README.md

Parser Combinators

A library of parser combinators, with which you can create your own parsers.

Parser combinators can be used for:

• Replacing complicated regular expressions with easy-to-understand parsers
• Incorporating custom languages into your application
• Introducing higher-order functions and parsing concepts

This package:

• Has full TypeScript support and is made with strict mode on
• Is thoroughly tested
• Is made in the Simplicity first philosophy
• Will be continuously improved in time

As of now it contains the following combinators:

• Standard combinators:
  • any
  • between
  • exhaust
  • many (and zeroOrMany, oneOrMany, oneOrManyRed)
  • map
  • optional
  • regex
  • sequence
  • string
• Utility combinators:
  • refer
  • expect
  • expectErase
  • surely
• Ready-made value combinators:
  • spaces
  • spacesPlus
  • wspaces
  • bool (and boolP)
  • int (and intP)
  • real (and realP)
• Whole parsers:
  • Extended Backus-Naur Form (EBNF)
  • JavaScript Object Notation (JSON)

Example usage:

Using standard combinators:

import { seq, str, any } from 'parser-combinators/parsers';
import { ParseText } from 'parser-combinators';

const parser = seq(str('a'), any(str('b'), str('c')));
const result = ParseText('ab', parser); // Will return ['a', 'b']

Using ready value combinators:

import { wspaces, str, realP, map } from 'parser-combinators/parsers';
import { ParseText } from 'parser-combinators';

const parser = map(
    seq(wspaces, str('number:'), wspaces, realP, wspaces),
    ([,,, data]) => data
);
const result = ParseText(' number: 1.75  ', parser); // Will return 1.75

Using ref to expand the parser's possibilities:

import { wspaces, str, realP, map } from 'parser-combinators/parsers';
import { ParseText } from 'parser-combinators';

const parser = ref(
    map(
        seq(wspaces, str('number:'), wspaces, realP, wspaces),
        ([,,, data]) => data
    ),
    data => data > 1.5,
    'The number must be over 1.5!'
);
const result = ParseText(' number: 1.25  ', parser); // Will throw a ParseError('The number must be over 1.5!')