1 /* 2 * Copyright (C) 2010 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package org.clearsilver; 18 19 import java.io.File; 20 import java.util.LinkedList; 21 import java.util.List; 22 23 /** 24 * Utility class containing helper methods 25 */ 26 public final class CSUtil { 27 28 private CSUtil() { } 29 30 public static final String HDF_LOADPATHS = "hdf.loadpaths"; 31 32 /** 33 * Helper function that returns a concatenation of the loadpaths in the 34 * provided HDF. 35 * @param hdf an HDF structure containing load paths. 36 * @return A list of loadpaths in order in which to search. 37 * @throws NullPointerException if no loadpaths are found. 38 */ 39 public static List<String> getLoadPaths(HDF hdf) { 40 return getLoadPaths(hdf, false); 41 } 42 43 /** 44 * Helper function that returns a concatenation of the loadpaths in the 45 * provided HDF. 46 * @param hdf an HDF structure containing load paths. 47 * @param allowEmpty if {@code true} then this will return an empty list when 48 * no loadpaths are found in the HDF object, otherwise a 49 * {@link NullPointerException} is thrown. Loadpaths are not needed if 50 * no files are read in or are all specified by absolute paths. 51 * @return A list of loadpaths in order in which to search. 52 * @throws NullPointerException if no loadpaths are found and allowEmpty is 53 * {@code false}. 54 */ 55 public static List<String> getLoadPaths(HDF hdf, boolean allowEmpty) { 56 List<String> list = new LinkedList<String>(); 57 HDF loadpathsHdf = hdf.getObj(HDF_LOADPATHS); 58 if (loadpathsHdf == null) { 59 if (allowEmpty) { 60 return list; 61 } else { 62 throw new NullPointerException("No HDF loadpaths located in the " 63 + "specified HDF structure"); 64 } 65 } 66 for (HDF lpHdf = loadpathsHdf.objChild(); lpHdf != null; 67 lpHdf = lpHdf.objNext()) { 68 list.add(lpHdf.objValue()); 69 } 70 return list; 71 } 72 73 /** 74 * Given an ordered list of directories to look in, locate the specified file. 75 * Returns <code>null</code> if file not found. 76 * @param loadpaths the ordered list of paths to search. 77 * @param filename the name of the file. 78 * @return a File object corresponding to the file. <code>null</code> if 79 * file not found. 80 */ 81 public static File locateFile(List<String> loadpaths, String filename) { 82 if (filename == null) { 83 throw new NullPointerException("No filename provided"); 84 } 85 if (loadpaths == null) { 86 throw new NullPointerException("No loadpaths provided."); 87 } 88 for (String path : loadpaths) { 89 File file = new File(path, filename); 90 if (file.exists()) { 91 return file; 92 } 93 } 94 return null; 95 } 96 } 97