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431 lines
8.9 KiB
Markdown
431 lines
8.9 KiB
Markdown
# argv.js
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Simple argv parser
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## Motivation
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I needed a new argv parser for a quick and dirty project I was working
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on and evaluating and selecting the proper existing parser and then
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learning its API, quirks and adapting the architecture to it seemed
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to be more complicated, require more effort and far less fun than
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putting together a trivial parser myself in a couple of hours.
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This code is an evolution of that parser.
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## Features
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- Simple
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- Supports both the _option_ (a-la `find`) and _command_ (a-la `git`) paradigms
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- Nestable
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parsers can be nested as option/command handlers defining independent
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nested contexts
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- Option expansion
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`-abc` expands to `-a -b -c` if `-abc` is not defined
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- Option/command value passing
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implicit `-a 123` (requires definition or manual handling) or explicit
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`-a=123`
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- Environment variable option/command values
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env can control option defaults
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- Reasonable defaults
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- `-help` – generate and print help,
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- `-version` – print version,
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- `-` – stop argument processing,
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- Extensible:
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- Hooks for option value conversion _(XXX should this be implemented???)_
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- Hooks for dynamic option/command handling
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- Customizable error and stop condition handling
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<!-- XXX ### Alternatives -->
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## Contents
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- [argv.js](#argvjs)
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- [Motivation](#motivation)
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- [Features](#features)
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- [Contents](#contents)
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- [Installation](#installation)
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- [Basic usage](#basic-usage)
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- [Configuration](#configuration)
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- [Options, commands and aliases](#options-commands-and-aliases)
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- [Help](#help)
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- [Value placeholders](#value-placeholders)
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- [Automatically defined values](#automatically-defined-values)
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- [`.doc`](#doc)
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- [`.usage`](#usage)
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- [`.version`](#version)
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- [`.license`](#license)
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- [`.examples`](#examples)
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- [`.footer`](#footer)
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- [Help formatting](#help-formatting)
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- [`.helpColumnOffset`](#helpcolumnoffset)
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- [`.helpColumnPrefix`](#helpcolumnprefix)
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- [`.helpArgumentSeparator`](#helpargumentseparator)
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- [`.helpValueSeparator`](#helpvalueseparator)
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- [Nested parsers](#nested-parsers)
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- [Components and API](#components-and-api)
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- [`THEN`, `STOP` and `ERROR`](#then-stop-and-error)
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- [`Parser(..)`](#parser)
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- [`.then(..)`](#then)
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- [`.stop(..)`](#stop)
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- [`.error(..)`](#error)
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- [`.off(..)`](#off)
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- [`<parser>(..)`](#parser-1)
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- [Advanced parser API](#advanced-parser-api)
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- [`.print(..)` / `.printError(..)`](#print--printerror)
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- [`.handlerDefault(..)`](#handlerdefault)
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- [`.handleArgument(..)`](#handleargument)
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- [`.handleArgumentValue(..)`](#handleargumentvalue)
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- [`.handleErrorExit(..)`](#handleerrorexit)
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- [License](#license-1)
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## Installation
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```shell
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$ npm install ig-argv
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```
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## Basic usage
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Create a script and make it runnable
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```shell
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$ touch script.js
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$ chmod +x script.js
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```
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Now for the code
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```javascript
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#!/usr/bin/env node
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// compatible with both node's and RequireJS' require(..)
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var argv = require('ig-argv')
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var parser = argv.Parser({
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// basic/quick option...
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'-b': '-basic',
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'-basic': function(){
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// ...
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},
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// full option settings...
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'-f': '-full',
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'-full': {
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doc: 'Option help',
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// option value to be displayed in help (optional)
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// NOTE: "attr" is used as a key to set the value if .handler
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// was not defined and is ingored in all other cases...
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arg: 'VALUE | attr',
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// envioroment value (optional)
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env: 'VALUE',
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// default value (optional)
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default: 123,
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// required status (optional)
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required: false,
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// handler (optional)
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handler: function(opts, key, value){
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// ...
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},
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},
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// command...
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// NOTE: the only difference between an option and a command is
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// the prefix ('-' vs. '@') that determines how it is parsed,
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// otherwise they are identical and can alias each other...
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'@cmd', '@command',
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'@command': {
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// ...
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},
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// example command-option alias...
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'@help': '-help',
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// nested parser...
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'@nested': argv.Parser({
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// ...
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}).then(function(){
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// ...
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}),
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})
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.then(function(){
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// XXX
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})
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// run the parser only if script.js is run directly...
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if(__filename == require.main){
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parser(process.argv) }
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```
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This will create a parser that supports the folowing:
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```shell
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$ ./script.js --help
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$ ./script.js command
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$ ./script.js nested -h
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$ ./script.js -fb
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```
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## Configuration
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This sections lists attributes and methods designed to be set/modified in
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`<spec>` passed to `Parser(..)`.
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Note that these attributes are the same attributes inherited by `<parser>`
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(parser instance) and are simply merged into the new instance created by
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`Parser(..)`, this there are no restrictions on what attributes/methods
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can be overloaded in this way but care must be taken when overloading
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elements that were not designed to be overloaded.
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```javascript
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var parser = Parser({
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})
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```
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### Options, commands and aliases
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### Help
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`Parser` defines a default help generator via the `-h` and `-help` options.
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By default `-help` will output in the following format:
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```
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<usage>
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<doc>
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Options:
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<option-spec> <option-val>
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- <option-doc>
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(<opt-required>, <opt-default>, <opt-env>)
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...
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Dynamic options:
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...
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Commands:
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...
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Examples:
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...
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<footer>
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```
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All sections are optional and will not be rendered if they contain no data.
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#### Value placeholders
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All documentation strings can contain special placeholders that
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will get replaced with appropriate values when rendering help.
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- `$SCRIPTNAME` replaced with the value of `.scriptName`,
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- `$VERSION` replaced with `.version`,
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- `$LICENSE` replaced with `.license`.
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#### Automatically defined values
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These values are set by the parser just before parsing starts:
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- `.script` - full script path, usually this is the value of `argv[0]`,
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- `.scriptName` - basename of the script,
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- `.scriptPath` - path of the script.
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These will be overwritten when the parser is called.
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#### `.doc`
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Script documentation.
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<spec>.doc = <string> | <function>
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Default value: `undefined`
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#### `.usage`
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Basic usage hint.
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<spec>.usage = <string> | <function> | undefined
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Default value: `"$SCRIPTNAME [OPTIONS]"`
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#### `.version`
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Version number.
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<spec>.usage = <string> | <function> | undefined
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If this is not defined `-version` will print `"0.0.0"`.
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Default value: `undefined`
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#### `.license`
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Short license information.
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<spec>.usage = <string> | <function> | undefined
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Default value: `undefined`
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#### `.examples`
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<spec>.usage = <string> | <list> | <function> | undefined
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Example list format:
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[
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[<example-code>, <example-doc>, ...],
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...
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]
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Default value: `undefined`
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#### `.footer`
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Aditional information.
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<spec>.footer = <string> | <function> | undefined
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Default value: `undefined`
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#### Help formatting
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##### `.helpColumnOffset`
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Default value: `3`
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##### `.helpColumnPrefix`
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Default value: `"- "`
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##### `.helpArgumentSeparator`
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Default value: `", "`
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##### `.helpValueSeparator`
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Default value: `" "`
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### Nested parsers
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## Components and API
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### `THEN`, `STOP` and `ERROR`
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Values that if returned by option/command handlers can control the parse flow.
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- `THEN` – Stop parsing and call `.then(..)` callbacks.
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- `STOP` – Stop parsing and call `.stop(..)` callbacks,
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skipping `.then(..)`.
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- `ERROR` – Stop parsing, call `.error(..)` callbacks and
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exit with an error.
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### `Parser(..)`
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Construct a parser instance
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```
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Parser(<spec>)
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-> <parser>
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```
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#### `.then(..)`
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Add callback to `then` "event".
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```
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<parser>.then(<callback>)
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-> <parser>
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```
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```
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callback(<unhandled>, <root-value>, <rest>)
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-> <obj>
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```
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`then` is triggered when parsing is done or stopped from an option handler by returning `THEN`.
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#### `.stop(..)`
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Add callback to `stop` "event".
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```
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<parser>.stop(<callback>)
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-> <parser>
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```
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```
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callback(<arg>, <rest>)
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-> <obj>
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```
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`stop` is triggered when a handler returns `STOP`.
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#### `.error(..)`
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Add callback to `error` "event".
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```
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<parser>.error(<callback>)
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-> <parser>
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```
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```
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callback(<reason>, <arg>, <rest>)
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-> <obj>
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```
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`error` is triggered when a handler returns `ERROR`.
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#### `.off(..)`
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Remove callback from "event".
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```
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<parser>.off(<event>, <callback>)
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-> <parser>
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```
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#### `<parser>(..)`
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Execute the `parser` insatance.
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Run the parser on `process.argv`
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```
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<parser>()
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-> <result>
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```
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Explicitly pass a list of arguments where `<argv>[0]` is treated as
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the script path.
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```
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<parser>(<argv>)
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-> <result>
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```
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Explicitly pass both a list of args and script path.
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```
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<parser>(<argv>, <main>)
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-> <result>
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```
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If `<main>` is present in `<argv>` all the arguments before it will
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be ignored, otherwise the whole list is processed as if `<main>` was
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its head.
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## Advanced parser API
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### `.print(..)` / `.printError(..)`
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### `.handlerDefault(..)`
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### `.handleArgument(..)`
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### `.handleArgumentValue(..)`
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### `.handleErrorExit(..)`
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## License
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[BSD 3-Clause License](./LICENSE)
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Copyright (c) 2016-2020, Alex A. Naanou,
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All rights reserved.
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<!-- vim:set ts=4 sw=4 spell : -->
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