cmdp - a simple command parser

cmdp is a simple tool for parsing commandline like inputs. This project was made overnight for the fun of it, with no intentions of being used seriously, but feel free to play around with it - and submit an issue if you find any.

In it's current state, cmdp will silently ignore errors found in the command syntax, and attempt to parse what can be parsed.

Installation

cmdp is available on npm, and may be installed from there.

npm install cmdp

Usage

cmdp consists of two things:

1. the lexer
2. the parser

Overall, it's a simple two-step process of turning some input into tokens using the lexer, which are then passed to the parser, that turns them into a command structure.

const cmdp = require("cmdp");

const tokens = cmdp.lex("npm install --save cmdp");
const command = cmdp.parse(tokens);

The command structure in this case will look like this:

{
    name: "npm",
    arguments: ["install", "cmdp"],
    options: [{ name: "save", value: undefined }]
}

cmdp's module may also be called directly, which will parse the first argument and output the result.

$ ./index.js "npm install --save cmdp"
{ name: 'echo', arguments: [ 'hello world' ], options: [] }

Input format

cmdp's input format is pretty standard.

<command> [argument] [(-|--)option[=value]]

An input must begin with a literal, which will be treated as the command name. Following the command name, will be either arguments or options.

Options are any literals, which are prefixed with either - or --. Everything else will be treated as an argument. Arguments and options are seperated by spaces.

cmdp treats options as completely seperate things from arguments, and doesn't care about where they might occur in the input, so long as it's after the command name. Arguments will be listed in the order in which they occur in the input.

Options come in short and long formats, prefixed with - and -- respectively. Long format options may contain - for clarity, eg. --save-dev. Short options consist of only a single character. Both types may specify an associated value with =, followed by any value type. Short options may be grouped, but in this case if a value is specified, it will be associated with the last option only.

cmdp will recognize the type of any value, and convert them to their correct JavaScript counterpart. Currently the following are supported:

name	format	description	type
literal	[a-zA-Z0-9\-_]+	any single group of characters	string
string	("|')(.*?)("|')	any character between a set of matching delimeters, ' or "	string
number	[0-9\.]+	any number using a dot for decimal seperation	number
boolean	(true|false)	either one when not inside of string delimeters	boolean
null	null	a literal null not inside of string delimeters	null

Command structure

The structure of a parsed command was already shown in the above example, but in detail it will contain:

property	type	description
name	string	the name of the command
arguments	Array.\<mixed\>	the argument values
options	Array.\<object\>	options without their "-" or "--" prefixes, and their associated value

An option consists of a name and a value. name will always be a string, while value will be a mixed type, or undefined.

Examples

The following are the results of different inputs, which have been lexed and parsed as shown above.

"Hello world"

echo "Hello world"

{
    name: 'echo',
    arguments: ['Hello world'],
    options: []
}

"Hello world" alternate

echo Hello world

{
    name: 'echo',
    arguments: ['Hello', 'world'],
    options: []
}

Options

ls -l --color=auto

{
    name: 'ls',
    arguments: [],
    options: [
        {
            name: 'l',
            value: undefined
        },
        {
            name: 'color',
            value: 'auto'
        }
    ]
}

Option groups

ps -aux

{
    name: 'ps',
    arguments: [],
    options: [
        {
            name: 'a',
            value: undefined
        },
        {
            name: 'u',
            value: undefined
        },
        {
            name: 'x',
            value: undefined
        }
    ]
}

Proper value types

is 42.123 "the meaning of life" false or null

{
    name: 'is',
    arguments: [42.123, 'the meaning of life', false, 'or', null],
    options: []
}

Tests

cmdp uses jasmine for testing purposes.

Tests may be found in the spec/ directory. Running then is as simple as npm test.

The amount of tests are currently limited, but more will be added (maybe).