1 files changed, 251 insertions, 0 deletions
diff --git a/widget/android/jni/Accessors.h b/widget/android/jni/Accessors.h
new file mode 100644
index 0000000000..7496cbcb5a
--- /dev/null
+++ b/widget/android/jni/Accessors.h
@@ -0,0 +1,251 @@
+/* -*- 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__