Implementing a multimap in Swift with Arrays and Dictionaries
- by stuffy
I'm trying to implement a basic multimap in Swift. Here's a relevant (non-functioning) snippet:
class Multimap<K: Hashable, V> {
var _dict = Dictionary<K, V[]>()
func put(key: K, value: V) {
if let existingValues = self._dict[key] {
existingValues += value
} else {
self._dict[key] = [value]
}
}
}
However, I'm getting an error on the existingValues += value line:
Could not find an overload for '+=' that accepts the supplied arguments
This seems to imply that the value type T[] is defined as an immutable array, but I can't find any way to explicitly declare it as mutable. Is this possible in Swift?
