antlr4

问题 I\'ve been searching A LOT about this and I couldn\'t find anything useful that REALLY helps me build an AST. I already know that ANTLR4 doesn\'t build AST like ANTLR3 used to do. Everyone say: \"Hey, use visitors!\", but I couldn\'t find any example or more detailed explanation on HOW can I do this... I have a grammar must like C, but with every commands written in Portuguese (portuga programming language). I can easily generate the parse tree using ANTLR4. My question is: What I need to do

问题 I\'d like to get started with ANTLR, but after spending a few hours reviewing the examples at the antlr.org site, I still can\'t get a clear understanding of the grammar to Java process. Is there some simple example, something like a four-operations calculator implemented with ANTLR going through the parser definition and all the way to the Java source code? 回答1: Note : this answer is for ANTLR3 ! If you're looking for an ANTLR4 example, then this Q&A demonstrates how to create a simple

问题 What is a semantic predicate in ANTLR? 回答1: ANTLR 4 For predicates in ANTLR 4, checkout these stack overflow 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 predicates. Example grammar Let's say you have a block of text consisting