ABNF

@hyperjump/abnf compiles grammars written in Augmented Backus-Naur Form (ABNF) into regular expressions. ABNF is the notation that RFCs use for syntax, so you can paste an RFC’s rules in and get a RegExp that matches what the RFC describes.

The following example compiles RFC 3339’s full-date:

import { abnf } from "@hyperjump/abnf";

const fullDate = abnf()`
  full-date     = date-fullyear "-" date-month "-" date-mday
  date-fullyear = 4DIGIT
  date-month    = 2DIGIT
  date-mday     = 2DIGIT
`;

fullDate.test("2004-01-15"); // true
fullDate.test("2004-1-15"); // false

The package offers the following:

RFC 5234 and RFC 7405. Rules, repetition, options, groups, numeric values, and case-insensitive and case-sensitive strings, with RFC 5234’s core rules, like ALPHA and DIGIT, built in.
A regular expression. The result is a RegExp with the u flag, as fast as one written by hand, which you can test strings with or compile once at build time.
What you know about the input. A context can supply rules to reference, characters that end a match, and characters the input can’t have. For more information, see Contexts.
Small. No dependencies. It has TypeScript types and works in Node.js and browsers.

@hyperjump/uri uses it for the patterns of URI schemes.

Install: setup for Node.js, browsers, and TypeScript
Write grammars: rule lists, expressions, sharing rules, and errors
Contexts: rules to reference, delimiters, and what the input can have

ABNF

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