argv.js

Simple argv parser

Motivation

I needed a new argv parser for a quick and dirty project I was working on and evaluating and selecting the proper existing parser and then learning its API, quirks and adapting the architecture to it seemed to be more complicated, require more effort and far less fun than putting together a trivial parser myself in a couple of hours.
This code is an evolution of that parser.

Features

• Simple
• Supports both the option (a-la find) and command (a-la git) paradigms
• Nestable
  parsers can be nested as option/command handlers defining independent nested contexts
• Option expansion
  -abc expands to -a -b -c if -abc is not defined
• Option/command value passing
  implicit -a 123 (requires definition or manual handling) or explicit -a=123
• Environment variable option/command values
  env can control option defaults
• Reasonable defaults
  • -help – generate and print help,
  • -version – print version,
  • - – stop argument processing,
• Extensible:
  • Hooks for option value conversion (XXX should this be implemented???)
  • Hooks for dynamic option/command handling
  • Customizable error and stop condition handling

Contents

• argv.js
  • Motivation
  • Features
  • Contents
  • Installation
  • Basic usage
  • Configuration
    • Options, commands and aliases
    • Help
      • Value placeholders
      • Automatically defined values
      • .doc
      • .usage
      • .version
      • .license
      • .examples
      • .footer
      • Help formatting
        • .helpColumnOffset
        • .helpColumnPrefix
        • .helpArgumentSeparator
        • .helpValueSeparator
    • Nested parsers
  • Components and API
    • THEN, STOP and ERROR
    • Parser(..)
      • .then(..)
      • .stop(..)
      • .error(..)
      • .off(..)
      • <parser>(..)
  • Advanced parser API
    • .print(..) / .printError(..)
    • .handlerDefault(..)
    • .handleArgument(..)
    • .handleArgumentValue(..)
    • .handleErrorExit(..)
  • License

Installation

$ npm install ig-argv

Basic usage

Create a script and make it runnable

$ touch script.js
$ chmod +x script.js

Now for the code

#!/usr/bin/env node

// compatible with both node's and RequireJS' require(..)
var argv = require('ig-argv')

var parser = argv.Parser({
		// basic/quick option...
		'-b': '-basic',
		'-basic': function(){
			// ...
		},

		// full option settings...
		'-f': '-full',
		'-full': {
			doc: 'Option help',
			// option value to be displayed in help (optional)
			// NOTE: "attr" is used as a key to set the value if .handler
			//		was not defined and is ingored in all other cases...
			arg: 'VALUE | attr',

			// envioroment value (optional)
			env: 'VALUE',
			// default value (optional)
			default: 123,
			// required status (optional)
			required: false,

			// handler (optional)
			handler: function(opts, key, value){
				// ...
			},
		},

		// command...
		// NOTE: the only difference between an option and a command is
		//		the prefix ('-' vs. '@') that determines how it is parsed,
		//		otherwise they are identical and can alias each other...
		'@cmd', '@command',
		'@command': {
			// ...
		},

		// example command-option alias...
		'@help': '-help',

		// nested parser...
		'@nested': argv.Parser({
			// ...
		}).then(function(){
			// ...
		}),
	})
	.then(function(){
		// XXX
	})

// run the parser only if script.js is run directly...
if(__filename == require.main){
	parser(process.argv) }

This will create a parser that supports the folowing:

$ ./script.js --help 

$ ./script.js command

$ ./script.js nested -h

$ ./script.js -fb

Configuration

This sections lists attributes and methods designed to be set/modified in <spec> passed to Parser(..).

Note that these attributes are the same attributes inherited by <parser> (parser instance) and are simply merged into the new instance created by Parser(..), this there are no restrictions on what attributes/methods can be overloaded in this way but care must be taken when overloading elements that were not designed to be overloaded.

var parser = Parser({

})

Options, commands and aliases

Help

Parser defines a default help generator via the -h and -help options.

By default -help will output in the following format:

<usage>

<doc>

Options:
	<option-spec> <option-val>		
				- <option-doc>
				  (<opt-required>, <opt-default>, <opt-env>)
	...

Dynamic options:
	...

Commands:
	...

Examples:
	...

<footer>

All sections are optional and will not be rendered if they contain no data.

Value placeholders

All documentation strings can contain special placeholders that will get replaced with appropriate values when rendering help.

• $SCRIPTNAME replaced with the value of .scriptName,
• $VERSION replaced with .version,
• $LICENSE replaced with .license.

Automatically defined values

These values are set by the parser just before parsing starts:

• .script - full script path, usually this is the value of argv[0],
• .scriptName - basename of the script,
• .scriptPath - path of the script.

These will be overwritten when the parser is called.

.doc

Script documentation.

<spec>.doc = <string> | <function>

Default value: undefined

.usage

Basic usage hint.

<spec>.usage = <string> | <function> | undefined

Default value: "$SCRIPTNAME [OPTIONS]"

.version

Version number.

<spec>.usage = <string> | <function> | undefined

If this is not defined -version will print "0.0.0".

Default value: undefined

.license

Short license information.

<spec>.usage = <string> | <function> | undefined

Default value: undefined

.examples

<spec>.usage = <string> | <list> | <function> | undefined

Example list format:

[
	[<example-code>, <example-doc>, ...],
	...
]

Default value: undefined

.footer

Aditional information.

<spec>.footer = <string> | <function> | undefined

Default value: undefined

Help formatting

.helpColumnOffset

Default value: 3

.helpColumnPrefix

Default value: "- "

.helpArgumentSeparator

Default value: ", "

.helpValueSeparator

Default value: " "

Nested parsers

Components and API

THEN, STOP and ERROR

Values that if returned by option/command handlers can control the parse flow.

• THEN – Stop parsing and call .then(..) callbacks.
• STOP – Stop parsing and call .stop(..) callbacks, skipping .then(..).
• ERROR – Stop parsing, call .error(..) callbacks and exit with an error.

Parser(..)

Construct a parser instance

Parser(<spec>)
	-> <parser>

.then(..)

Add callback to then "event".

<parser>.then(<callback>)
	-> <parser>

callback(<unhandled>, <root-value>, <rest>)
	-> <obj>

then is triggered when parsing is done or stopped from an option handler by returning THEN.

.stop(..)

Add callback to stop "event".

<parser>.stop(<callback>)
	-> <parser>

callback(<arg>, <rest>)
	-> <obj>

stop is triggered when a handler returns STOP.

.error(..)

Add callback to error "event".

<parser>.error(<callback>)
	-> <parser>

callback(<reason>, <arg>, <rest>)
	-> <obj>

error is triggered when a handler returns ERROR.

.off(..)

Remove callback from "event".

	<parser>.off(<event>, <callback>)
		-> <parser>

<parser>(..)

Execute the parser insatance.

Run the parser on process.argv

<parser>()
	-> <result>

Explicitly pass a list of arguments where <argv>[0] is treated as the script path.

<parser>(<argv>)
	-> <result>

Explicitly pass both a list of args and script path.

<parser>(<argv>, <main>)
	-> <result>

If <main> is present in <argv> all the arguments before it will be ignored, otherwise the whole list is processed as if <main> was its head.

Advanced parser API

.print(..) / .printError(..)

.handlerDefault(..)

.handleArgument(..)

.handleArgumentValue(..)

.handleErrorExit(..)

License

BSD 3-Clause License

Copyright (c) 2016-2020, Alex A. Naanou,
All rights reserved.