Sync of libtextclassifier from Google3.
Exported by: knowledge/cerebra/sense/text_classifier/lib/export_to_aosp.sh
Bug: 67618889
Test: Builds. Tested also with oc-mr1 and tested that smartselect/sharing features work.
Change-Id: I25ad82cdd5eed20c60e83e7eb94dae6ab08b3690
diff --git a/util/java/scoped_local_ref.h b/util/java/scoped_local_ref.h
new file mode 100644
index 0000000..d995468
--- /dev/null
+++ b/util/java/scoped_local_ref.h
@@ -0,0 +1,65 @@
+/*
+ * 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.
+ */
+
+#ifndef LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_LOCAL_REF_H_
+#define LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_LOCAL_REF_H_
+
+#include <jni.h>
+#include <memory>
+#include <type_traits>
+
+#include "util/base/logging.h"
+
+namespace libtextclassifier {
+
+// A deleter to be used with std::unique_ptr to delete JNI local references.
+class LocalRefDeleter {
+ public:
+ // Style guide violating implicit constructor so that the LocalRefDeleter
+ // is implicitly constructed from the second argument to ScopedLocalRef.
+ LocalRefDeleter(JNIEnv* env) : env_(env) {} // NOLINT(runtime/explicit)
+
+ LocalRefDeleter(const LocalRefDeleter& orig) = default;
+
+ // Copy assignment to allow move semantics in ScopedLocalRef.
+ LocalRefDeleter& operator=(const LocalRefDeleter& rhs) {
+ // As the deleter and its state are thread-local, ensure the envs
+ // are consistent but do nothing.
+ TC_CHECK_EQ(env_, rhs.env_);
+ return *this;
+ }
+
+ // The delete operator.
+ void operator()(jobject o) const { env_->DeleteLocalRef(o); }
+
+ private:
+ // The env_ stashed to use for deletion. Thread-local, don't share!
+ JNIEnv* const env_;
+};
+
+// A smart pointer that deletes a JNI local reference when it goes out
+// of scope. Usage is:
+// ScopedLocalRef<jobject> scoped_local(env->JniFunction(), env);
+//
+// Note that this class is not thread-safe since it caches JNIEnv in
+// the deleter. Do not use the same jobject across different threads.
+template <typename T>
+using ScopedLocalRef =
+ std::unique_ptr<typename std::remove_pointer<T>::type, LocalRefDeleter>;
+
+} // namespace libtextclassifier
+
+#endif // LIBTEXTCLASSIFIER_UTIL_JAVA_SCOPED_LOCAL_REF_H_