mark-util-character

mark utility to handle character codes.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • asciiAlpha(code)
  • asciiAlphanumeric(code)
  • asciiAtext(code)
  • asciiControl(code)
  • asciiDigit(code)
  • asciiHexDigit(code)
  • asciiPunctuation(code)
  • checker(test)
  • eos(code)
  • htab(code)
  • idContinue(code)
  • idStart(code)
  • isCode(value)
  • lineEndingOrWhitespace(code)
  • lineEnding(code)
  • space(code)
  • streamBreak(code)
  • unicodePunctuation(code)
  • unicodeWhitespace(code)
  • vtab(code)
  • whitespace(code)
• Types
  • LineEnding
  • Serialize
  • Space
  • Whitespace
• Project
  • Version
  • Contribute
  • Sponsor
• Related

What is this?

This package exposes algorithms for checking whether character codes match certain groups.

When should I use this?

This package is useful when creating your own your own mark extensions and utilities.

Install

This package is ESM only.

In Node.js with yarn:

yarn add @flex-development/mark-util-character

In Deno with esm.sh:

import { asciiAlpha } from 'https://esm.sh/@flex-development/mark-util-character'

In browsers with esm.sh:

<script type="module">
  import { asciiAlpha } from 'https://esm.sh/@flex-development/mark-util-character'
</script>

Use

import { asciiAlpha, streamBreak } from '@flex-development/mark-util-character'
import { codes } from '@flex-development/mark-util-symbol'

console.dir(asciiAlpha(codes.atSign)) // false
console.dir(asciiAlpha(codes.uppercaseA)) // true

console.dir(streamBreak(codes.eos)) // false
console.dir(streamBreak(codes.break)) // true

API

This package exports the following identifiers:

• asciiAlpha
• asciiAlphanumeric
• asciiAtext
• asciiControl
• asciiDigit
• asciiHexDigit
• asciiPunctuation
• checker
• eos
• htab
• idContinue
• idStart
• isCode
• lineEndingOrWhitespace
• lineEnding
• space
• streamBreak
• unicodePunctuation
• unicodeWhitespace
• vtab
• whitespace

There is no default export.

asciiAlpha(code)

Check whether a character code represents an ASCII alpha (a through z, case insensitive).

An ASCII alpha is an ASCII upper alpha or ASCII lower alpha.
An ASCII upper alpha is a character in the inclusive range U+0041 (A) to U+005A (Z).
An ASCII lower alpha is a character in the inclusive range U+0061 (a) to U+007A (z).

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

asciiAlphanumeric(code)

Check whether a character code represents an ASCII alphanumeric (a through z, case insensitive, or 0 through 9).

An ASCII alphanumeric is an ASCII digit (see asciiDigit) or ASCII alpha (see asciiAlpha).

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

asciiAtext(code)

Check whether a character code represents an ASCII atext.

atext is an ASCII alphanumeric (see asciiAlphanumeric), or a character in the following inclusive ranges:

• U+0023 NUMBER SIGN (#) to U+0027 APOSTROPHE (')
• U+002A ASTERISK (*)
• U+002B PLUS SIGN (+)
• U+002D DASH (-)
• U+002F SLASH (/)
• U+003D EQUALS TO (=)
• U+003F QUESTION MARK (?)
• U+005E CARET (^) to U+0060 GRAVE ACCENT (`)
• U+007B LEFT CURLY BRACE ({) to U+007E TILDE (~)

See https://tools.ietf.org/html/rfc5322 for more info.

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

asciiControl(code)

Check whether a character code is an ASCII control character.

An ASCII control is a character in the inclusive range U+0000 NULL (NUL) to U+001F (US), or U+007F (DEL).

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

asciiDigit(code)

Check whether a character code represents an ASCII digit (0 through 9).

An ASCII digit is a character in the inclusive range U+0030 (0) to U+0039 (9).

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

asciiHexDigit(code)

Check whether a character code represents an ASCII hex digit (a through f, case insensitive, or 0 through 9).

An ASCII hex digit is an ASCII digit (see asciiDigit), ASCII upper hex digit, or an ASCII lower hex digit.
An ASCII upper hex digit is a character in the inclusive range U+0041 (A) to U+0046 (F).
An ASCII lower hex digit is a character in the inclusive range U+0061 (a) to U+0066 (f).

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

asciiPunctuation(code)

Check whether a character code represents ASCII punctuation.

An ASCII punctuation is a character in the following inclusive ranges:

• U+0021 EXCLAMATION MARK (!) to U+002F SLASH (/)
• U+003A COLON (:) to U+0040 AT SIGN (@)
• U+005B LEFT SQUARE BRACKET ([) to U+0060 GRAVE ACCENT (`)
• U+007B LEFT CURLY BRACE ({) to U+007E TILDE (~)

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

checker(test[, serialize])

Create a code check, i.e. guard, from a regular expression.

After serializing a character code, the guard will check if the character matches the bound regex.

Parameters

• test (RegExp | string) — the regular expression or regular expression pattern
• serialize (Serialize | null | undefined, optional) — serialize a character code

Returns

(CodeCheck) The code check

eos(code)

Check if code is the end-of-stream code.

Parameters

• code (unknown) — the character code to check

Returns

(code is typeof codes.eos) true if code is codes.eos, false otherwise

htab(code)

Check if code represents a horizontal tab.

Parameters

• code (unknown) — the character code to check

Returns

(code is typeof codes.ht | typeof codes.vht) true if code is codes.horizontalTab (aka codes.vht) or codes.ht, false otherwise

idContinue(code)

Check whether a character code can continue an identifier.

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

idStart(code)

Check whether a character code can start an identifier.

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

isCode(value)

Check if value looks like a character code.

Parameters

• value (unknown) — the thing to check

Returns

(value is Code) true if value is a number or null, false otherwise

lineEndingOrWhitespace(code)

Check if code represents a line ending or whitespace.

Parameters

• code (unknown) — the character code to check

Returns

(code is LineEnding | Whitespace) true if code is line ending or whitespace code, false otherwise

lineEnding(code)

Check if code represents a line ending.

Parameters

• code (unknown) — the character code to check

Returns

(code is LineEnding) true if code is line ending code, false otherwise

space(code)

Check if code represents space.

Parameters

• code (unknown) — the character code to check

Returns

(code is Space) true if code is space code, false otherwise

streamBreak(code)

Check if code represents a stream break.

The stream break code can be written between chunks to signal separation, or a "pause" in the current stream.

Parameters

• code (unknown) — the character code to check

Returns

(code is typeof codes.break) true if code is codes.break, false otherwise

unicodePunctuation(code)

Check whether a character code represents Unicode punctuation.

A Unicode punctuation is a character in the following Unicode categories:

• Pc (Punctuation, Connector)
• Pd (Punctuation, Dash)
• Pe (Punctuation, Close)
• Pf (Punctuation, Final quote)
• Pi (Punctuation, Initial quote)
• Po (Punctuation, Other)
• Ps (Punctuation, Open)

or an ASCII punctuation (see asciiPunctuation).

See also:

• https://www.fileformat.info/info/unicode/category/Pc/list.htm
• https://www.fileformat.info/info/unicode/category/Pd/list.htm
• https://www.fileformat.info/info/unicode/category/Pe/list.htm
• https://www.fileformat.info/info/unicode/category/Pf/list.htm
• https://www.fileformat.info/info/unicode/category/Pi/list.htm
• https://www.fileformat.info/info/unicode/category/Po/list.htm
• https://www.fileformat.info/info/unicode/category/Ps/list.htm

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

unicodeWhitespace(code)

Check whether a character code represents Unicode whitespace.

A Unicode whitespace is a character in the Unicode Zs (Separator, Space) category or one of the following:

• U+0009 CHARACTER TABULATION (HT)
• U+000A LINE FEED (LF),
• U+000C FORM FEED (FF)
• U+000D CARRIAGE RETURN (CR)

See also:

• https://www.fileformat.info/info/unicode/category/Zs/list.htm

Parameters

• code (Code) — the character code to check

Returns

(boolean) Whether the character code matches

vtab(code)

Check if code represents a vertical tab.

Parameters

• code (unknown) — the character code to check

Returns

(boolean) true if code is codes.vt, false otherwise

whitespace(code)

Check if code represents whitespace.

Parameters

• code (unknown) — the character code to check

Returns

(code is Whitespace) true if code is whitespace code, false otherwise

Types

This package is fully typed with TypeScript.

LineEnding

Union of codes representing a line ending.

type LineEnding =
  | typeof codes.carriageReturn
  | typeof codes.carriageReturnLineFeed
  | typeof codes.cr
  | typeof codes.crlf
  | typeof codes.lf
  | typeof codes.lineFeed
  | typeof codes.ls
  | typeof codes.ps
  | typeof codes.vcr
  | typeof codes.vlf

Serialize

Serialize a character code.

Parameters

• code (Code) — the character code to serialize

Returns

(string) The character produced from code

Space

Union of codes representing space.

type Space = typeof codes.space | typeof codes.virtualSpace | typeof codes.vs

Whitespace

Union of codes representing whitespace.

type Whitespace =
  | Space
  | typeof codes.horizontalTab
  | typeof codes.ht
  | typeof codes.vht

Project

Version

mark-util-character adheres to semver.

Contribute

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.

Sponsor

Small primitives power larger systems. Support long-term stability by sponsoring Flex Development.

Related

• @flex-development/mark — the specification
• @flex-development/mark-compiler — finite state machine event compiler
• @flex-development/mark-parser — finite state machine parser