android/android-emu/android/base/Version.h

// Copyright 2015 The Android Open Source Project
//
// This software is licensed under the terms of the GNU General Public
// License version 2, as published by the Free Software Foundation, and
// may be copied, distributed, and modified under those terms.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

#pragma once

#include "android/base/StringView.h"

#include <string>
#include <tuple>

namespace android {
namespace base {

// Class |Version| is a class for software version manipulations
// it is able to parse, store, compare and convert version back to string
// Expected string format is "major.minor.micro[.build]", where all
// components are unsigned numbers (and, hopefully, reasonably small)
class Version {
public:
    enum Component { kMajor, kMinor, kMicro, kBuild };

    using ComponentType = unsigned int;

    // This is the value for an invalid/missing version component.
    static constexpr ComponentType kNone = static_cast<ComponentType>(-1);

    explicit Version(StringView ver);

    constexpr Version();

    constexpr Version(ComponentType major,
                      ComponentType minor,
                      ComponentType micro,
                      ComponentType build = 0);

    constexpr bool isValid() const;

    constexpr bool operator<(const Version& other) const;
    constexpr bool operator==(const Version& other) const;
    constexpr bool operator!=(const Version& other) const;

    static constexpr Version invalid();

    std::string toString() const;

    template <Component C>
    constexpr ComponentType component() const {
        return std::get<static_cast<size_t>(C)>(mData);
    }

private:
    ComponentType& component(Component c);

private:
    static const int kComponentCount = kBuild + 1;

    std::tuple<ComponentType, ComponentType, ComponentType, ComponentType>
            mData;
};

// all constexpr functions have to be defined in the header, just like templates

constexpr Version::Version() : Version(kNone, kNone, kNone) {}

constexpr Version::Version(ComponentType major,
                           ComponentType minor,
                           ComponentType micro,
                           ComponentType build)
    : mData(major, minor, micro, build) {}

constexpr bool Version::isValid() const {
    return *this != invalid();
}

constexpr bool Version::operator<(const Version& other) const {
    return mData < other.mData;
}

constexpr bool Version::operator==(const Version& other) const {
    return mData == other.mData;
}

constexpr bool Version::operator!=(const Version& other) const {
    return !(*this == other);
}

constexpr Version Version::invalid() {
    return Version(kNone, kNone, kNone);
}

}  // namespace android
}  // namespace base