Timeout.parse constructor

Timeout.parse(String timeout)

Parse the timeout from a user-provided string.

This supports the following formats:

  • Number "x", which produces a relative timeout with the given scale factor.

  • (Number ("d" | "h" | "m" | "s" | "ms" | "us") (" ")?)+, which produces an absolute timeout with the duration given by the sum of the given units.

  • "none", which produces Timeout.none.

Throws a FormatException if timeout is not in a valid format

Implementation 

factory Timeout.parse(String timeout) {
  var scanner = StringScanner(timeout);

  // First check for the string "none".
  if (scanner.scan("none")) {
    scanner.expectDone();
    return Timeout.none;
  }

  // Scan a number. This will be either a time unit or a scale factor.
  scanner.expect(_untilUnit, name: "number");
  var number = double.parse(scanner.lastMatch[0]);

  // A number followed by "x" is a scale factor.
  if (scanner.scan("x") || scanner.scan("X")) {
    scanner.expectDone();
    return Timeout.factor(number);
  }

  // Parse time units until none are left. The condition is in the middle of
  // the loop because we've already parsed the first number.
  var microseconds = 0.0;
  while (true) {
    scanner.expect(_unit, name: "unit");
    microseconds += _microsecondsFor(number, scanner.lastMatch[0]);

    scanner.scan(_whitespace);

    // Scan the next number, if it's avaialble.
    if (!scanner.scan(_untilUnit)) break;
    number = double.parse(scanner.lastMatch[0]);
  }

  scanner.expectDone();
  return Timeout(Duration(microseconds: microseconds.round()));
}