[incubator-kie-drools-5948] [new-parser] Broken testIncompatibleListO…

[tkobayas]

…nAccumulateFunction

Issue:

• [new-parser] Broken testIncompatibleListOnAccumulateFunction #5948

[tkobayas]

This is not an elegant change. But in the previous rule, chunk? for the DRL_ACTION greedily eats DRL_RESULT result. So I changed to this one, which makes DRL_RESULT higher priority. If there is a better way to write, please let me know.

[yurloc]

FYI, I've come up with a chunk rule version that can do parenthesis matching and nesting and is not greedy:

chunk : .*? (LPAREN chunk RPAREN .*?)* ;

If you want to experiment, change the chunk rule like that and revert lines 343-344. BUT there seems to be a serious performance problem with this approach as manifested by org.drools.testcoverage.regression.FusionAfterBeforeTest#testExpireEventsWhenSharingAllRules that times out with this chunk version.

I was curious if it's possible to make the chunk rule behave the same as the nesting chunk method in the old parser. It's nice that it can be done but it seems unusable for larger inputs. It's a reminder that we should be careful about using nongreedy parser subrules as also suggested in the docs:

Nongreedy subrules should be used sparingly because they complicate the recognition problem and sometimes make it tricky to decipher how the lexer will match text.

[tkobayas]

Thanks, @yurloc . I confirmed what you wrote. So the current fix would be this PR as is, and then we will consider "expected value format" rather than chunk, so that we can reduce the ambiguity, right? I listed it in #5972

[tkobayas]

@yurloc @mariofusco @gitgabrio Please review, thanks!