31 lines
833 B
C++
31 lines
833 B
C++
// Copyright Louis Dionne 2013-2017
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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#include <boost/hana/assert.hpp>
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#include <boost/hana/eval.hpp>
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#include <boost/hana/extend.hpp>
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#include <boost/hana/extract.hpp>
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#include <boost/hana/lazy.hpp>
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#include <sstream>
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namespace hana = boost::hana;
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int main() {
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std::stringstream s("1 2 3");
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auto i = hana::make_lazy([&] {
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int i;
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s >> i;
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return i;
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})();
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auto i_plus_one = hana::extend(i, [](auto lazy_int) {
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return hana::eval(lazy_int) + 1;
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});
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BOOST_HANA_RUNTIME_CHECK(hana::extract(i_plus_one) == 2);
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BOOST_HANA_RUNTIME_CHECK(hana::extract(i_plus_one) == 3);
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BOOST_HANA_RUNTIME_CHECK(hana::extract(i_plus_one) == 4);
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}
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