackable_derived_type some_data_member;
* some_other_functor_type some_other_functor;
* };
* }
*
* namespace sigc
* {
* template <>
* struct visitor<some_ns::some_functor>
* {
* template <class T_action>
* static void do_visit_each(const T_action& _A_action,
* const some_ns::some_functor& _A_target)
* {
* sigc::visit_each(_A_action, _A_target.some_data_member);
* sigc::visit_each(_A_action, _A_target.some_other_functor);
* }
* };
* }
* @endcode
*
* @ingroup sigcfunctors
*/
template <class T_functor>
struct visitor
{
template <class T_action>
static void do_visit_each(const T_action& _A_action, const T_functor& _A_functor)
{
_A_action(_A_functor);
}
};
/** This function performs a functor on each of the targets of a functor.
*
* @ingroup sigcfunctors
*/
template <class T_action, class T_functor>
void visit_each(const T_action& _A_action, const T_functor& _A_functor)
{ sigc::visitor<T_functor>::do_visit_each(_A_action, _A_functor); }
/** This function performs a functor on each of the targets
* of a functor limited to a restricted type.
*
* @ingroup sigcfunctors
*/
template <class T_type, class T_action, class T_functor>
void visit_each_type(const T_action& _A_action, const T_functor& _A_functor)
{
typedef internal::limit_derived_target<T_type, T_action> type_limited_action;
type_limited_action limited_action(_A_action);
//specifying the types of the template specialization prevents disconnection of bound trackable references (such as with std::ref()),
//probably because the visit_each<> specializations take various different template types,
//in various sequences, and we are probably specifying only a subset of them with this.
//
//But this is required by the AIX (and maybe IRIX MipsPro and Tru64) compilers.
//I guess that std::ref() therefore does not work on those platforms. murrayc
// sigc::visit_each<type_limited_action, T_functor>(limited_action, _A_functor);
//g++ (even slightly old ones) is our primary platform, so we could use the non-crashing version.
//However, the explicit version also fixes a crash in a slightly more common case: http://bugzilla.gnome.org/show_bug.cgi?id=169225
//Users (and distributors) of libsigc++ on AIX (and maybe IRIX MipsPro and Tru64) do
//need to use the version above instead, to allow compilation.
//Added 2014-03-20: The preceding comment probably does not apply any more,
//now when the visit_each<>() overloads have been replaced by visitor<> specializations.
//It's probably safe to add explicit template parameters on calls to visit_each(),
//visit_each_type() and visitor::do_visit_each(), if necessary.
sigc::visit_each(limited_action, _A_functor);
}
} /* namespace sigc */
#endif