From 5f8de423f190bbb79a62f804151bc24824fa32d8 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <mattatobin@localhost.localdomain>
Date: Fri, 2 Feb 2018 04:16:08 -0500
Subject: Add m-esr52 at 52.6.0

---
 widget/android/jni/Refs.h | 953 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 953 insertions(+)
 create mode 100644 widget/android/jni/Refs.h

(limited to 'widget/android/jni/Refs.h')

diff --git a/widget/android/jni/Refs.h b/widget/android/jni/Refs.h
new file mode 100644
index 000000000..9f54ee5cd
--- /dev/null
+++ b/widget/android/jni/Refs.h
@@ -0,0 +1,953 @@
+#ifndef mozilla_jni_Refs_h__
+#define mozilla_jni_Refs_h__
+
+#include <jni.h>
+
+#include "mozilla/Move.h"
+#include "mozilla/jni/Utils.h"
+
+#include "nsError.h" // for nsresult
+#include "nsString.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace jni {
+
+// Wrapped object reference (e.g. jobject, jclass, etc...)
+template<class Cls, typename JNIType> class Ref;
+// Represents a calling context for JNI methods.
+template<class Cls, typename JNIType> class Context;
+// Wrapped local reference that inherits from Ref.
+template<class Cls> class LocalRef;
+// Wrapped global reference that inherits from Ref.
+template<class Cls> class GlobalRef;
+// Wrapped dangling reference that's owned by someone else.
+template<class Cls> class DependentRef;
+
+
+// Class to hold the native types of a method's arguments.
+// For example, if a method has signature (ILjava/lang/String;)V,
+// its arguments class would be jni::Args<int32_t, jni::String::Param>
+template<typename...>
+struct Args {};
+
+
+class Object;
+
+// Base class for Ref and its specializations.
+template<class Cls, typename Type>
+class Ref
+{
+    template<class C, typename T> friend class Ref;
+
+    using Self = Ref<Cls, Type>;
+    using bool_type = void (Self::*)() const;
+    void non_null_reference() const {}
+
+    // A Cls-derivative that allows copying
+    // (e.g. when acting as a return value).
+    struct CopyableCtx : public Context<Cls, Type>
+    {
+        CopyableCtx(JNIEnv* env, Type instance)
+            : Context<Cls, Type>(env, instance)
+        {}
+
+        CopyableCtx(const CopyableCtx& cls)
+            : Context<Cls, Type>(cls.Env(), cls.Get())
+        {}
+    };
+
+    // Private copy constructor so that there's no danger of assigning a
+    // temporary LocalRef/GlobalRef to a Ref, and potentially use the Ref
+    // after the source had been freed.
+    Ref(const Ref&) = default;
+
+protected:
+    static JNIEnv* FindEnv()
+    {
+        return Cls::callingThread == CallingThread::GECKO ?
+                GetGeckoThreadEnv() : GetEnvForThread();
+    }
+
+    Type mInstance;
+
+    // Protected jobject constructor because outside code should be using
+    // Ref::From. Using Ref::From makes it very easy to see which code is using
+    // raw JNI types for future refactoring.
+    explicit Ref(Type instance) : mInstance(instance) {}
+
+public:
+    using JNIType = Type;
+
+    // Construct a Ref form a raw JNI reference.
+    static Ref<Cls, Type> From(JNIType obj)
+    {
+        return Ref<Cls, Type>(obj);
+    }
+
+    // Construct a Ref form a generic object reference.
+    static Ref<Cls, Type> From(const Ref<Object, jobject>& obj)
+    {
+        return Ref<Cls, Type>(JNIType(obj.Get()));
+    }
+
+    MOZ_IMPLICIT Ref(decltype(nullptr)) : mInstance(nullptr) {}
+
+    // Get the raw JNI reference.
+    JNIType Get() const
+    {
+        return mInstance;
+    }
+
+    bool operator==(const Ref& other) const
+    {
+        // Treat two references of the same object as being the same.
+        return mInstance == other.mInstance || JNI_FALSE !=
+                FindEnv()->IsSameObject(mInstance, other.mInstance);
+    }
+
+    bool operator!=(const Ref& other) const
+    {
+        return !operator==(other);
+    }
+
+    bool operator==(decltype(nullptr)) const
+    {
+        return !mInstance;
+    }
+
+    bool operator!=(decltype(nullptr)) const
+    {
+        return !!mInstance;
+    }
+
+    CopyableCtx operator->() const
+    {
+        return CopyableCtx(FindEnv(), mInstance);
+    }
+
+    // Any ref can be cast to an object ref.
+    operator Ref<Object, jobject>() const
+    {
+        return Ref<Object, jobject>(mInstance);
+    }
+
+    // Null checking (e.g. !!ref) using the safe-bool idiom.
+    operator bool_type() const
+    {
+        return mInstance ? &Self::non_null_reference : nullptr;
+    }
+
+    // We don't allow implicit conversion to jobject because that can lead
+    // to easy mistakes such as assigning a temporary LocalRef to a jobject,
+    // and using the jobject after the LocalRef has been freed.
+
+    // We don't allow explicit conversion, to make outside code use Ref::Get.
+    // Using Ref::Get makes it very easy to see which code is using raw JNI
+    // types to make future refactoring easier.
+
+    // operator JNIType() const = delete;
+};
+
+
+// Represents a calling context for JNI methods.
+template<class Cls, typename Type>
+class Context : public Ref<Cls, Type>
+{
+    using Ref = jni::Ref<Cls, Type>;
+
+    static jclass sClassRef; // global reference
+
+protected:
+    JNIEnv* const mEnv;
+
+public:
+    static jclass RawClassRef()
+    {
+        return sClassRef;
+    }
+
+    Context()
+        : Ref(nullptr)
+        , mEnv(Ref::FindEnv())
+    {}
+
+    Context(JNIEnv* env, Type instance)
+        : Ref(instance)
+        , mEnv(env)
+    {}
+
+    jclass ClassRef() const
+    {
+        if (!sClassRef) {
+            const jclass cls = GetClassRef(mEnv, Cls::name);
+            sClassRef = jclass(mEnv->NewGlobalRef(cls));
+            mEnv->DeleteLocalRef(cls);
+        }
+        return sClassRef;
+    }
+
+    JNIEnv* Env() const
+    {
+        return mEnv;
+    }
+
+    bool operator==(const Ref& other) const
+    {
+        // Treat two references of the same object as being the same.
+        return Ref::mInstance == other.mInstance || JNI_FALSE !=
+                mEnv->IsSameObject(Ref::mInstance, other.mInstance);
+    }
+
+    bool operator!=(const Ref& other) const
+    {
+        return !operator==(other);
+    }
+
+    bool operator==(decltype(nullptr)) const
+    {
+        return !Ref::mInstance;
+    }
+
+    bool operator!=(decltype(nullptr)) const
+    {
+        return !!Ref::mInstance;
+    }
+
+    Cls operator->() const
+    {
+        MOZ_ASSERT(Ref::mInstance, "Null jobject");
+        return Cls(*this);
+    }
+};
+
+
+template<class Cls, typename Type = jobject>
+class ObjectBase
+{
+protected:
+    const jni::Context<Cls, Type>& mCtx;
+
+    jclass ClassRef() const { return mCtx.ClassRef(); }
+    JNIEnv* Env() const { return mCtx.Env(); }
+    Type Instance() const { return mCtx.Get(); }
+
+public:
+    using Ref = jni::Ref<Cls, Type>;
+    using Context = jni::Context<Cls, Type>;
+    using LocalRef = jni::LocalRef<Cls>;
+    using GlobalRef = jni::GlobalRef<Cls>;
+    using Param = const Ref&;
+
+    static const CallingThread callingThread = CallingThread::ANY;
+    static const char name[];
+
+    explicit ObjectBase(const Context& ctx) : mCtx(ctx) {}
+
+    Cls* operator->()
+    {
+        return static_cast<Cls*>(this);
+    }
+};
+
+// Binding for a plain jobject.
+class Object : public ObjectBase<Object, jobject>
+{
+public:
+    explicit Object(const Context& ctx) : ObjectBase<Object, jobject>(ctx) {}
+};
+
+// Binding for a built-in object reference other than jobject.
+template<typename T>
+class TypedObject : public ObjectBase<TypedObject<T>, T>
+{
+public:
+    explicit TypedObject(const Context<TypedObject<T>, T>& ctx)
+        : ObjectBase<TypedObject<T>, T>(ctx)
+    {}
+};
+
+
+// Define bindings for built-in types.
+using String = TypedObject<jstring>;
+using Class = TypedObject<jclass>;
+using Throwable = TypedObject<jthrowable>;
+
+using BooleanArray = TypedObject<jbooleanArray>;
+using ByteArray = TypedObject<jbyteArray>;
+using CharArray = TypedObject<jcharArray>;
+using ShortArray = TypedObject<jshortArray>;
+using IntArray = TypedObject<jintArray>;
+using LongArray = TypedObject<jlongArray>;
+using FloatArray = TypedObject<jfloatArray>;
+using DoubleArray = TypedObject<jdoubleArray>;
+using ObjectArray = TypedObject<jobjectArray>;
+
+
+namespace detail {
+
+// See explanation in LocalRef.
+template<class Cls> struct GenericObject { using Type = Object; };
+template<> struct GenericObject<Object>
+{
+    struct Type {
+        using Ref = jni::Ref<Type, jobject>;
+        using Context = jni::Context<Type, jobject>;
+    };
+};
+template<class Cls> struct GenericLocalRef
+{
+    template<class C> struct Type : jni::Object {};
+};
+template<> struct GenericLocalRef<Object>
+{
+    template<class C> using Type = jni::LocalRef<C>;
+};
+
+} // namespace
+
+template<class Cls>
+class LocalRef : public Cls::Context
+{
+    template<class C> friend class LocalRef;
+
+    using Ctx = typename Cls::Context;
+    using Ref = typename Cls::Ref;
+    using JNIType = typename Ref::JNIType;
+
+    // In order to be able to convert LocalRef<Object> to LocalRef<Cls>, we
+    // need constructors and copy assignment operators that take in a
+    // LocalRef<Object> argument. However, if Cls *is* Object, we would have
+    // duplicated constructors and operators with LocalRef<Object> arguments. To
+    // avoid this conflict, we use GenericObject, which is defined as Object for
+    // LocalRef<non-Object> and defined as a dummy class for LocalRef<Object>.
+    using GenericObject = typename detail::GenericObject<Cls>::Type;
+
+    // Similarly, GenericLocalRef is useed to convert LocalRef<Cls> to,
+    // LocalRef<Object>. It's defined as LocalRef<C> for Cls == Object,
+    // and defined as a dummy template class for Cls != Object.
+    template<class C> using GenericLocalRef
+            = typename detail::GenericLocalRef<Cls>::template Type<C>;
+
+    static JNIType NewLocalRef(JNIEnv* env, JNIType obj)
+    {
+        return JNIType(obj ? env->NewLocalRef(obj) : nullptr);
+    }
+
+    LocalRef(JNIEnv* env, JNIType instance) : Ctx(env, instance) {}
+
+    LocalRef& swap(LocalRef& other)
+    {
+        auto instance = other.mInstance;
+        other.mInstance = Ctx::mInstance;
+        Ctx::mInstance = instance;
+        return *this;
+    }
+
+public:
+    // Construct a LocalRef from a raw JNI local reference. Unlike Ref::From,
+    // LocalRef::Adopt returns a LocalRef that will delete the local reference
+    // when going out of scope.
+    static LocalRef Adopt(JNIType instance)
+    {
+        return LocalRef(Ref::FindEnv(), instance);
+    }
+
+    static LocalRef Adopt(JNIEnv* env, JNIType instance)
+    {
+        return LocalRef(env, instance);
+    }
+
+    // Copy constructor.
+    LocalRef(const LocalRef<Cls>& ref)
+        : Ctx(ref.mEnv, NewLocalRef(ref.mEnv, ref.mInstance))
+    {}
+
+    // Move constructor.
+    LocalRef(LocalRef<Cls>&& ref)
+        : Ctx(ref.mEnv, ref.mInstance)
+    {
+        ref.mInstance = nullptr;
+    }
+
+    explicit LocalRef(JNIEnv* env = Ref::FindEnv())
+        : Ctx(env, nullptr)
+    {}
+
+    // Construct a LocalRef from any Ref,
+    // which means creating a new local reference.
+    MOZ_IMPLICIT LocalRef(const Ref& ref)
+        : Ctx(Ref::FindEnv(), nullptr)
+    {
+        Ctx::mInstance = NewLocalRef(Ctx::mEnv, ref.Get());
+    }
+
+    LocalRef(JNIEnv* env, const Ref& ref)
+        : Ctx(env, NewLocalRef(env, ref.Get()))
+    {}
+
+    // Move a LocalRef<Object> into a LocalRef<Cls> without
+    // creating/deleting local references.
+    MOZ_IMPLICIT LocalRef(LocalRef<GenericObject>&& ref)
+        : Ctx(ref.mEnv, JNIType(ref.mInstance))
+    {
+        ref.mInstance = nullptr;
+    }
+
+    template<class C>
+    MOZ_IMPLICIT LocalRef(GenericLocalRef<C>&& ref)
+        : Ctx(ref.mEnv, ref.mInstance)
+    {
+        ref.mInstance = nullptr;
+    }
+
+    // Implicitly converts nullptr to LocalRef.
+    MOZ_IMPLICIT LocalRef(decltype(nullptr))
+        : Ctx(Ref::FindEnv(), nullptr)
+    {}
+
+    ~LocalRef()
+    {
+        if (Ctx::mInstance) {
+            Ctx::mEnv->DeleteLocalRef(Ctx::mInstance);
+            Ctx::mInstance = nullptr;
+        }
+    }
+
+    // Get the raw JNI reference that can be used as a return value.
+    // Returns the same JNI type (jobject, jstring, etc.) as the underlying Ref.
+    typename Ref::JNIType Forget()
+    {
+        const auto obj = Ctx::Get();
+        Ctx::mInstance = nullptr;
+        return obj;
+    }
+
+    LocalRef<Cls>& operator=(LocalRef<Cls> ref)
+    {
+        return swap(ref);
+    }
+
+    LocalRef<Cls>& operator=(const Ref& ref)
+    {
+        LocalRef<Cls> newRef(Ctx::mEnv, ref);
+        return swap(newRef);
+    }
+
+    LocalRef<Cls>& operator=(LocalRef<GenericObject>&& ref)
+    {
+        LocalRef<Cls> newRef(mozilla::Move(ref));
+        return swap(newRef);
+    }
+
+    template<class C>
+    LocalRef<Cls>& operator=(GenericLocalRef<C>&& ref)
+    {
+        LocalRef<Cls> newRef(mozilla::Move(ref));
+        return swap(newRef);
+    }
+
+    LocalRef<Cls>& operator=(decltype(nullptr))
+    {
+        LocalRef<Cls> newRef(Ctx::mEnv, nullptr);
+        return swap(newRef);
+    }
+};
+
+
+template<class Cls>
+class GlobalRef : public Cls::Ref
+{
+    using Ref = typename Cls::Ref;
+    using JNIType = typename Ref::JNIType;
+
+    static JNIType NewGlobalRef(JNIEnv* env, JNIType instance)
+    {
+        return JNIType(instance ? env->NewGlobalRef(instance) : nullptr);
+    }
+
+    GlobalRef& swap(GlobalRef& other)
+    {
+        auto instance = other.mInstance;
+        other.mInstance = Ref::mInstance;
+        Ref::mInstance = instance;
+        return *this;
+    }
+
+public:
+    GlobalRef()
+        : Ref(nullptr)
+    {}
+
+    // Copy constructor
+    GlobalRef(const GlobalRef& ref)
+        : Ref(NewGlobalRef(GetEnvForThread(), ref.mInstance))
+    {}
+
+    // Move constructor
+    GlobalRef(GlobalRef&& ref)
+        : Ref(ref.mInstance)
+    {
+        ref.mInstance = nullptr;
+    }
+
+    MOZ_IMPLICIT GlobalRef(const Ref& ref)
+        : Ref(NewGlobalRef(GetEnvForThread(), ref.Get()))
+    {}
+
+    GlobalRef(JNIEnv* env, const Ref& ref)
+        : Ref(NewGlobalRef(env, ref.Get()))
+    {}
+
+    MOZ_IMPLICIT GlobalRef(const LocalRef<Cls>& ref)
+        : Ref(NewGlobalRef(ref.Env(), ref.Get()))
+    {}
+
+    // Implicitly converts nullptr to GlobalRef.
+    MOZ_IMPLICIT GlobalRef(decltype(nullptr))
+        : Ref(nullptr)
+    {}
+
+    ~GlobalRef()
+    {
+        if (Ref::mInstance) {
+            Clear(GetEnvForThread());
+        }
+    }
+
+    // Get the raw JNI reference that can be used as a return value.
+    // Returns the same JNI type (jobject, jstring, etc.) as the underlying Ref.
+    typename Ref::JNIType Forget()
+    {
+        const auto obj = Ref::Get();
+        Ref::mInstance = nullptr;
+        return obj;
+    }
+
+    void Clear(JNIEnv* env)
+    {
+        if (Ref::mInstance) {
+            env->DeleteGlobalRef(Ref::mInstance);
+            Ref::mInstance = nullptr;
+        }
+    }
+
+    GlobalRef<Cls>& operator=(GlobalRef<Cls> ref)
+    {
+        return swap(ref);
+    }
+
+    GlobalRef<Cls>& operator=(const Ref& ref)
+    {
+        GlobalRef<Cls> newRef(ref);
+        return swap(newRef);
+    }
+
+    GlobalRef<Cls>& operator=(const LocalRef<Cls>& ref)
+    {
+        GlobalRef<Cls> newRef(ref);
+        return swap(newRef);
+    }
+
+    GlobalRef<Cls>& operator=(decltype(nullptr))
+    {
+        GlobalRef<Cls> newRef(nullptr);
+        return swap(newRef);
+    }
+};
+
+
+template<class Cls>
+class DependentRef : public Cls::Ref
+{
+    using Ref = typename Cls::Ref;
+
+public:
+    DependentRef(typename Ref::JNIType instance)
+        : Ref(instance)
+    {}
+
+    DependentRef(const DependentRef& ref)
+        : Ref(ref.Get())
+    {}
+};
+
+
+class StringParam;
+
+template<>
+class TypedObject<jstring> : public ObjectBase<TypedObject<jstring>, jstring>
+{
+    using Base = ObjectBase<TypedObject<jstring>, jstring>;
+
+public:
+    using Param = const StringParam&;
+
+    explicit TypedObject(const Context& ctx) : Base(ctx) {}
+
+    size_t Length() const
+    {
+        const size_t ret = Base::Env()->GetStringLength(Base::Instance());
+        MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+        return ret;
+    }
+
+    nsString ToString() const
+    {
+        const jchar* const str = Base::Env()->GetStringChars(
+                Base::Instance(), nullptr);
+        const jsize len = Base::Env()->GetStringLength(Base::Instance());
+
+        nsString result(reinterpret_cast<const char16_t*>(str), len);
+        Base::Env()->ReleaseStringChars(Base::Instance(), str);
+        return result;
+    }
+
+    nsCString ToCString() const
+    {
+        return NS_ConvertUTF16toUTF8(ToString());
+    }
+
+    // Convert jstring to a nsString.
+    operator nsString() const
+    {
+        return ToString();
+    }
+
+    // Convert jstring to a nsCString.
+    operator nsCString() const
+    {
+        return ToCString();
+    }
+};
+
+// Define a custom parameter type for String,
+// which accepts both String::Ref and nsAString/nsACString
+class StringParam : public String::Ref
+{
+    using Ref = String::Ref;
+
+private:
+    // Not null if we should delete ref on destruction.
+    JNIEnv* const mEnv;
+
+    static jstring GetString(JNIEnv* env, const nsAString& str)
+    {
+        const jstring result = env->NewString(
+                reinterpret_cast<const jchar*>(str.BeginReading()),
+                str.Length());
+        MOZ_CATCH_JNI_EXCEPTION(env);
+        return result;
+    }
+
+public:
+    MOZ_IMPLICIT StringParam(decltype(nullptr))
+        : Ref(nullptr)
+        , mEnv(nullptr)
+    {}
+
+    MOZ_IMPLICIT StringParam(const Ref& ref)
+        : Ref(ref.Get())
+        , mEnv(nullptr)
+    {}
+
+    MOZ_IMPLICIT StringParam(const nsAString& str, JNIEnv* env = Ref::FindEnv())
+        : Ref(GetString(env, str))
+        , mEnv(env)
+    {}
+
+    MOZ_IMPLICIT StringParam(const char16_t* str, JNIEnv* env = Ref::FindEnv())
+        : Ref(GetString(env, nsDependentString(str)))
+        , mEnv(env)
+    {}
+
+    MOZ_IMPLICIT StringParam(const nsACString& str, JNIEnv* env = Ref::FindEnv())
+        : Ref(GetString(env, NS_ConvertUTF8toUTF16(str)))
+        , mEnv(env)
+    {}
+
+    MOZ_IMPLICIT StringParam(const char* str, JNIEnv* env = Ref::FindEnv())
+        : Ref(GetString(env, NS_ConvertUTF8toUTF16(str)))
+        , mEnv(env)
+    {}
+
+    StringParam(StringParam&& other)
+        : Ref(other.Get())
+        , mEnv(other.mEnv)
+    {
+        other.mInstance = nullptr;
+    }
+
+    ~StringParam()
+    {
+        if (mEnv && Get()) {
+            mEnv->DeleteLocalRef(Get());
+        }
+    }
+
+    operator String::LocalRef() const
+    {
+        // We can't return our existing ref because the returned
+        // LocalRef could be freed first, so we need a new local ref.
+        return String::LocalRef(mEnv ? mEnv : Ref::FindEnv(), *this);
+    }
+};
+
+
+namespace detail {
+    template<typename T> struct TypeAdapter;
+}
+
+// Ref specialization for arrays.
+template<typename JNIType, class ElementType>
+class ArrayRefBase : public ObjectBase<TypedObject<JNIType>, JNIType>
+{
+    using Base = ObjectBase<TypedObject<JNIType>, JNIType>;
+
+public:
+    explicit ArrayRefBase(const Context<TypedObject<JNIType>, JNIType>& ctx)
+        : Base(ctx)
+    {}
+
+    static typename Base::LocalRef New(const ElementType* data, size_t length) {
+        using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+        static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                      "Size of native type must match size of JNI type");
+        JNIEnv* const jenv = mozilla::jni::GetEnvForThread();
+        auto result =
+            (jenv->*detail::TypeAdapter<ElementType>::NewArray)(length);
+        MOZ_CATCH_JNI_EXCEPTION(jenv);
+        (jenv->*detail::TypeAdapter<ElementType>::SetArray)(
+                result, jsize(0), length,
+                reinterpret_cast<const JNIElemType*>(data));
+        MOZ_CATCH_JNI_EXCEPTION(jenv);
+        return Base::LocalRef::Adopt(jenv, result);
+    }
+
+    size_t Length() const
+    {
+        const size_t ret = Base::Env()->GetArrayLength(Base::Instance());
+        MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+        return ret;
+    }
+
+    ElementType GetElement(size_t index) const
+    {
+        using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+        static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                      "Size of native type must match size of JNI type");
+
+        ElementType ret;
+        (Base::Env()->*detail::TypeAdapter<ElementType>::GetArray)(
+                Base::Instance(), jsize(index), 1,
+                reinterpret_cast<JNIElemType*>(&ret));
+        MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+        return ret;
+    }
+
+    nsTArray<ElementType> GetElements() const
+    {
+        using JNIElemType = typename detail::TypeAdapter<ElementType>::JNIType;
+        static_assert(sizeof(ElementType) == sizeof(JNIElemType),
+                      "Size of native type must match size of JNI type");
+
+        const jsize len = size_t(Base::Env()->GetArrayLength(Base::Instance()));
+
+        nsTArray<ElementType> array((size_t(len)));
+        array.SetLength(size_t(len));
+        (Base::Env()->*detail::TypeAdapter<ElementType>::GetArray)(
+                Base::Instance(), 0, len,
+                reinterpret_cast<JNIElemType*>(array.Elements()));
+        return array;
+    }
+
+    ElementType operator[](size_t index) const
+    {
+        return GetElement(index);
+    }
+
+    operator nsTArray<ElementType>() const
+    {
+        return GetElements();
+    }
+};
+
+#define DEFINE_PRIMITIVE_ARRAY_REF(JNIType, ElementType) \
+    template<> \
+    class TypedObject<JNIType> : public ArrayRefBase<JNIType, ElementType> \
+    { \
+    public: \
+        explicit TypedObject(const Context& ctx) \
+            : ArrayRefBase<JNIType, ElementType>(ctx) \
+        {} \
+    }
+
+DEFINE_PRIMITIVE_ARRAY_REF(jbooleanArray, bool);
+DEFINE_PRIMITIVE_ARRAY_REF(jbyteArray,    int8_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jcharArray,    char16_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jshortArray,   int16_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jintArray,     int32_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jlongArray,    int64_t);
+DEFINE_PRIMITIVE_ARRAY_REF(jfloatArray,   float);
+DEFINE_PRIMITIVE_ARRAY_REF(jdoubleArray,  double);
+
+#undef DEFINE_PRIMITIVE_ARRAY_REF
+
+
+class ByteBuffer : public ObjectBase<ByteBuffer, jobject>
+{
+public:
+    explicit ByteBuffer(const Context& ctx)
+        : ObjectBase<ByteBuffer, jobject>(ctx)
+    {}
+
+    static LocalRef New(void* data, size_t capacity)
+    {
+        JNIEnv* const env = GetEnvForThread();
+        const auto ret = LocalRef::Adopt(
+                env, env->NewDirectByteBuffer(data, jlong(capacity)));
+        MOZ_CATCH_JNI_EXCEPTION(env);
+        return ret;
+    }
+
+    void* Address()
+    {
+        void* const ret = Env()->GetDirectBufferAddress(Instance());
+        MOZ_CATCH_JNI_EXCEPTION(Env());
+        return ret;
+    }
+
+    size_t Capacity()
+    {
+        const size_t ret = size_t(Env()->GetDirectBufferCapacity(Instance()));
+        MOZ_CATCH_JNI_EXCEPTION(Env());
+        return ret;
+    }
+};
+
+
+template<>
+class TypedObject<jobjectArray>
+    : public ObjectBase<TypedObject<jobjectArray>, jobjectArray>
+{
+    using Base = ObjectBase<TypedObject<jobjectArray>, jobjectArray>;
+
+public:
+    explicit TypedObject(const Context& ctx) : Base(ctx) {}
+
+    size_t Length() const
+    {
+        const size_t ret = Base::Env()->GetArrayLength(Base::Instance());
+        MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+        return ret;
+    }
+
+    Object::LocalRef GetElement(size_t index) const
+    {
+        auto ret = Object::LocalRef::Adopt(
+                Base::Env(), Base::Env()->GetObjectArrayElement(
+                    Base::Instance(), jsize(index)));
+        MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+        return ret;
+    }
+
+    nsTArray<Object::LocalRef> GetElements() const
+    {
+        const jsize len = size_t(Base::Env()->GetArrayLength(Base::Instance()));
+
+        nsTArray<Object::LocalRef> array((size_t(len)));
+        for (jsize i = 0; i < len; i++) {
+            array.AppendElement(Object::LocalRef::Adopt(
+                    Base::Env(), Base::Env()->GetObjectArrayElement(
+                        Base::Instance(), i)));
+            MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+        }
+        return array;
+    }
+
+    Object::LocalRef operator[](size_t index) const
+    {
+        return GetElement(index);
+    }
+
+    operator nsTArray<Object::LocalRef>() const
+    {
+        return GetElements();
+    }
+
+    void SetElement(size_t index, Object::Param element) const
+    {
+        Base::Env()->SetObjectArrayElement(
+                Base::Instance(), jsize(index), element.Get());
+        MOZ_CATCH_JNI_EXCEPTION(Base::Env());
+    }
+};
+
+
+// Support conversion from LocalRef<T>* to LocalRef<Object>*:
+//   LocalRef<Foo> foo;
+//   Foo::GetFoo(&foo); // error because parameter type is LocalRef<Object>*.
+//   Foo::GetFoo(ReturnTo(&foo)); // OK because ReturnTo converts the argument.
+template<class Cls>
+class ReturnToLocal
+{
+private:
+    LocalRef<Cls>* const localRef;
+    LocalRef<Object> objRef;
+
+public:
+    explicit ReturnToLocal(LocalRef<Cls>* ref) : localRef(ref) {}
+    operator LocalRef<Object>*() { return &objRef; }
+
+    ~ReturnToLocal()
+    {
+        if (objRef) {
+            *localRef = mozilla::Move(objRef);
+        }
+    }
+};
+
+template<class Cls>
+ReturnToLocal<Cls> ReturnTo(LocalRef<Cls>* ref)
+{
+    return ReturnToLocal<Cls>(ref);
+}
+
+
+// Support conversion from GlobalRef<T>* to LocalRef<Object/T>*:
+//   GlobalRef<Foo> foo;
+//   Foo::GetFoo(&foo); // error because parameter type is LocalRef<Foo>*.
+//   Foo::GetFoo(ReturnTo(&foo)); // OK because ReturnTo converts the argument.
+template<class Cls>
+class ReturnToGlobal
+{
+private:
+    GlobalRef<Cls>* const globalRef;
+    LocalRef<Object> objRef;
+    LocalRef<Cls> clsRef;
+
+public:
+    explicit ReturnToGlobal(GlobalRef<Cls>* ref) : globalRef(ref) {}
+    operator LocalRef<Object>*() { return &objRef; }
+    operator LocalRef<Cls>*() { return &clsRef; }
+
+    ~ReturnToGlobal()
+    {
+        if (objRef) {
+            *globalRef = (clsRef = mozilla::Move(objRef));
+        } else if (clsRef) {
+            *globalRef = clsRef;
+        }
+    }
+};
+
+template<class Cls>
+ReturnToGlobal<Cls> ReturnTo(GlobalRef<Cls>* ref)
+{
+    return ReturnToGlobal<Cls>(ref);
+}
+
+} // namespace jni
+} // namespace mozilla
+
+#endif // mozilla_jni_Refs_h__
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