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
29 import java.util.Collections;
30 import java.util.HashMap;
31 import java.util.LinkedHashMap;
32 import java.util.LinkedHashSet;
33 import java.util.LinkedList;
34 import java.util.List;
35 import java.util.Map;
36 import java.util.Queue;
37 import java.util.Set;
38 import java.util.function.Consumer;
39 import java.util.function.Function;
40
41 public abstract class Dag<N> extends Interner<N> {
42 public final Map<N, Set<N>> fromTo = new LinkedHashMap<>();
43 public final Map<N, Set<N>> toFrom = new LinkedHashMap<>();
44
45 public void add(N from, N to, Consumer<N> ifAbsent) {
46 toFrom.computeIfAbsent(to, _ -> new LinkedHashSet<>()).add(from);
47 fromTo.computeIfAbsent(from, _ -> new LinkedHashSet<>()).add(to);
48 if (add(from)) {
49 ifAbsent.accept(from);
50 }
51 if (add(to)) {
52 ifAbsent.accept(to);
53 }
54 }
55
56 public void add(N from, N to) {
57 add(from, to, _ -> {});
58 }
59
60 public final List<N> rankOrdered = new LinkedList<>();
61
62 public void view(String name, Function<N, String> dotNodeLabelRenderer) {
63 JDot.digraph(name, $ ->
64 fromTo.forEach((l, r) ->
65 r.forEach(e ->
66 $.edge(dotNodeLabelRenderer.apply(l), dotNodeLabelRenderer.apply(e))
67 )
68 ));
69 }
70
71 public boolean isDag() {
72 return !fromTo.isEmpty();
73 }
74
75 public void closeRanks() {
76 if (fromTo.isEmpty()) {
77 rankOrdered.addAll(interned.values());
78 } else {
79 Map<N, Integer> outDegree = new HashMap<>();
80 fromTo.keySet().forEach(parent -> {
81 outDegree.put(parent, fromTo.get(parent).size());
82 fromTo.get(parent).forEach(child ->
83 outDegree.putIfAbsent(child, 0)
84 );
85 });
86
87 Queue<N> queue = new LinkedList<>(outDegree.entrySet().stream()
88 .filter(e -> e.getValue() == 0)
89 .map(Map.Entry::getKey)
90 .toList()
91 );
92
93 while (queue.poll() instanceof N current) { // basically a null check
94 rankOrdered.add(current);
95 toFrom.getOrDefault(current, Collections.emptySet())
96 .forEach(parent -> {
97 int remainingChildren = outDegree.get(parent) - 1;
98 outDegree.put(parent, remainingChildren);
99 if (remainingChildren == 0) {
100 queue.add(parent);
101 }
102 });
103 }
104 }
105 }
106 }