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81 lines
2.1 KiB
C++
81 lines
2.1 KiB
C++
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/*=============================================================================
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Copyright (c) 2014 Paul Fultz II
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protect.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 BOOST_HOF_GUARD_FUNCTION_PROTECT_H
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#define BOOST_HOF_GUARD_FUNCTION_PROTECT_H
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/// protect
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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 `protect` function adaptor can be used to make a bind expression be
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/// treated as a normal function instead. Both `bind` and
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/// [`lazy`](/include/boost/hof/lazy) eargerly evaluates nested bind expressions.
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/// The `protect` adaptor masks the type so `bind` or
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/// [`lazy`](/include/boost/hof/lazy) no longer recognizes the function as bind
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/// expression and evaluates it.
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///
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/// Synopsis
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/// --------
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///
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/// template<class F>
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/// constexpr protect_adaptor<F> protect(F f);
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///
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/// Semantics
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/// ---------
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///
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/// assert(lazy(f)(protect(lazy(g)(_1)))() == f(lazy(g)(_1)))
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///
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/// Requirements
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/// ------------
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///
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/// F must be:
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///
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/// * [ConstInvocable](ConstInvocable)
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/// * MoveConstructible
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///
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/// Example
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/// -------
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///
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/// #include <boost/hof.hpp>
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/// #include <cassert>
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/// using namespace boost::hof;
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///
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/// int main() {
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/// auto lazy_id = lazy(identity)(_1);
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/// auto lazy_apply = lazy(apply)(protect(lazy_id), _1);
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/// assert(lazy_apply(3) == 3);
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/// }
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///
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/// See Also
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/// --------
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///
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/// * [lazy](lazy)
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///
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#include <utility>
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#include <boost/hof/reveal.hpp>
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#include <boost/hof/detail/forward.hpp>
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#include <boost/hof/detail/make.hpp>
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#include <boost/hof/detail/static_const_var.hpp>
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namespace boost { namespace hof {
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template<class F>
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struct protect_adaptor : detail::callable_base<F>
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{
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typedef protect_adaptor fit_rewritable1_tag;
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BOOST_HOF_INHERIT_CONSTRUCTOR(protect_adaptor, detail::callable_base<F>)
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};
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BOOST_HOF_DECLARE_STATIC_VAR(protect, detail::make<protect_adaptor>);
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}} // namespace boost::hof
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#endif
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