tools/aapt2/xml/XmlDom.cpp - platform/frameworks/base - Gitiles

 /*
  * 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 "XmlDom.h"

 #include <expat.h>

 #include <cassert>
 #include <memory>
 #include <stack>
 #include <string>
 #include <tuple>

 #include "android-base/logging.h"

 #include "XmlPullParser.h"
 #include "util/Util.h"

 namespace aapt {
 namespace xml {

 constexpr char kXmlNamespaceSep = 1;

 struct Stack {
   std::unique_ptr<xml::Node> root;
   std::stack<xml::Node*> node_stack;
   std::string pending_comment;
 };

 /**
  * Extracts the namespace and name of an expanded element or attribute name.
  */
 static void SplitName(const char* name, std::string* out_ns,
                       std::string* out_name) {
   const char* p = name;
   while (*p != 0 && *p != kXmlNamespaceSep) {
     p++;
   }

   if (*p == 0) {
     out_ns->clear();
     *out_name = StringPiece(name).ToString();
   } else {
     *out_ns = StringPiece(name, (p - name)).ToString();
     *out_name = StringPiece(p + 1).ToString();
   }
 }

 static void AddToStack(Stack* stack, XML_Parser parser,
                        std::unique_ptr<Node> node) {
   node->line_number = XML_GetCurrentLineNumber(parser);
   node->column_number = XML_GetCurrentColumnNumber(parser);

   Node* this_node = node.get();
   if (!stack->node_stack.empty()) {
     stack->node_stack.top()->AppendChild(std::move(node));
   } else {
     stack->root = std::move(node);
   }

   if (!NodeCast<Text>(this_node)) {
     stack->node_stack.push(this_node);
   }
 }

 static void XMLCALL StartNamespaceHandler(void* user_data, const char* prefix,
                                           const char* uri) {
   XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
   Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

   std::unique_ptr<Namespace> ns = util::make_unique<Namespace>();
   if (prefix) {
     ns->namespace_prefix = StringPiece(prefix).ToString();
   }

   if (uri) {
     ns->namespace_uri = StringPiece(uri).ToString();
   }

   AddToStack(stack, parser, std::move(ns));
 }

 static void XMLCALL EndNamespaceHandler(void* user_data, const char* prefix) {
   XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
   Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

   CHECK(!stack->node_stack.empty());
   stack->node_stack.pop();
 }

 static bool less_attribute(const Attribute& lhs, const Attribute& rhs) {
   return std::tie(lhs.namespace_uri, lhs.name, lhs.value) <
          std::tie(rhs.namespace_uri, rhs.name, rhs.value);
 }

 static void XMLCALL StartElementHandler(void* user_data, const char* name,
                                         const char** attrs) {
   XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
   Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

   std::unique_ptr<Element> el = util::make_unique<Element>();
   SplitName(name, &el->namespace_uri, &el->name);

   while (*attrs) {
     Attribute attribute;
     SplitName(*attrs++, &attribute.namespace_uri, &attribute.name);
     attribute.value = StringPiece(*attrs++).ToString();

     // Insert in sorted order.
     auto iter = std::lower_bound(el->attributes.begin(), el->attributes.end(),
                                  attribute, less_attribute);
     el->attributes.insert(iter, std::move(attribute));
   }

   el->comment = std::move(stack->pending_comment);
   AddToStack(stack, parser, std::move(el));
 }

 static void XMLCALL EndElementHandler(void* user_data, const char* name) {
   XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
   Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

   CHECK(!stack->node_stack.empty());
   // stack->nodeStack.top()->comment = std::move(stack->pendingComment);
   stack->node_stack.pop();
 }

 static void XMLCALL CharacterDataHandler(void* user_data, const char* s,
                                          int len) {
   XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
   Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

   if (!s || len <= 0) {
     return;
   }

   // See if we can just append the text to a previous text node.
   if (!stack->node_stack.empty()) {
     Node* currentParent = stack->node_stack.top();
     if (!currentParent->children.empty()) {
       Node* last_child = currentParent->children.back().get();
       if (Text* text = NodeCast<Text>(last_child)) {
         text->text += StringPiece(s, len).ToString();
         return;
       }
     }
   }

   std::unique_ptr<Text> text = util::make_unique<Text>();
   text->text = StringPiece(s, len).ToString();
   AddToStack(stack, parser, std::move(text));
 }

 static void XMLCALL CommentDataHandler(void* user_data, const char* comment) {
   XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
   Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

   if (!stack->pending_comment.empty()) {
     stack->pending_comment += '\n';
   }
   stack->pending_comment += comment;
 }

 std::unique_ptr<XmlResource> Inflate(std::istream* in, IDiagnostics* diag,
                                      const Source& source) {
   Stack stack;

   XML_Parser parser = XML_ParserCreateNS(nullptr, kXmlNamespaceSep);
   XML_SetUserData(parser, &stack);
   XML_UseParserAsHandlerArg(parser);
   XML_SetElementHandler(parser, StartElementHandler, EndElementHandler);
   XML_SetNamespaceDeclHandler(parser, StartNamespaceHandler,
                               EndNamespaceHandler);
   XML_SetCharacterDataHandler(parser, CharacterDataHandler);
   XML_SetCommentHandler(parser, CommentDataHandler);

   char buffer[1024];
   while (!in->eof()) {
     in->read(buffer, sizeof(buffer) / sizeof(buffer[0]));
     if (in->bad() && !in->eof()) {
       stack.root = {};
       diag->Error(DiagMessage(source) << strerror(errno));
       break;
     }

     if (XML_Parse(parser, buffer, in->gcount(), in->eof()) ==
         XML_STATUS_ERROR) {
       stack.root = {};
       diag->Error(DiagMessage(source.WithLine(XML_GetCurrentLineNumber(parser)))
                   << XML_ErrorString(XML_GetErrorCode(parser)));
       break;
     }
   }

   XML_ParserFree(parser);
   if (stack.root) {
     return util::make_unique<XmlResource>(ResourceFile{{}, {}, source},
                                           std::move(stack.root));
   }
   return {};
 }

 static void CopyAttributes(Element* el, android::ResXMLParser* parser) {
   const size_t attr_count = parser->getAttributeCount();
   if (attr_count > 0) {
     el->attributes.reserve(attr_count);
     for (size_t i = 0; i < attr_count; i++) {
       Attribute attr;
       size_t len;
       const char16_t* str16 = parser->getAttributeNamespace(i, &len);
       if (str16) {
         attr.namespace_uri = util::Utf16ToUtf8(StringPiece16(str16, len));
       }

       str16 = parser->getAttributeName(i, &len);
       if (str16) {
         attr.name = util::Utf16ToUtf8(StringPiece16(str16, len));
       }

       str16 = parser->getAttributeStringValue(i, &len);
       if (str16) {
         attr.value = util::Utf16ToUtf8(StringPiece16(str16, len));
       }
       el->attributes.push_back(std::move(attr));
     }
   }
 }

 std::unique_ptr<XmlResource> Inflate(const void* data, size_t data_len,
                                      IDiagnostics* diag, const Source& source) {
   // We import the android namespace because on Windows NO_ERROR is a macro, not
   // an enum, which
   // causes errors when qualifying it with android::
   using namespace android;

   std::unique_ptr<Node> root;
   std::stack<Node*> node_stack;

   ResXMLTree tree;
   if (tree.setTo(data, data_len) != NO_ERROR) {
     return {};
   }

   ResXMLParser::event_code_t code;
   while ((code = tree.next()) != ResXMLParser::BAD_DOCUMENT &&
          code != ResXMLParser::END_DOCUMENT) {
     std::unique_ptr<Node> new_node;
     switch (code) {
       case ResXMLParser::START_NAMESPACE: {
         std::unique_ptr<Namespace> node = util::make_unique<Namespace>();
         size_t len;
         const char16_t* str16 = tree.getNamespacePrefix(&len);
         if (str16) {
           node->namespace_prefix = util::Utf16ToUtf8(StringPiece16(str16, len));
         }

         str16 = tree.getNamespaceUri(&len);
         if (str16) {
           node->namespace_uri = util::Utf16ToUtf8(StringPiece16(str16, len));
         }
         new_node = std::move(node);
         break;
       }

       case ResXMLParser::START_TAG: {
         std::unique_ptr<Element> node = util::make_unique<Element>();
         size_t len;
         const char16_t* str16 = tree.getElementNamespace(&len);
         if (str16) {
           node->namespace_uri = util::Utf16ToUtf8(StringPiece16(str16, len));
         }

         str16 = tree.getElementName(&len);
         if (str16) {
           node->name = util::Utf16ToUtf8(StringPiece16(str16, len));
         }

         CopyAttributes(node.get(), &tree);

         new_node = std::move(node);
         break;
       }

       case ResXMLParser::TEXT: {
         std::unique_ptr<Text> node = util::make_unique<Text>();
         size_t len;
         const char16_t* str16 = tree.getText(&len);
         if (str16) {
           node->text = util::Utf16ToUtf8(StringPiece16(str16, len));
         }
         new_node = std::move(node);
         break;
       }

       case ResXMLParser::END_NAMESPACE:
       case ResXMLParser::END_TAG:
         CHECK(!node_stack.empty());
         node_stack.pop();
         break;

       default:
         LOG(FATAL) << "unhandled XML chunk type";
         break;
     }

     if (new_node) {
       new_node->line_number = tree.getLineNumber();

       Node* this_node = new_node.get();
       if (!root) {
         CHECK(node_stack.empty()) << "node stack should be empty";
         root = std::move(new_node);
       } else {
         CHECK(!node_stack.empty()) << "node stack should not be empty";
         node_stack.top()->AppendChild(std::move(new_node));
       }

       if (!NodeCast<Text>(this_node)) {
         node_stack.push(this_node);
       }
     }
   }
   return util::make_unique<XmlResource>(ResourceFile{}, std::move(root));
 }

 std::unique_ptr<Node> Namespace::Clone() {
   auto ns = util::make_unique<Namespace>();
   ns->comment = comment;
   ns->line_number = line_number;
   ns->column_number = column_number;
   ns->namespace_prefix = namespace_prefix;
   ns->namespace_uri = namespace_uri;

   ns->children.reserve(children.size());
   for (const std::unique_ptr<xml::Node>& child : children) {
     ns->AppendChild(child->Clone());
   }
   return std::move(ns);
 }

 Element* FindRootElement(XmlResource* doc) {
   return FindRootElement(doc->root.get());
 }

 Element* FindRootElement(Node* node) {
   if (!node) {
     return nullptr;
   }

   Element* el = nullptr;
   while ((el = NodeCast<Element>(node)) == nullptr) {
     if (node->children.empty()) {
       return nullptr;
     }
     // We are looking for the first element, and namespaces can only have one
     // child.
     node = node->children.front().get();
   }
   return el;
 }

 void Node::AppendChild(std::unique_ptr<Node> child) {
   child->parent = this;
   children.push_back(std::move(child));
 }

 void Node::InsertChild(size_t index, std::unique_ptr<Node> child) {
   child->parent = this;
   children.insert(children.begin() + index, std::move(child));
 }

 Attribute* Element::FindAttribute(const StringPiece& ns,
                                   const StringPiece& name) {
   for (auto& attr : attributes) {
     if (ns == attr.namespace_uri && name == attr.name) {
       return &attr;
     }
   }
   return nullptr;
 }

 Element* Element::FindChild(const StringPiece& ns, const StringPiece& name) {
   return FindChildWithAttribute(ns, name, {}, {}, {});
 }

 Element* Element::FindChildWithAttribute(const StringPiece& ns,
                                          const StringPiece& name,
                                          const StringPiece& attr_ns,
                                          const StringPiece& attr_name,
                                          const StringPiece& attr_value) {
   for (auto& child_node : children) {
     Node* child = child_node.get();
     while (NodeCast<Namespace>(child)) {
       if (child->children.empty()) {
         break;
       }
       child = child->children[0].get();
     }

     if (Element* el = NodeCast<Element>(child)) {
       if (ns == el->namespace_uri && name == el->name) {
         if (attr_ns.empty() && attr_name.empty()) {
           return el;
         }

         Attribute* attr = el->FindAttribute(attr_ns, attr_name);
         if (attr && attr_value == attr->value) {
           return el;
         }
       }
     }
   }
   return nullptr;
 }

 std::vector<Element*> Element::GetChildElements() {
   std::vector<Element*> elements;
   for (auto& child_node : children) {
     Node* child = child_node.get();
     while (NodeCast<Namespace>(child)) {
       if (child->children.empty()) {
         break;
       }
       child = child->children[0].get();
     }

     if (Element* el = NodeCast<Element>(child)) {
       elements.push_back(el);
     }
   }
   return elements;
 }

 std::unique_ptr<Node> Element::Clone() {
   auto el = util::make_unique<Element>();
   el->comment = comment;
   el->line_number = line_number;
   el->column_number = column_number;
   el->name = name;
   el->namespace_uri = namespace_uri;

   el->attributes.reserve(attributes.size());
   for (xml::Attribute& attr : attributes) {
     // Don't copy compiled values or attributes.
     el->attributes.push_back(
         xml::Attribute{attr.namespace_uri, attr.name, attr.value});
   }

   el->children.reserve(children.size());
   for (const std::unique_ptr<xml::Node>& child : children) {
     el->AppendChild(child->Clone());
   }
   return std::move(el);
 }

 std::unique_ptr<Node> Text::Clone() {
   auto t = util::make_unique<Text>();
   t->comment = comment;
   t->line_number = line_number;
   t->column_number = column_number;
   t->text = text;
   return std::move(t);
 }

 void PackageAwareVisitor::Visit(Namespace* ns) {
   bool added = false;
   if (Maybe<ExtractedPackage> maybe_package =
           ExtractPackageFromNamespace(ns->namespace_uri)) {
     ExtractedPackage& package = maybe_package.value();
     package_decls_.push_back(
         PackageDecl{ns->namespace_prefix, std::move(package)});
     added = true;
   }

   Visitor::Visit(ns);

   if (added) {
     package_decls_.pop_back();
   }
 }

 Maybe<ExtractedPackage> PackageAwareVisitor::TransformPackageAlias(
     const StringPiece& alias, const StringPiece& local_package) const {
   if (alias.empty()) {
     return ExtractedPackage{local_package.ToString(), false /* private */};
   }

   const auto rend = package_decls_.rend();
   for (auto iter = package_decls_.rbegin(); iter != rend; ++iter) {
     if (alias == iter->prefix) {
       if (iter->package.package.empty()) {
         return ExtractedPackage{local_package.ToString(),
                                 iter->package.private_namespace};
       }
       return iter->package;
     }
   }
   return {};
 }

 }  // namespace xml
 }  // namespace aapt
	/*
	* 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 "XmlDom.h"

	#include <expat.h>

	#include <cassert>
	#include <memory>
	#include <stack>
	#include <string>
	#include <tuple>

	#include "android-base/logging.h"

	#include "XmlPullParser.h"
	#include "util/Util.h"

	namespace aapt {
	namespace xml {

	constexpr char kXmlNamespaceSep = 1;

	struct Stack {
	std::unique_ptr<xml::Node> root;
	std::stack<xml::Node*> node_stack;
	std::string pending_comment;
	};

	/**
	* Extracts the namespace and name of an expanded element or attribute name.
	*/
	static void SplitName(const char* name, std::string* out_ns,
	std::string* out_name) {
	const char* p = name;
	while (p != 0 && p != kXmlNamespaceSep) {
	p++;
	}

	if (*p == 0) {
	out_ns->clear();
	*out_name = StringPiece(name).ToString();
	} else {
	*out_ns = StringPiece(name, (p - name)).ToString();
	*out_name = StringPiece(p + 1).ToString();
	}
	}

	static void AddToStack(Stack* stack, XML_Parser parser,
	std::unique_ptr<Node> node) {
	node->line_number = XML_GetCurrentLineNumber(parser);
	node->column_number = XML_GetCurrentColumnNumber(parser);

	Node* this_node = node.get();
	if (!stack->node_stack.empty()) {
	stack->node_stack.top()->AppendChild(std::move(node));
	} else {
	stack->root = std::move(node);
	}

	if (!NodeCast<Text>(this_node)) {
	stack->node_stack.push(this_node);
	}
	}

	static void XMLCALL StartNamespaceHandler(void* user_data, const char* prefix,
	const char* uri) {
	XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
	Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

	std::unique_ptr<Namespace> ns = util::make_unique<Namespace>();
	if (prefix) {
	ns->namespace_prefix = StringPiece(prefix).ToString();
	}

	if (uri) {
	ns->namespace_uri = StringPiece(uri).ToString();
	}

	AddToStack(stack, parser, std::move(ns));
	}

	static void XMLCALL EndNamespaceHandler(void* user_data, const char* prefix) {
	XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
	Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

	CHECK(!stack->node_stack.empty());
	stack->node_stack.pop();
	}

	static bool less_attribute(const Attribute& lhs, const Attribute& rhs) {
	return std::tie(lhs.namespace_uri, lhs.name, lhs.value) <
	std::tie(rhs.namespace_uri, rhs.name, rhs.value);
	}

	static void XMLCALL StartElementHandler(void* user_data, const char* name,
	const char** attrs) {
	XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
	Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

	std::unique_ptr<Element> el = util::make_unique<Element>();
	SplitName(name, &el->namespace_uri, &el->name);

	while (*attrs) {
	Attribute attribute;
	SplitName(*attrs++, &attribute.namespace_uri, &attribute.name);
	attribute.value = StringPiece(*attrs++).ToString();

	// Insert in sorted order.
	auto iter = std::lower_bound(el->attributes.begin(), el->attributes.end(),
	attribute, less_attribute);
	el->attributes.insert(iter, std::move(attribute));
	}

	el->comment = std::move(stack->pending_comment);
	AddToStack(stack, parser, std::move(el));
	}

	static void XMLCALL EndElementHandler(void* user_data, const char* name) {
	XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
	Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

	CHECK(!stack->node_stack.empty());
	// stack->nodeStack.top()->comment = std::move(stack->pendingComment);
	stack->node_stack.pop();
	}

	static void XMLCALL CharacterDataHandler(void* user_data, const char* s,
	int len) {
	XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
	Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

	if (!s \|\| len <= 0) {
	return;
	}

	// See if we can just append the text to a previous text node.
	if (!stack->node_stack.empty()) {
	Node* currentParent = stack->node_stack.top();
	if (!currentParent->children.empty()) {
	Node* last_child = currentParent->children.back().get();
	if (Text* text = NodeCast<Text>(last_child)) {
	text->text += StringPiece(s, len).ToString();
	return;
	}
	}
	}

	std::unique_ptr<Text> text = util::make_unique<Text>();
	text->text = StringPiece(s, len).ToString();
	AddToStack(stack, parser, std::move(text));
	}

	static void XMLCALL CommentDataHandler(void* user_data, const char* comment) {
	XML_Parser parser = reinterpret_cast<XML_Parser>(user_data);
	Stack* stack = reinterpret_cast<Stack*>(XML_GetUserData(parser));

	if (!stack->pending_comment.empty()) {
	stack->pending_comment += '\n';
	}
	stack->pending_comment += comment;
	}

	std::unique_ptr<XmlResource> Inflate(std::istream* in, IDiagnostics* diag,
	const Source& source) {
	Stack stack;

	XML_Parser parser = XML_ParserCreateNS(nullptr, kXmlNamespaceSep);
	XML_SetUserData(parser, &stack);
	XML_UseParserAsHandlerArg(parser);
	XML_SetElementHandler(parser, StartElementHandler, EndElementHandler);
	XML_SetNamespaceDeclHandler(parser, StartNamespaceHandler,
	EndNamespaceHandler);
	XML_SetCharacterDataHandler(parser, CharacterDataHandler);
	XML_SetCommentHandler(parser, CommentDataHandler);

	char buffer[1024];
	while (!in->eof()) {
	in->read(buffer, sizeof(buffer) / sizeof(buffer[0]));
	if (in->bad() && !in->eof()) {
	stack.root = {};
	diag->Error(DiagMessage(source) << strerror(errno));
	break;
	}

	if (XML_Parse(parser, buffer, in->gcount(), in->eof()) ==
	XML_STATUS_ERROR) {
	stack.root = {};
	diag->Error(DiagMessage(source.WithLine(XML_GetCurrentLineNumber(parser)))
	<< XML_ErrorString(XML_GetErrorCode(parser)));
	break;
	}
	}

	XML_ParserFree(parser);
	if (stack.root) {
	return util::make_unique<XmlResource>(ResourceFile{{}, {}, source},
	std::move(stack.root));
	}
	return {};
	}

	static void CopyAttributes(Element* el, android::ResXMLParser* parser) {
	const size_t attr_count = parser->getAttributeCount();
	if (attr_count > 0) {
	el->attributes.reserve(attr_count);
	for (size_t i = 0; i < attr_count; i++) {
	Attribute attr;
	size_t len;
	const char16_t* str16 = parser->getAttributeNamespace(i, &len);
	if (str16) {
	attr.namespace_uri = util::Utf16ToUtf8(StringPiece16(str16, len));
	}

	str16 = parser->getAttributeName(i, &len);
	if (str16) {
	attr.name = util::Utf16ToUtf8(StringPiece16(str16, len));
	}

	str16 = parser->getAttributeStringValue(i, &len);
	if (str16) {
	attr.value = util::Utf16ToUtf8(StringPiece16(str16, len));
	}
	el->attributes.push_back(std::move(attr));
	}
	}
	}

	std::unique_ptr<XmlResource> Inflate(const void* data, size_t data_len,
	IDiagnostics* diag, const Source& source) {
	// We import the android namespace because on Windows NO_ERROR is a macro, not
	// an enum, which
	// causes errors when qualifying it with android::
	using namespace android;

	std::unique_ptr<Node> root;
	std::stack<Node*> node_stack;

	ResXMLTree tree;
	if (tree.setTo(data, data_len) != NO_ERROR) {
	return {};
	}

	ResXMLParser::event_code_t code;
	while ((code = tree.next()) != ResXMLParser::BAD_DOCUMENT &&
	code != ResXMLParser::END_DOCUMENT) {
	std::unique_ptr<Node> new_node;
	switch (code) {
	case ResXMLParser::START_NAMESPACE: {
	std::unique_ptr<Namespace> node = util::make_unique<Namespace>();
	size_t len;
	const char16_t* str16 = tree.getNamespacePrefix(&len);
	if (str16) {
	node->namespace_prefix = util::Utf16ToUtf8(StringPiece16(str16, len));
	}

	str16 = tree.getNamespaceUri(&len);
	if (str16) {
	node->namespace_uri = util::Utf16ToUtf8(StringPiece16(str16, len));
	}
	new_node = std::move(node);
	break;
	}

	case ResXMLParser::START_TAG: {
	std::unique_ptr<Element> node = util::make_unique<Element>();
	size_t len;
	const char16_t* str16 = tree.getElementNamespace(&len);
	if (str16) {
	node->namespace_uri = util::Utf16ToUtf8(StringPiece16(str16, len));
	}

	str16 = tree.getElementName(&len);
	if (str16) {
	node->name = util::Utf16ToUtf8(StringPiece16(str16, len));
	}

	CopyAttributes(node.get(), &tree);

	new_node = std::move(node);
	break;
	}

	case ResXMLParser::TEXT: {
	std::unique_ptr<Text> node = util::make_unique<Text>();
	size_t len;
	const char16_t* str16 = tree.getText(&len);
	if (str16) {
	node->text = util::Utf16ToUtf8(StringPiece16(str16, len));
	}
	new_node = std::move(node);
	break;
	}

	case ResXMLParser::END_NAMESPACE:
	case ResXMLParser::END_TAG:
	CHECK(!node_stack.empty());
	node_stack.pop();
	break;

	default:
	LOG(FATAL) << "unhandled XML chunk type";
	break;
	}

	if (new_node) {
	new_node->line_number = tree.getLineNumber();

	Node* this_node = new_node.get();
	if (!root) {
	CHECK(node_stack.empty()) << "node stack should be empty";
	root = std::move(new_node);
	} else {
	CHECK(!node_stack.empty()) << "node stack should not be empty";
	node_stack.top()->AppendChild(std::move(new_node));
	}

	if (!NodeCast<Text>(this_node)) {
	node_stack.push(this_node);
	}
	}
	}
	return util::make_unique<XmlResource>(ResourceFile{}, std::move(root));
	}

	std::unique_ptr<Node> Namespace::Clone() {
	auto ns = util::make_unique<Namespace>();
	ns->comment = comment;
	ns->line_number = line_number;
	ns->column_number = column_number;
	ns->namespace_prefix = namespace_prefix;
	ns->namespace_uri = namespace_uri;

	ns->children.reserve(children.size());
	for (const std::unique_ptr<xml::Node>& child : children) {
	ns->AppendChild(child->Clone());
	}
	return std::move(ns);
	}

	Element* FindRootElement(XmlResource* doc) {
	return FindRootElement(doc->root.get());
	}

	Element* FindRootElement(Node* node) {
	if (!node) {
	return nullptr;
	}

	Element* el = nullptr;
	while ((el = NodeCast<Element>(node)) == nullptr) {
	if (node->children.empty()) {
	return nullptr;
	}
	// We are looking for the first element, and namespaces can only have one
	// child.
	node = node->children.front().get();
	}
	return el;
	}

	void Node::AppendChild(std::unique_ptr<Node> child) {
	child->parent = this;
	children.push_back(std::move(child));
	}

	void Node::InsertChild(size_t index, std::unique_ptr<Node> child) {
	child->parent = this;
	children.insert(children.begin() + index, std::move(child));
	}

	Attribute* Element::FindAttribute(const StringPiece& ns,
	const StringPiece& name) {
	for (auto& attr : attributes) {
	if (ns == attr.namespace_uri && name == attr.name) {
	return &attr;
	}
	}
	return nullptr;
	}

	Element* Element::FindChild(const StringPiece& ns, const StringPiece& name) {
	return FindChildWithAttribute(ns, name, {}, {}, {});
	}

	Element* Element::FindChildWithAttribute(const StringPiece& ns,
	const StringPiece& name,
	const StringPiece& attr_ns,
	const StringPiece& attr_name,
	const StringPiece& attr_value) {
	for (auto& child_node : children) {
	Node* child = child_node.get();
	while (NodeCast<Namespace>(child)) {
	if (child->children.empty()) {
	break;
	}
	child = child->children[0].get();
	}

	if (Element* el = NodeCast<Element>(child)) {
	if (ns == el->namespace_uri && name == el->name) {
	if (attr_ns.empty() && attr_name.empty()) {
	return el;
	}

	Attribute* attr = el->FindAttribute(attr_ns, attr_name);
	if (attr && attr_value == attr->value) {
	return el;
	}
	}
	}
	}
	return nullptr;
	}

	std::vector<Element*> Element::GetChildElements() {
	std::vector<Element*> elements;
	for (auto& child_node : children) {
	Node* child = child_node.get();
	while (NodeCast<Namespace>(child)) {
	if (child->children.empty()) {
	break;
	}
	child = child->children[0].get();
	}

	if (Element* el = NodeCast<Element>(child)) {
	elements.push_back(el);
	}
	}
	return elements;
	}

	std::unique_ptr<Node> Element::Clone() {
	auto el = util::make_unique<Element>();
	el->comment = comment;
	el->line_number = line_number;
	el->column_number = column_number;
	el->name = name;
	el->namespace_uri = namespace_uri;

	el->attributes.reserve(attributes.size());
	for (xml::Attribute& attr : attributes) {
	// Don't copy compiled values or attributes.
	el->attributes.push_back(
	xml::Attribute{attr.namespace_uri, attr.name, attr.value});
	}

	el->children.reserve(children.size());
	for (const std::unique_ptr<xml::Node>& child : children) {
	el->AppendChild(child->Clone());
	}
	return std::move(el);
	}

	std::unique_ptr<Node> Text::Clone() {
	auto t = util::make_unique<Text>();
	t->comment = comment;
	t->line_number = line_number;
	t->column_number = column_number;
	t->text = text;
	return std::move(t);
	}

	void PackageAwareVisitor::Visit(Namespace* ns) {
	bool added = false;
	if (Maybe<ExtractedPackage> maybe_package =
	ExtractPackageFromNamespace(ns->namespace_uri)) {
	ExtractedPackage& package = maybe_package.value();
	package_decls_.push_back(
	PackageDecl{ns->namespace_prefix, std::move(package)});
	added = true;
	}

	Visitor::Visit(ns);

	if (added) {
	package_decls_.pop_back();
	}
	}

	Maybe<ExtractedPackage> PackageAwareVisitor::TransformPackageAlias(
	const StringPiece& alias, const StringPiece& local_package) const {
	if (alias.empty()) {
	return ExtractedPackage{local_package.ToString(), false /* private */};
	}

	const auto rend = package_decls_.rend();
	for (auto iter = package_decls_.rbegin(); iter != rend; ++iter) {
	if (alias == iter->prefix) {
	if (iter->package.package.empty()) {
	return ExtractedPackage{local_package.ToString(),
	iter->package.private_namespace};
	}
	return iter->package;
	}
	}
	return {};
	}

	} // namespace xml
	} // namespace aapt