index.js

'use strict';

function isNumber(x) {
	if (typeof x === 'number') { return true; }
	if ((/^0x[0-9a-f]+$/i).test(x)) { return true; }
	return (/^[-+]?(?:\d+(?:\.\d*)?|\.\d+)(e[-+]?\d+)?$/).test(x);
}

function isConstructorOrProto(obj, key) {
	return key === 'constructor' && (typeof obj[key] === 'function' || key === '__proto__');
}

function hasKey(obj, keys) {
	var o = obj;
	keys.slice(0, -1).forEach(function (key) {
		o = o[key] || {};
	});

	var key = keys[keys.length - 1];
	return key in o;
}

function setKey(obj, keys, value) {
	var o = obj;
	var key;
	for (var i = 0; i < keys.length - 1; i++) {
		key = keys[i];
		if (key === '__proto__' || isConstructorOrProto(o, key)) {
			return;
		}
		if (o[key] === undefined) { o[key] = {}; }
		if (
			o[key] === Object.prototype
			|| o[key] === Number.prototype
            || o[key] === String.prototype
		) {
			o[key] = {};
		}
		if (o[key] === Array.prototype) { o[key] = []; }
		o = o[key];
	}

	key = keys[keys.length - 1];
	if (key === '__proto__') { return; }
	if (
		o === Object.prototype
		|| o === Number.prototype
        || o === String.prototype
	) {
		o = {};
	}
	if (o === Array.prototype) { o = []; }
	if (o[key] === undefined || typeof o[key] === 'boolean') {
		o[key] = value;
	} else if (Array.isArray(o[key])) {
		o[key].push(value);
	} else {
		o[key] = [o[key], value];
	}
}

module.exports = function (args, opts) {
	if (!opts) { opts = {}; }

	var flags = { bools: {}, strings: {} };

	if (typeof opts.boolean === 'boolean' && opts.boolean) {
		flags.allBools = true;
	} else {
		[].concat(opts.boolean).filter(Boolean).forEach(function (key) {
			flags.bools[key] = true;
		});
	}

	var aliases = {};
	Object.keys(opts.alias || {}).forEach(function (key) {
		aliases[key] = [].concat(opts.alias[key]);
		aliases[key].forEach(function (x) {
			aliases[x] = [key].concat(aliases[key].filter(function (y) {
				return x !== y;
			}));
		});
	});

	[].concat(opts.string).filter(Boolean).forEach(function (key) {
		flags.strings[key] = true;
		if (aliases[key]) {
			[].concat(aliases[key]).forEach(function (k) {
				flags.strings[k] = true;
			});
		}
	});

	var defaults = opts.default || {};

	var argv = { _: [] };

	function setArg(key, val) {
		var value = !flags.strings[key] && isNumber(val)
			? Number(val)
			: val;
		setKey(argv, key.split('.'), value);

		(aliases[key] || []).forEach(function (x) {
			setKey(argv, x.split('.'), value);
		});
	}

	Object.keys(flags.bools).forEach(function (key) {
		setArg(key, defaults[key] === undefined ? false : defaults[key]);
	});

	var notFlags = [];

	if (args.indexOf('--') !== -1) {
		notFlags = args.slice(args.indexOf('--') + 1);
		args = args.slice(0, args.indexOf('--'));
	}

	for (var i = 0; i < args.length; i++) {
		var arg = args[i];
		var key;
		var next;

		if ((/^--.+=/).test(arg)) {
			// Using [\s\S] instead of . because js doesn't support the
			// 'dotall' regex modifier. See:
			// http://stackoverflow.com/a/1068308/13216
			var m = arg.match(/^--([^=]+)=([\s\S]*)$/);
			setArg(m[1], m[2]);
		} else if ((/^--no-.+/).test(arg)) {
			key = arg.match(/^--no-(.+)/)[1];
			setArg(key, false);
		} else if ((/^--.+/).test(arg)) {
			key = arg.match(/^--(.+)/)[1];
			next = args[i + 1];
			if (next !== undefined && !(/^-/).test(next)
            && !flags.bools[key]
            && !flags.allBools
            && (aliases[key] ? !flags.bools[aliases[key]] : true)) {
				setArg(key, next);
				i += 1;
			} else if ((/^(true|false)$/).test(next)) {
				setArg(key, next === 'true');
				i += 1;
			} else {
				setArg(key, flags.strings[key] ? '' : true);
			}
		} else if ((/^-[^-]+/).test(arg)) {
			var letters = arg.slice(1, -1).split('');

			var broken = false;
			for (var j = 0; j < letters.length; j++) {
				next = arg.slice(j + 2);

				if (next === '-') {
					setArg(letters[j], next);
					continue;
				}

				if ((/[A-Za-z]/).test(letters[j])
                && (/-?\d+(\.\d*)?(e-?\d+)?$/).test(next)) {
					setArg(letters[j], next);
					broken = true;
					break;
				}

				if (letters[j + 1] && letters[j + 1].match(/\W/)) {
					setArg(letters[j], arg.slice(j + 2));
					broken = true;
					break;
				} else {
					setArg(letters[j], flags.strings[letters[j]] ? '' : true);
				}
			}

			key = arg.slice(-1)[0];
			if (!broken && key !== '-') {
				if (args[i + 1] && !(/^(-|--)[^-]/).test(args[i + 1])
                && !flags.bools[key]
                && (aliases[key] ? !flags.bools[aliases[key]] : true)) {
					setArg(key, args[i + 1]);
					i += 1;
				} else if (args[i + 1] && (/true|false/).test(args[i + 1])) {
					setArg(key, args[i + 1] === 'true');
					i += 1;
				} else {
					setArg(key, flags.strings[key] ? '' : true);
				}
			}
		} else {
			argv._.push(flags.strings._ || !isNumber(arg) ? arg : Number(arg));
		}
	}

	Object.keys(defaults).forEach(function (k) {
		if (!hasKey(argv, k.split('.'))) {
			setKey(argv, k.split('.'), defaults[k]);

			(aliases[k] || []).forEach(function (x) {
				setKey(argv, x.split('.'), defaults[k]);
			});
		}
	});

	if (opts['--']) {
		argv['--'] = notFlags.slice();
	} else {
		notFlags.forEach(function (k) {
			argv._.push(k);
		});
	}

	return argv;
};