In Scala I need some classes to implement a dictionary. Or basically a set of key/value pairs where the keys are Scala strings and the associated values are abitrary scala objects. It is possible for a key to be associated with multiple values in the dictionary.

abstract class Dictionary { /* put(k,v) adds value v to the dictionary under key k. put may be called with the same key multiple times, all key->values pairs get stored in the dictionary */ def put(key:String, value: Any):Unit

/* get(k) returns Some(v) where v is one of the values associated with key k in the dictionary, if any. It returns None if k is associated to no value. */ def get(key:String):Option[Any]

/* remove(k) removes one value v associated with key k from the dictionary, if any, and returns it as Some(v). It returns None if k is associated to no value. */ def remove(key:String):Option[Any]

/* toList() returns a list containing all the key/value pairs in the dictionary. If multiple values have the same key k, each is listed in a separate pair with k. */ def toList():List[(String,Any)]

/* toString() returns a string containing all the key/value pairs in the dictionary. The string has the form Dictionary(key_1 -> value_1, ..., key_n -> value_n) where each key_i is a key and each value_i is (the string representation of) the corresponding value. If multiple values have the same key k, each is present in a separate pair with k. */ override def toString():String

/* getAll(k) returns the list of all the values associated with key k in the dictionary. */ def getAll(key:String):List[Any] = //replace with your implementation

/* removeAll(k) removes from the dictionary all the values associated with key k in the dictionary, if any. */ def removeAll(key:String) { // replace with your implementation } }

class ListDictionary extends Dictionary { /* the dictionary is implemented using a list of key/value pairs */ private var d = List[(String,Any)]() //implementation of Dictionary's abstract methods here

}