Method naturalCompare

visage_utils/string_utils.cpp:120–179

  }

  int String::naturalCompare(const std::u32string& a, const std::u32string& b) {
    size_t i = 0;
    size_t j = 0;

    auto is_digit = [](char32_t c) { return c >= U'0' && c <= U'9'; };

    while (i < a.size() && j < b.size()) {
      if (is_digit(a[i]) && is_digit(b[j])) {
        size_t leading_zeros_a = 0;
        size_t leading_zeros_b = 0;

        while (i < a.size() && a[i] == U'0') {
          ++leading_zeros_a;
          ++i;
        }

        while (j < b.size() && b[j] == U'0') {
          ++leading_zeros_b;
          ++j;
        }

        size_t start_a = i;
        size_t start_b = j;

        while (i < a.size() && is_digit(a[i]))
          ++i;

        while (j < b.size() && is_digit(b[j]))
          ++j;

        size_t len_a = i - start_a;
        size_t len_b = j - start_b;

        if (len_a != len_b)
          return len_a < len_b ? -1 : 1;

        for (size_t k = 0; k < len_a; ++k) {
          if (a[start_a + k] != b[start_b + k])
            return a[start_a + k] < b[start_b + k] ? -1 : 1;
        }

        if (leading_zeros_a != leading_zeros_b)
          return leading_zeros_a < leading_zeros_b ? -1 : 1;
      }
      else {
        if (a[i] != b[j])
          return a[i] < b[j] ? -1 : 1;

        ++i;
        ++j;
      }
    }

    if (i < a.size())
      return 1;
    if (j < b.size())
      return -1;