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From Andrew Christianson <andrew.christian...@nextcentury.com>
Subject Re: MiNiFi C++ Expression Language
Date Thu, 04 May 2017 12:47:17 GMT
> I am not aware of it being actively worked [1]. This would require using
> ANTLR4, but I don't believe C++ support is well tested [2].  Someone can
> correct me if I'm wrong, but there would have to be changes to both sides.

Both sides as in ANTLR4 and MiNiFi, or as in MiNiFi and NiFi?

> It generated code, but I'm
> uncertain of cross platform compatibility with the expression language. If
> that's not expected or required that will remove some limitations as a
> result of moving to ANTLR4.

Similarly, do you mean compatibility between NiFi and MiNiFi, or the OS/CPU platform? If we're
talking compatibility between NiFi and MiNiFi on the expr language, maybe Aldrin or Joe has
the answer on whether this is a design goal/requirement.

On a side note, have we looked into porting the grammar to bison? Bison is significantly more
tested/supported. It is GNU, but my understanding is that the generated code is not tied to
GNU, just the generator (bison). Calling it as part of the build process should be compatible
with Apache.

- Andy
________________________________________
From: Marc P. <marc.parisi@gmail.com>
Sent: Thursday, May 4, 2017 8:13:15 AM
To: dev@nifi.apache.org
Subject: Re: MiNiFi C++ Expression Language

Andrew,
  I am not aware of it being actively worked [1]. This would require using
ANTLR4, but I don't believe C++ support is well tested [2].  Someone can
correct me if I'm wrong, but there would have to be changes to both sides.
I attempted a quick straw man with grammars, but didn't take it very far
after making initial changes to the grammar. It generated code, but I'm
uncertain of cross platform compatibility with the expression language. If
that's not expected or required that will remove some limitations as a
result of moving to ANTLR4.

[1] https://issues.apache.org/jira/browse/MINIFI-140
[2] http://www.soft-gems.net/index.php/tools/49-the-antlr4-c-target-is-here

On Thu, May 4, 2017 at 8:07 AM, Andrew Christianson <
andrew.christianson@nextcentury.com> wrote:

> All,
>
> I see that we do not have support for the expression language yet in
> MiNiFi C++. Is anyone actively working on this, and if so, is there an ETA?
> If no one is working on it, is there a general plan for how it should be
> implemented? I think I recall seeing references to ANTLR

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