AAPT2: Better debugging output

Test: make aapt2_tests
Change-Id: I7778b773201381538dc1f2e376abee4eb33e44c0
diff --git a/tools/aapt2/text/Printer.h b/tools/aapt2/text/Printer.h
new file mode 100644
index 0000000..94b3c0b
--- /dev/null
+++ b/tools/aapt2/text/Printer.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2017 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_TEXT_PRINTER_H
+#define AAPT_TEXT_PRINTER_H
+
+#include "android-base/macros.h"
+#include "androidfw/StringPiece.h"
+
+#include "io/Io.h"
+
+namespace aapt {
+namespace text {
+
+// An indenting Printer that helps write formatted text to the OutputStream.
+class Printer {
+ public:
+  explicit Printer(::aapt::io::OutputStream* out) : out_(out) {
+  }
+
+  void Print(const ::android::StringPiece& str);
+  void Println(const ::android::StringPiece& str);
+  void Println();
+
+  void Indent();
+  void Undent();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(Printer);
+
+  ::aapt::io::OutputStream* out_;
+  int indent_level_ = 0;
+  bool needs_indent_ = false;
+  bool error_ = false;
+};
+
+}  // namespace text
+}  // namespace aapt
+
+#endif  // AAPT_TEXT_PRINTER_H