antlr4ts

What is antlr4ts?

The antlr4ts npm package is a TypeScript target for ANTLR (Another Tool for Language Recognition), which is a powerful parser generator for reading, processing, executing, or translating structured text or binary files. It is widely used for building languages, tools, and frameworks.

What are antlr4ts's main functionalities?

Grammar Definition

Define a grammar using ANTLR syntax. This example defines a simple grammar that recognizes the word 'hello' followed by an identifier.

grammar Hello;

r  : 'hello' ID;
ID : [a-z]+;
WS : [ \t\r\n]+ -> skip;

Generating Parser and Lexer

Generate a lexer and parser from the defined grammar and use them to parse an input string. This example shows how to create a lexer and parser for the 'Hello' grammar and parse the input 'hello world'.

const antlr4ts = require('antlr4ts');
const HelloLexer = require('./HelloLexer');
const HelloParser = require('./HelloParser');

const input = 'hello world';
const inputStream = antlr4ts.CharStreams.fromString(input);
const lexer = new HelloLexer.HelloLexer(inputStream);
const tokenStream = new antlr4ts.CommonTokenStream(lexer);
const parser = new HelloParser.HelloParser(tokenStream);
const tree = parser.r();
console.log(tree.toStringTree(parser));

Tree Walking

Walk the parse tree using a custom listener. This example shows how to create a custom listener that logs when entering a rule and how to walk the parse tree using this listener.

const antlr4ts = require('antlr4ts');
const HelloLexer = require('./HelloLexer');
const HelloParser = require('./HelloParser');
const HelloListener = require('./HelloListener');

class CustomHelloListener extends HelloListener.HelloListener {
  enterR(ctx) {
    console.log('Entering R: ' + ctx.getText());
  }
}

const input = 'hello world';
const inputStream = antlr4ts.CharStreams.fromString(input);
const lexer = new HelloLexer.HelloLexer(inputStream);
const tokenStream = new antlr4ts.CommonTokenStream(lexer);
const parser = new HelloParser.HelloParser(tokenStream);
const tree = parser.r();

const listener = new CustomHelloListener();
antlr4ts.tree.ParseTreeWalker.DEFAULT.walk(listener, tree);

Other packages similar to antlr4ts

pegjs

PEG.js is a simple parser generator for JavaScript that produces fast parsers with excellent error reporting. Unlike ANTLR, which uses LL(*) parsing, PEG.js uses Parsing Expression Grammars (PEGs). PEG.js is simpler to use for smaller projects but may not handle complex grammars as efficiently as ANTLR.

nearley

Nearley is a fast, powerful parser toolkit for JavaScript. It uses Earley parsing, which can parse all context-free grammars, including ambiguous ones. Nearley is more flexible than ANTLR but can be slower for certain types of grammars.

jison

Jison is a parser generator that converts a context-free grammar into a JavaScript parser. It is similar to Bison but for JavaScript. Jison is easier to integrate with JavaScript projects but may not offer the same level of optimization and features as ANTLR.

README

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