antlr4ts - TypeScript/JavaScript target for ANTLR 4

Overview

Releases: See the GitHub Releases page for release notes and links to the distribution
Feedback: Use GitHub Issues for issues (bugs, enhancements, features, and questions)

Requirements

This project has separate requirements for developers and end users.

💡 The requirements listed on this page only cover user scenarios - that is, scenarios where developers wish to use ANTLR 4 for parsing tasks inside of a TypeScript application. If you are interested in contributing to ANTLR 4 itself, see CONTRIBUTING.md for contributor documentation.

End user requirements

Parsers generated by the ANTLR 4 TypeScript target have a runtime dependency on the antlr4ts package. The package is tested and known to work with Node.js 6.7.

Development requirements

The tool used to generate TypeScript code from an ANTLR 4 grammar is written in Java. To fully utilize the ANTLR 4 TypeScript target (including the ability to regenerate code from a grammar file after changes are made), a Java Runtime Environment (JRE) needs to be installed on the developer machine. The generated code itself uses several features new to TypeScript 2.0.

Java Runtime Environment 1.6+ (1.8+ recommended)
TypeScript 2.0+

Getting started

Install antlr4ts as a runtime dependency using your preferred package manager.

npm install antlr4ts --save

yarn add antlr4ts

Install antlr4ts-cli as a development dependency using your preferred package manager.

npm install antlr4ts-cli --save-dev

yarn add -D antlr4ts-cli

Add a grammar to your project, e.g. path/to/MyGrammar.g4

Add a script to package.json for compiling your grammar to TypeScript

"scripts": {
  // ...
  "antlr4ts": "antlr4ts -visitor path/to/MyGrammar.g4"
}

Use your grammar in TypeScript

import { ANTLRInputStream, CommonTokenStream } from 'antlr4ts';

// Create the lexer and parser
let inputStream = new ANTLRInputStream("text");
let lexer = new MyGrammarLexer(inputStream);
let tokenStream = new CommonTokenStream(lexer);
let parser = new MyGrammarParser(tokenStream);

// Parse the input, where `compilationUnit` is whatever entry point you defined
let tree = parser.compilationUnit();

The two main ways to inspect the tree are by using a listener or a visitor, you can read about the differences between the two here.

Listener Approach

// ...
import { MyGrammarParserListener } from './MyGrammarParserListener'
import { FunctionDeclarationContext } from './MyGrammarParser'
import { ParseTreeWalker } from 'antlr4ts/tree/ParseTreeWalker'


class EnterFunctionListener implements MyGrammarParserListener {
  // Assuming a parser rule with name: `functionDeclaration`
  enterFunctionDeclaration(context: FunctionDeclarationContext) {
    console.log(`Function start line number ${context._start.line}`)
    // ...
  }

  // other enterX functions...
}

// Create the listener
const listener: MyGrammarParserListener = new EnterFunctionListener();
// Use the entry point for listeners
ParseTreeWalker.DEFAULT.walk(listener, tree)

Visitor Approach

Note you must pass the -visitor flag to antlr4ts to get the generated visitor file.

// ...
import { MyGrammarParserVisitor } from './MyGrammarParserVisitor'
import { AbstractParseTreeVisitor } from 'antlr4ts/tree/AbstractParseTreeVisitor'

// Extend the AbstractParseTreeVisitor to get default visitor behaviour
class CountFunctionsVisitor extends AbstractParseTreeVisitor<number> implements MyGrammarParserVisitor<number> {

  defaultResult() {
    return 0
  }

  aggregateResult(aggregate: number, nextResult: number) {
    return aggregate + nextResult
  }

  visitFunctionDeclaration(context: FunctionDeclarationContext): number {
    return 1 + super.visitChildren(context)
  }
}

// Create the visitor
const countFunctionsVisitor = new CountFunctionsVisitor()
// Use the visitor entry point
countFunctionsVisitor.visit(tree)

ng-galien/antlr4ts