+++ /dev/null
-/*
- * Copyright 2005-2011 the original author or authors.
- *
- * Licensed 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.wamblee.xmlrouter.impl;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-
-import org.wamblee.xmlrouter.config.Transformation;
-
-/**
- * This class manages transformations and computes the shortest transformations
- * paths based on the provided transformations.
- *
- * @author Erik Brakkee
- *
- */
-public class TransformationPaths {
-
- private Collection<Transformation> transformations;
- private List<String> vertices;
- private TransformationPath[][] matrix;
-
- /**
- * Construct the transformations.
- */
- public TransformationPaths(Collection<Transformation> aTransformations) {
- transformations = aTransformations;
- vertices = new ArrayList<String>();
- matrix = new TransformationPath[0][0];
- computeTransformationSequences();
- }
-
- /**
- * Gets the possible target types based on an input type.
- *
- * @param aType
- * Input type.
- * @return Possible target types.
- */
- public Collection<String> getPossibleTargetTypes(String aType) {
- int index = vertices.indexOf(aType);
- Set<String> res = new HashSet<String>();
- for (int j = 0; j < vertices.size(); j++) {
- if (matrix[index][j] != null) {
- String value = matrix[index][j].getToType();
- if (value == null) {
- value = aType;
- }
- res.add(value);
- }
- }
- res.add(aType);
- return res;
- }
-
- /**
- * Gets the transformation path from A to B.
- *
- * @param aFrom
- * From
- * @param aTo
- * To
- * @return Transformatkon path or null if not found.
- */
- public TransformationPath getPath(String aFrom, String aTo) {
- int i = vertices.indexOf(aFrom);
- if (i < 0) {
- if (aFrom.equals(aTo)) {
- return new TransformationPath();
- }
- return null;
- }
-
- int j = vertices.indexOf(aTo);
- if (j < 0) {
- return null;
- }
- return matrix[i][j];
- }
-
- /**
- * Computest the transformation sequences using Floyd's algorithm.
- */
- private void computeTransformationSequences() {
- vertices = new ArrayList<String>();
-
- // Obtain possible starting points.
- Set<String> v = new HashSet<String>();
- for (Transformation transformation : transformations) {
- v.add(transformation.getFromType());
- v.add(transformation.getToType());
- }
-
- vertices.addAll(v);
-
- matrix = new TransformationPath[vertices.size()][vertices.size()];
-
- // Floyd's algorithm.
- int nvertices = vertices.size();
- for (int i = 0; i < nvertices; i++) {
- matrix[i][i] = new TransformationPath();
- }
- for (Transformation transformation : transformations) {
- int from = vertices.indexOf(transformation.getFromType());
- int to = vertices.indexOf(transformation.getToType());
- TransformationPath path = new TransformationPath(transformation);
- matrix[from][to] = path;
- }
-
- for (int k = 0; k < nvertices; k++) {
- for (int i = 0; i < nvertices; i++) {
- for (int j = 0; j < nvertices; j++) {
- // if the path from i to j through k is shorter then the
- // existing path then
- // replace it.
- int lij = getPathLength(i, j);
- int lik = getPathLength(i, k);
- int lkj = getPathLength(k, j);
- if (lik + lkj < lij) {
- matrix[i][j] = matrix[i][k].appendPath(matrix[k][j]);
- }
- }
- }
- }
- }
-
- private int getPathLength(int i, int j) {
- // We use MAX_INT/3 as infinity. This ensures that the default integer
- // comparison in Floyd's algorithm does not lead to overflow.
- return matrix[i][j] == null ? Integer.MAX_VALUE / 3 : matrix[i][j]
- .size();
- }
-
- @Override
- public String toString() {
- StringBuffer buf = new StringBuffer();
- buf.append("Transformations(");
- int nvertices = vertices.size();
- for (int i = 0; i < nvertices; i++) {
- for (int j = 0; j < nvertices; j++) {
- TransformationPath path = matrix[i][j];
- if (path != null) {
- buf.append(vertices.get(i));
- buf.append(" -> ");
- buf.append(vertices.get(j));
- buf.append(": ");
- buf.append(path);
- buf.append("\n");
- }
- }
- }
- buf.append(")");
- return buf.toString();
- }
-}
git://wamblee.org / xmlrouter / blobdiff