whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? slp(
    1. SlpTokenTypeValue type,
    2. int number
    )?,
  2. TResult? alp(
    1. AlpTokenTypeValue type,
    2. int number
    )?,
  3. TResult? unknown()?,
})

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({TResult? Function( SlpTokenTypeValue type,  int number)?  slp,TResult? Function( AlpTokenTypeValue type,  int number)?  alp,TResult? Function()?  unknown,}) {final _that = this;
switch (_that) {
case SlpTokenType() when slp != null:
return slp(_that.type,_that.number);case AlpTokenType() when alp != null:
return alp(_that.type,_that.number);case UnknownTokenType() when unknown != null:
return unknown();case _:
  return null;

}
}