Function Compare

internal/number.h:81–85

template <typename T>
constexpr ComparisonResult Compare(T a, T b) {
  return (a > b)    ? ComparisonResult::kGreater
         : (a == b) ? ComparisonResult::kEqual
                    : ComparisonResult::kLesser;
}

constexpr ComparisonResult DoubleCompare(double a, double b) {
  // constexpr friendly isnan check.