Disclaimer: The fix below is intended to solve a specific problem with some dependencies conflict, mostly databinding issues can cause this error but are only a consequence of wrong XML or code and the solution below will not work in this case. Double check your XML/code correctness before trying the below solution. This is a … Read more
Ok, let’s build a simple math example. Building an AST is totally overkill for such a task but it’s a nice way to show the principle. I’ll do it in C# but the Java version would be very similar. The grammar First, let’s write a very basic math grammar to work with: grammar Math; compileUnit … Read more
Since I’ve had a little bit of a struggle with the two existing answers, I’d like to share the solution I ended up with. First of all I created my own version of an ErrorListener like Sam Harwell suggested: public class ThrowingErrorListener extends BaseErrorListener { public static final ThrowingErrorListener INSTANCE = new ThrowingErrorListener(); @Override public … Read more
ANTLR 4 For predicates in ANTLR 4, checkout these stackoverflow Q&A’s: Syntax of semantic predicates in Antlr4 Semantic predicates in ANTLR4? ANTLR 3 A semantic predicate is a way to enforce extra (semantic) rules upon grammar actions using plain code. There are 3 types of semantic predicates: validating semantic predicates; gated semantic predicates; disambiguating semantic … Read more
Note: this answer is for ANTLR3! If you’re looking for an ANTLR4 example, then this Q&A demonstrates how to create a simple expression parser, and evaluator using ANTLR4. You first create a grammar. Below is a small grammar that you can use to evaluate expressions that are built using the 4 basic math operators: +, … Read more