@types/moo

What is @types/moo?

@types/moo provides TypeScript type definitions for the Moo library, which is a tokenizer for JavaScript. Moo is used to create lexers that can tokenize strings based on specified rules.

What are @types/moo's main functionalities?

Basic Tokenization

This feature allows you to define a set of rules for tokenizing a string. The code sample demonstrates how to create a lexer that can tokenize whitespace, numbers, words, and newlines.

const moo = require('moo');

const lexer = moo.compile({
  WS: /[ \t]+/,
  number: /[0-9]+/,
  word: /[a-zA-Z]+/,
  NL: { match: /\n/, lineBreaks: true },
});

lexer.reset('foo 123\nbar');

let token;
while (token = lexer.next()) {
  console.log(token);
}

Custom Token Properties

This feature allows you to define custom properties for tokens. The code sample shows how to convert the value of number tokens to a JavaScript number.

const moo = require('moo');

const lexer = moo.compile({
  WS: /[ \t]+/,
  number: { match: /[0-9]+/, value: x => Number(x) },
  word: /[a-zA-Z]+/,
  NL: { match: /\n/, lineBreaks: true },
});

lexer.reset('foo 123\nbar');

let token;
while (token = lexer.next()) {
  console.log(token);
}

Error Handling

This feature allows you to handle errors during tokenization. The code sample demonstrates how to catch and handle unexpected characters in the input string.

const moo = require('moo');

const lexer = moo.compile({
  WS: /[ \t]+/,
  number: /[0-9]+/,
  word: /[a-zA-Z]+/,
  NL: { match: /\n/, lineBreaks: true },
  error: moo.error,
});

lexer.reset('foo 123\nbar$');

let token;
while (token = lexer.next()) {
  if (token.type === 'error') {
    console.error('Unexpected character:', token);
  } else {
    console.log(token);
  }
}

Other packages similar to @types/moo

lex

The 'lex' package is another lexer generator for JavaScript. It provides similar functionality to Moo but with a different API. While Moo uses a more declarative approach to define token rules, 'lex' uses a more traditional state machine approach.

jison-lex

The 'jison-lex' package is part of the Jison parser generator toolkit. It provides lexer functionality similar to Moo but is designed to work seamlessly with Jison parsers. It is more feature-rich and integrates tightly with the Jison parser generator.

nearley

The 'nearley' package is a parser toolkit that includes lexer functionality. It is more powerful and flexible than Moo, allowing for complex parsing tasks. Nearley uses a different approach to parsing, based on Earley parsing algorithms, which can handle a wider range of grammars.

README

Installation

npm install --save @types/moo

Summary

This package contains type definitions for moo (https://github.com/tjvr/moo#readme).

Details

Files were exported from https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/moo.

Additional Details

• Last updated: Tue, 07 Nov 2023 09:09:39 GMT
• Dependencies: none

Credits

These definitions were written by Nikita Litvin, Jörg Vehlow, and Martien Oranje.