The Definitive ANTLR 4 Reference, 2nd Edition

Accessing Token and Rule Attributes

Let’s use the CSV grammar from ​Parsing Comma-Separated Values​ as a foundation for exploring some more action-related features. We’re going to build an application that creates a map from column name to field for each row and prints out information gained from parsing the data. Our goal here is really just to learn more about rule-related actions and attributes.

First, let’s take a look at how to define local variables using the locals section. As with parameters and return values, the declarations in a locals section become fields in the rule context object. Because we get a new rule context object for every rule invocation, we get a new copy of the locals as we’d expect. The following augmented ...