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//
// immer: immutable data structures for C++
// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
//
// This software is distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
//
#pragma once
#include "dada.hpp"
namespace {
template <typename VP, typename VT>
struct transient_tester
{
VP vp;
VT vt;
dadaism d = {};
bool transient = false;
transient_tester(VP vp)
: vp{vp}
, vt{vp.transient()}
{}
bool step()
{
auto s = d.next();
if (soft_dada()) {
auto new_transient = !transient;
try {
if (new_transient)
vt = vp.transient();
else
vp = vt.persistent();
} catch (const dada_error&) {
return false;
}
transient = new_transient;
return true;
} else
return false;
}
};
template <typename VP>
transient_tester<VP, typename VP::transient_type> as_transient_tester(VP p)
{
return {std::move(p)};
}
} // anonymous namespace
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