1 package edu.berkeley.sbp.util;
4 import java.lang.reflect.*;
5 import java.lang.ref.*;
6 import edu.berkeley.sbp.util.*;
7 import edu.berkeley.sbp.*;
9 /** implementation of <tt>Topology</tt> for any class via equals()/hashCode() */
10 public class DiscreteTopology<V> implements Topology<V> {
12 private static final DiscreteTopology empty = new DiscreteTopology();
14 HashSet<V> hs = new HashSet<V>();
16 public DiscreteTopology() { }
17 public DiscreteTopology(V v) { hs.add(v); }
18 DiscreteTopology(HashSet<V> hs) { this.hs.addAll(hs); }
20 public Topology<V> empty() { return (Topology<V>)empty; }
22 public HashSet<V> hs() {
23 HashSet<V> ret = new HashSet<V>();
28 public boolean contains(V v) { return hs.contains(v); }
30 public Topology<V> unwrap() { return this; }
31 public Topology<V> complement() { throw new Error(); }
32 public Topology<V> intersect(Topology<V> t) { return new DiscreteTopology(hs().retainAll(((DiscreteTopology<V>)t.unwrap()).hs)); }
33 public Topology<V> minus(Topology<V> t) { return new DiscreteTopology(hs().removeAll(((DiscreteTopology<V>)t.unwrap()).hs)); }
34 public Topology<V> union(Topology<V> t) { return new DiscreteTopology(hs().addAll(((DiscreteTopology<V>)t.unwrap()).hs)); }
35 public boolean disjoint(Topology<V> t) { return ((DiscreteTopology)intersect(t).unwrap()).size()==0; }
36 public boolean containsAll(Topology<V> t) { return hs.containsAll(((DiscreteTopology<V>)t.unwrap()).hs); }
38 public int hashCode() { return hs.hashCode(); }
39 public boolean equals(Object o) { return o!=null && o instanceof DiscreteTopology && ((DiscreteTopology<V>)o).hs.equals(hs); }
40 public int size() { return hs.size(); }