AssetManager2: Add GetResourceId

Add ability to lookup a resource by name.

Test: make libandroidfw_tests
Change-Id: I262ba5ce4c9892458226fbdb44cf21f9877fb92d

libs/androidfw/ResourceUtils.cpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2017 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 "androidfw/ResourceUtils.h"
+
+namespace android {
+
+bool ExtractResourceName(const StringPiece& str, StringPiece* out_package, StringPiece* out_type,
+                         StringPiece* out_entry) {
+  *out_package = "";
+  *out_type = "";
+  bool has_package_separator = false;
+  bool has_type_separator = false;
+  const char* start = str.data();
+  const char* end = start + str.size();
+  const char* current = start;
+  while (current != end) {
+    if (out_type->size() == 0 && *current == '/') {
+      has_type_separator = true;
+      out_type->assign(start, current - start);
+      start = current + 1;
+    } else if (out_package->size() == 0 && *current == ':') {
+      has_package_separator = true;
+      out_package->assign(start, current - start);
+      start = current + 1;
+    }
+    current++;
+  }
+  out_entry->assign(start, end - start);
+
+  return !(has_package_separator && out_package->empty()) &&
+         !(has_type_separator && out_type->empty());
+}
+
+}  // namespace android