AAPT2: Change XmlDom to exclude Namespace as a node

In preparation for exporting an XML proto format for UAM to consume,
this change brings the XML DOM API more in line with other APIs that
do not make the Namespace a separate node.

Treating Namespace declarations as just properties of an Element
node makes the implementation of algorithms much simpler, as
the constraints that Namespace nodes have only one child
are now built in and traversing to find Element nodes
is much simpler.

Also made a bunch of quality of life improvements, like formatting and
comment style.

Test: make aapt2_tests
Change-Id: Ib97ff1c4252b7907e2cc1f13a448dc4ca3b809a4
diff --git a/tools/aapt2/link/ManifestFixer_test.cpp b/tools/aapt2/link/ManifestFixer_test.cpp
index 80edb35..da7f410 100644
--- a/tools/aapt2/link/ManifestFixer_test.cpp
+++ b/tools/aapt2/link/ManifestFixer_test.cpp
@@ -122,7 +122,7 @@
   xml::Element* el;
   xml::Attribute* attr;
 
-  el = xml::FindRootElement(doc.get());
+  el = doc->root.get();
   ASSERT_NE(nullptr, el);
   el = el->FindChild({}, "uses-sdk");
   ASSERT_NE(nullptr, el);
@@ -141,7 +141,7 @@
                           options);
   ASSERT_NE(nullptr, doc);
 
-  el = xml::FindRootElement(doc.get());
+  el = doc->root.get();
   ASSERT_NE(nullptr, el);
   el = el->FindChild({}, "uses-sdk");
   ASSERT_NE(nullptr, el);
@@ -160,7 +160,7 @@
                           options);
   ASSERT_NE(nullptr, doc);
 
-  el = xml::FindRootElement(doc.get());
+  el = doc->root.get();
   ASSERT_NE(nullptr, el);
   el = el->FindChild({}, "uses-sdk");
   ASSERT_NE(nullptr, el);
@@ -177,7 +177,7 @@
                           options);
   ASSERT_NE(nullptr, doc);
 
-  el = xml::FindRootElement(doc.get());
+  el = doc->root.get();
   ASSERT_NE(nullptr, el);
   el = el->FindChild({}, "uses-sdk");
   ASSERT_NE(nullptr, el);
@@ -199,7 +199,7 @@
                                                             options);
   ASSERT_NE(nullptr, doc);
 
-  xml::Element* manifest_el = xml::FindRootElement(doc.get());
+  xml::Element* manifest_el = doc->root.get();
   ASSERT_NE(nullptr, manifest_el);
   ASSERT_EQ("manifest", manifest_el->name);
 
@@ -248,7 +248,7 @@
                                                             options);
   ASSERT_NE(nullptr, doc);
 
-  xml::Element* manifestEl = xml::FindRootElement(doc.get());
+  xml::Element* manifestEl = doc->root.get();
   ASSERT_NE(nullptr, manifestEl);
 
   xml::Attribute* attr = nullptr;
@@ -297,7 +297,7 @@
                                                             options);
   ASSERT_NE(nullptr, doc);
 
-  xml::Element* manifest_el = xml::FindRootElement(doc.get());
+  xml::Element* manifest_el = doc->root.get();
   ASSERT_NE(nullptr, manifest_el);
 
   xml::Element* instrumentation_el =
@@ -321,7 +321,7 @@
                                                             options);
   ASSERT_NE(nullptr, doc);
 
-  xml::Element* manifest_el = xml::FindRootElement(doc.get());
+  xml::Element* manifest_el = doc->root.get();
   ASSERT_NE(nullptr, manifest_el);
 
   xml::Attribute* attr =
@@ -344,7 +344,7 @@
       Verify("<manifest package=\"android\" coreApp=\"true\" />");
   ASSERT_NE(nullptr, doc);
 
-  xml::Element* el = xml::FindRootElement(doc.get());
+  xml::Element* el = doc->root.get();
   ASSERT_NE(nullptr, el);
 
   EXPECT_EQ("manifest", el->name);
diff --git a/tools/aapt2/link/XmlCompatVersioner.cpp b/tools/aapt2/link/XmlCompatVersioner.cpp
index f1f4e3b..20ebdc6 100644
--- a/tools/aapt2/link/XmlCompatVersioner.cpp
+++ b/tools/aapt2/link/XmlCompatVersioner.cpp
@@ -107,7 +107,7 @@
   std::unique_ptr<xml::XmlResource> cloned_doc = util::make_unique<xml::XmlResource>(doc->file);
   cloned_doc->file.config.sdkVersion = static_cast<uint16_t>(target_api);
 
-  cloned_doc->root = doc->root->Clone([&](const xml::Element& el, xml::Element* out_el) {
+  cloned_doc->root = doc->root->CloneElement([&](const xml::Element& el, xml::Element* out_el) {
     for (const auto& attr : el.attributes) {
       if (!attr.compiled_attribute) {
         // Just copy if this isn't a compiled attribute.
diff --git a/tools/aapt2/link/XmlCompatVersioner_test.cpp b/tools/aapt2/link/XmlCompatVersioner_test.cpp
index ce6605c..29ad25f 100644
--- a/tools/aapt2/link/XmlCompatVersioner_test.cpp
+++ b/tools/aapt2/link/XmlCompatVersioner_test.cpp
@@ -19,6 +19,12 @@
 #include "Linkers.h"
 #include "test/Test.h"
 
+using ::aapt::test::ValueEq;
+using ::testing::Eq;
+using ::testing::IsNull;
+using ::testing::NotNull;
+using ::testing::SizeIs;
+
 namespace aapt {
 
 constexpr auto TYPE_DIMENSION = android::ResTable_map::TYPE_DIMENSION;
@@ -68,12 +74,12 @@
 };
 
 TEST_F(XmlCompatVersionerTest, NoRulesOnlyStripsAndCopies) {
-  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
+  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"(
       <View xmlns:android="http://schemas.android.com/apk/res/android"
           xmlns:app="http://schemas.android.com/apk/res-auto"
           android:paddingHorizontal="24dp"
           app:foo="16dp"
-          foo="bar"/>)EOF");
+          foo="bar"/>)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
@@ -84,35 +90,35 @@
   XmlCompatVersioner versioner(&rules);
   std::vector<std::unique_ptr<xml::XmlResource>> versioned_docs =
       versioner.Process(context_.get(), doc.get(), api_range);
-  ASSERT_EQ(2u, versioned_docs.size());
+  ASSERT_THAT(versioned_docs, SizeIs(2u));
 
   xml::Element* el;
 
   // Source XML file's sdkVersion == 0, so the first one must also have the same sdkVersion.
-  EXPECT_EQ(static_cast<uint16_t>(0), versioned_docs[0]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[0].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(2u, el->attributes.size());
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
-  EXPECT_NE(nullptr, el->FindAttribute(xml::kSchemaAuto, "foo"));
-  EXPECT_NE(nullptr, el->FindAttribute({}, "foo"));
+  EXPECT_THAT(versioned_docs[0]->file.config.sdkVersion, Eq(0u));
+  el = versioned_docs[0]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(2u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), IsNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAuto, "foo"), NotNull());
+  EXPECT_THAT(el->FindAttribute({}, "foo"), NotNull());
 
-  EXPECT_EQ(static_cast<uint16_t>(SDK_LOLLIPOP_MR1), versioned_docs[1]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[1].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(3u, el->attributes.size());
-  EXPECT_NE(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
-  EXPECT_NE(nullptr, el->FindAttribute(xml::kSchemaAuto, "foo"));
-  EXPECT_NE(nullptr, el->FindAttribute({}, "foo"));
+  EXPECT_THAT(versioned_docs[1]->file.config.sdkVersion, Eq(SDK_LOLLIPOP_MR1));
+  el = versioned_docs[1]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(3u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), NotNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAuto, "foo"), NotNull());
+  EXPECT_THAT(el->FindAttribute({}, "foo"), NotNull());
 }
 
 TEST_F(XmlCompatVersionerTest, SingleRule) {
-  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
+  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"(
       <View xmlns:android="http://schemas.android.com/apk/res/android"
           xmlns:app="http://schemas.android.com/apk/res-auto"
           android:paddingHorizontal="24dp"
           app:foo="16dp"
-          foo="bar"/>)EOF");
+          foo="bar"/>)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
@@ -129,51 +135,51 @@
   XmlCompatVersioner versioner(&rules);
   std::vector<std::unique_ptr<xml::XmlResource>> versioned_docs =
       versioner.Process(context_.get(), doc.get(), api_range);
-  ASSERT_EQ(2u, versioned_docs.size());
+  ASSERT_THAT(versioned_docs, SizeIs(2u));
 
   xml::Element* el;
 
-  EXPECT_EQ(static_cast<uint16_t>(0), versioned_docs[0]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[0].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(4u, el->attributes.size());
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
-  EXPECT_NE(nullptr, el->FindAttribute(xml::kSchemaAuto, "foo"));
-  EXPECT_NE(nullptr, el->FindAttribute({}, "foo"));
+  EXPECT_THAT(versioned_docs[0]->file.config.sdkVersion, Eq(0u));
+  el = versioned_docs[0]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(4u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), IsNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAuto, "foo"), NotNull());
+  EXPECT_THAT(el->FindAttribute({}, "foo"), NotNull());
 
   xml::Attribute* attr = el->FindAttribute(xml::kSchemaAndroid, "paddingLeft");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingRight");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
-  EXPECT_EQ(static_cast<uint16_t>(SDK_LOLLIPOP_MR1), versioned_docs[1]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[1].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(5u, el->attributes.size());
-  EXPECT_NE(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
-  EXPECT_NE(nullptr, el->FindAttribute(xml::kSchemaAuto, "foo"));
-  EXPECT_NE(nullptr, el->FindAttribute({}, "foo"));
+  EXPECT_THAT(versioned_docs[1]->file.config.sdkVersion, Eq(SDK_LOLLIPOP_MR1));
+  el = versioned_docs[1]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(5u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), NotNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAuto, "foo"), NotNull());
+  EXPECT_THAT(el->FindAttribute({}, "foo"), NotNull());
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingLeft");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingRight");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 }
 
 TEST_F(XmlCompatVersionerTest, ChainedRule) {
-  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
+  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"(
       <View xmlns:android="http://schemas.android.com/apk/res/android"
-          android:paddingHorizontal="24dp" />)EOF");
+          android:paddingHorizontal="24dp" />)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
@@ -193,71 +199,70 @@
   XmlCompatVersioner versioner(&rules);
   std::vector<std::unique_ptr<xml::XmlResource>> versioned_docs =
       versioner.Process(context_.get(), doc.get(), api_range);
-  ASSERT_EQ(3u, versioned_docs.size());
+  ASSERT_THAT(versioned_docs, SizeIs(3u));
 
   xml::Element* el;
 
-  EXPECT_EQ(static_cast<uint16_t>(0), versioned_docs[0]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[0].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(2u, el->attributes.size());
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
+  EXPECT_THAT(versioned_docs[0]->file.config.sdkVersion, Eq(0u));
+  el = versioned_docs[0]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(2u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), IsNull());
 
   xml::Attribute* attr = el->FindAttribute(xml::kSchemaAndroid, "paddingLeft");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingRight");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
-  EXPECT_EQ(static_cast<uint16_t>(SDK_HONEYCOMB), versioned_docs[1]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[1].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(1u, el->attributes.size());
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingLeft"));
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingRight"));
+  EXPECT_THAT(versioned_docs[1]->file.config.sdkVersion, Eq(SDK_HONEYCOMB));
+  el = versioned_docs[1]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(1u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), IsNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingLeft"), IsNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingRight"), IsNull());
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "progressBarPadding");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
-  EXPECT_EQ(static_cast<uint16_t>(SDK_LOLLIPOP_MR1), versioned_docs[2]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[2].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(2u, el->attributes.size());
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingLeft"));
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingRight"));
+  EXPECT_THAT(versioned_docs[2]->file.config.sdkVersion, Eq(SDK_LOLLIPOP_MR1));
+  el = versioned_docs[2]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(2u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingLeft"), IsNull());
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingRight"), IsNull());
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "progressBarPadding");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
 }
 
 TEST_F(XmlCompatVersionerTest, DegradeRuleOverridesExistingAttribute) {
-  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
+  auto doc = test::BuildXmlDomForPackageName(context_.get(), R"(
       <View xmlns:android="http://schemas.android.com/apk/res/android"
           android:paddingHorizontal="24dp"
           android:paddingLeft="16dp"
-          android:paddingRight="16dp"/>)EOF");
+          android:paddingRight="16dp"/>)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
-  Item* padding_horizontal_value = xml::FindRootElement(doc.get())
-                                       ->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal")
-                                       ->compiled_value.get();
-  ASSERT_NE(nullptr, padding_horizontal_value);
+  Item* padding_horizontal_value =
+      doc->root->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal")->compiled_value.get();
+  ASSERT_THAT(padding_horizontal_value, NotNull());
 
   XmlCompatVersioner::Rules rules;
   rules[R::attr::paddingHorizontal] =
@@ -271,50 +276,50 @@
   XmlCompatVersioner versioner(&rules);
   std::vector<std::unique_ptr<xml::XmlResource>> versioned_docs =
       versioner.Process(context_.get(), doc.get(), api_range);
-  ASSERT_EQ(2u, versioned_docs.size());
+  ASSERT_THAT(versioned_docs, SizeIs(2u));
 
   xml::Element* el;
 
-  EXPECT_EQ(static_cast<uint16_t>(0), versioned_docs[0]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[0].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(2u, el->attributes.size());
-  EXPECT_EQ(nullptr, el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"));
+  EXPECT_THAT(versioned_docs[0]->file.config.sdkVersion, Eq(0u));
+  el = versioned_docs[0]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(2u));
+  EXPECT_THAT(el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal"), IsNull());
 
   xml::Attribute* attr = el->FindAttribute(xml::kSchemaAndroid, "paddingLeft");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
-  ASSERT_TRUE(padding_horizontal_value->Equals(attr->compiled_value.get()));
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
+  ASSERT_THAT(*attr->compiled_value, ValueEq(padding_horizontal_value));
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingRight");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
-  ASSERT_TRUE(padding_horizontal_value->Equals(attr->compiled_value.get()));
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
+  ASSERT_THAT(*attr->compiled_value, ValueEq(padding_horizontal_value));
 
-  EXPECT_EQ(static_cast<uint16_t>(SDK_LOLLIPOP_MR1), versioned_docs[1]->file.config.sdkVersion);
-  el = xml::FindRootElement(versioned_docs[1].get());
-  ASSERT_NE(nullptr, el);
-  EXPECT_EQ(3u, el->attributes.size());
+  EXPECT_THAT(versioned_docs[1]->file.config.sdkVersion, Eq(SDK_LOLLIPOP_MR1));
+  el = versioned_docs[1]->root.get();
+  ASSERT_THAT(el, NotNull());
+  EXPECT_THAT(el->attributes, SizeIs(3u));
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingHorizontal");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
-  ASSERT_TRUE(padding_horizontal_value->Equals(attr->compiled_value.get()));
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
+  ASSERT_THAT(*attr->compiled_value, ValueEq(padding_horizontal_value));
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingLeft");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
-  ASSERT_TRUE(padding_horizontal_value->Equals(attr->compiled_value.get()));
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
+  ASSERT_THAT(*attr->compiled_value, ValueEq(padding_horizontal_value));
 
   attr = el->FindAttribute(xml::kSchemaAndroid, "paddingRight");
-  ASSERT_NE(nullptr, attr);
-  ASSERT_NE(nullptr, attr->compiled_value);
-  ASSERT_TRUE(padding_horizontal_value->Equals(attr->compiled_value.get()));
+  ASSERT_THAT(attr, NotNull());
+  ASSERT_THAT(attr->compiled_value, NotNull());
   ASSERT_TRUE(attr->compiled_attribute);
+  ASSERT_THAT(*attr->compiled_value, ValueEq(padding_horizontal_value));
 }
 
 }  // namespace aapt
diff --git a/tools/aapt2/link/XmlNamespaceRemover.cpp b/tools/aapt2/link/XmlNamespaceRemover.cpp
index 24aa566..b5e2423 100644
--- a/tools/aapt2/link/XmlNamespaceRemover.cpp
+++ b/tools/aapt2/link/XmlNamespaceRemover.cpp
@@ -24,37 +24,19 @@
 
 namespace {
 
-/**
- * Visits each xml Node, removing URI references and nested namespaces.
- */
+// Visits each xml Node, removing URI references and nested namespaces.
 class XmlVisitor : public xml::Visitor {
  public:
   explicit XmlVisitor(bool keep_uris) : keep_uris_(keep_uris) {}
 
   void Visit(xml::Element* el) override {
-    // Strip namespaces
-    for (auto& child : el->children) {
-      while (child && xml::NodeCast<xml::Namespace>(child.get())) {
-        if (child->children.empty()) {
-          child = {};
-        } else {
-          child = std::move(child->children.front());
-          child->parent = el;
-        }
-      }
-    }
-    el->children.erase(
-        std::remove_if(el->children.begin(), el->children.end(),
-                       [](const std::unique_ptr<xml::Node>& child) -> bool {
-                         return child == nullptr;
-                       }),
-        el->children.end());
+    el->namespace_decls.clear();
 
     if (!keep_uris_) {
       for (xml::Attribute& attr : el->attributes) {
-        attr.namespace_uri = std::string();
+        attr.namespace_uri.clear();
       }
-      el->namespace_uri = std::string();
+      el->namespace_uri.clear();
     }
     xml::Visitor::Visit(el);
   }
@@ -67,19 +49,11 @@
 
 }  // namespace
 
-bool XmlNamespaceRemover::Consume(IAaptContext* context,
-                                  xml::XmlResource* resource) {
+bool XmlNamespaceRemover::Consume(IAaptContext* context, xml::XmlResource* resource) {
   if (!resource->root) {
     return false;
   }
-  // Replace any root namespaces until the root is a non-namespace node
-  while (xml::NodeCast<xml::Namespace>(resource->root.get())) {
-    if (resource->root->children.empty()) {
-      break;
-    }
-    resource->root = std::move(resource->root->children.front());
-    resource->root->parent = nullptr;
-  }
+
   XmlVisitor visitor(keep_uris_);
   resource->root->Accept(&visitor);
   return true;
diff --git a/tools/aapt2/link/XmlNamespaceRemover_test.cpp b/tools/aapt2/link/XmlNamespaceRemover_test.cpp
index a176c03..df4920f 100644
--- a/tools/aapt2/link/XmlNamespaceRemover_test.cpp
+++ b/tools/aapt2/link/XmlNamespaceRemover_test.cpp
@@ -18,6 +18,10 @@
 
 #include "test/Test.h"
 
+using ::testing::NotNull;
+using ::testing::SizeIs;
+using ::testing::StrEq;
+
 namespace aapt {
 
 class XmlUriTestVisitor : public xml::Visitor {
@@ -25,16 +29,14 @@
   XmlUriTestVisitor() = default;
 
   void Visit(xml::Element* el) override {
-    for (const auto& attr : el->attributes) {
-      EXPECT_EQ(std::string(), attr.namespace_uri);
-    }
-    EXPECT_EQ(std::string(), el->namespace_uri);
-    xml::Visitor::Visit(el);
-  }
+    EXPECT_THAT(el->namespace_decls, SizeIs(0u));
 
-  void Visit(xml::Namespace* ns) override {
-    EXPECT_EQ(std::string(), ns->namespace_uri);
-    xml::Visitor::Visit(ns);
+    for (const auto& attr : el->attributes) {
+      EXPECT_THAT(attr.namespace_uri, StrEq(""));
+    }
+    EXPECT_THAT(el->namespace_uri, StrEq(""));
+
+    xml::Visitor::Visit(el);
   }
 
  private:
@@ -45,10 +47,9 @@
  public:
   XmlNamespaceTestVisitor() = default;
 
-  void Visit(xml::Namespace* ns) override {
-    ADD_FAILURE() << "Detected namespace: " << ns->namespace_prefix << "=\""
-                  << ns->namespace_uri << "\"";
-    xml::Visitor::Visit(ns);
+  void Visit(xml::Element* el) override {
+    EXPECT_THAT(el->namespace_decls, SizeIs(0u));
+    xml::Visitor::Visit(el);
   }
 
  private:
@@ -58,8 +59,7 @@
 class XmlNamespaceRemoverTest : public ::testing::Test {
  public:
   void SetUp() override {
-    context_ =
-        test::ContextBuilder().SetCompilationPackage("com.app.test").Build();
+    context_ = test::ContextBuilder().SetCompilationPackage("com.app.test").Build();
   }
 
  protected:
@@ -75,8 +75,8 @@
   XmlNamespaceRemover remover;
   ASSERT_TRUE(remover.Consume(context_.get(), doc.get()));
 
-  xml::Node* root = doc.get()->root.get();
-  ASSERT_NE(root, nullptr);
+  xml::Node* root = doc->root.get();
+  ASSERT_THAT(root, NotNull());
 
   XmlUriTestVisitor visitor;
   root->Accept(&visitor);
@@ -93,8 +93,8 @@
   XmlNamespaceRemover remover;
   ASSERT_TRUE(remover.Consume(context_.get(), doc.get()));
 
-  xml::Node* root = doc.get()->root.get();
-  ASSERT_NE(root, nullptr);
+  xml::Node* root = doc->root.get();
+  ASSERT_THAT(root, NotNull());
 
   XmlNamespaceTestVisitor visitor;
   root->Accept(&visitor);
@@ -112,8 +112,8 @@
   XmlNamespaceRemover remover;
   ASSERT_TRUE(remover.Consume(context_.get(), doc.get()));
 
-  xml::Node* root = doc.get()->root.get();
-  ASSERT_NE(root, nullptr);
+  xml::Node* root = doc->root.get();
+  ASSERT_THAT(root, NotNull());
 
   XmlNamespaceTestVisitor visitor;
   root->Accept(&visitor);
diff --git a/tools/aapt2/link/XmlReferenceLinker.cpp b/tools/aapt2/link/XmlReferenceLinker.cpp
index 721fc26..bcecd20 100644
--- a/tools/aapt2/link/XmlReferenceLinker.cpp
+++ b/tools/aapt2/link/XmlReferenceLinker.cpp
@@ -144,7 +144,9 @@
     xml::PackageAwareVisitor::Visit(el);
   }
 
-  bool HasError() { return error_ || reference_visitor_.HasError(); }
+  bool HasError() {
+    return error_ || reference_visitor_.HasError();
+  }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(XmlVisitor);
diff --git a/tools/aapt2/link/XmlReferenceLinker_test.cpp b/tools/aapt2/link/XmlReferenceLinker_test.cpp
index 228cfb9..ef99355 100644
--- a/tools/aapt2/link/XmlReferenceLinker_test.cpp
+++ b/tools/aapt2/link/XmlReferenceLinker_test.cpp
@@ -79,20 +79,20 @@
 };
 
 TEST_F(XmlReferenceLinkerTest, LinkBasicAttributes) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
-        <View xmlns:android="http://schemas.android.com/apk/res/android"
-              android:layout_width="match_parent"
-              android:background="@color/green"
-              android:text="hello"
-              android:attr="\?hello"
-              nonAaptAttr="1"
-              nonAaptAttrRef="@id/id"
-              class="hello" />)EOF");
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+      <View xmlns:android="http://schemas.android.com/apk/res/android"
+            android:layout_width="match_parent"
+            android:background="@color/green"
+            android:text="hello"
+            android:attr="\?hello"
+            nonAaptAttr="1"
+            nonAaptAttrRef="@id/id"
+            class="hello" />)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
-  xml::Element* view_el = xml::FindRootElement(doc.get());
+  xml::Element* view_el = doc->root.get();
   ASSERT_THAT(view_el, NotNull());
 
   xml::Attribute* xml_attr = view_el->FindAttribute(xml::kSchemaAndroid, "layout_width");
@@ -138,32 +138,32 @@
 }
 
 TEST_F(XmlReferenceLinkerTest, PrivateSymbolsAreNotLinked) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
-        <View xmlns:android="http://schemas.android.com/apk/res/android"
-              android:colorAccent="@android:color/hidden" />)EOF");
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+      <View xmlns:android="http://schemas.android.com/apk/res/android"
+          android:colorAccent="@android:color/hidden" />)");
 
   XmlReferenceLinker linker;
   ASSERT_FALSE(linker.Consume(context_.get(), doc.get()));
 }
 
 TEST_F(XmlReferenceLinkerTest, PrivateSymbolsAreLinkedWhenReferenceHasStarPrefix) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
     <View xmlns:android="http://schemas.android.com/apk/res/android"
-          android:colorAccent="@*android:color/hidden" />)EOF");
+          android:colorAccent="@*android:color/hidden" />)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 }
 
 TEST_F(XmlReferenceLinkerTest, LinkMangledAttributes) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
-            <View xmlns:support="http://schemas.android.com/apk/res/com.android.support"
-                  support:colorAccent="#ff0000" />)EOF");
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+      <View xmlns:support="http://schemas.android.com/apk/res/com.android.support"
+          support:colorAccent="#ff0000" />)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
-  xml::Element* view_el = xml::FindRootElement(doc.get());
+  xml::Element* view_el = doc->root.get();
   ASSERT_THAT(view_el, NotNull());
 
   xml::Attribute* xml_attr =
@@ -175,14 +175,14 @@
 }
 
 TEST_F(XmlReferenceLinkerTest, LinkAutoResReference) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
-            <View xmlns:app="http://schemas.android.com/apk/res-auto"
-                  app:colorAccent="@app:color/red" />)EOF");
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+      <View xmlns:app="http://schemas.android.com/apk/res-auto"
+          app:colorAccent="@app:color/red" />)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
-  xml::Element* view_el = xml::FindRootElement(doc.get());
+  xml::Element* view_el = doc->root.get();
   ASSERT_THAT(view_el, NotNull());
 
   xml::Attribute* xml_attr = view_el->FindAttribute(xml::kSchemaAuto, "colorAccent");
@@ -196,17 +196,15 @@
 }
 
 TEST_F(XmlReferenceLinkerTest, LinkViewWithShadowedPackageAlias) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
-            <View xmlns:app="http://schemas.android.com/apk/res/android"
-                  app:attr="@app:id/id">
-              <View xmlns:app="http://schemas.android.com/apk/res/com.app.test"
-                    app:attr="@app:id/id"/>
-            </View>)EOF");
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+      <View xmlns:app="http://schemas.android.com/apk/res/android" app:attr="@app:id/id">
+        <View xmlns:app="http://schemas.android.com/apk/res/com.app.test" app:attr="@app:id/id"/>
+      </View>)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
-  xml::Element* view_el = xml::FindRootElement(doc.get());
+  xml::Element* view_el = doc->root.get();
   ASSERT_THAT(view_el, NotNull());
 
   // All attributes and references in this element should be referring to
@@ -235,14 +233,14 @@
 }
 
 TEST_F(XmlReferenceLinkerTest, LinkViewWithLocalPackageAndAliasOfTheSameName) {
-  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"EOF(
-            <View xmlns:android="http://schemas.android.com/apk/res/com.app.test"
-                  android:attr="@id/id"/>)EOF");
+  std::unique_ptr<xml::XmlResource> doc = test::BuildXmlDomForPackageName(context_.get(), R"(
+      <View xmlns:android="http://schemas.android.com/apk/res/com.app.test"
+          android:attr="@id/id"/>)");
 
   XmlReferenceLinker linker;
   ASSERT_TRUE(linker.Consume(context_.get(), doc.get()));
 
-  xml::Element* view_el = xml::FindRootElement(doc.get());
+  xml::Element* view_el = doc->root.get();
   ASSERT_THAT(view_el, NotNull());
 
   // All attributes and references in this element should be referring to