What would be the benefit of switching to ANTLR 4 as a parser generator?

Due to the lack of significant improvements of JavaCC over the last years, I got the impression one should think about a switch of the parser generator.

After playing around and testing a bit of ANLTR 4 I am quite impressed about the easieness to transform and improve JavaCCs JSQLParser grammar to ANTLR 4. Still there are some things to solve:

• keywords as identifier: solution would be like now
• deparsing has to be separated again since the tree node classes of ANTLR could not be provided, like in JavaCC but are automatically generated
• tooling around JSqlParser should be rebuild (e.g. TableNameExtractor)

But there are significant improvements automatically at hand.

• ANTRL 4 generates listener and visitors for the parse tree.
• semantic predicates to disable rules
• the grammar is much easiear to read
• automatic operator precedence

I appreciate any comments to this.

Maybe there is another generator at hand that would be even better to use.

Update: After playing around with JJTree a bit, I noticed that most of my significant improvements of ANTLR 4 are already there.

• listener and visitor patterns are generated on demand

• the readability of the grammar is no point, because I did not compare a cleaned up JavaCC grammar with the clean ANTLR 4 grammar, using ANTLR 4 I would also like to have some container objects (e.g. Select) created

• semantic predicates to disable rules are not available but not needed at the moment, lexical states are there

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Therefore the a significant improvement would be automatic operator precedence, which would result in a smaller grammar. A significant disadvantage would be performance. JavaCC (at the moment) outperforms ANTLR 4.

The discussion took place (here)<issues/557>.