ScopedGlobalRef.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#pragma once
 
#include <jni.h>
#include <cstddef>
#include <type_traits>
#include "corefunctions.h"
 
namespace facebook::yoga::vanillajni {
 
template <typename T>
class ScopedGlobalRef {
  static_assert(
      std::is_same<T, jclass>() || std::is_same<T, jobject>() ||
          std::is_same<T, jstring>() || std::is_same<T, jthrowable>() ||
          std::is_same<T, jbyteArray>() || std::is_same<T, jintArray>() ||
          std::is_same<T, jshortArray>() || std::is_same<T, jcharArray>() ||
          std::is_same<T, jlongArray>() || std::is_same<T, jfloatArray>() ||
          std::is_same<T, jdoubleArray>() || std::is_same<T, jobjectArray>() ||
          std::is_same<T, jbooleanArray>(),
      "ScopedGlobalRef instantiated for invalid type");
 
 public:
  explicit ScopedGlobalRef(T globalRef) : mGlobalRef(globalRef) {}
 
  explicit ScopedGlobalRef() : mGlobalRef(NULL) {}
 
  ScopedGlobalRef(ScopedGlobalRef&& s) noexcept : mGlobalRef(s.release()) {}
 
  ScopedGlobalRef& operator=(ScopedGlobalRef&& s) noexcept {
    reset(s.release());
    return *this;
  }
 
  ~ScopedGlobalRef() {
    reset();
  }
 
  void reset(T ptr = NULL) {
    if (ptr != mGlobalRef) {
      if (mGlobalRef != NULL) {
        vanillajni::getCurrentEnv()->DeleteGlobalRef(mGlobalRef);
      }
      mGlobalRef = ptr;
    }
  }
 
  T release() {
    T globalRef = mGlobalRef;
    mGlobalRef = NULL;
    return globalRef;
  }
 
  T get() const {
    return mGlobalRef;
  }
 
  operator bool() const {
    return mGlobalRef != NULL;
  }
 
  ScopedGlobalRef(const ScopedGlobalRef& ref) = delete;
  ScopedGlobalRef& operator=(const ScopedGlobalRef& other) = delete;
 
 private:
  T mGlobalRef;
};
 
template <typename T>
ScopedGlobalRef<T> make_global_ref(T globalRef) {
  return ScopedGlobalRef<T>(globalRef);
}
 
} // namespace facebook::yoga::vanillajni