Add dependency support for ApkBuilder ant step.

Change-Id: I7230a2aa3df5fab8b420f1ed2f359621fbda7f5a

6 files changed, 309 insertions, 157 deletions

diff --git a/anttasks/src/com/android/ant/AaptExecTask.java b/anttasks/src/com/android/ant/AaptExecTask.java
index 4d16d1f..fc0de71 100644
--- a/anttasks/src/com/android/ant/AaptExecTask.java
+++ b/anttasks/src/com/android/ant/AaptExecTask.java
@@ -16,8 +16,6 @@
 
 package com.android.ant;
 
-import com.android.ant.DependencyGraph.InputPath;
-
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Project;
 import org.apache.tools.ant.taskdefs.ExecTask;
@@ -337,11 +335,6 @@ public final class AaptExecTask extends BaseTask {
             }
         }
 
-        // as is its AndroidManifest.xml
-        if (mManifest != null) {
-            paths.add(new File(mManifest));
-        }
-
         // and if libraries exist, their res folders folders too.
         if (libResRef instanceof Path) {
             for (String path : ((Path)libResRef).list()) {
@@ -349,20 +342,17 @@ public final class AaptExecTask extends BaseTask {
             }
         }
 
-        // If we're here to generate a .ap_ file we need to use assets as an input path as well.
-        if (!generateRClass) {
-            File assetsDir = new File(mAssets);
-            if (mAssets != null && assetsDir.isDirectory()) {
-                paths.add(assetsDir);
-            }
-        }
-
         // Now we figure out what we need to do
         if (generateRClass) {
             // in this case we only want to run aapt if an XML file was touched, or if any
             // file is added/removed
             List<InputPath> inputPaths = getInputPaths(paths, Collections.singleton("xml"));
 
+            // let's not forget the manifest as an input path (with no extension restrictions).
+            if (mManifest != null) {
+                inputPaths.add(new InputPath(new File(mManifest)));
+            }
+
             // Check to see if our dependencies have changed. If not, then skip
             if (initDependencies(mRFolder + File.separator + "R.java.d", inputPaths)
                               && dependenciesHaveChanged() == false) {
@@ -372,10 +362,23 @@ public final class AaptExecTask extends BaseTask {
                 System.out.println("Generating resource IDs...");
             }
         } else {
-            // in this case we want to run aapt if any file updated/removed/added in any of the
-            // input path
+            // in this case we want to run aapt if any file was updated/removed/added in any of the
+            // input paths
             List<InputPath> inputPaths = getInputPaths(paths, null /*extensionsToCheck*/);
 
+            // let's not forget the manifest as an input path.
+            if (mManifest != null) {
+                inputPaths.add(new InputPath(new File(mManifest)));
+            }
+
+            // If we're here to generate a .ap_ file we need to use assets as an input path as well.
+            if (mAssets != null) {
+                File assetsDir = new File(mAssets);
+                if (assetsDir.isDirectory()) {
+                    inputPaths.add(new InputPath(assetsDir));
+                }
+            }
+
             // Find our dependency file. It should have the same name as our target .ap_ but
             // with a .d extension
             String dependencyFilePath = mApkFolder + File.separator + mApkName;
diff --git a/anttasks/src/com/android/ant/ApkBuilderTask.java b/anttasks/src/com/android/ant/ApkBuilderTask.java
index 3f8dec1..88bd59c 100644
--- a/anttasks/src/com/android/ant/ApkBuilderTask.java
+++ b/anttasks/src/com/android/ant/ApkBuilderTask.java
@@ -20,17 +20,18 @@ import com.android.sdklib.build.ApkBuilder;
 import com.android.sdklib.build.ApkCreationException;
 import com.android.sdklib.build.DuplicateFileException;
 import com.android.sdklib.build.SealedApkException;
+import com.android.sdklib.build.ApkBuilder.FileEntry;
 
 import org.apache.tools.ant.BuildException;
-import org.apache.tools.ant.Task;
 import org.apache.tools.ant.types.Path;
 
 import java.io.File;
 import java.io.FilenameFilter;
 import java.util.ArrayList;
+import java.util.List;
 import java.util.regex.Pattern;
 
-public class ApkBuilderTask extends Task {
+public class ApkBuilderTask extends BaseTask {
 
     private final static Pattern PATTERN_JAR_EXT = Pattern.compile("^.+\\.jar$",
             Pattern.CASE_INSENSITIVE);
@@ -42,17 +43,30 @@ public class ApkBuilderTask extends Task {
     private boolean mDebugPackaging = false;
     private boolean mDebugSigning = false;
     private boolean mHasCode = true;
-    private String mAbiFilter = null;
 
     private Path mDexPath;
 
     private final ArrayList<Path> mZipList = new ArrayList<Path>();
-    private final ArrayList<Path> mFileList = new ArrayList<Path>();
     private final ArrayList<Path> mSourceList = new ArrayList<Path>();
     private final ArrayList<Path> mJarfolderList = new ArrayList<Path>();
     private final ArrayList<Path> mJarfileList = new ArrayList<Path>();
     private final ArrayList<Path> mNativeList = new ArrayList<Path>();
 
+    private static class SourceFolderInputPath extends InputPath {
+        public SourceFolderInputPath(File file) {
+            super(file);
+        }
+
+        @Override
+        public boolean ignores(File file) {
+            if (file.isDirectory()) {
+                return !ApkBuilder.checkFolderForPackaging(file.getName());
+            } else {
+                return !ApkBuilder.checkFileForPackaging(file.getName());
+            }
+        }
+    }
+
     /**
      * Sets the value of the "outfolder" attribute.
      * @param outFolder the value.
@@ -113,21 +127,6 @@ public class ApkBuilderTask extends Task {
     }
 
     /**
-     * Sets an ABI filter. If non <code>null</code>, then only native libraries matching the given
-     * ABI will be packaged with the APK.
-     * @param abiFilter the ABI to accept (and reject all other). If null or empty string, no ABIs
-     * are rejected. This must be a single ABI name as defined by the Android NDK. For a list
-     * of valid ABI names, see $NDK/docs/CPU-ARCH-ABIS.TXT
-     */
-    public void setAbifilter(String abiFilter) {
-        if (abiFilter != null && abiFilter.length() > 0) {
-            mAbiFilter = abiFilter.trim();
-        } else {
-            mAbiFilter = null;
-        }
-    }
-
-    /**
      * Sets the hascode attribute. Default is true.
      * If set to false, then <dex> and <sourcefolder> nodes are ignored and not processed.
      * @param hasCode the value of the attribute.
@@ -159,17 +158,6 @@ public class ApkBuilderTask extends Task {
     }
 
     /**
-     * Returns an object representing a nested <var>file</var> element.
-     */
-    public Object createFile() {
-        System.out.println("WARNING: Using deprecated <file> inner element in ApkBuilderTask." +
-        "Use <dex path=...> instead.");
-        Path path = new Path(getProject());
-        mFileList.add(path);
-        return path;
-    }
-
-    /**
      * Returns an object representing a nested <var>sourcefolder</var> element.
      */
     public Object createSourcefolder() {
@@ -236,48 +224,43 @@ public class ApkBuilderTask extends Task {
         }
 
         try {
-            if (mDebugSigning) {
-                System.out.println(String.format(
-                        "Creating %s and signing it with a debug key...", outputFile.getName()));
-            } else {
-                System.out.println(String.format(
-                        "Creating %s for release...", outputFile.getName()));
-            }
+            // build list of input files/folders to compute dependencies
+            // add the content of the zip files.
+            List<InputPath> inputPaths = new ArrayList<InputPath>();
 
-            ApkBuilder apkBuilder = new ApkBuilder(
-                    outputFile,
-                    new File(mOutFolder, mResourceFile),
-                    dexFile,
-                    mDebugSigning ? ApkBuilder.getDebugKeystore() : null,
-                    mVerbose ? System.out : null);
-            apkBuilder.setDebugMode(mDebugPackaging);
+            // resource file
+            InputPath resourceInputPath = new InputPath(new File(mOutFolder, mResourceFile));
+            inputPaths.add(resourceInputPath);
 
+            // dex file
+            inputPaths.add(new InputPath(dexFile));
 
-            // add the content of the zip files.
+            // zip input files
+            List<File> zipFiles = new ArrayList<File>();
             for (Path pathList : mZipList) {
                 for (String path : pathList.list()) {
-                    apkBuilder.addZipFile(new File(path));
+                    File f =  new File(path);
+                    zipFiles.add(f);
+                    inputPaths.add(new InputPath(f));
                 }
             }
 
-            // add the files that go to the root of the archive (this is deprecated)
-            for (Path pathList : mFileList) {
-                for (String path : pathList.list()) {
-                    File f = new File(path);
-                    apkBuilder.addFile(f, f.getName());
-                }
-            }
-
-            // now go through the list of file to directly add the to the list.
+            // now go through the list of source folders used to add non java files.
+            List<File> sourceFolderList = new ArrayList<File>();
             if (mHasCode) {
                 for (Path pathList : mSourceList) {
                     for (String path : pathList.list()) {
-                        apkBuilder.addSourceFolder(new File(path));
+                        File f =  new File(path);
+                        sourceFolderList.add(f);
+                        // because this is a source folder but we only care about non
+                        // java files.
+                        inputPaths.add(new SourceFolderInputPath(f));
                     }
                 }
             }
 
             // now go through the list of jar folders.
+            List<File> jarFileList = new ArrayList<File>();
             for (Path pathList : mJarfolderList) {
                 for (String path : pathList.list()) {
                     // it's ok if top level folders are missing
@@ -290,7 +273,9 @@ public class ApkBuilderTask extends Task {
                         });
 
                         for (String filename : filenames) {
-                            apkBuilder.addResourcesFromJar(new File(folder, filename));
+                            File f = new File(folder, filename);
+                            jarFileList.add(f);
+                            inputPaths.add(new InputPath(f));
                         }
                     }
                 }
@@ -299,25 +284,101 @@ public class ApkBuilderTask extends Task {
             // now go through the list of jar files.
             for (Path pathList : mJarfileList) {
                 for (String path : pathList.list()) {
-                    apkBuilder.addResourcesFromJar(new File(path));
+                    File f = new File(path);
+                    jarFileList.add(f);
+                    inputPaths.add(new InputPath(f));
                 }
             }
 
             // now the native lib folder.
+            List<FileEntry> nativeFileList = new ArrayList<FileEntry>();
             for (Path pathList : mNativeList) {
                 for (String path : pathList.list()) {
                     // it's ok if top level folders are missing
                     File folder = new File(path);
                     if (folder.isDirectory()) {
-                        apkBuilder.addNativeLibraries(folder, mAbiFilter);
+                        List<FileEntry> entries = ApkBuilder.getNativeFiles(folder,
+                                mDebugPackaging);
+                        // add the list to the list of native files and then create an input
+                        // path for each file
+                        nativeFileList.addAll(entries);
+
+                        for (FileEntry entry : entries) {
+                            inputPaths.add(new InputPath(entry.mFile));
+                        }
                     }
                 }
             }
 
+            // Finally figure out the path to the dependency file.
+            String depFile = outputFile.getAbsolutePath() + ".d";
+
+            // check dependencies
+            if (initDependencies(depFile, inputPaths) && dependenciesHaveChanged() == false) {
+                System.out.println(
+                        "No changes. No need to create apk.");
+                return;
+            }
+
+            if (mDebugSigning) {
+                System.out.println(String.format(
+                        "Creating %s and signing it with a debug key...", outputFile.getName()));
+            } else {
+                System.out.println(String.format(
+                        "Creating %s for release...", outputFile.getName()));
+            }
+
+            ApkBuilder apkBuilder = new ApkBuilder(
+                    outputFile,
+                    resourceInputPath.getFile(),
+                    dexFile,
+                    mDebugSigning ? ApkBuilder.getDebugKeystore() : null,
+                    mVerbose ? System.out : null);
+            apkBuilder.setDebugMode(mDebugPackaging);
+
+
+            // add the content of the zip files.
+            for (File f : zipFiles) {
+                apkBuilder.addZipFile(f);
+            }
+
+            // now go through the list of file to directly add the to the list.
+            for (File f : sourceFolderList) {
+                apkBuilder.addSourceFolder(f);
+            }
+
+            // now go through the list of jar folders.
+            for (Path pathList : mJarfolderList) {
+                for (String path : pathList.list()) {
+                    // it's ok if top level folders are missing
+                    File folder = new File(path);
+                    if (folder.isDirectory()) {
+                        String[] filenames = folder.list(new FilenameFilter() {
+                            public boolean accept(File dir, String name) {
+                                return PATTERN_JAR_EXT.matcher(name).matches();
+                            }
+                        });
+
+                        for (String filename : filenames) {
+                            apkBuilder.addResourcesFromJar(new File(folder, filename));
+                        }
+                    }
+                }
+            }
+
+            // now go through the list of jar files.
+            for (File f : jarFileList) {
+                apkBuilder.addResourcesFromJar(f);
+            }
+
+            // and finally the native files
+            apkBuilder.addNativeLibraries(nativeFileList);
 
             // close the archive
             apkBuilder.sealApk();
 
+            // and generate the dependency file
+            generateDependencyFile(depFile, inputPaths, outputFile.getAbsolutePath());
         } catch (DuplicateFileException e) {
             System.err.println(String.format(
                     "Found duplicate file for APK: %1$s\nOrigin 1: %2$s\nOrigin 2: %3$s",
@@ -331,4 +392,9 @@ public class ApkBuilderTask extends Task {
             throw new BuildException(e);
         }
     }
+
+    @Override
+    protected String getExecTaskName() {
+        return "apkbuilder";
+    }
 }
diff --git a/anttasks/src/com/android/ant/BaseTask.java b/anttasks/src/com/android/ant/BaseTask.java
index 8a82fe9..b1c37b8 100644
--- a/anttasks/src/com/android/ant/BaseTask.java
+++ b/anttasks/src/com/android/ant/BaseTask.java
@@ -16,8 +16,6 @@
 
 package com.android.ant;
 
-import com.android.ant.DependencyGraph.InputPath;
-
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Task;
 
@@ -113,11 +111,11 @@ public abstract class BaseTask extends Task {
     }
 
     protected void generateDependencyFile(String depFilePath,
-            List<File> inputs, String outputFile) {
-        File file = new File(depFilePath);
+            List<InputPath> inputs, String outputFile) {
+        File depFile = new File(depFilePath);
 
         try {
-            PrintStream ps = new PrintStream(file);
+            PrintStream ps = new PrintStream(depFile);
 
             // write the output file.
             ps.print(outputFile);
@@ -126,11 +124,12 @@ public abstract class BaseTask extends Task {
             //write the input files
             int count = inputs.size();
             for (int i = 0 ; i < count ; i++) {
-                File input = inputs.get(i);
-                if (input.isDirectory()) {
-                    writeContent(ps, input);
+                InputPath input = inputs.get(i);
+                File file = input.getFile();
+                if (file.isDirectory()) {
+                    writeContent(ps, file, input);
                 } else {
-                    ps.print(input.getAbsolutePath());
+                    ps.print(file.getAbsolutePath());
                     ps.println(" \\");
                 }
             }
@@ -141,13 +140,17 @@ public abstract class BaseTask extends Task {
         }
     }
 
-    private void writeContent(PrintStream ps, File input) {
-        File[] files = input.listFiles();
+    private void writeContent(PrintStream ps, File file, InputPath input) {
+        if (input.ignores(file)) {
+            return;
+        }
+
+        File[] files = file.listFiles();
         if (files != null) {
             for (File f : files) {
                 if (f.isDirectory()) {
-                    writeContent(ps, f);
-                } else {
+                    writeContent(ps, f, input);
+                } else if (input.ignores(f) == false) {
                     ps.print(f.getAbsolutePath());
                     ps.println(" \\");
                 }
diff --git a/anttasks/src/com/android/ant/DependencyGraph.java b/anttasks/src/com/android/ant/DependencyGraph.java
index b51965d..9c5e8ad 100644
--- a/anttasks/src/com/android/ant/DependencyGraph.java
+++ b/anttasks/src/com/android/ant/DependencyGraph.java
@@ -47,22 +47,6 @@ public class DependencyGraph {
     private long mDepFileLastModified;
     private final List<InputPath> mNewInputs;
 
-    public static class InputPath {
-        File mFile;
-        /**
-         * A set of extensions. Only files with an extension in this set will
-         * be considered for a modification check. All deleted/created files will still be
-         * checked. If this is null, all files will be checked for modification date
-         */
-        Set<String> mExtensionsToCheck;
-
-        public InputPath(File file, Set<String> extensions) {
-            mFile = file;
-            mExtensionsToCheck = extensions;
-        }
-    }
-
-
     public DependencyGraph(String dependencyFilePath, List<InputPath> newInputPaths) {
         mNewInputs = newInputPaths;
         parseDependencyFile(dependencyFilePath);
@@ -225,7 +209,7 @@ public class DependencyGraph {
      * This should be followed by a call to {@link #checkPrereqFiles(long)} which
      * will process the remaining files in the prereq list.
      *
-     * If a change is found, this will return immediatly with either
+     * If a change is found, this will return immediately with either
      * {@link DependencyStatus#NEW_FILE} or {@link DependencyStatus#UPDATED_FILE}.
      *
      * @param oldestTarget the timestamp of the oldest output file to compare against.
@@ -236,15 +220,14 @@ public class DependencyGraph {
     private DependencyStatus checkInputs(long oldestTarget) {
         if (mNewInputs != null) {
             for (InputPath input : mNewInputs) {
-                if (input.mFile.isDirectory()) {
-                    DependencyStatus status = checkInputFolder(input.mFile,
-                            input.mExtensionsToCheck, oldestTarget);
+                File file = input.getFile();
+                if (file.isDirectory()) {
+                    DependencyStatus status = checkInputFolder(file, input, oldestTarget);
                     if (status != DependencyStatus.NONE) {
                         return status;
                     }
-                } else if (input.mFile.isFile()) {
-                    DependencyStatus status = checkInputFile(input.mFile,
-                            input.mExtensionsToCheck, oldestTarget);
+                } else if (file.isFile()) {
+                    DependencyStatus status = checkInputFile(file, input, oldestTarget);
                     if (status != DependencyStatus.NONE) {
                         return status;
                     }
@@ -260,31 +243,33 @@ public class DependencyGraph {
      * Check all the files in the tree under root and check to see if the files are
      * listed under the dependencies, or if they have been modified. Recurses into subdirs.
      *
-     * @param rootFolder the folder to search through.
-     * @param extensionsToCheck a set of extensions. Only files with an extension in this set will
-     *        be considered for a modification check. All deleted/created files will still be
-     *        checked. If this is null, all files will be checked for modification date
+     * @param folder the folder to search through.
+     * @param inputFolder the root level inputFolder
      * @param oldestTarget the time stamp of the oldest output file to compare against.
      *
      * @return the status of the file in the folder.
      */
-    private DependencyStatus checkInputFolder(File rootFolder, Set<String> extensionsToCheck,
+    private DependencyStatus checkInputFolder(File folder, InputPath inputFolder,
             long oldestTarget) {
-        File[] files = rootFolder.listFiles();
+        if (inputFolder.ignores(folder)) {
+            return DependencyStatus.NONE;
+        }
+
+        File[] files = folder.listFiles();
         if (files == null) {
-            System.err.println("ERROR " + rootFolder.toString() + " is not a dir or can't be read");
+            System.err.println("ERROR " + folder.toString() + " is not a dir or can't be read");
             return DependencyStatus.ERROR;
         }
         // Loop through files in this folder
         for (File file : files) {
             // If this is a directory, recurse into it
             if (file.isDirectory()) {
-                DependencyStatus status = checkInputFolder(file, extensionsToCheck, oldestTarget);
+                DependencyStatus status = checkInputFolder(file, inputFolder, oldestTarget);
                 if (status != DependencyStatus.NONE) {
                     return status;
                 }
             } else if (file.isFile()) {
-                DependencyStatus status = checkInputFile(file, extensionsToCheck, oldestTarget);
+                DependencyStatus status = checkInputFile(file, inputFolder, oldestTarget);
                 if (status != DependencyStatus.NONE) {
                     return status;
                 }
@@ -294,8 +279,12 @@ public class DependencyGraph {
         return DependencyStatus.NONE;
     }
 
-    private DependencyStatus checkInputFile(File file, Set<String> extensionsToCheck,
+    private DependencyStatus checkInputFile(File file, InputPath inputFolder,
             long oldestTarget) {
+        if (inputFolder.ignores(file)) {
+            return DependencyStatus.NONE;
+        }
+
         // if it's a file, remove it from the list of prereqs.
         // This way if files in this folder don't trigger a build we'll have less
         // files to go through manually
@@ -303,9 +292,9 @@ public class DependencyGraph {
             // turns out this is a new file!
             return DependencyStatus.NEW_FILE;
         } else {
-            // check the time stamp on this file if it's a file we care about based on the
-            // list of extensions to check.
-            if (extensionsToCheck == null || extensionsToCheck.contains(getExtension(file))) {
+            // check the time stamp on this file if it's a file we care about based what the
+            // input folder decides.
+            if (inputFolder.checksForModification(file)) {
                 if (file.lastModified() > oldestTarget) {
                     return DependencyStatus.UPDATED_FILE;
                 }
@@ -324,31 +313,45 @@ public class DependencyGraph {
      * @return the status of the files
      */
     private DependencyStatus checkPrereqFiles(long oldestTarget) {
+        // TODO: Optimize for the case of a specific file as inputPath.
+        //       We should have a map of filepath to inputpath to quickly search through them?
+
         // Loop through our prereq files and make sure they still exist
         for (File prereq : mPrereqs) {
             if (prereq.exists() == false) {
                 return DependencyStatus.MISSING_FILE;
             }
 
-            // check the time stamp on this file if it's a file we care about based on the
-            // list of extensions to check.
-            // to get the extensions to check, we look in which input folder this file is.
-            Set<String> extensionsToCheck = null;
+            // check the time stamp on this file if it's a file we care about.
+            // To know if we care about the file we have to find the matching input.
             if (mNewInputs != null) {
                 String filePath = prereq.getAbsolutePath();
                 for (InputPath input : mNewInputs) {
-                    if (filePath.startsWith(input.mFile.getAbsolutePath())) {
-                        extensionsToCheck = input.mExtensionsToCheck;
-                        break;
+                    File inputFile = input.getFile();
+                    // if the input path is a directory, check if the prereq file is in it,
+                    // otherwise check if the prereq file match exactly the input path.
+                    if (inputFile.isDirectory()) {
+                        if (filePath.startsWith(inputFile.getAbsolutePath())) {
+                            // ok file is inside a directory type input folder.
+                            // check if we need to check this type of file, and if yes, check it.
+                            if (input.checksForModification(prereq)) {
+                                if (prereq.lastModified() > oldestTarget) {
+                                    return DependencyStatus.UPDATED_FILE;
+                                }
+                            }
+                        }
+                    } else {
+                        // this is a file input path, we must check if the match is exact.
+                        if (prereq.equals(inputFile)) {
+                            if (input.checksForModification(prereq)) {
+                                if (prereq.lastModified() > oldestTarget) {
+                                    return DependencyStatus.UPDATED_FILE;
+                                }
+                            }
+                        }
                     }
                 }
             }
-
-            if (extensionsToCheck == null || extensionsToCheck.contains(getExtension(prereq))) {
-                if (prereq.lastModified() > oldestTarget) {
-                    return DependencyStatus.UPDATED_FILE;
-                }
-            }
         }
 
         // If we get this far, then all our prereq are okay
@@ -415,19 +418,4 @@ public class DependencyGraph {
         }
         return null;
     }
-
-    /**
-      *  Gets the extension (if present) on a file by looking at the filename
-      *  @param file the file to get the extension of
-      *  @return the extension if present, or the empty string if the filename doesn't have
-      *          and extension.
-      */
-    private static String getExtension(File file) {
-        String filename = file.getName();
-        if (filename.lastIndexOf('.') == -1) {
-            return "";
-        }
-        // Don't include the leading '.' in the extension
-        return filename.substring(filename.lastIndexOf('.') + 1);
-    }
 }
diff --git a/anttasks/src/com/android/ant/DexExecTask.java b/anttasks/src/com/android/ant/DexExecTask.java
index e4296b2..4016417 100644
--- a/anttasks/src/com/android/ant/DexExecTask.java
+++ b/anttasks/src/com/android/ant/DexExecTask.java
@@ -16,8 +16,6 @@
 
 package com.android.ant;
 
-import com.android.ant.DependencyGraph.InputPath;
-
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.taskdefs.ExecTask;
 import org.apache.tools.ant.types.FileSet;
@@ -163,7 +161,7 @@ public class DexExecTask extends BaseTask {
         task.createArg().setValue(mOutput);
 
 
-        for (File f :paths) {
+        for (File f : paths) {
             task.createArg().setValue(f.getAbsolutePath());
         }
 
@@ -171,7 +169,7 @@ public class DexExecTask extends BaseTask {
         task.execute();
 
         // generate the dependency file.
-        generateDependencyFile(depFile, paths, mOutput);
+        generateDependencyFile(depFile, inputPaths, mOutput);
     }
 
     @Override
diff --git a/anttasks/src/com/android/ant/InputPath.java b/anttasks/src/com/android/ant/InputPath.java
new file mode 100644
index 0000000..3327385
--- /dev/null
+++ b/anttasks/src/com/android/ant/InputPath.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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 com.android.ant;
+
+import java.io.File;
+import java.util.Set;
+
+public class InputPath {
+
+    private final File mFile;
+    /**
+     * A set of extensions. Only files with an extension in this set will
+     * be considered for a modification check. All deleted/created files will still be
+     * checked.
+     */
+    private final Set<String> mTouchedExtensions;
+
+    public InputPath(File file) {
+        this(file, null);
+    }
+
+    public InputPath(File file, Set<String> extensionsToCheck) {
+        mFile = file;
+        mTouchedExtensions = extensionsToCheck;
+    }
+
+    public File getFile() {
+        return mFile;
+    }
+
+    /**
+     * Returns whether this input path (likely actually a folder) must check this files for
+     * modification (all files are checked for add/delete).
+     *
+     * This is configured by constructing the {@link InputPath} with additional restriction
+     * parameters such as specific extensions.
+     * @param file the file to check
+     * @return true if the file must be checked for modification.
+     */
+    public boolean checksForModification(File file) {
+        if (ignores(file)) {
+            return false;
+        }
+
+        if (mTouchedExtensions != null &&
+                mTouchedExtensions.contains(getExtension(file)) == false) {
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Returns whether the InputPath ignores a given file or folder. If it is ignored then
+     * the file (or folder) is not checked for any event (modification/add/delete).
+     * If it's a folder, then it and its content are completely ignored.
+     * @param file the file or folder to check
+     * @return true if the file or folder are ignored.
+     */
+    public boolean ignores(File file) {
+        return false;
+    }
+
+    /**
+     *  Gets the extension (if present) on a file by looking at the filename
+     *  @param file the file to get the extension of
+     *  @return the extension if present, or the empty string if the filename doesn't have
+     *          and extension.
+     */
+   protected static String getExtension(File file) {
+       String filename = file.getName();
+       int index = filename.lastIndexOf('.');
+       if (index == -1) {
+           return "";
+       }
+       // Don't include the leading '.' in the extension
+       return filename.substring(index + 1);
+   }
+
+}