As mentioned by Sam (280Z28), ANTLR 4 does not have rewrite operators. When generating the parser, ANTLR 4 creates some listener classes that you can use to listen for “enter” and “exit” events of all parser rules. Also, ANTLR 4 supports “direct left recursive rules”, so your expression rules can be defined in a single … Read more
Negating can occur inside lexer and parser rules. Inside lexer rules you can negate characters, and inside parser rules you can negate tokens (lexer rules). But both lexer- and parser rules can only negate either single characters, or single tokens, respectively. A couple of examples: lexer rules To match one or more characters except lowercase … 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
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