AAPT2: Separate out the various steps

An early refactor. Some ideas became clearer as
development continued. Now the various phases are much
clearer and more easily reusable.

Also added a ton of tests!

Change-Id: Ic8f0a70c8222370352e63533b329c40457c0903e
diff --git a/tools/aapt2/util/Files.h b/tools/aapt2/util/Files.h
new file mode 100644
index 0000000..c58ba5d
--- /dev/null
+++ b/tools/aapt2/util/Files.h
@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef AAPT_FILES_H
+#define AAPT_FILES_H
+
+#include "Diagnostics.h"
+#include "Maybe.h"
+#include "Source.h"
+
+#include "util/StringPiece.h"
+
+#include <utils/FileMap.h>
+#include <cassert>
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace aapt {
+namespace file {
+
+#ifdef _WIN32
+constexpr const char sDirSep = '\\';
+#else
+constexpr const char sDirSep = '/';
+#endif
+
+enum class FileType {
+    kUnknown = 0,
+    kNonexistant,
+    kRegular,
+    kDirectory,
+    kCharDev,
+    kBlockDev,
+    kFifo,
+    kSymlink,
+    kSocket,
+};
+
+FileType getFileType(const StringPiece& path);
+
+/*
+ * Lists files under the directory `root`. Files are listed
+ * with just their leaf (filename) names.
+ */
+std::vector<std::string> listFiles(const StringPiece& root);
+
+/*
+ * Appends a path to `base`, separated by the directory separator.
+ */
+void appendPath(std::string* base, const StringPiece& part);
+
+/*
+ * Appends a series of paths to `base`, separated by the
+ * system directory separator.
+ */
+template <typename... Ts >
+void appendPath(std::string* base, const StringPiece& part, const Ts&... parts);
+
+/*
+ * Makes all the directories in `path`. The last element in the path
+ * is interpreted as a directory.
+ */
+bool mkdirs(const StringPiece& path);
+
+/**
+ * Returns all but the last part of the path.
+ */
+StringPiece getStem(const StringPiece& path);
+
+/**
+ * Returns the last part of the path with extension.
+ */
+StringPiece getFilename(const StringPiece& path);
+
+/**
+ * Returns the extension of the path. This is the entire string after
+ * the first '.' of the last part of the path.
+ */
+StringPiece getExtension(const StringPiece& path);
+
+/**
+ * Converts a package name (com.android.app) to a path: com/android/app
+ */
+std::string packageToPath(const StringPiece& package);
+
+/**
+ * Creates a FileMap for the file at path.
+ */
+Maybe<android::FileMap> mmapPath(const StringPiece& path, std::string* outError);
+
+/*
+ * Filter that determines which resource files/directories are
+ * processed by AAPT. Takes a pattern string supplied by the user.
+ * Pattern format is specified in the
+ * FileFilter::setPattern(const std::string&) method.
+ */
+class FileFilter {
+public:
+    FileFilter(IDiagnostics* diag) : mDiag(diag) {
+    }
+
+    /*
+     * Patterns syntax:
+     * - Delimiter is :
+     * - Entry can start with the flag ! to avoid printing a warning
+     *   about the file being ignored.
+     * - Entry can have the flag "<dir>" to match only directories
+     *   or <file> to match only files. Default is to match both.
+     * - Entry can be a simplified glob "<prefix>*" or "*<suffix>"
+     *   where prefix/suffix must have at least 1 character (so that
+     *   we don't match a '*' catch-all pattern.)
+     * - The special filenames "." and ".." are always ignored.
+     * - Otherwise the full string is matched.
+     * - match is not case-sensitive.
+     */
+    bool setPattern(const StringPiece& pattern);
+
+    /**
+     * Applies the filter, returning true for pass, false for fail.
+     */
+    bool operator()(const std::string& filename, FileType type) const;
+
+private:
+    IDiagnostics* mDiag;
+    std::vector<std::string> mPatternTokens;
+};
+
+inline void appendPath(std::string* base, const StringPiece& part) {
+    assert(base);
+    *base += sDirSep;
+    base->append(part.data(), part.size());
+}
+
+template <typename... Ts >
+void appendPath(std::string* base, const StringPiece& part, const Ts&... parts) {
+    assert(base);
+    *base += sDirSep;
+    base->append(part.data(), part.size());
+    appendPath(base, parts...);
+}
+
+} // namespace file
+} // namespace aapt
+
+#endif // AAPT_FILES_H