libcruft-util/json/constraint/inequality.hpp

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Copyright 2018 Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include "base.hpp"

#include "../tree.hpp"

#include <functional>
#include <variant>


///////////////////////////////////////////////////////////////////////////////
namespace util::json::schema::constraint {
    template <template <typename> class ComparatorT>
    class inequality final : public base {
    public:
        inequality (::json::tree::node const&);
        virtual ~inequality () = default;

        output_iterator validate (output_iterator, ::json::tree::node &target) const noexcept override;
        std::ostream& describe (std::ostream&) const override;

    private:
        using uint_t = ::json::tree::number::uint_t;
        using sint_t = ::json::tree::number::sint_t;
        using real_t = ::json::tree::number::real_t;

        std::variant<uint_t,sint_t,real_t> m_value;
    };


    using minimum = inequality<std::greater_equal>;
    using maximum = inequality<std::less_equal>;
    using exclusive_minimum = inequality<std::greater>;
    using exclusive_maximum = inequality<std::less>;


    // this is not technically an inequality, but the implementation fits in
    // nicely here.
    template <typename T>
    struct is_multiple {
        bool operator() (T, T) const noexcept;
    };

    using multiple_of = inequality<is_multiple>;
}