1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package optkl.util;
26
27 import optkl.jdot.ui.JDot;
28 import java.util.Collections;
29 import java.util.HashMap;
30 import java.util.LinkedHashMap;
31 import java.util.LinkedHashSet;
32 import java.util.LinkedList;
33 import java.util.List;
34 import java.util.Map;
35 import java.util.Queue;
36 import java.util.Set;
37 import java.util.function.Consumer;
38 import java.util.function.Function;
39
40 public abstract class Dag<N> extends Interner<N> {
41 public final Map<N, Set<N>> fromTo = new LinkedHashMap<>();
42 public final Map<N, Set<N>> toFrom = new LinkedHashMap<>();
43
44 public void add(N from, N to, Consumer<N> ifAbsent) {
45 toFrom.computeIfAbsent(to,_->new LinkedHashSet<>()).add(from);
46 fromTo.computeIfAbsent(from,_->new LinkedHashSet<>()).add(to);
47 if (add(from)){
48 ifAbsent.accept(from);
49 }
50 if (add(to)){
51 ifAbsent.accept(to);
52 }
53 }
54
55 public void add(N from, N to) {
56 add(from,to,_->{});
57 }
58 public final List<N> rankOrdered = new LinkedList<>();
59
60 public void view(String name, Function<N, String> dotNodeLabelRenderer) {
61 JDot.digraph(name, $ ->
62 fromTo.forEach((l, r) ->
63 r.forEach(e ->
64 $.edge(dotNodeLabelRenderer.apply(l), dotNodeLabelRenderer.apply(e))
65 )
66 ));
67 }
68
69 public boolean isDag() {
70 return !fromTo.isEmpty();
71 }
72
73 public void closeRanks() {
74 if (fromTo.isEmpty()){
75 rankOrdered.addAll(interned.values());
76 }else {
77 Map<N, Integer> outDegree = new HashMap<>();
78 fromTo.keySet().forEach(parent -> {
79 outDegree.put(parent, fromTo.get(parent).size());
80 fromTo.get(parent).forEach(child ->
81 outDegree.putIfAbsent(child, 0)
82 );
83 });
84
85 Queue<N> queue = new LinkedList<>(outDegree.entrySet().stream()
86 .filter(e -> e.getValue() == 0)
87 .map(Map.Entry::getKey)
88 .toList()
89 );
90
91 while (queue.poll() instanceof N current) { // basically a null check
92 rankOrdered.add(current);
93 toFrom.getOrDefault(current, Collections.emptySet())
94 .forEach(parent -> {
95 int remainingChildren = outDegree.get(parent) - 1;
96 outDegree.put(parent, remainingChildren);
97 if (remainingChildren == 0) {
98 queue.add(parent);
99 }
100 });
101 }
102 }
103 }
104 }