lenses.cpp

TEST_CASE("lenses, fallback")
{
    auto first      = at_i(0);
    auto first_name = first | optlift(attr(&person::name)) | fallback("NULL");

    auto v1 = immer::vector<person>{};
    CHECK(view(first_name, v1) == "NULL");
    CHECK(view(first_name, set(at_i(0), v1, person{{}, "foo"})) == "NULL");

    v1 = v1.push_back({{}, "foo"});
    CHECK(view(first_name, v1) == "foo");
    CHECK(view(first_name, set(at_i(0), v1, person{{}, "bar"})) == "bar");
    CHECK(view(first_name, set(first_name, v1, "bar")) == "bar");
}

TEST_CASE("lenses, optlift")
{
    auto first          = at_i(0);
    auto birthday       = attr(&person::birthday);
    auto month          = attr(&yearday::month);
    auto birthday_month = birthday | month;

    SECTION("lifting composed lenses") {
        auto first_month = first
                | optlift(birthday_month);

        auto p1 = person{{5, 4}, "juanpe"};

        auto v1 = immer::vector<person>{};
        CHECK(view(first_month, v1) == std::nullopt);
        CHECK(view(first_month, set(at_i(0), v1, p1)) == std::nullopt);

        v1 = v1.push_back(p1);
        CHECK(view(first_month, v1) == 4);
        p1.birthday.month = 6;
        CHECK(view(first_month, set(at_i(0), v1, p1)) == 6);
        CHECK(view(first_month, set(first_month, v1, 8)) == 8);
    }

    SECTION("composing lifted lenses") {
        auto first_month = first
                | optlift(birthday)
                | optlift(month);

        auto p1 = person{{5, 4}, "juanpe"};

        auto v1 = immer::vector<person>{};
        CHECK(view(first_month, v1) == std::nullopt);
        CHECK(view(first_month, set(at_i(0), v1, p1)) == std::nullopt);

        v1 = v1.push_back(p1);
        CHECK(view(first_month, v1) == 4);
        p1.birthday.month = 6;
        CHECK(view(first_month, set(at_i(0), v1, p1)) == 6);
        CHECK(view(first_month, set(first_month, v1, 8)) == 8);
    }
}