@molt/types

⛑ Advanced Types for parsing CLI flags and more.

Installation

npm add @molt/types

Namespaces

FlagName

The FlagName namespace provides a Parse type and some other utility types. Parse turns an expression of CLI flags into structured object type data at the type level.

Features

• Capture long flag
• Capture short flag
• Capture alias short flags
• Capture alias long flags
• Flexible syntax
  • Optional leading dashes --/-
  • Kebab/camel case agnostic fooBar/foo-bar
• Clear human-friendly error messages when parsing fails.
  • Catch name duplicate
  • Enforce reserved names
• Statically Normalize kebob case to camel case

API

.parse

Examples

// Errors

FlagName.Parse<''>
// Error: You must specify at least one name for your flag.
FlagName.Parse<'--foo-bar', { reservedNames: 'foo-bar'; usedNames: undefined }>
FlagName.Parse<'--foo-bar', { reservedNames: 'fooBar'; usedNames: undefined }>
// Error: The name "foo-bar" cannot be used because it is reserved.
FlagName.Parse<'--fooBar', { reservedNames: 'foo-bar'; usedNames: undefined }>
// Error: The name "fooBar" cannot be used because it is reserved.
FlagName.Parse<'-a', { usedNames: 'a'; reservedNames: undefined }>
// Error: The name "a" cannot be used because it is already used for another flag.
FlagName.Parse<'--v'>
//Error: A long flag must be two (2) or more characters but you have: '--v
FlagName.Parse<'-foo'>
// Error: A short flag must be exactly one (1) character but you have: '-foo'.
FlagName.Parse<'--foo --foo'>
// Error: Your alias "foo" is a duplicate.

import { FlagName } from '@molt/types'

const defineFlag = <Name>(
  name: FlagName.Errors.$Is<FlagName.Parse<Name>> extends true ? FlagName.Parse<Name> : Name
) => {
  // ...
}

defineFlag(``) // Static type error
defineFlag(`-`) // Static type error
defineFlag(`--`) // Static type error
defineFlag(`--a`) // Static type error
defineFlag(`-ab`) // Static type error
defineFlag(`--foo --foo`) // Static type error
defineFlag(`--foo-bar --fooBar`) // Static type error
defineFlag(`--version -`) // Static type error
defineFlag(`-v -v`) // Static type error
defineFlag(`--version`) // ok
defineFlag(`--version --ver`) // ok
defineFlag(`--version --ver -v`) // ok
defineFlag(`-v`) // ok