Antlr4 Javascript Visitor

Question

I\'m currently trying to develope a JavaScript Compiler with the help of an Antlr4 Visitor. I\'ve got this already implemented with Java but cannot figure out how to do this

Answer 1

The basic idea behind the visitor is that you have to handle all the logic by yourself. To do this I generated the visitor using antlr. My own visitor overrides all functions that I need to implement my logic.

1. create lexer, tokens, ...

   var antlr4 = require('antlr4/index');
   var SimpleJavaLexer = require('generated/GrammarLexer');
   var SimpleJavaParser = require('generated/GrammarParser');
   var SimpleJavaVisitor = require('generated/GrammarVisitor');
   var Visitor = require('./Visitor');
   
   var input = "TestInput";
   var chars = new antlr4.InputStream(input);
   var lexer = new GrammarLexer.GrammarLexer(chars);
   var tokens = new antlr4.CommonTokenStream(lexer);
   var parser = new GrammarParser.GrammarParser(tokens);
   var visitor = new Visitor.Visitor();
   parser.buildParseTrees = true;
   var tree = parser.parse();
   

2. and call your entry function

   visitor.visitTest(tree);
   

3. inside your new visitor you need to implement your new logic to determine which function to call next (the right context as argument is important)

   var GrammarVisitor =     require('generated/GrammarVisitor').GrammarVisitor;
   
   function Visitor () {
     SimpleJavaVisitor.call(this);
     return this;
   };
   
   Visitor.prototype = Object.create(GrammarVisitor.prototype);
   Visitor.prototype.constructor = Visitor;
   Visitor.prototype.visitTest = function(ctx) {
       // implement logic to determine which function to visit
       // then call next function and with the right context
       this.visitBlock(ctx.block());
   };
   

I hope you can understand my basic idea. If anybody got any questions just comment.