parsec

Generator-based ES6 CLI options parser.

Synopsis | Install | Examples

Synopsis

Parsec is a lovingly crafted command line options parser using ES6 generators in around 100 LOC.

Parsec.parse(process.argv) // -T850
  .options(["T", "terminator"], { default: 800 })
  .options("model", { default: 101 })
  .options("name", { default: "Schwa" })

{
  "T": "850",
  "terminator": "850",
  "model": "101",
  "m": "101",
  "name": "Schwa",
  "n": "Schwa"
}

Install

npm install parsec

Usage

Parsec automatically slices arguments starting from index 2, but you can specify the sliceIndex via the second argument to parse.

Syntax

Parsec.parse(argv[, {
  sliceIndex = 2,
  operandsKey = "_",
  noFlags = true
}])
  .options("option string")
  .options([aliases], { default })
  ...

Parsec uses the first letter of an option string as an alias:

Parsec.parse(["-tla"], { sliceIndex: 0 })
  .options("three")
  .options("letter")
  .options("abbreviation")

{
  "t": true,
  "l": true,
  "a": true,
  "three": true,
  "letter": true,
  "abbreviation": true
}

Pass an array of aliases, or specify default values via { default: value }

Parsec.parse(["-G"], { sliceIndex: 0 })
  .options(["G", "g", "great"])
  .options(["r", "R"], { default: 8 })

{
  "G":true,
  "g":true,
  "great":true,
  "r":8,
  "R":8
}

You can negate options using a --no- prefix before an option.

Parsec.parse(["--no-woman-no-cry", "--no-wonder=false"],
  { sliceIndex: 0 })

{
  "woman-no-cry": false,
  "wonder": true
}

API

Parsec.parse(args, opts)

The only one method you will probably deal with.

opts

• operandsKey = "_"
• sliceIndex = 2
• noFlags = true

Parsec.prototype.tuples

Returns an iterator that yields objects of the form { prev, curr, next } for each item in a list.

Parsec.prototype.map

Maps CLI arguments to custom Token objects.

• Short Options

{ isShort, tokens }

• Long Options

{ isLong, key, value, token }

• Operands

{ token, isBare }

Parsec.prototype.shorts

Token sub-iterator for short options.

Parsec.prototype.tokens

Token iterator for options:

{ curr, next, value }

Parsec.prototype.entries

Iterator for entries:

{ key, value }

Properties

operandsKey = "_"

Use a different key name for the operands list.

noFlags = true

Set to false to opt out.

Parsec.parse(["--no-love=false", "--no-war", "--no-no", "ok"],
  { sliceIndex: 0 })

  {
    "love": true,
    "war": false,
    "no-no": "ok"
  }

Roadmap ✈

• Add loose type support.
• Invalid option check.

License

MIT © Jorge Bucaran