Method getAsInteger

ext/src/llvm/StringRef.cpp:514–587

}

bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
  StringRef Str = *this;

  // Autosense radix if not specified.
  if (Radix == 0)
    Radix = GetAutoSenseRadix(Str);

  assert(Radix > 1 && Radix <= 36);

  // Empty strings (after the radix autosense) are invalid.
  if (Str.empty()) return true;

  // Skip leading zeroes.  This can be a significant improvement if
  // it means we don't need > 64 bits.
  while (!Str.empty() && Str.front() == '0')
    Str = Str.substr(1);

  // If it was nothing but zeroes....
  if (Str.empty()) {
    Result = APInt(64, 0);
    return false;
  }

  // (Over-)estimate the required number of bits.
  unsigned Log2Radix = 0;
  while ((1U << Log2Radix) < Radix) Log2Radix++;
  bool IsPowerOf2Radix = ((1U << Log2Radix) == Radix);

  unsigned BitWidth = Log2Radix * Str.size();
  if (BitWidth < Result.getBitWidth())
    BitWidth = Result.getBitWidth(); // don't shrink the result
  else if (BitWidth > Result.getBitWidth())
    Result = Result.zext(BitWidth);

  APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
  if (!IsPowerOf2Radix) {
    // These must have the same bit-width as Result.
    RadixAP = APInt(BitWidth, Radix);
    CharAP = APInt(BitWidth, 0);
  }

  // Parse all the bytes of the string given this radix.
  Result = 0;
  while (!Str.empty()) {
    unsigned CharVal;
    if (Str[0] >= '0' && Str[0] <= '9')
      CharVal = Str[0]-'0';
    else if (Str[0] >= 'a' && Str[0] <= 'z')
      CharVal = Str[0]-'a'+10;
    else if (Str[0] >= 'A' && Str[0] <= 'Z')
      CharVal = Str[0]-'A'+10;
    else
      return true;

    // If the parsed value is larger than the integer radix, the string is
    // invalid.
    if (CharVal >= Radix)
      return true;