Syntax of semantic predicates in Antlr4

Question

In What is a \'semantic predicate\' in ANTLR3? Bart Kiers gives a very well overview about the different semantic predicates in Antlr3.

Too bad the syntax/semantics

Answer 1

There is now just a single type of semantic predicates, which looks like this:

{ <<boolean-epxression>> }?

And the input attribute from the abstract class Parser (which your generated parser extends from) now has an underscore in front of it.

So, in your case, the following ANTLR v3 syntax:

{input.LT(1).getType() == RBRACE}? =>

would look like this in ANTLR v4:

{_input.LT(1).getType() == RBRACE}?