parseDecimal static method

Int32 parseDecimal(String s)

Strict decimal parse: throws IntegerError on overflow/underflow, unlike the wrapping constructor.

Implementation

static Int32 parseDecimal(String s) {
  if (s.isEmpty) {
    throw ArgumentException.invalidOperationArguments(
      "parseDecimal",
      reason: 'Invalid decimal literal.',
      details: {"value": s},
    );
  }
  final negative = s.startsWith('-');
  final digits = negative ? s.substring(1) : s;
  // A valid i32 magnitude has at most 10 digits ("2147483648"); rejecting
  // longer strings up front means int.parse below never sees more digits
  // than that, so it stays exact on web.
  if (digits.isEmpty ||
      digits.length > 10 ||
      !RegExp(r'^[0-9]+$').hasMatch(digits)) {
    throw ArgumentException.invalidOperationArguments(
      "parseDecimal",
      reason: 'Invalid decimal literal.',
      details: {"value": s},
    );
  }
  final mag = int.parse(digits);
  if (negative) {
    if (mag > 0x80000000) throw IntegerError.overflow;
    return Int32._((0x100000000 - mag) & BinaryOps.mask32);
  } else {
    if (mag > 0x7FFFFFFF) throw IntegerError.overflow;
    return Int32._(mag);
  }
}