feat():initial version

install/boost_1_75_0/include/boost/hof/protect.hpp

@@ -0,0 +1,80 @@
+/*=============================================================================
+    Copyright (c) 2014 Paul Fultz II
+    protect.h
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+
+#ifndef BOOST_HOF_GUARD_FUNCTION_PROTECT_H
+#define BOOST_HOF_GUARD_FUNCTION_PROTECT_H
+
+/// protect
+/// =======
+/// 
+/// Description
+/// -----------
+/// 
+/// The `protect` function adaptor can be used to make a bind expression be
+/// treated as a normal function instead. Both `bind` and
+/// [`lazy`](/include/boost/hof/lazy) eargerly evaluates nested bind expressions.
+/// The `protect` adaptor masks the type so `bind` or
+/// [`lazy`](/include/boost/hof/lazy) no longer recognizes the function as bind
+/// expression and evaluates it.
+/// 
+/// Synopsis
+/// --------
+/// 
+///     template<class F>
+///     constexpr protect_adaptor<F> protect(F f);
+/// 
+/// Semantics
+/// ---------
+/// 
+///     assert(lazy(f)(protect(lazy(g)(_1)))() == f(lazy(g)(_1)))
+/// 
+/// Requirements
+/// ------------
+/// 
+/// F must be:
+/// 
+/// * [ConstInvocable](ConstInvocable)
+/// * MoveConstructible
+/// 
+/// Example
+/// -------
+/// 
+///     #include <boost/hof.hpp>
+///     #include <cassert>
+///     using namespace boost::hof;
+/// 
+///     int main() {
+///         auto lazy_id = lazy(identity)(_1);
+///         auto lazy_apply = lazy(apply)(protect(lazy_id), _1);
+///         assert(lazy_apply(3) == 3);
+///     }
+/// 
+/// See Also
+/// --------
+/// 
+/// * [lazy](lazy)
+/// 
+
+#include <utility>
+#include <boost/hof/reveal.hpp>
+#include <boost/hof/detail/forward.hpp>
+#include <boost/hof/detail/make.hpp>
+#include <boost/hof/detail/static_const_var.hpp>
+
+namespace boost { namespace hof {
+
+template<class F>
+struct protect_adaptor : detail::callable_base<F>
+{
+    typedef protect_adaptor fit_rewritable1_tag;
+    BOOST_HOF_INHERIT_CONSTRUCTOR(protect_adaptor, detail::callable_base<F>)
+};
+
+BOOST_HOF_DECLARE_STATIC_VAR(protect, detail::make<protect_adaptor>);
+
+}} // namespace boost::hof
+#endif