AAPT2: Fail compiling when private symbols are referenced

Also moved some XML specific stuff into its own directory,
and refactored ReferenceLinker a bit.

Change-Id: I912247a82023c1bbf72dc191fbdaf62858cbec0c
diff --git a/tools/aapt2/xml/XmlUtil_test.cpp b/tools/aapt2/xml/XmlUtil_test.cpp
new file mode 100644
index 0000000..7796b3e
--- /dev/null
+++ b/tools/aapt2/xml/XmlUtil_test.cpp
@@ -0,0 +1,54 @@
+/*
+ * 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.
+ */
+
+#include "test/Common.h"
+#include "xml/XmlUtil.h"
+
+#include <gtest/gtest.h>
+
+namespace aapt {
+
+TEST(XmlUtilTest, ExtractPackageFromNamespace) {
+    AAPT_ASSERT_FALSE(xml::extractPackageFromNamespace(u"com.android"));
+    AAPT_ASSERT_FALSE(xml::extractPackageFromNamespace(u"http://schemas.android.com/apk"));
+    AAPT_ASSERT_FALSE(xml::extractPackageFromNamespace(u"http://schemas.android.com/apk/res"));
+    AAPT_ASSERT_FALSE(xml::extractPackageFromNamespace(u"http://schemas.android.com/apk/res/"));
+    AAPT_ASSERT_FALSE(xml::extractPackageFromNamespace(
+            u"http://schemas.android.com/apk/prv/res/"));
+
+    Maybe<xml::ExtractedPackage> p =
+            xml::extractPackageFromNamespace(u"http://schemas.android.com/apk/res/a");
+    AAPT_ASSERT_TRUE(p);
+    EXPECT_EQ(std::u16string(u"a"), p.value().package);
+    EXPECT_EQ(false, p.value().privateNamespace);
+
+    p = xml::extractPackageFromNamespace(u"http://schemas.android.com/apk/prv/res/android");
+    AAPT_ASSERT_TRUE(p);
+    EXPECT_EQ(std::u16string(u"android"), p.value().package);
+    EXPECT_EQ(true, p.value().privateNamespace);
+
+    p = xml::extractPackageFromNamespace(u"http://schemas.android.com/apk/prv/res/com.test");
+    AAPT_ASSERT_TRUE(p);
+    EXPECT_EQ(std::u16string(u"com.test"), p.value().package);
+    EXPECT_EQ(true, p.value().privateNamespace);
+
+    p = xml::extractPackageFromNamespace(u"http://schemas.android.com/apk/res-auto");
+    AAPT_ASSERT_TRUE(p);
+    EXPECT_EQ(std::u16string(), p.value().package);
+    EXPECT_EQ(true, p.value().privateNamespace);
+}
+
+} // namespace aapt