intcmp.hxx

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#pragma once
 
#include <sal/config.h>
 
#include <type_traits>
#include <utility>
 
#include <o3tl/safeint.hxx>
 
namespace o3tl
{
// An approximation of the C++20 integer comparison functions
// (<https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0586r2.html> "Safe integral
// comparisons"):
#if defined __cpp_lib_integer_comparison_functions
 
using std::cmp_equal;
using std::cmp_not_equal;
using std::cmp_less;
using std::cmp_greater;
using std::cmp_less_equal;
using std::cmp_greater_equal;
 
#else
 
template <typename T1, typename T2> constexpr bool cmp_equal(T1 value1, T2 value2) noexcept
{
    // coverity[same_on_both_sides: FALSE]
    if constexpr (std::is_signed_v<T1> == std::is_signed_v<T2>)
    {
        return value1 == value2;
    }
    else if constexpr (std::is_signed_v<T1>)
    {
        return value1 >= 0 && o3tl::make_unsigned(value1) == value2;
    }
    else
    {
        return value2 >= 0 && value1 == o3tl::make_unsigned(value2);
    }
}
 
template <typename T1, typename T2> constexpr bool cmp_not_equal(T1 value1, T2 value2) noexcept
{
    return !cmp_equal(value1, value2);
}
 
template <typename T1, typename T2> constexpr bool cmp_less(T1 value1, T2 value2) noexcept
{
    if constexpr (std::is_signed_v<T1> == std::is_signed_v<T2>)
    {
        return value1 < value2;
    }
    else if constexpr (std::is_signed_v<T1>)
    {
        return value1 < 0 || o3tl::make_unsigned(value1) < value2;
    }
    else
    {
        return value2 >= 0 && value1 < o3tl::make_unsigned(value2);
    }
}
 
template <typename T1, typename T2> constexpr bool cmp_greater(T1 value1, T2 value2) noexcept
{
    return cmp_less(value2, value1);
}
 
template <typename T1, typename T2> constexpr bool cmp_less_equal(T1 value1, T2 value2) noexcept
{
    return !cmp_greater(value1, value2);
}
 
template <typename T1, typename T2> constexpr bool cmp_greater_equal(T1 value1, T2 value2) noexcept
{
    return !cmp_less(value1, value2);
}
 
#endif
 
// A convenient operator syntax around the standard integer comparison functions:
template <typename T> struct IntCmp
{
    explicit constexpr IntCmp(T theValue)
        : value(theValue)
    {
    }
 
    T value;
};
 
template <typename T1, typename T2> constexpr bool operator==(IntCmp<T1> value1, IntCmp<T2> value2)
{
    return o3tl::cmp_equal(value1.value, value2.value);
}
 
template <typename T1, typename T2> constexpr bool operator!=(IntCmp<T1> value1, IntCmp<T2> value2)
{
    return o3tl::cmp_not_equal(value1.value, value2.value);
}
 
template <typename T1, typename T2> constexpr bool operator<(IntCmp<T1> value1, IntCmp<T2> value2)
{
    return o3tl::cmp_less(value1.value, value2.value);
}
 
template <typename T1, typename T2> constexpr bool operator>(IntCmp<T1> value1, IntCmp<T2> value2)
{
    return o3tl::cmp_greater(value1.value, value2.value);
}
 
template <typename T1, typename T2> constexpr bool operator<=(IntCmp<T1> value1, IntCmp<T2> value2)
{
    return o3tl::cmp_less_equal(value1.value, value2.value);
}
 
template <typename T1, typename T2> constexpr bool operator>=(IntCmp<T1> value1, IntCmp<T2> value2)
{
    return o3tl::cmp_greater_equal(value1.value, value2.value);
}
}
 
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