[res] Simplify XmlPullParser::FindAttribute() and StringPool::Sort

1. FindAttribute used to do lots of work that C++17 does
   automatically

2. Use function_ref for a more efficient callback passing

Test: aapt2_tests
Flag: EXEMPT minor refactor
Change-Id: I4f172cca16c05422992b107e347ed01479fff898

1 files changed, 12 insertions, 14 deletions

diff --git a/libs/androidfw/StringPool.cpp b/libs/androidfw/StringPool.cpp
index ad445c042e63..629f14683b19 100644
--- a/libs/androidfw/StringPool.cpp
+++ b/libs/androidfw/StringPool.cpp
@@ -297,24 +297,22 @@ void StringPool::Prune() {
 template <typename E>
 static void SortEntries(
     std::vector<std::unique_ptr<E>>& entries,
-    const std::function<int(const StringPool::Context&, const StringPool::Context&)>& cmp) {
+    base::function_ref<int(const StringPool::Context&, const StringPool::Context&)> cmp) {
   using UEntry = std::unique_ptr<E>;
+  std::sort(entries.begin(), entries.end(), [cmp](const UEntry& a, const UEntry& b) -> bool {
+    int r = cmp(a->context, b->context);
+    if (r == 0) {
+      r = a->value.compare(b->value);
+    }
+    return r < 0;
+  });
+}
 
-  if (cmp != nullptr) {
-    std::sort(entries.begin(), entries.end(), [&cmp](const UEntry& a, const UEntry& b) -> bool {
-      int r = cmp(a->context, b->context);
-      if (r == 0) {
-        r = a->value.compare(b->value);
-      }
-      return r < 0;
-    });
-  } else {
-    std::sort(entries.begin(), entries.end(),
-              [](const UEntry& a, const UEntry& b) -> bool { return a->value < b->value; });
-  }
+void StringPool::Sort() {
+  Sort([](auto&&, auto&&) { return 0; });
 }
 
-void StringPool::Sort(const std::function<int(const Context&, const Context&)>& cmp) {
+void StringPool::Sort(base::function_ref<int(const Context&, const Context&)> cmp) {
   SortEntries(styles_, cmp);
   SortEntries(strings_, cmp);
   ReAssignIndices();