Add a utility method for constructing a relative path

git-svn-id: https://smali.googlecode.com/svn/trunk@754 55b6fa8a-2a1e-11de-a435-ffa8d773f76a

util/src/main/java/org/jf/util/PathUtil.java

@@ -0,0 +1,125 @@
+/*
+ * [The "BSD licence"]
+ * Copyright (c) 2010 Ben Gruver
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.jf.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+
+public class PathUtil {
+    private PathUtil() {
+    }
+
+    public static File getRelativeFile(File baseFile, File fileToRelativize) throws IOException {
+        if (baseFile.isFile()) {
+            baseFile = baseFile.getParentFile();
+        }
+
+        return new File(getRelativeFileInternal(baseFile.getCanonicalFile(), fileToRelativize.getCanonicalFile()));
+    }
+
+    public static String getRelativePath(String basePath, String pathToRelativize) throws IOException {
+        File baseFile = new File(basePath);
+        if (baseFile.isFile()) {
+            baseFile = baseFile.getParentFile();
+        }
+
+        return getRelativeFileInternal(baseFile.getCanonicalFile(),
+                new File(pathToRelativize).getCanonicalFile());
+    }
+
+    static String getRelativeFileInternal(File canonicalBaseFile, File canonicalFileToRelativize) {
+        ArrayList<String> basePath = getPathComponents(canonicalBaseFile);
+        ArrayList<String> pathToRelativize = getPathComponents(canonicalFileToRelativize);
+
+        //if the roots aren't the same (i.e. different drives on a windows machine), we can't construct a relative
+        //path from one to the other, so just return the canonical file
+        if (!basePath.get(0).equals(pathToRelativize.get(0))) {
+            return canonicalFileToRelativize.getPath();
+        }
+
+        int commonDirs;
+        StringBuilder sb = new StringBuilder();
+
+        for (commonDirs=1; commonDirs<basePath.size() && commonDirs<pathToRelativize.size(); commonDirs++) {
+            if (!basePath.get(commonDirs).equals(pathToRelativize.get(commonDirs))) {
+                break;
+            }
+        }
+
+        boolean first = true;
+        for (int i=commonDirs; i<basePath.size(); i++) {
+            if (!first) {
+                sb.append(File.separatorChar);
+            } else {
+                first = false;
+            }
+
+            sb.append("..");
+        }
+
+        first = true;
+        for (int i=commonDirs; i<pathToRelativize.size(); i++) {
+            if (first) {
+                if (sb.length() != 0) {
+                    sb.append(File.separatorChar);
+                }
+                first = false;
+            } else {
+                sb.append(File.separatorChar);
+            }
+            
+            sb.append(pathToRelativize.get(i));
+        }
+
+        if (sb.length() == 0) {
+            return ".";
+        }
+
+        return sb.toString();
+    }
+
+    private static ArrayList<String> getPathComponents(File file) {
+        ArrayList<String> path = new ArrayList<String>();
+
+        while (file != null) {
+            File parentFile = file.getParentFile();
+
+            if (parentFile == null) {
+                path.add(0, file.getPath());
+            } else {
+                path.add(0, file.getName());
+            }
+
+            file = parentFile;
+        }
+
+        return path;
+    }
+}