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#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
{
Value(jboolean z) { val.z = z; }
Value(jbyte b) { val.b = b; }
Value(jchar c) { val.c = c; }
Value(jshort s) { val.s = s; }
Value(jint i) { val.i = i; }
Value(jlong j) { val.j = j; }
Value(jfloat f) { val.f = f; }
Value(jdouble d) { val.d = d; }
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.RawClassRef(), 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.RawClassRef(), 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.RawClassRef(), 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.RawClassRef(), 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.RawClassRef(), 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;
// Define the sClassRef member declared in Refs.h and
// used by Method and Field above.
template<class C, typename T> jclass Context<C, T>::sClassRef;
} // namespace jni
} // namespace mozilla
#endif // mozilla_jni_Accessors_h__
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