CLI Input Parser

A configuration-forward TypeScript library to parse command line inputs with support for flagged and non-flagged arguments.

Table of Contents

1. Summary
2. Installation
3. Usage
   • Step 1: Create a Configuration
   • Step 2: Create a Parser
   • Step 3: Parse Some Input
   • Step 4: Use the Parsed Input
4. Error Handling
   • Help
   • Other Errors
5. Contributing
6. License

Summary

The CLI Input Parser allows you to define a configuration for supported commands and their arguments, and then parse input strings based on this configuration. It supports flagged arguments (starting with a dash) and non-flagged arguments, with optional validation using string lists or regular expressions.

Installation

To install the CLI Input Parser, use npm:

npm install cli-input-parser

Usage

Step 1: Create a Configuration

The configuration specifies a list of supported commands. Each command can have optional flagged arguments. Both flagged and non-flagged arguments can specify their expected/accepted formats using either a list of strings or a regular expression. Flagged arguments are those that start with a dash (-). Below are some examples:

const config: ParserConfig = {
    supportedCommands: [
        // example1 -m/--mode <string> -n/--number <number> [arg1 ... argN]
        {
            name: 'example1',
            flags: [
                {
                    character: 'm', // -m
                    verbose: 'mode', // --mode
                    accepts: ['dev', 'prod'], // Accepts 'dev' or 'prod'
                },
                {
                    character: 'n', // -n
                    verbose: 'number', // --number
                    accepts: /^(?:[1-9]|[1-9][0-9])$/, // Accepts 1-99
                },
            ],
            accepts: ['non', 'flagged', 'arguments'],
        },
        // example2 -v/--verbose
        {
            name: 'example2',
            flags: [
                {
                    character: 'v', // -v
                    verbose: 'verbose', // --verbose
                },
            ],
        },
    ],
};

Step 2: Create a Parser

A valid configuration must be passed to the parser upon construction.

import { CLIParser } from 'cli-input-parser';
const parser = new CLIParser(config);

Step 3: Parse Some Input

Use the parser to parse input strings based on the configuration.

const input = 'example1 -m dev -n 42 argument1 argument2';
const parsed = parser.parse(input);

Step 4: Use the Parsed Input

The parsed input separates flagged and non-flagged arguments. Here is the type definition of the parsed input:

export interface ParsedInput {
    command: string;
    flaggedArgs: Array<{
        flag: string;
        value?: unknown;
    }>;
    flaglessArgs: unknown[];
}

To access specific flagged arguments:

// Example to get the -m/--mode arg from example1 above.
let mode = '';
if (parsed.hasFlagWithValue('m')) {
    mode = parsed.getFlagValue('m');
}

// Example to check if -v/--verbose flag is present from example2 above.
let verbose = parsed.hasFlag('v');

Error Handling

Help

Any command passed with the -h or --help argument will throw the CLINeedsHelp error. Currently, it is the user's responsibility to handle this error. Future versions may include built-in help messages in the configuration.

Other Errors

All other errors when calling parse will throw the CLIParseError error.

Contributing

Contributions are welcome! Please submit pull requests or issues to the repository.

License

This project is licensed under the MIT License.