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      1 /*
      2  * [The "BSD licence"]
      3  * Copyright (c) 2010 Ben Gruver
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 package org.jf.util;
     30 
     31 import com.google.common.collect.Lists;
     32 
     33 import java.io.File;
     34 import java.io.IOException;
     35 import java.util.ArrayList;
     36 import java.util.List;
     37 
     38 public class PathUtil {
     39     private PathUtil() {
     40     }
     41 
     42     public static File getRelativeFile(File baseFile, File fileToRelativize) throws IOException {
     43         if (baseFile.isFile()) {
     44             baseFile = baseFile.getParentFile();
     45         }
     46 
     47         return new File(getRelativeFileInternal(baseFile.getCanonicalFile(), fileToRelativize.getCanonicalFile()));
     48     }
     49 
     50     static String getRelativeFileInternal(File canonicalBaseFile, File canonicalFileToRelativize) {
     51         List<String> basePath = getPathComponents(canonicalBaseFile);
     52         List<String> pathToRelativize = getPathComponents(canonicalFileToRelativize);
     53 
     54         //if the roots aren't the same (i.e. different drives on a windows machine), we can't construct a relative
     55         //path from one to the other, so just return the canonical file
     56         if (!basePath.get(0).equals(pathToRelativize.get(0))) {
     57             return canonicalFileToRelativize.getPath();
     58         }
     59 
     60         int commonDirs;
     61         StringBuilder sb = new StringBuilder();
     62 
     63         for (commonDirs=1; commonDirs<basePath.size() && commonDirs<pathToRelativize.size(); commonDirs++) {
     64             if (!basePath.get(commonDirs).equals(pathToRelativize.get(commonDirs))) {
     65                 break;
     66             }
     67         }
     68 
     69         boolean first = true;
     70         for (int i=commonDirs; i<basePath.size(); i++) {
     71             if (!first) {
     72                 sb.append(File.separatorChar);
     73             } else {
     74                 first = false;
     75             }
     76 
     77             sb.append("..");
     78         }
     79 
     80         first = true;
     81         for (int i=commonDirs; i<pathToRelativize.size(); i++) {
     82             if (first) {
     83                 if (sb.length() != 0) {
     84                     sb.append(File.separatorChar);
     85                 }
     86                 first = false;
     87             } else {
     88                 sb.append(File.separatorChar);
     89             }
     90 
     91             sb.append(pathToRelativize.get(i));
     92         }
     93 
     94         if (sb.length() == 0) {
     95             return ".";
     96         }
     97 
     98         return sb.toString();
     99     }
    100 
    101     private static List<String> getPathComponents(File file) {
    102         ArrayList<String> path = new ArrayList<String>();
    103 
    104         while (file != null) {
    105             File parentFile = file.getParentFile();
    106 
    107             if (parentFile == null) {
    108                 path.add(file.getPath());
    109             } else {
    110                 path.add(file.getName());
    111             }
    112 
    113             file = parentFile;
    114         }
    115 
    116         return Lists.reverse(path);
    117     }
    118 }
    119