| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| package org.apache.myfaces.tobago.internal.config; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.lang.invoke.MethodHandles; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| public class TobagoConfigSorter { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()); |
| |
| private final List<Vertex> vertices = new ArrayList<>(); |
| |
| public TobagoConfigSorter(final List<TobagoConfigFragment> fragmentList) { |
| for (TobagoConfigFragment tobagoConfigFragment : fragmentList) { |
| vertices.add(new Vertex(tobagoConfigFragment)); |
| } |
| } |
| |
| /** |
| * Topological sorting with setup and cycle check. |
| * |
| * @throws IllegalStateException When detecting a cycle. |
| */ |
| public List<TobagoConfigFragment> topologicalSort() { |
| |
| createEdges(); |
| checkCycles(); |
| |
| List<TobagoConfigFragment> result = new ArrayList<>(); |
| |
| for (Vertex vertex : vertices) { |
| topologicalSort0(vertex, result); |
| } |
| |
| logResult(result); |
| |
| return result; |
| } |
| |
| /** |
| * Internal recursive method for the topological sort. |
| */ |
| private void topologicalSort0(Vertex vertex, List<TobagoConfigFragment> result) { |
| if (vertex.isVisited()) { |
| return; |
| } |
| |
| vertex.setVisited(true); |
| |
| // recursion for all vertices adjacent to this vertex |
| for (Vertex adjacent : vertex.getAdjacencyList()) { |
| topologicalSort0(adjacent, result); |
| } |
| |
| result.add(vertex.getFragment()); |
| } |
| |
| private void logResult(List<TobagoConfigFragment> result) { |
| if (LOG.isInfoEnabled()) { |
| StringBuilder builder = new StringBuilder("Order of the Tobago config files: "); |
| for (TobagoConfigFragment fragment : result) { |
| final String name = fragment.getName(); |
| if (LOG.isDebugEnabled()) { |
| builder.append("name="); |
| if (name == null) { |
| builder.append("<unnamed>"); |
| } else { |
| builder.append("'"); |
| builder.append(name); |
| builder.append("'"); |
| } |
| builder.append(" url='"); |
| builder.append(fragment.getUrl()); |
| builder.append("'"); |
| } else { |
| builder.append(name); |
| builder.append(", "); |
| } |
| } |
| LOG.info(builder.toString()); |
| } |
| } |
| |
| |
| private void createEdges() { |
| |
| // collecting all relations, which are relevant for us. We don't need "before" and "after" of unknown names. |
| for (final Vertex vertex : vertices) { |
| final TobagoConfigFragment current = vertex.getFragment(); |
| |
| for (final String befores : current.getBefore()) { |
| final TobagoConfigFragment before = findByName(befores); |
| if (before != null) { |
| findVertex(before).addAdjacent(findVertex(current)); |
| } |
| } |
| for (final String afters : current.getAfter()) { |
| final TobagoConfigFragment after = findByName(afters); |
| if (after != null) { |
| findVertex(current).addAdjacent(findVertex(after)); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Cycle detection: if the base in reachable form its own, than there is a cycle. |
| * |
| * @throws IllegalStateException When detecting a cycle. |
| */ |
| private void checkCycles() { |
| LOG.debug("Cycle detection:"); |
| for (Vertex vertex : vertices) { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug("Checking reachable vertices from base {}", vertex.getFragment()); |
| } |
| checkCycles0(vertex, vertex); |
| } |
| } |
| |
| private void checkCycles0(final Vertex vertex, final Vertex base) { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug("vertex: {}", vertex.toString()); |
| LOG.debug("base: {}", base.getFragment().toString()); |
| } |
| for (Vertex adjacent : vertex.getAdjacencyList()) { |
| if (base == adjacent) { |
| throw new IllegalStateException("Cycle detected name='" + vertex + "' base=" + base + "! "); |
| } |
| checkCycles0(adjacent, base); |
| } |
| } |
| |
| private Vertex findVertex(final TobagoConfigFragment fragment) { |
| for (Vertex vertex : vertices) { |
| if (vertex.getFragment() == fragment) { |
| return vertex; |
| } |
| } |
| throw new RuntimeException("Problem with sorting! This might be a bug."); |
| } |
| |
| private TobagoConfigFragment findByName(final String name) { |
| for (final Vertex vertex : vertices) { |
| TobagoConfigFragment fragment = vertex.getFragment(); |
| if (name.equals(fragment.getName())) { |
| return fragment; |
| } |
| } |
| return null; |
| } |
| |
| private static class Vertex { |
| |
| private final TobagoConfigFragment fragment; |
| private final List<Vertex> adjacencyList; |
| private boolean visited; |
| |
| private Vertex(final TobagoConfigFragment fragment) { |
| this.fragment = fragment; |
| this.adjacencyList = new ArrayList<>(); |
| } |
| |
| public boolean isVisited() { |
| return visited; |
| } |
| |
| public void setVisited(boolean visited) { |
| this.visited = visited; |
| } |
| |
| public TobagoConfigFragment getFragment() { |
| return fragment; |
| } |
| |
| public void addAdjacent(Vertex higher) { |
| adjacencyList.add(higher); |
| } |
| |
| public List<Vertex> getAdjacencyList() { |
| return adjacencyList; |
| } |
| |
| @Override |
| public String toString() { |
| StringBuilder builder = new StringBuilder(); |
| builder.append(fragment); |
| builder.append(" -> ["); |
| for (Vertex vertex : adjacencyList) { |
| builder.append(vertex.getFragment()); |
| builder.append(", "); |
| } |
| if (builder.charAt(builder.length() - 1) == ' ') { |
| builder.delete(builder.length() - 2, builder.length()); |
| } |
| builder.append("]"); |
| return builder.toString(); |
| } |
| } |
| } |