1324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver/* 2324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * [The "BSD license"] 3324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * Copyright (c) 2010 Terence Parr 4324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * All rights reserved. 5324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 6324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * Redistribution and use in source and binary forms, with or without 7324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * modification, are permitted provided that the following conditions 8324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * are met: 9324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 1. Redistributions of source code must retain the above copyright 10324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * notice, this list of conditions and the following disclaimer. 11324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 2. Redistributions in binary form must reproduce the above copyright 12324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * notice, this list of conditions and the following disclaimer in the 13324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * documentation and/or other materials provided with the distribution. 14324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 3. The name of the author may not be used to endorse or promote products 15324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * derived from this software without specific prior written permission. 16324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 17324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver */ 28324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruverpackage org.antlr.misc; 29324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 30324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruverimport java.util.*; 31324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 32324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver/** A generic graph with edges; Each node as a single Object payload. 33324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * This is only used to topologically sort a list of file dependencies 34324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * at the moment. 35324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver */ 36324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruverpublic class Graph { 37324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 38324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public static class Node { 39324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Object payload; 40324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver List<Node> edges; // points at which nodes? 41324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 42324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public Node(Object payload) { this.payload = payload; } 43324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 44324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public void addEdge(Node n) { 45324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver if ( edges==null ) edges = new ArrayList<Node>(); 46324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver if ( !edges.contains(n) ) edges.add(n); 47324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 48324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 49324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public String toString() { return payload.toString(); } 50324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 51324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 52324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver /** Map from node payload to node containing it */ 53324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver protected Map<Object,Node> nodes = new HashMap<Object,Node>(); 54324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 55324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public void addEdge(Object a, Object b) { 56324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver //System.out.println("add edge "+a+" to "+b); 57324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Node a_node = getNode(a); 58324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Node b_node = getNode(b); 59324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver a_node.addEdge(b_node); 60324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 61324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 62324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver protected Node getNode(Object a) { 63324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Node existing = nodes.get(a); 64324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver if ( existing!=null ) return existing; 65324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Node n = new Node(a); 66324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver nodes.put(a, n); 67324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver return n; 68324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 69324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 70324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver /** DFS-based topological sort. A valid sort is the reverse of 71324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * the post-order DFA traversal. Amazingly simple but true. 72324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * For sorting, I'm not following convention here since ANTLR 73324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * needs the opposite. Here's what I assume for sorting: 74324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 75324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * If there exists an edge u -> v then u depends on v and v 76324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * must happen before u. 77324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * 78324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * So if this gives nonreversed postorder traversal, I get the order 79324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver * I want. 80324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver */ 81324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public List<Object> sort() { 82324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Set<Node> visited = new OrderedHashSet<Node>(); 83324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver ArrayList<Object> sorted = new ArrayList<Object>(); 84324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver while ( visited.size() < nodes.size() ) { 85324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver // pick any unvisited node, n 86324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Node n = null; 87324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver for (Iterator it = nodes.values().iterator(); it.hasNext();) { 88324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver n = (Node)it.next(); 89324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver if ( !visited.contains(n) ) break; 90324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 91324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver DFS(n, visited, sorted); 92324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 93324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver return sorted; 94324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 95324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver 96324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver public void DFS(Node n, Set<Node> visited, ArrayList<Object> sorted) { 97324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver if ( visited.contains(n) ) return; 98324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver visited.add(n); 99324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver if ( n.edges!=null ) { 100324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver for (Iterator it = n.edges.iterator(); it.hasNext();) { 101324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver Node target = (Node) it.next(); 102324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver DFS(target, visited, sorted); 103324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 104324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 105324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver sorted.add(n.payload); 106324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver } 107324c4644fee44b9898524c09511bd33c3f12e2dfBen Gruver}