third_party/boost/spirit/test/x3/with.cpp

/*=============================================================================
    Copyright (c) 2015 Joel de Guzman

    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/detail/lightweight_test.hpp>
#include <boost/spirit/home/x3.hpp>
#include "test.hpp"

namespace x3 = boost::spirit::x3;

struct my_tag;

struct my_rule_class
{
    template <typename Iterator, typename Exception, typename Context>
    x3::error_handler_result
    on_error(Iterator&, Iterator const&, Exception const&, Context const& context)
    {
        x3::get<my_tag>(context)++;
        return x3::error_handler_result::fail;
    }

    template <typename Iterator, typename Attribute, typename Context>
    inline void
    on_success(Iterator const&, Iterator const&, Attribute&, Context const& context)
    {
        x3::get<my_tag>(context)++;
    }
};

int
main()
{
    using spirit_test::test_attr;
    using spirit_test::test;

    using boost::spirit::x3::rule;
    using boost::spirit::x3::int_;
    using boost::spirit::x3::with;

// read from a mutable field is not allowed on these compilers
#if (!defined(_MSC_VER) || _MSC_VER >= 1910) && \
    (!defined(__clang__) || __clang_major__ >= 7)
    BOOST_SPIRIT_ASSERT_CONSTEXPR_CTORS(with<my_tag>(0)['x']);
#endif
    {
        constexpr int i = 0;
        BOOST_SPIRIT_ASSERT_CONSTEXPR_CTORS(with<my_tag>(i)['x']);
    }

    { // injecting data into the context in the grammar

        int val = 0;
        auto r = rule<my_rule_class, char const*>() =
            '(' > int_ > ',' > int_ > ')'
            ;

        auto start =
            with<my_tag>(std::ref(val)) [ r ]
            ;

        BOOST_TEST(test("(123,456)", start));
        BOOST_TEST(!test("(abc,def)", start));
        BOOST_TEST(val == 2);
    }

    { // injecting non-const lvalue into the context
        int val = 0;
        auto const r  = int_[([](auto& ctx){
            x3::get<my_tag>(ctx) += x3::_attr(ctx);
        })];
        BOOST_TEST(test("123,456", with<my_tag>(val)[r % ',']));
        BOOST_TEST(579 == val);
    }

    { // injecting rvalue into the context
        auto const r1 = int_[([](auto& ctx){
            x3::get<my_tag>(ctx) += x3::_attr(ctx);
        })];
        auto const r2 = rule<struct my_rvalue_rule_class, int>() =
            x3::lit('(') >> (r1 % ',') >> x3::lit(')')[([](auto& ctx){
                x3::_val(ctx) = x3::get<my_tag>(ctx);
            })];
        int attr = 0;
        BOOST_TEST(test_attr("(1,2,3)", with<my_tag>(100)[r2], attr));
        BOOST_TEST(106 == attr);
    }

    { // injecting const/non-const lvalue and rvalue into the context
        struct functor {
            int operator()(int& val) {
                return val * 10; // non-const ref returns 10 * injected val
            }
            int operator()(int const& val) {
                return val; // const ref returns injected val
            }
        };

        auto f = [](auto& ctx){
            x3::_val(ctx) = x3::_attr(ctx) + functor()(x3::get<my_tag>(ctx));
        };
        auto const r = rule<struct my_rule_class2, int>() = int_[f];

        int attr = 0;
        int const cval = 10;
        BOOST_TEST(test_attr("5", with<my_tag>(cval)[r], attr));
        BOOST_TEST(15 == attr); // x3::get returns const ref to cval

        attr = 0;
        int val = 10;
        BOOST_TEST(test_attr("5", with<my_tag>(val)[r], attr));
        BOOST_TEST(105 == attr); // x3::get returns ref to val

        attr = 0;

        BOOST_TEST(test_attr("5", with<my_tag>(10)[r], attr));
        // x3::get returns ref to member variable of with_directive
        BOOST_TEST(105 == attr);
    }

    return boost::report_errors();
}