My bad, what does the sketch of the plan *look like*? -Andy ________________________________________ From: Andrew Christianson Sent: Thursday, May 4, 2017 10:59:07 AM To: dev@nifi.apache.org Subject: Re: MiNiFi C++ Expression Language
What does the sketch of the plan to do the separate implementation? Write a flex/bison grammar, hook it into the cmake build, and start using it? Any constraints on features or syntax that this separate implementation must support? -Andy ________________________________________ From: Matt Burgess <mattyb...@gmail.com> Sent: Thursday, May 4, 2017 9:37:34 AM To: dev@nifi.apache.org Subject: Re: MiNiFi C++ Expression Language No plans that I know of. In the meantime, EL support for MiNiFi is kind of held hostage, so maybe the separate implementation is more viable in the nearer term. If/When the ANTLR4 upgrade happens, we could replace whatever exists by then with the cross-platform ANTLR target generation, and test the whole kit and caboodle. Anyone out there familiar with the aforementioned tools (or willing to hand-roll one)? What do you think about this "EL bootstrapping" approach? Thanks, Matt > On May 4, 2017, at 9:22 AM, Andrew Christianson > <andrew.christian...@nextcentury.com> wrote: > > Got it. So the crux of the problem is porting from v3 to v4, plus the added > uncertainty of the C++ v4 target. > > I'm assuming that NiFi wants to eventually get onto v4 anyway. If that's the > case, then porting to v4 is probably the ticket. Are there any concrete plans > to do so in the NiFi mother project yet? > > -Andy > ________________________________________ > From: Matt Burgess <mattyb...@gmail.com> > Sent: Thursday, May 4, 2017 9:18:00 AM > To: dev@nifi.apache.org > Subject: Re: MiNiFi C++ Expression Language > > Correct, the current NiFi EL grammar is ANTLR3. > > >> On May 4, 2017, at 9:12 AM, Andrew Christianson >> <andrew.christian...@nextcentury.com> wrote: >> >> Do I understand correctly that NiFi is currently using ANTLRv3? >> ________________________________________ >> From: Matt Burgess <mattyb...@gmail.com> >> Sent: Thursday, May 4, 2017 9:05:35 AM >> To: dev@nifi.apache.org >> Subject: Re: MiNiFi C++ Expression Language >> >> I haven't used Flex/Bison since a trivial example in college, so I'm not >> sure about the LOE for getting that set up, maybe there's a Maven-built >> project out there that we could look at for inspiration, but that seems >> unlikely :) >> >> An ANTLR4 refactor (assuming the C++ target is in good shape) would give us >> NiFi/MiNiFi EL compatibility (and full-featured EL support in MiNiFi C++), >> but we'd have to accept the risks of introducing bugs, regressions, etc. as >> a result of the refactor. Basically we'd just need to test the heck out of >> it on all platforms, which isn't a bad thing but adds to the LOE for the >> ANTLR4 upgrade, versus a smaller testing "surface" for incremental >> development of a C/C++ based grammar. >> >> >> On May 4, 2017, at 8:51 AM, Andrew Christianson >> <andrew.christian...@nextcentury.com> wrote: >> >>>> I tried a quick ANTLR4 upgrade myself, it's indeed a big job to refactor >>>> the existing grammar. Since the source and target for MiNiFi C++ is, well, >>>> C++, an alternative could be to use lex/yacc (Flex/Bison) [1], Lemon [2], >>>> Ragel [3], etc. The downside is maintaining two grammars, but we are doing >>>> that with all the MiNiFi components already. The upside is being able to >>>> support EL incrementally as the grammar is developed. What do you think? >>> >>> This seems like a pragmatic approach. What's the level-of-effort required >>> to do the initial grammar port and set up the build tooling? Less than >>> refactoring for ANTLR4? I'm not as familiar with the EL grammar situation. >>> >>> -Andy >>> ________________________________________ >>> From: Matt Burgess <mattyb...@gmail.com> >>> Sent: Thursday, May 4, 2017 8:46:20 AM >>> To: dev@nifi.apache.org >>> Subject: Re: MiNiFi C++ Expression Language >>> >>> I tried a quick ANTLR4 upgrade myself, it's indeed a big job to refactor >>> the existing grammar. Since the source and target for MiNiFi C++ is, well, >>> C++, an alternative could be to use lex/yacc (Flex/Bison) [1], Lemon [2], >>> Ragel [3], etc. The downside is maintaining two grammars, but we are doing >>> that with all the MiNiFi components already. The upside is being able to >>> support EL incrementally as the grammar is developed. What do you think? >>> >>> Regards, >>> Matt >>> >>> [1] http://dinosaur.compilertools.net/ >>> [2] http://www.hwaci.com/sw/lemon/ >>> [3] http://www.colm.net/open-source/ragel/ >>> >>> >>> >>> Sent from my iPhone >>>> On May 4, 2017, at 8:13 AM, Marc P. <marc.par...@gmail.com> wrote: >>>> >>>> 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.christian...@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
