vfile utility to read characters from a file

• What is this?
• When should I use this?
• Install
• Use
• API
  • Reader(file[, start])
    • Reader#char
    • Reader#eof
    • Reader#index
    • Reader#now()
    • Reader#offset([point])
    • Reader#peek([k])
    • Reader#peekMatch(test)
    • Reader#point([offset])
    • Reader#previous
    • Reader#read([k])
    • Reader#start
  • CharacterMatch
  • Character
• Types
• Contribute

This package implements an input reader that can be used to read characters from a file.

This package is useful when characters need to be read individually or by regex match, such as when building a parser or tokenizer.

This package is ESM only.

In Node.js (version 18+) with yarn:

yarn add @flex-development/vfile-reader

See Git - Protocols | Yarn  for details regarding installing from Git.

In Deno with esm.sh:

import { Reader } from 'https://esm.sh/@flex-development/vfile-reader'

In browsers with esm.sh:

<script type="module">
  import { Reader } from 'https://esm.sh/@flex-development/vfile-reader'
</script>

import { Reader } from '@flex-development/vfile-reader'
import { read } from 'to-vfile'
import type { VFile } from 'vfile'

const file: VFile = await read('hrt.ts')
const reader: Reader = new Reader(file)

while (!reader.eof) console.log(reader.read())

This package exports the identifier Reader. There is no default export.

Create a new character reader.

Pass a start point to make reader locations relative to a specific place. Any point or offset accessed will be relative to the given point.

• file (Value | VFile) — file to read
• start (Point | null | undefined) — point before first character in file

(Character) Current character or null, with null denoting end of file. Equivalent to reader.peek(0).

(boolean) Boolean indicating if reader has reached the end of file, with true denoting end of file.

(Offset) Index of current character.

Get the current point in the file.

(Point) Current point in file, relative to reader#start.

See Location#offset([point]).

Get the next k-th character from the file without changing the position of the reader, with null denoting end of file.

• k (number | undefined) — difference between index of next k-th character and index of current character
  • default: 1

(Character) Peeked character or null.

Get the next match from the file without changing the position of the reader, with null denoting no match.

• test (RegExp) — character test

(CharacterMatch) Peeked character match or null.

See Location#point([offset]).

(Character) Previous character or null, with null denoting beginning or end of file. Equivalent to reader.peek(-1).

Get the next k-th character from the file, with null denoting end of file.

Unlike peek, this method changes the position of the reader.

• k (number | undefined) — difference between index of next k-th character and index of current character
  • default: 1

(Character) Next k-th character or null.

(Point) Point before first character in file.

Match in a source file, with null denoting no match (TypeScript type).

type CharacterMatch = RegExpExecArray | null

Character in a source file, with null denoting the end of file (TypeScript type).

type Character = string | null

This package is fully typed with TypeScript.

See CONTRIBUTING.md.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.