strong_int.hxx

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#ifndef INCLUDED_O3TL_STRONG_INT_HXX
#define INCLUDED_O3TL_STRONG_INT_HXX

#include <sal/config.h>
#include <limits>
#include <cassert>
#include <type_traits>

namespace o3tl
{

#if !defined __COVERITY__

namespace detail {

template<typename T1, typename T2> constexpr
typename std::enable_if<
    std::is_signed<T1>::value && std::is_signed<T2>::value, bool>::type
isInRange(T2 value) {
    return value >= std::numeric_limits<T1>::min()
        && value <= std::numeric_limits<T1>::max();
}

template<typename T1, typename T2> constexpr
typename std::enable_if<
    std::is_signed<T1>::value && std::is_unsigned<T2>::value, bool>::type
isInRange(T2 value) {
    return value
        <= static_cast<typename std::make_unsigned<T1>::type>(
            std::numeric_limits<T1>::max());
}

template<typename T1, typename T2> constexpr
typename std::enable_if<
    std::is_unsigned<T1>::value && std::is_signed<T2>::value, bool>::type
isInRange(T2 value) {
    return value >= 0
        && (static_cast<typename std::make_unsigned<T2>::type>(value)
            <= std::numeric_limits<T1>::max());
}

template<typename T1, typename T2> constexpr
typename std::enable_if<
    std::is_unsigned<T1>::value && std::is_unsigned<T2>::value, bool>::type
isInRange(T2 value) {
    return value <= std::numeric_limits<T1>::max();
}

}

#endif

template <typename UNDERLYING_TYPE, typename PHANTOM_TYPE>
struct strong_int
{
public:
    template<typename T> explicit constexpr strong_int(
        T value,
        typename std::enable_if<std::is_integral<T>::value, int>::type = 0):
        m_value(value)
    {
#if !defined __COVERITY__
        // catch attempts to pass in out-of-range values early
        assert(detail::isInRange<UNDERLYING_TYPE>(value)
               && "out of range");
#endif
    }
    strong_int() : m_value(0) {}

    explicit constexpr operator UNDERLYING_TYPE() const { return m_value; }
    explicit operator bool() const { return m_value != 0; }
    UNDERLYING_TYPE get() const { return m_value; }

    bool operator<(strong_int const & other) const { return m_value < other.m_value; }
    bool operator<=(strong_int const & other) const { return m_value <= other.m_value; }
    bool operator>(strong_int const & other) const { return m_value > other.m_value; }
    bool operator>=(strong_int const & other) const { return m_value >= other.m_value; }
    bool operator==(strong_int const & other) const { return m_value == other.m_value; }
    bool operator!=(strong_int const & other) const { return m_value != other.m_value; }
    strong_int& operator++() { ++m_value; return *this; }
    strong_int operator++(int) { UNDERLYING_TYPE nOldValue = m_value; ++m_value; return strong_int(nOldValue); }
    strong_int& operator--() { --m_value; return *this; }
    strong_int operator--(int) { UNDERLYING_TYPE nOldValue = m_value; --m_value; return strong_int(nOldValue); }
    strong_int& operator+=(strong_int const & other) { m_value += other.m_value; return *this; }
    strong_int& operator-=(strong_int const & other) { m_value -= other.m_value; return *this; }

    bool anyOf(strong_int v) const {
      return *this == v;
    }

    template<typename... Args>
    bool anyOf(strong_int first, Args... args) const {
      return *this == first || anyOf(args...);
    }

private:
    UNDERLYING_TYPE m_value;
};

template <typename UT, typename PT>
strong_int<UT,PT> operator+(strong_int<UT,PT> const & lhs, strong_int<UT,PT> const & rhs)
{
    return strong_int<UT,PT>(lhs.get() + rhs.get());
}

template <typename UT, typename PT>
strong_int<UT,PT> operator-(strong_int<UT,PT> const & lhs, strong_int<UT,PT> const & rhs)
{
    return strong_int<UT,PT>(lhs.get() - rhs.get());
}

}; // namespace o3tl

#endif /* INCLUDED_O3TL_STRONG_INT_HXX */

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