Add additional type aliases in field and method classes

Author: xezon

include/jni/field.hpp

@@ -16,6 +16,7 @@ namespace jni
 
         public:
             using TagType = TheTag;
+            using FieldType = T;
 
             Field(JNIEnv& env, const Class<TagType>& clazz, const char* name)
               : field(GetFieldID(env, clazz, name, TypeSignature<T>()()))

include/jni/method.hpp

@@ -19,6 +19,8 @@ namespace jni
 
         public:
             using TagType = TheTag;
+            using MethodType = R (Args...);
+            using ReturnType = R;
 
             Method(JNIEnv& env, const Class<TagType>& clazz, const char* name)
               : method(GetMethodID(env, clazz, name, TypeSignature<R (Args...)>()()))

include/jni/static_field.hpp

@@ -16,6 +16,7 @@ namespace jni
 
         public:
             using TagType = TheTag;
+            using FieldType = T;
 
             StaticField(JNIEnv& env, const Class<TagType>& clazz, const char* name)
               : field(GetStaticFieldID(env, clazz, name, TypeSignature<T>()()))

include/jni/static_method.hpp

@@ -19,6 +19,8 @@ namespace jni
 
         public:
             using TagType = TheTag;
+            using MethodType = R (Args...);
+            using ReturnType = R;
 
             StaticMethod(JNIEnv& env, const Class<TagType>& clazz, const char* name)
               : method(GetStaticMethodID(env, clazz, name, TypeSignature<R (Args...)>()()))