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// file : odb/details/function-wrapper.hxx
// copyright : Copyright (c) 2009-2019 Code Synthesis Tools CC
// license : GNU GPL v2; see accompanying LICENSE file
#ifndef ODB_DETAILS_FUNCTION_WRAPPER_HXX
#define ODB_DETAILS_FUNCTION_WRAPPER_HXX
#include <odb/pre.hxx>
#include <odb/details/config.hxx> // ODB_CXX11
#ifdef ODB_CXX11
# include <functional> // std::function
# include <type_traits> // std::enable_if, std::is_convertible
#endif
namespace odb
{
namespace details
{
// Low-level 'callable object' wrapper similar to std::function but
// that works in both C++98 and 11. In particular, the call site can
// be compiled in C++98 and the registration site in C++11 and it
// will work.
//
template <typename F>
struct function_wrapper
{
~function_wrapper ();
explicit
function_wrapper (F* = 0);
#ifdef ODB_CXX11
typedef typename std::function<F> std_function_type;
// This overload accepts lambdas and std::functions, but when the
// argument is convertible to F*, then we disable it in favor of the
// other overload (above), which is more efficient.
//
// Subtlety alert: if you're thinking of changing this to accept a
// std::function<F> argument, stop. That creates an overload ambiguity
// when the actual parameter is a lambda, which is convertible to either
// std::function<F> or F*.
//
template <typename F1>
function_wrapper(F1,
typename std::enable_if<
!std::is_convertible<F1, F*>::value>::type* = 0);
#endif
// Destructive copy construction and assignment (aka move). These
// should really only be called by containers when they need to
// reallocate the underlying buffer and move the elements.
//
function_wrapper (const function_wrapper<F>&);
function_wrapper&
operator= (const function_wrapper<F>&);
void swap (function_wrapper<F>&);
// Conversion to bool.
//
public:
typedef void (function_wrapper<F>::*bool_convertible) ();
void true_value () {}
operator bool_convertible () const
{
return function != 0 ? &function_wrapper<F>::true_value : 0;
}
public:
F* function;
void (*deleter) (const void*);
const void* std_function;
};
}
}
#include <odb/details/function-wrapper.ixx>
#include <odb/details/function-wrapper.txx>
#include <odb/post.hxx>
#endif // ODB_DETAILS_FUNCTION_WRAPPER_HXX
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