OptionParser

Command-line option parser similar to getopt

npm install OptionParser
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OptionParser is a library to help you parse command-line options, similar to how getopt works. An effort is made to make it POSIX compliant and easy for people to use. Features of many other implementations have been integrated in order to provide significant flexibility and to make it easier to use.

Examples in this guide are written in PHP, but it is easy to translate that across to JavaScript. The syntax is nearly identical. There are also sample parsers in the examples directory in the repository for both languages.

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Features

  • -x (short options)
  • -xxxyxxz (combined and repeating short options)
  • --long (long option)
  • -x=Value, --long=Value (optional and required values)
  • -xValue --long Value (special format for required values)
  • -- (signify the end of options)
  • Can stop on the first unparsed option
  • Can autocomplete long options
  • Returns unparsed options
  • Flexible option handling

Languages Supported

How to use

First, create the parser object:

$parser = new OptionParser();

Next, you add some options. I'll jump right in and add the standard "help" option, triggered with either -h or --help.

$parser->addOption('h', 'help', 'Display this help message')
    ->action($parser->helpAction());

Finally, parse the command line options.

$parser->parse();

How To Use Parameters

The whole point of the library is to make it really easy to handle the parsing of options to your program. Let's run through a few examples here:

Toggle a Flag With A Callback

In PHP you can pass more than just callbacks; names of functions, an array with the class name and method, and anything else that works with call_user_func(). For JavaScript, this only works for closures. Let's have this option only work with the short option "-f".

$flagWasSet = false;

$parser->addOption('f', null, 'Toggle a flag')
    ->action(function () use (&$flagWasSet) {
        $flagWasSet = true;
    });

Pass a Required Value

Many options need a specific value, such as an input file to process. Here is another option that is specified by "-i" or "--input" that requires a filename of the input file. It uses a callback, just like the above example.

$inputFile = 'php://stdin';

$parser->addOption('i', 'input', 'Specify an input file')
    ->argument('FILE')  // You can name the argument anything you like
    ->action(function ($value) use (&$inputFile) {
        $inputFile = $value;
    });

Optional Value and Parameter Object

Closures in PHP are not quite the same as JavaScript since you need to explicitly list the variables that are in scope for the execution of the function. An alternative would be to use the returned object from setting up the option on the parser. Here, we add a debug option that lets you set the debug level, but can default to 5 if you don't set one explicitly.

$debugLevel = 0;

$debugOption = $parser->addOption(null, 'debug',
     'Sets the debug level; if set, default is 5')
    ->argument('Level', false);  // See note below

// Don't forget to set up the other options here

$parser->parse();

// Now use the $debugOption object to set the debug value
if ($debugOption->count()) {
    $debugLevel = $debugOption->value();
}

The first parameter to OptionParameter->argument() is the name of the parameter, as seen in the generated help message. It doesn't affect the execution of the parser in any other way. The second parameter, false, makes the argument optional.

$debugOption->count() returns the number of times the argument was specified. $debugOption->value() returns the last value passed to the parameter. For detailed information, check out the documentation for OptionParameter.

Named Parameters

Keeping references to the objects can be tedious. Here is the above example altered to name the parameter and then use the named parameter. I'm naming the parameter "dddd" to help contrast against the previous code.

$debugLevel = 0;

$parser->addOption(null, 'debug',
     'Sets the debug level, default is 5', 'dddd')
    ->argument('Level', false);

// Don't forget to set up the other options here

$parser->parse();

if ($parser->dddd->count()) {
    $debugLevel = $parser->dddd->value();
}

Getopt

Lastly, PHP has a unique format for handling command-line arguments using the built-in function getopt(). After setting up options and calling $parser->parse(), you can get back an array that mimics getopt()'s return value. This should make it easier to plug this parser into your code and benefit from the better option handling without retooling anything after the call to getopt() that you'd normally make.

// Set up options and then call parse()
$parser->parse();

// Get back an array of options like PHP's getopt()
$options = $parser->getopt();

Unparsed Options

If you plan on making a program that takes a list of files or needs to work on the options that were passed to the program but were not parsed by OptionParser, that's really simple:

$unparsed = $parser->parse();

This will contain an array of options, split out into individual options. If you passed "-abcd" to your program and it handled "-a", "-b", and "-c", then $unparsed would be an array that only contains "-d".

More Reading

You can read the documentation for the individual classes to understand more about what they do and how they work.

Reference implementations are available in the examples directory in the repository.

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