auto import from //depot/cupcake/@135843
diff --git a/tools/idegen/src/Configuration.java b/tools/idegen/src/Configuration.java
new file mode 100644
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--- /dev/null
+++ b/tools/idegen/src/Configuration.java
@@ -0,0 +1,263 @@
+/*
+ * Copyright (C) 2008 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.
+ */
+
+import java.io.File;
+import java.io.IOException;
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.SortedSet;
+import java.util.regex.Pattern;
+
+/**
+ * Immutable representation of an IDE configuration. Assumes that the current
+ * directory is the project's root directory.
+ */
+public class Configuration {
+
+    /** Java source tree roots. */
+    public final SortedSet<File> sourceRoots;
+
+    /** Found .jar files (that weren't excluded). */
+    public final List<File> jarFiles;
+
+    /** Excluded directories which may or may not be under a source root. */
+    public final SortedSet<File> excludedDirs;
+
+    /** The root directory for this tool. */
+    public final File toolDirectory;
+
+    /** File name used for excluded path files. */
+    private static final String EXCLUDED_PATHS = "excluded-paths";
+
+    /**
+     * Constructs a Configuration by traversing the directory tree, looking
+     * for .java and .jar files and identifying source roots.
+     */
+    public Configuration() throws IOException {
+        this.toolDirectory = new File("development/tools/idegen");
+        if (!toolDirectory.isDirectory()) {
+            // The wrapper script should have already verified this.
+            throw new AssertionError("Not in root directory.");
+        }
+
+        Stopwatch stopwatch = new Stopwatch();
+
+        Excludes excludes = readExcludes();
+
+        stopwatch.reset("Read excludes");
+
+        List<File> jarFiles = new ArrayList<File>(500);
+        SortedSet<File> excludedDirs = new TreeSet<File>();
+        SortedSet<File> sourceRoots = new TreeSet<File>();
+
+        traverse(new File("."), sourceRoots, jarFiles, excludedDirs, excludes);
+
+        stopwatch.reset("Traversed tree");
+
+        Log.debug(sourceRoots.size() + " source roots");
+        Log.debug(jarFiles.size() + " jar files");
+        Log.debug(excludedDirs.size() + " excluded dirs");
+
+        this.sourceRoots = Collections.unmodifiableSortedSet(sourceRoots);
+        this.jarFiles = Collections.unmodifiableList(jarFiles);
+        this.excludedDirs = Collections.unmodifiableSortedSet(excludedDirs);
+    }
+
+    /**
+     * Reads excluded path files.
+     */
+    private Excludes readExcludes() throws IOException {
+        List<Pattern> patterns = new ArrayList<Pattern>();
+
+        File globalExcludes = new File(toolDirectory, EXCLUDED_PATHS);
+        parseFile(globalExcludes, patterns);
+
+        // Look for Google-specific excludes.
+        // TODO: Traverse all vendor-specific directories.
+        File googleExcludes = new File("./vendor/google/" + EXCLUDED_PATHS);
+        if (googleExcludes.exists()) {
+            parseFile(googleExcludes, patterns);
+        }
+
+        // Look for user-specific excluded-paths file in current directory.
+        File localExcludes = new File(EXCLUDED_PATHS);
+        if (localExcludes.exists()) {
+            parseFile(localExcludes, patterns);
+        }
+
+        return new Excludes(patterns);
+    }
+
+    /**
+     * Recursively finds .java source roots, .jar files, and excluded
+     * directories.
+     */
+    private static void traverse(File directory, Set<File> sourceRoots,
+            Collection<File> jarFiles, Collection<File> excludedDirs,
+            Excludes excludes) throws IOException {
+        /*
+         * Note it would be faster to stop traversing a source root as soon as
+         * we encounter the first .java file, but it appears we have nested
+         * source roots in our generated source directory (specifically,
+         * R.java files and aidl .java files don't share the same source
+         * root).
+         */
+
+        boolean firstJavaFile = true;
+        for (File file : directory.listFiles()) {
+            // Trim preceding "./" from path.
+            String path = file.getPath().substring(2);
+
+            // Keep track of source roots for .java files.
+            if (path.endsWith(".java")) {
+                if (firstJavaFile) {
+                    // Only parse one .java file per directory.
+                    firstJavaFile = false;
+
+                    File sourceRoot = rootOf(file);
+                    if (sourceRoot != null) {
+                        sourceRoots.add(sourceRoot);
+                    }
+                }
+                                
+                continue;
+            }
+
+            // Keep track of .jar files.
+            if (path.endsWith(".jar")) {
+                if (!excludes.exclude(path)) {
+                    jarFiles.add(file);
+                } else {
+                    Log.debug("Skipped: " + file);
+                }
+
+                continue;
+            }
+
+            // Traverse nested directories.
+            if (file.isDirectory()) {
+                if (excludes.exclude(path)) {
+                    // Don't recurse into excluded dirs.
+                    Log.debug("Excluding: " + path);
+                    excludedDirs.add(file);
+                } else {
+                    traverse(file, sourceRoots, jarFiles, excludedDirs,
+                            excludes);
+                }
+            }
+        }
+    }
+
+    /**
+     * Determines the source root for a given .java file. Returns null
+     * if the file doesn't have a package or if the file isn't in the
+     * correct directory structure.
+     */
+    private static File rootOf(File javaFile) throws IOException {
+        String packageName = parsePackageName(javaFile);
+        if (packageName == null) {
+            // No package.
+            // TODO: Treat this as a source root?
+            return null;
+        }
+
+        String packagePath = packageName.replace('.', File.separatorChar);
+        File parent = javaFile.getParentFile();
+        String parentPath = parent.getPath();
+        if (!parentPath.endsWith(packagePath)) {
+            // Bad dir structure.
+            return null;
+        }
+
+        return new File(parentPath.substring(
+                0, parentPath.length() - packagePath.length()));
+    }
+
+    /**
+     * Reads a Java file and parses out the package name. Returns null if none
+     * found.
+     */
+    private static String parsePackageName(File file) throws IOException {
+        BufferedReader in = new BufferedReader(new FileReader(file));
+        try {
+            String line;
+            while ((line = in.readLine()) != null) {
+                String trimmed = line.trim();
+                if (trimmed.startsWith("package")) {
+                    // TODO: Make this more robust.
+                    // Assumes there's only once space after "package" and the
+                    // line ends in a ";".
+                    return trimmed.substring(8, trimmed.length() - 1);
+                }
+            }
+
+            return null;
+        } finally {
+            in.close();
+        }
+    }
+
+    /**
+     * Picks out excluded directories that are under source roots.
+     */
+    public SortedSet<File> excludesUnderSourceRoots() {
+        // TODO: Refactor this to share the similar logic in
+        // Eclipse.constructExcluding().
+        SortedSet<File> picked = new TreeSet<File>();
+        for (File sourceRoot : sourceRoots) {
+            String sourcePath = sourceRoot.getPath() + "/";
+            SortedSet<File> tailSet = excludedDirs.tailSet(sourceRoot);
+            for (File file : tailSet) {
+                if (file.getPath().startsWith(sourcePath)) {
+                    picked.add(file);
+                } else {
+                    break;
+                }
+            }
+        }
+        return picked;
+    }
+
+    /**
+     * Reads a list of regular expressions from a file, one per line, and adds
+     * the compiled patterns to the given collection. Ignores lines starting
+     * with '#'.
+     *
+     * @param file containing regular expressions, one per line
+     * @param patterns collection to add compiled patterns from file to
+     */
+    public static void parseFile(File file, Collection<Pattern> patterns)
+            throws IOException {
+        BufferedReader in = new BufferedReader(new FileReader(file));
+        try {
+            String line;
+            while ((line = in.readLine()) != null) {
+                String trimmed = line.trim();
+                if (trimmed.length() > 0 && !trimmed.startsWith("#")) {
+                    patterns.add(Pattern.compile(trimmed));
+                }
+            }
+        } finally {
+            in.close();
+        }
+    }
+}