optist

In a Nutshell

This is a command line option parser that tries not to outsmart the user, but still tries to get the job done.

Example

const Optist = require('optist');

var opt = ((new Optist())
           .simple('a')
           .simple('b')
           .counter('c')
           .simple('d', ['dddddd', 'dddddddd', 'DDD'])
           .string('s', 'string-of-3-chars', /^.{3}$/)
           .multi('m', 'multi-opt')
           .opts([ { shortName: ['A', 'O'], longName: 'all', description: 'It is A and O' },
                   { shortName: 'S', longName: 'required-string', hasArg: true, required: true } ])
           .help('test')
           .parse());

console.log('a', opt.value('a'));
console.log('b', opt.value('b'));
console.log('c', opt.value('c'));
console.log('d', opt.value('d'));
console.log('m', opt.value('m'));
console.log(opt.rest());

Reference

Optist()

Constructor for a command line parser. Does not take arguments.

Optist.prototype.simple(shortName, longName)

An alias of:

Optist.prototype.o(shortName, longName, false, false, undefined, false, undefined);

This is a simple option that can either be passed once or omitted in the argument list. The value of the option is true if it's present in the argument list, and false otherwise.

Optist.prototype.counter(shortName, longName)

An alias of:

Optist.prototype.o(shortName, longName, false, false, undefined, true, undefined);

This is an option without arguments which can be passed multiple times. The value of the option is the number of times it was present in the argument list.

Optist.prototype.string(shortName, longName, allowedValues)

A simple single-shot option with an optional set of allowed values. Parameter allowedValues can be either a single string or RegExp object or array of strings or RegExp objects or a mixed array of both. If the option is passed, the parsing fails in case the option argument does not match to any of the allowed values.

Without allowedValues parameter, this function is alias of:

Optist.prototype.o(shortName, longName, true, false, undefined, false, undefined);

Optist.prototype.multi(shortName, longName)

An alias of:

Optist.prototype.o(shortName, longName, true, false, undefined, true, undefined);

This is an option with an argument that can be passed multiple times. All passed arguments are collected in an array and are available as a value after the parsing. If the option is not present in the argument list at all, then the value is an empty array.

Optist.prototype.describeOpt = function(name, description)

Attach a free form text description for an option. This can be done only once for each individual option.

Optist.prototype.describeParam(num, name, description)

Attach a name and a free form text description for an additional command line parameter. This can be done only once for each individual parameter. Parameters are numbered from 0 up.

Optist.prototype.attachOptArgCb(name, optArgCb)

Attach an argument processing callback to the previously defined option. The option can be referred by any of its aliases, short or long. This function can not be called, if optArgCb has already been set for the function.

Optist.prototype.o(shortName, longName, hasArg, required, defaultValue, multi, optArgCb, requiresAlso, conflictsWith, environment)

A full featured interface for option definition.

shortName

A single character string giving the short name of the option. Can't be a dash (-) or an equal sign (=). Can be an array of multiple short aliases of the same option.

longName

A multicharacter string giving the long name of the option. Can't be a single character and can't contain an equal sign (=). The first or the last character can't be a dash (-). Can be an array of multiple long aliases of the same option.

hasArg

If false, the option does not accept an argument. If true, the argument must be passed.

required

If true, the option must be present in the argument list. For the required option, it is not possible to give a default value.

defaultValue

A default value for an option in case it's not present. The default value must always be a string. In case there is an optArgCb for the option, it must be able to process also this default value. A default value can only be set for options accepting an argument.

multi

If true, the option can appear multiple times in the argument list. If the option does not accept an argument, it makes the option a counter, i.e. the value of the option after the parsing, is the number of times the option was present in the command line. If the option accepts the argument, it makes the value of the option after parsing an array containing all arguments given to the option in the order they were given or in case the option is not present at all either an empty array or if there is a default value, then an array containig only the default value.

If not true, the option can only appear once in the argument list.

optArgCb

An processing callback a command line option argument. This can only be defined for options accepting an argument. The option argument is always passed as string to the callback and the callback is expected to return the argument in a processed form. The returned value does not have to be a string but can be anything except undefined. If the processing of the argument fails, the callback should return undefined, which triggers an error in command line parsing.

Since this callback is always also called for possible default values of the option, side effects are not desireable.

Pre-made callbacks are available in util module of the optist package.

requiresAlso

A single string or array of strings listing options that are also required if this option is present.

conflictsWith

A single string or array of strings listing options that must not be present if this option is present.

environment

If the option is not given on the command line, read its value from the environment with a given name. For options without argument, the allowed values are 'yes' and 'no' (with aliases 'true'/'false' and '+'/'-' respectively).

Optist.prototype.opts(options)

A shortcut method to define multiple options. Each option definition is an object with properties from list: shortName, longName, hasArg, required, defaultValue, multi, optArgCb, description. See Optist.prototype.o() for definition of each property.

Optist.prototype.additional(restRequireMin, restRequireMax)

Set the minimum and/or maximum number of additional parameters that must be left in the argument list after the options have been parsed. This can be done only before parsing and can be set only once. Alternatively the limits can be set also with additional function arguments for parse/parsePosix methods, but it is recommended to use Optist.prototype.additional API instead, because the information can in future, also be enclosed into usage messages.

Optist.prototype.help(command)

Enable the automatic help message generation and attach it to command line options -h and --help. Those options must not be otherwise attached. In case of parsing error of command line options, the help message is automatically shown and program terminated with non-zero exit code. This function can only be called before parsing.

If parameter command is given, the program name is oveddidden in the help messages. Command defaults to:

fs.basename(process.argv[0]) + ' ' + fs.basename(process.argv[1])

Optist.prototype.parse(av, restRequireMin, restRequireMax)

Parse the argument list. The parsing stops when the first non-option argument is detected or when the parsing is explicitly stopped by two dashes '--' in the argument list. This is the sane way. The rest of the argument list can be retrieved using Optist.prototype.rest() interface. The parameters restRequireMin and restRequireMax can be used in order to set constraints for the number of arguments that must be left in the argument list, after the parsing has completed.

If the argument list av is omitted or set to undefined, it defaults to process.argv.slice(2).

Optist.prototype.parsePosix(av, restRequireMin, restRequireMax)

Parse the argument list in weird but kinda Posixly standard way. The parsing stops, if it's explicitly stopped by two dashes '--' in the argument list. Otherwise, non-option arguments are skipped and the parsing resumed until entire argument list has been processed. Whatever was skipped on the way, can be retrieved using Optist.prototype.rest() interface. In my opinion, this is totally bonkers, but in case this is how you like it, so be it. Otherwise this interface acts like Optist.prototype.parse().

Optist.prototype.rest()

Return whatever is left of the argument list after the options have been parsed and removed. This function always returns a new array, so the caller modifying the array is ok. This function can be called multiple times and a new array is returned each time.

Optist.prototype.value(name)

Lookup the value of an option after parsing the command line. The name of the option can be given either as a long or short option name. If the option has multiple aliases, all names return the same value.

Optist.prototype.values()

Return all option values agter parsing the command line. Return value is an object with all aliases of the options as properties and a corresponding option value as a value of each property. Options that have no value given in the command line or does not have a default value, are omitted. The exception is a multi type options that are either [] or 0 depending on whether they accept an argument or not.

In addition, the non-option argument list (as returned with Optist.prototype.rest()) is stored to the object with property name consisting of a single dash (i.e. '-').

Optist.prototype.forEach(cb)

Iterate over the defined options after parsing and call a caller provided callback for each option. Parameters passed to the callback are primary short option name, primary long option name and option value. If option was not given on the command line and has no default value, the value is then passed as undefined. Also if the short or long option name does not exist, it is passed as undefined.

opt.forEach(function(s, l, v) {
  console.log('short:', s, 'long:', l, 'value:, v);
});

Utilities

Some generic argument callbacks are provided by util library. Those functions can be passed as optArgCb in option definition. User can of course also define custom callbacks.

const Optist = require('optist');
const ou = require('optist/util');

var opt = ((new Optist())
           .o(undefined, 'integer-option', true, false, '42', false, ou.integerCb)
           .parse())
console.log('integer option:',
            opt.value('integer-option'),
            'of type',
            typeof(opt.value('integer-option')));

Author

Timo J. Rinne [e-mail]

License

MIT License