Expect.hpp

// Copyright 2021 Rainer Schoenberger
// 
// 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.

#pragma once

#include <cstdlib>
#include <stdexcept>

template<class T>
class Expect
{
    public:
        bool isValid() const
        {
            return m_valid;
        };

        T& unwrap()
        {
            if(not m_valid)
            {
                throw(std::runtime_error("Unwrapping non existing value."));
            }
            return m_value;
        }

        Expect() :
            m_valid(false)
        {};

        Expect(T && f_value) :
            m_valid(true),
            m_value{f_value}
        {};

    private:
        const bool m_valid;
        T m_value;
};