MyPlusMinusVisitor.js

// jshint ignore: start
var antlr4 = require('antlr4/index');

// This class defines a complete generic visitor for a parse tree produced by PlusMinusParser.

function MyPlusMinusVisitor() {
	antlr4.tree.ParseTreeVisitor.call(this);
	return this;
}

MyPlusMinusVisitor.prototype = Object.create(antlr4.tree.ParseTreeVisitor.prototype);
MyPlusMinusVisitor.prototype.constructor = MyPlusMinusVisitor;

// Visit a parse tree produced by PlusMinusParser#statement.
MyPlusMinusVisitor.prototype.visitInput = function(ctx) {
    var operation = ctx.plusOrMinus(),
        operationConstructorString,
        operationVisitFnName;

    // operation is plus or minus, but how can I tell which one?
    // Taking it from the name of the constructor of the child (very ugly)
    operationConstructorString = operation.constructor.toString();
    operationConstructorString = operationConstructorString.substr('function '.length);
    operationConstructorString = operationConstructorString.substr(0, operationConstructorString.indexOf('('));

    operationVisitFnName = "visit" + operationConstructorString.substring(0, operationConstructorString.length - "context".length);

    // Here I finally have the visit function that I need, visitPlusOp or visitMinusOp
    return this[operationVisitFnName](operation);
};

// Visit a parse tree produced by PlusMinusParser#Plus.
MyPlusMinusVisitor.prototype.visitPlus = function(ctx) {
    return parseInt(ctx.numberLeft().getText(), 10) + parseInt(ctx.numberRight().getText(), 10);

};


// Visit a parse tree produced by PlusMinusParser#Minus.
MyPlusMinusVisitor.prototype.visitMinus = function(ctx) {
    return parseInt(ctx.numberLeft().getText()) - parseInt(ctx.numberRight().getText(), 10);
};




exports.MyPlusMinusVisitor = MyPlusMinusVisitor;