Dictionaries / Maps
Frequently we want to store values associated with keys.
Simple examples:
- Phone book maps Name to Phone #.
- DNS servers map domain names to IP addresses
Interface:
interface Map<K, V> {
void set(K key, V val);
V get(K key);
void del(K key);
int size();
boolean containsKey(K key);
Set<K> keySet();
}
Implementations:
record Entry<K, V>(K key, V val) {
// pass
}
// An assocation list:
// Immutable, so doesn't match our interface above.
ConsList<Entry<K, V>> alist;
class ConsMap<K, V> implements Map<K, V>{
ConsList<Entry<K, V>> data;
// Operations create a new ConsList, but we hide that
// as an implementation detail
}
// Just like set, this could be sorted or unsorted.
ArrayList<Entry<K, V>> array_map;
- ALists
- TreeMap
public record AssocList<K, V>(ConsList<Pair<K, V>> data) {
// methods
}
record Pair<K, V>(K key, V val) {
// pass
}
Today:
- Finish ConsMap
- Build TreeMap
public record AssocList<K, V>(ConsList<Pair<K, V>> data) {
// methods
}
record Pair<K, V>(K key, V val) {
// pass
}
