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- ///////////////////////////////////////////////////////////////////////////////
- // calculator.hpp
- //
- // Copyright 2008 Eric Niebler. 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)
- #include <boost/proto/core.hpp>
- #include <boost/proto/context.hpp>
- #include <boost/test/unit_test.hpp>
- using namespace boost;
- struct placeholder {};
- proto::terminal<placeholder>::type const _1 = {{}};
- struct calculator : proto::callable_context<calculator const>
- {
- typedef int result_type;
- calculator(int i)
- : i_(i)
- {}
- int operator ()(proto::tag::terminal, placeholder) const
- {
- return this->i_;
- }
- int operator ()(proto::tag::terminal, int j) const
- {
- return j;
- }
- template<typename Left, typename Right>
- int operator ()(proto::tag::plus, Left const &left, Right const &right) const
- {
- return proto::eval(left, *this) + proto::eval(right, *this);
- }
- template<typename Left, typename Right>
- int operator ()(proto::tag::minus, Left const &left, Right const &right) const
- {
- return proto::eval(left, *this) - proto::eval(right, *this);
- }
- template<typename Left, typename Right>
- int operator ()(proto::tag::multiplies, Left const &left, Right const &right) const
- {
- return proto::eval(left, *this) * proto::eval(right, *this);
- }
- template<typename Left, typename Right>
- int operator ()(proto::tag::divides, Left const &left, Right const &right) const
- {
- return proto::eval(left, *this) / proto::eval(right, *this);
- }
- private:
- int i_;
- };
- template<typename Fun, typename Expr>
- struct functional
- {
- typedef typename proto::result_of::eval<Expr, Fun>::type result_type;
- functional(Expr const &expr)
- : expr_(expr)
- {}
- template<typename T>
- result_type operator ()(T const &t) const
- {
- Fun fun(t);
- return proto::eval(this->expr_, fun);
- }
- private:
- Expr const &expr_;
- };
- template<typename Fun, typename Expr>
- functional<Fun, Expr> as(Expr const &expr)
- {
- return functional<Fun, Expr>(expr);
- }
- void test_calculator()
- {
- BOOST_CHECK_EQUAL(10, proto::eval(((_1 + 42)-3)/4, calculator(1)));
- BOOST_CHECK_EQUAL(11, proto::eval(((_1 + 42)-3)/4, calculator(5)));
- BOOST_CHECK_EQUAL(10, as<calculator>(((_1 + 42)-3)/4)(1));
- BOOST_CHECK_EQUAL(11, as<calculator>(((_1 + 42)-3)/4)(5));
- }
- using namespace unit_test;
- ///////////////////////////////////////////////////////////////////////////////
- // init_unit_test_suite
- //
- test_suite* init_unit_test_suite( int argc, char* argv[] )
- {
- test_suite *test = BOOST_TEST_SUITE("test immediate evaluation of proto parse trees");
- test->add(BOOST_TEST_CASE(&test_calculator));
- return test;
- }
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