val_int_compare.h

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#ifndef VAL_INT_COMPARE_INCLUDED
#define VAL_INT_COMPARE_INCLUDED
 
#include <assert.h>
#include <functional>
 
#include "my_inttypes.h"
 
/**
  Holds value/unsigned_flag for the result of val_int(),
  so that we can compare with operator<(), operator==() and operator<=()
 */
class Integer_value {
 public:
  constexpr Integer_value(longlong val, bool unsigned_flag)
      : m_val(val), m_unsigned_flag(unsigned_flag) {}
 
  constexpr longlong val() const { return m_val; }
  constexpr bool is_unsigned() const { return m_unsigned_flag; }
 
  ulonglong val_unsigned() const {
    assert(!is_negative());
    return static_cast<ulonglong>(m_val);
  }
 
  constexpr bool is_negative() const { return !is_unsigned() && val() < 0; }
 
 private:
  const longlong m_val;
  const bool m_unsigned_flag;
};
 
inline bool operator<(const Integer_value &lhs, const Integer_value &rhs) {
  const bool lhs_is_neg = lhs.is_negative();
  const bool rhs_is_neg = rhs.is_negative();
  if (lhs_is_neg != rhs_is_neg)
    // Different signs, lhs is smaller if it is negative.
    return lhs_is_neg;
  if (lhs_is_neg)
    // Both are negative, compare as signed.
    return lhs.val() < rhs.val();
 
  // Both are non-negative, compare as unsigned
  return std::less<ulonglong>()(lhs.val(), rhs.val());
}
 
inline bool operator==(const Integer_value &lhs, const Integer_value &rhs) {
  const bool lhs_is_neg = lhs.is_negative();
  const bool rhs_is_neg = rhs.is_negative();
  if (lhs_is_neg != rhs_is_neg)
    // Different signs, cannot be equal
    return false;
 
  // Same sign, compare values.
  return lhs.val() == rhs.val();
}
 
inline bool operator<=(const Integer_value &lhs, const Integer_value &rhs) {
  return lhs < rhs || lhs == rhs;
}
 
#endif  // VAL_INT_COMPARE_INCLUDED