Function VersionCompare

Source/cmSystemTools.cxx:3761–3815

namespace {
bool VersionCompare(cmSystemTools::CompareOp op, char const* lhss,
                    char const* rhss)
{
  char const* endl = lhss;
  char const* endr = rhss;

  while (((*endl >= '0') && (*endl <= '9')) ||
         ((*endr >= '0') && (*endr <= '9'))) {
    // Do component-wise comparison, ignoring leading zeros
    // (components are treated as integers, not as mantissas)
    while (*endl == '0') {
      endl++;
    }
    while (*endr == '0') {
      endr++;
    }

    char const* beginl = endl;
    char const* beginr = endr;

    // count significant digits
    while ((*endl >= '0') && (*endl <= '9')) {
      endl++;
    }
    while ((*endr >= '0') && (*endr <= '9')) {
      endr++;
    }

    // compare number of digits first
    ptrdiff_t r = ((endl - beginl) - (endr - beginr));
    if (r == 0) {
      // compare the digits if number of digits is equal
      r = strncmp(beginl, beginr, endl - beginl);
    }

    if (r < 0) {
      // lhs < rhs, so true if operation is LESS
      return (op & cmSystemTools::OP_LESS) != 0;
    }
    if (r > 0) {
      // lhs > rhs, so true if operation is GREATER
      return (op & cmSystemTools::OP_GREATER) != 0;
    }

    if (*endr == '.') {
      endr++;
    }

    if (*endl == '.') {
      endl++;
    }
  }
  // lhs == rhs, so true if operation is EQUAL
  return (op & cmSystemTools::OP_EQUAL) != 0;
}
}

bool cmSystemTools::VersionCompare(cmSystemTools::CompareOp op,