How to match multiple enum cases in switch-statement on tuple?-CodePudding

I have a switch statement that check a tuple. One of the part of the tuple is an enum. How can I match multiple enum cases inside that tuple?

I've tried several things, which all lead to compiler errors. Here's one attempt:

switch (enumValue, myArray.isEmpty)
{
case (.one, true):  // Fine.
    ...

case ((.one, .two), false): // Error: Tuple pattern cannot match values of the non-tuple type 'MyEnum'
     ...
}

Is there a way to do this?

CodePudding user response：

case is expecting a Tuple (Enum, Bool). However, ((.one, .two), false) is of type ((Enum, Enum), Bool), so what you should write is the following:

case (.one, false), (.two, false):

CodePudding user response：

You can't match multiple enum cases inside the tuple, you need to specify each enum case in a separate tuple. Alternatively, if you only care about the Bool value being false regardless of the enum case, you can use case (_, false):,

case (.one, false), (.two, false):
  ...
case (_, false):
  ...

CodePudding user response：

I think you need to repeat the whole pattern again:

switch (enumValue, myArray.isEmpty)
{
    case (.one, false), (.two, false):
     ...
}

If you don't like this, you can try making your enum less flat - grouping similar cases together. So rather than:

enum MyEnum {
    case one, two, three
}

you do:

enum OneOrTwo {
    case one, two
}

enum MyEnum {
    case oneOrTwo(OneOrTwo), three
}

Though you may not always find good names for these groups :(