Reduce repetition in generated C bindings.

[mahesh-hegde]

Currently generated code makes heavy use of in-line method calls and error checks. There's a lot of repetition.

FFI_PLUGIN_EXPORT
jobject com_fasterxml_jackson_core_JsonParser_nextToken(jobject self_) {
    load_env();
    load_class_gr(&_c_com_fasterxml_jackson_core_JsonParser, "com/fasterxml/jackson/core/JsonParser");
    if (_c_com_fasterxml_jackson_core_JsonParser == NULL) return (jobject)0;
    load_method(_c_com_fasterxml_jackson_core_JsonParser, &_m_com_fasterxml_jackson_core_JsonParser_nextToken, "nextToken", "()Lcom/fasterxml/jackson/core/JsonToken;");
    if (_m_com_fasterxml_jackson_core_JsonParser_nextToken == NULL) return (jobject)0;
    jobject _result = (*jniEnv)->CallObjectMethod(jniEnv, self_, _m_com_fasterxml_jackson_core_JsonParser_nextToken);
    return to_global_ref(_result);
}

Here, a lot of stuff is repetitive, and will probably inflate the dylib size.

Probably this can be reduced to

FFI_PLUGIN_EXPORT
jobject com_fasterxml_jackson_core_JsonParser_nextToken(jobject self_) {
    CallObjectMethodHelper(
        &_c_com_fasterxml_jackson_core_JsonParser, // variable holding class reference
        "com/fasterxml/jackson/core/JsonParser",          // class name literal
       &_m_com_fasterxml_jackson_core_JsonParser_nextToken, // variable holding a method ID
       "nextToken", "()Lcom/fasterxml/jackson/core/JsonToken;" // method name and signature literals
      self_,
      // possibly next arguments, maybe variadic list.
   );
}

theoretically, the best compression one can achieve is storing the identifying tuple of a method to a table, so nothing is duplicated. But realistically, I think there's some low hanging fruit here.

[mahesh-hegde]

cc @dcharkes

Also, related issue regarding generated C code #788. I think that can be fixed along with this.

[mahesh-hegde]

Closing this in favor of #660