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81 lines
2.3 KiB
C++
81 lines
2.3 KiB
C++
/*=============================================================================
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Copyright (c) 2014 Paul Fultz II
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function.h
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef FIT_GUARD_FUNCTION_FUNCTION_H
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#define FIT_GUARD_FUNCTION_FUNCTION_H
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/// FIT_STATIC_FUNCTION
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/// ===================
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///
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/// Description
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/// -----------
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///
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/// The `FIT_STATIC_FUNCTION` macro allows initializing a function object from
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/// a `constexpr` expression. It also ensures that the function object will
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/// have a unique address across translation units. This helps to avoid ODR
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/// violations. As such, the object that is deduced is default constructed.
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///
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/// By default, all functions defined with `FIT_STATIC_FUNCTION` use the
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/// [`fit::reveal`](/include/fit/reveal) adaptor to improve error messages.
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///
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/// Example
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/// -------
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///
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/// #include <fit.hpp>
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/// #include <cassert>
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///
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/// struct sum_f
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/// {
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/// template<class T, class U>
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/// T operator()(T x, U y) const
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/// {
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/// return x+y;
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/// }
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/// };
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///
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/// FIT_STATIC_FUNCTION(sum) = sum_f();
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/// FIT_STATIC_FUNCTION(partial_sum) = fit::partial(sum_f());
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///
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/// int main() {
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/// assert(sum(1, 2) == partial_sum(1)(2));
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/// }
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///
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#include <fit/reveal.hpp>
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#if !FIT_HAS_INLINE_VARIABLES
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#include <fit/detail/static_const_var.hpp>
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#include <fit/detail/constexpr_deduce.hpp>
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#endif
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namespace fit {
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namespace detail {
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struct reveal_static_const_factory
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{
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constexpr reveal_static_const_factory()
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{}
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template<class F>
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constexpr reveal_adaptor<F> operator=(const F& f) const
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{
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#if FIT_HAS_INLINE_VARIABLES
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#else
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static_assert(FIT_IS_DEFAULT_CONSTRUCTIBLE(F), "Static functions must be default constructible");
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#endif
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return reveal_adaptor<F>(f);
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}
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};
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}} // namespace fit
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#if FIT_HAS_INLINE_VARIABLES
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#define FIT_STATIC_FUNCTION(name) inline const constexpr auto name = fit::detail::reveal_static_const_factory()
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#else
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#define FIT_STATIC_FUNCTION(name) FIT_STATIC_CONST_VAR(name) = FIT_DETAIL_MSVC_CONSTEXPR_DEDUCE fit::detail::reveal_static_const_factory()
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#endif
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#endif
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