Add <macro> tag to aapt2

AAPT2 Macros are compile-time resources definitions that are expanded
when referenced during the link phase.

A macro must be defined in the res/values.xml directory. A macro
definition for a macro named "foo" looks like the following:
 <macro name="foo">contents</macro>

When "@macro/foo" is used in the res/values directory or in a compiled
XML file, the contents of the macro replace the macro reference and
then the substituted contents are compiled and linked. If the macro
contents reference xml namespaces from its original definition, the
namespaces of the original macro definition will be used to determine
which package is being referenced.

Macros can be used anywhere resources can be referenced using the
@package:type/entry syntax.

Macros are not included in the final resource table or the R.java since
they are not actual resources.

Bug: 175616308
Test: aapt2_tests
Change-Id: I48b29ab6564357b32b4b4e32bff7ef06036382bc

1 files changed, 85 insertions, 25 deletions

diff --git a/tools/aapt2/ResourceParser.cpp b/tools/aapt2/ResourceParser.cpp
index 24c60b740bc3..1efabbb46fd5 100644
--- a/tools/aapt2/ResourceParser.cpp
+++ b/tools/aapt2/ResourceParser.cpp
@@ -627,6 +627,16 @@ bool ResourceParser::ParseResource(xml::XmlPullParser* parser,
     }
 
     return true;
+  } else if (resource_type == "macro") {
+    if (!maybe_name) {
+      diag_->Error(DiagMessage(out_resource->source)
+                   << "<" << parser->element_name() << "> missing 'name' attribute");
+      return false;
+    }
+
+    out_resource->name.type = ResourceType::kMacro;
+    out_resource->name.entry = maybe_name.value().to_string();
+    return ParseMacro(parser, out_resource);
   }
 
   if (can_be_item) {
@@ -726,6 +736,24 @@ bool ResourceParser::ParseItem(xml::XmlPullParser* parser,
   return true;
 }
 
+std::optional<FlattenedXmlSubTree> ResourceParser::CreateFlattenSubTree(
+    xml::XmlPullParser* parser) {
+  const size_t begin_xml_line = parser->line_number();
+
+  std::string raw_value;
+  StyleString style_string;
+  std::vector<UntranslatableSection> untranslatable_sections;
+  if (!FlattenXmlSubtree(parser, &raw_value, &style_string, &untranslatable_sections)) {
+    return {};
+  }
+
+  return FlattenedXmlSubTree{.raw_value = raw_value,
+                             .style_string = style_string,
+                             .untranslatable_sections = untranslatable_sections,
+                             .namespace_resolver = parser,
+                             .source = source_.WithLine(begin_xml_line)};
+}
+
 /**
  * Reads the entire XML subtree and attempts to parse it as some Item,
  * with typeMask denoting which items it can be. If allowRawValue is
@@ -733,42 +761,46 @@ bool ResourceParser::ParseItem(xml::XmlPullParser* parser,
  * an Item. If allowRawValue is false, nullptr is returned in this
  * case.
  */
-std::unique_ptr<Item> ResourceParser::ParseXml(xml::XmlPullParser* parser,
-                                               const uint32_t type_mask,
+std::unique_ptr<Item> ResourceParser::ParseXml(xml::XmlPullParser* parser, const uint32_t type_mask,
                                                const bool allow_raw_value) {
-  const size_t begin_xml_line = parser->line_number();
-
-  std::string raw_value;
-  StyleString style_string;
-  std::vector<UntranslatableSection> untranslatable_sections;
-  if (!FlattenXmlSubtree(parser, &raw_value, &style_string, &untranslatable_sections)) {
+  auto sub_tree = CreateFlattenSubTree(parser);
+  if (!sub_tree.has_value()) {
     return {};
   }
+  return ParseXml(sub_tree.value(), type_mask, allow_raw_value, *table_, config_, *diag_);
+}
 
-  if (!style_string.spans.empty()) {
+std::unique_ptr<Item> ResourceParser::ParseXml(const FlattenedXmlSubTree& xmlsub_tree,
+                                               const uint32_t type_mask, const bool allow_raw_value,
+                                               ResourceTable& table,
+                                               const android::ConfigDescription& config,
+                                               IDiagnostics& diag) {
+  if (!xmlsub_tree.style_string.spans.empty()) {
     // This can only be a StyledString.
     std::unique_ptr<StyledString> styled_string =
-        util::make_unique<StyledString>(table_->string_pool.MakeRef(
-            style_string, StringPool::Context(StringPool::Context::kNormalPriority, config_)));
-    styled_string->untranslatable_sections = std::move(untranslatable_sections);
+        util::make_unique<StyledString>(table.string_pool.MakeRef(
+            xmlsub_tree.style_string,
+            StringPool::Context(StringPool::Context::kNormalPriority, config)));
+    styled_string->untranslatable_sections = xmlsub_tree.untranslatable_sections;
     return std::move(styled_string);
   }
 
   auto on_create_reference = [&](const ResourceName& name) {
     // name.package can be empty here, as it will assume the package name of the
     // table.
-    std::unique_ptr<Id> id = util::make_unique<Id>();
-    id->SetSource(source_.WithLine(begin_xml_line));
-    table_->AddResource(NewResourceBuilder(name).SetValue(std::move(id)).Build(), diag_);
+    auto id = util::make_unique<Id>();
+    id->SetSource(xmlsub_tree.source);
+    return table.AddResource(NewResourceBuilder(name).SetValue(std::move(id)).Build(), &diag);
   };
 
   // Process the raw value.
-  std::unique_ptr<Item> processed_item =
-      ResourceUtils::TryParseItemForAttribute(raw_value, type_mask, on_create_reference);
+  std::unique_ptr<Item> processed_item = ResourceUtils::TryParseItemForAttribute(
+      xmlsub_tree.raw_value, type_mask, on_create_reference);
   if (processed_item) {
     // Fix up the reference.
-    if (Reference* ref = ValueCast<Reference>(processed_item.get())) {
-      ResolvePackage(parser, ref);
+    if (auto ref = ValueCast<Reference>(processed_item.get())) {
+      ref->allow_raw = allow_raw_value;
+      ResolvePackage(xmlsub_tree.namespace_resolver, ref);
     }
     return processed_item;
   }
@@ -777,17 +809,16 @@ std::unique_ptr<Item> ResourceParser::ParseXml(xml::XmlPullParser* parser,
   if (type_mask & android::ResTable_map::TYPE_STRING) {
     // Use the trimmed, escaped string.
     std::unique_ptr<String> string = util::make_unique<String>(
-        table_->string_pool.MakeRef(style_string.str, StringPool::Context(config_)));
-    string->untranslatable_sections = std::move(untranslatable_sections);
+        table.string_pool.MakeRef(xmlsub_tree.style_string.str, StringPool::Context(config)));
+    string->untranslatable_sections = xmlsub_tree.untranslatable_sections;
     return std::move(string);
   }
 
   if (allow_raw_value) {
     // We can't parse this so return a RawString if we are allowed.
-    return util::make_unique<RawString>(
-        table_->string_pool.MakeRef(util::TrimWhitespace(raw_value),
-                                    StringPool::Context(config_)));
-  } else if (util::TrimWhitespace(raw_value).empty()) {
+    return util::make_unique<RawString>(table.string_pool.MakeRef(
+        util::TrimWhitespace(xmlsub_tree.raw_value), StringPool::Context(config)));
+  } else if (util::TrimWhitespace(xmlsub_tree.raw_value).empty()) {
     // If the text is empty, and the value is not allowed to be a string, encode it as a @null.
     return ResourceUtils::MakeNull();
   }
@@ -850,6 +881,35 @@ bool ResourceParser::ParseString(xml::XmlPullParser* parser,
   return true;
 }
 
+bool ResourceParser::ParseMacro(xml::XmlPullParser* parser, ParsedResource* out_resource) {
+  auto sub_tree = CreateFlattenSubTree(parser);
+  if (!sub_tree) {
+    return false;
+  }
+
+  if (out_resource->config != ConfigDescription::DefaultConfig()) {
+    diag_->Error(DiagMessage(out_resource->source)
+                 << "<macro> tags cannot be declared in configurations other than the default "
+                    "configuration'");
+    return false;
+  }
+
+  auto macro = std::make_unique<Macro>();
+  macro->raw_value = std::move(sub_tree->raw_value);
+  macro->style_string = std::move(sub_tree->style_string);
+  macro->untranslatable_sections = std::move(sub_tree->untranslatable_sections);
+
+  for (const auto& decl : parser->package_decls()) {
+    macro->alias_namespaces.emplace_back(
+        Macro::Namespace{.alias = decl.prefix,
+                         .package_name = decl.package.package,
+                         .is_private = decl.package.private_namespace});
+  }
+
+  out_resource->value = std::move(macro);
+  return true;
+}
+
 bool ResourceParser::ParsePublic(xml::XmlPullParser* parser, ParsedResource* out_resource) {
   if (options_.visibility) {
     diag_->Error(DiagMessage(out_resource->source)