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diff --git a/widget/android/jni/Accessors.h b/widget/android/jni/Accessors.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_jni_Accessors_h__
+#define mozilla_jni_Accessors_h__
+
+#include <jni.h>
+
+#include "mozilla/jni/Refs.h"
+#include "mozilla/jni/Types.h"
+#include "mozilla/jni/Utils.h"
+#include "AndroidBridge.h"
+
+namespace mozilla {
+namespace jni {
+
+namespace detail {
+
+// Helper class to convert an arbitrary type to a jvalue, e.g. Value(123).val.
+struct Value {
+ explicit Value(jboolean z) { val.z = z; }
+ explicit Value(jbyte b) { val.b = b; }
+ explicit Value(jchar c) { val.c = c; }
+ explicit Value(jshort s) { val.s = s; }
+ explicit Value(jint i) { val.i = i; }
+ explicit Value(jlong j) { val.j = j; }
+ explicit Value(jfloat f) { val.f = f; }
+ explicit Value(jdouble d) { val.d = d; }
+ explicit Value(jobject l) { val.l = l; }
+
+ jvalue val;
+};
+
+} // namespace detail
+
+using namespace detail;
+
+// Base class for Method<>, Field<>, and Constructor<>.
+class Accessor {
+ static void GetNsresult(JNIEnv* env, nsresult* rv) {
+ if (env->ExceptionCheck()) {
+#ifdef MOZ_CHECK_JNI
+ env->ExceptionDescribe();
+#endif
+ env->ExceptionClear();
+ *rv = NS_ERROR_FAILURE;
+ } else {
+ *rv = NS_OK;
+ }
+ }
+
+ protected:
+ // Called after making a JNIEnv call.
+ template <class Traits>
+ static void EndAccess(const typename Traits::Owner::Context& ctx,
+ nsresult* rv) {
+ if (Traits::exceptionMode == ExceptionMode::ABORT) {
+ MOZ_CATCH_JNI_EXCEPTION(ctx.Env());
+
+ } else if (Traits::exceptionMode == ExceptionMode::NSRESULT) {
+ GetNsresult(ctx.Env(), rv);
+ }
+ }
+};
+
+// Member<> is used to call a JNI method given a traits class.
+template <class Traits, typename ReturnType = typename Traits::ReturnType>
+class Method : public Accessor {
+ typedef Accessor Base;
+ typedef typename Traits::Owner::Context Context;
+
+ protected:
+ static jmethodID sID;
+
+ static void BeginAccess(const Context& ctx) {
+ MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+ static_assert(Traits::dispatchTarget == DispatchTarget::CURRENT,
+ "Dispatching not supported for method call");
+
+ if (sID) {
+ return;
+ }
+
+ if (Traits::isStatic) {
+ MOZ_ALWAYS_TRUE(
+ sID = AndroidBridge::GetStaticMethodID(
+ ctx.Env(), ctx.ClassRef(), Traits::name, Traits::signature));
+ } else {
+ MOZ_ALWAYS_TRUE(
+ sID = AndroidBridge::GetMethodID(ctx.Env(), ctx.ClassRef(),
+ Traits::name, Traits::signature));
+ }
+ }
+
+ static void EndAccess(const Context& ctx, nsresult* rv) {
+ return Base::EndAccess<Traits>(ctx, rv);
+ }
+
+ public:
+ template <typename... Args>
+ static ReturnType Call(const Context& ctx, nsresult* rv,
+ const Args&... args) {
+ JNIEnv* const env = ctx.Env();
+ BeginAccess(ctx);
+
+ jvalue jargs[] = {Value(TypeAdapter<Args>::FromNative(env, args)).val...};
+
+ auto result = TypeAdapter<ReturnType>::ToNative(
+ env, Traits::isStatic ? (env->*TypeAdapter<ReturnType>::StaticCall)(
+ ctx.ClassRef(), sID, jargs)
+ : (env->*TypeAdapter<ReturnType>::Call)(
+ ctx.Get(), sID, jargs));
+
+ EndAccess(ctx, rv);
+ return result;
+ }
+};
+
+// Define sID member.
+template <class T, typename R>
+jmethodID Method<T, R>::sID;
+
+// Specialize void because C++ forbids us from
+// using a "void" temporary result variable.
+template <class Traits>
+class Method<Traits, void> : public Method<Traits, bool> {
+ typedef Method<Traits, bool> Base;
+ typedef typename Traits::Owner::Context Context;
+
+ public:
+ template <typename... Args>
+ static void Call(const Context& ctx, nsresult* rv, const Args&... args) {
+ JNIEnv* const env = ctx.Env();
+ Base::BeginAccess(ctx);
+
+ jvalue jargs[] = {Value(TypeAdapter<Args>::FromNative(env, args)).val...};
+
+ if (Traits::isStatic) {
+ env->CallStaticVoidMethodA(ctx.ClassRef(), Base::sID, jargs);
+ } else {
+ env->CallVoidMethodA(ctx.Get(), Base::sID, jargs);
+ }
+
+ Base::EndAccess(ctx, rv);
+ }
+};
+
+// Constructor<> is used to construct a JNI instance given a traits class.
+template <class Traits>
+class Constructor : protected Method<Traits, typename Traits::ReturnType> {
+ typedef typename Traits::Owner::Context Context;
+ typedef typename Traits::ReturnType ReturnType;
+ typedef Method<Traits, ReturnType> Base;
+
+ public:
+ template <typename... Args>
+ static ReturnType Call(const Context& ctx, nsresult* rv,
+ const Args&... args) {
+ JNIEnv* const env = ctx.Env();
+ Base::BeginAccess(ctx);
+
+ jvalue jargs[] = {Value(TypeAdapter<Args>::FromNative(env, args)).val...};
+
+ auto result = TypeAdapter<ReturnType>::ToNative(
+ env, env->NewObjectA(ctx.ClassRef(), Base::sID, jargs));
+
+ Base::EndAccess(ctx, rv);
+ return result;
+ }
+};
+
+// Field<> is used to access a JNI field given a traits class.
+template <class Traits>
+class Field : public Accessor {
+ typedef Accessor Base;
+ typedef typename Traits::Owner::Context Context;
+ typedef typename Traits::ReturnType GetterType;
+ typedef typename Traits::SetterType SetterType;
+
+ private:
+ static jfieldID sID;
+
+ static void BeginAccess(const Context& ctx) {
+ MOZ_ASSERT_JNI_THREAD(Traits::callingThread);
+ static_assert(Traits::dispatchTarget == DispatchTarget::CURRENT,
+ "Dispatching not supported for field access");
+
+ if (sID) {
+ return;
+ }
+
+ if (Traits::isStatic) {
+ MOZ_ALWAYS_TRUE(
+ sID = AndroidBridge::GetStaticFieldID(
+ ctx.Env(), ctx.ClassRef(), Traits::name, Traits::signature));
+ } else {
+ MOZ_ALWAYS_TRUE(sID = AndroidBridge::GetFieldID(ctx.Env(), ctx.ClassRef(),
+ Traits::name,
+ Traits::signature));
+ }
+ }
+
+ static void EndAccess(const Context& ctx, nsresult* rv) {
+ return Base::EndAccess<Traits>(ctx, rv);
+ }
+
+ public:
+ static GetterType Get(const Context& ctx, nsresult* rv) {
+ JNIEnv* const env = ctx.Env();
+ BeginAccess(ctx);
+
+ auto result = TypeAdapter<GetterType>::ToNative(
+ env, Traits::isStatic
+ ?
+
+ (env->*TypeAdapter<GetterType>::StaticGet)(ctx.ClassRef(), sID)
+ :
+
+ (env->*TypeAdapter<GetterType>::Get)(ctx.Get(), sID));
+
+ EndAccess(ctx, rv);
+ return result;
+ }
+
+ static void Set(const Context& ctx, nsresult* rv, SetterType val) {
+ JNIEnv* const env = ctx.Env();
+ BeginAccess(ctx);
+
+ if (Traits::isStatic) {
+ (env->*TypeAdapter<SetterType>::StaticSet)(
+ ctx.ClassRef(), sID, TypeAdapter<SetterType>::FromNative(env, val));
+ } else {
+ (env->*TypeAdapter<SetterType>::Set)(
+ ctx.Get(), sID, TypeAdapter<SetterType>::FromNative(env, val));
+ }
+
+ EndAccess(ctx, rv);
+ }
+};
+
+// Define sID member.
+template <class T>
+jfieldID Field<T>::sID;
+
+} // namespace jni
+} // namespace mozilla
+
+#endif // mozilla_jni_Accessors_h__
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