discord.js-commando/src/types/base.js

The official command framework for Discord.js

/** A type for command arguments */
class ArgumentType {
	/**
	 * @param {CommandoClient} client - The client the argument type is for
	 * @param {string} id - The argument type ID (this is what you specify in {@link ArgumentInfo#type})
	 */
	constructor(client, id) {
		if(!client) throw new Error('A client must be specified.');
		if(typeof id !== 'string') throw new Error('Argument type ID must be a string.');
		if(id !== id.toLowerCase()) throw new Error('Argument type ID must be lowercase.');

		/**
		 * Client that this argument type is for
		 * @name ArgumentType#client
		 * @type {CommandoClient}
		 * @readonly
		 */
		Object.defineProperty(this, 'client', { value: client });

		/**
		 * ID of this argument type (this is what you specify in {@link ArgumentInfo#type})
		 * @type {string}
		 */
		this.id = id;
	}

	// eslint-disable-next-line valid-jsdoc
	/**
	 * Validates a value string against the type
	 * @param {string} val - Value to validate
	 * @param {CommandoMessage} originalMsg - Message that triggered the command
	 * @param {Argument} arg - Argument the value was obtained from
	 * @param {?CommandoMessage} [currentMsg=originalMsg] - Current response message
	 * @return {boolean|string|Promise<boolean|string>} Whether the value is valid, or an error message
	 * @abstract
	 */
	validate(val, originalMsg, arg, currentMsg = originalMsg) { // eslint-disable-line no-unused-vars
		throw new Error(`${this.constructor.name} doesn't have a validate() method.`);
	}

	// eslint-disable-next-line valid-jsdoc
	/**
	 * Parses the raw value string into a usable value
	 * @param {string} val - Value to parse
	 * @param {CommandoMessage} originalMsg - Message that triggered the command
	 * @param {Argument} arg - Argument the value was obtained from
	 * @param {?CommandoMessage} [currentMsg=originalMsg] - Current response message
	 * @return {*|Promise<*>} Usable value
	 * @abstract
	 */
	parse(val, originalMsg, arg, currentMsg = originalMsg) { // eslint-disable-line no-unused-vars
		throw new Error(`${this.constructor.name} doesn't have a parse() method.`);
	}

	/**
	 * Checks whether a value is considered to be empty. This determines whether the default value for an argument
	 * should be used and changes the response to the user under certain circumstances.
	 * @param {string} val - Value to check for emptiness
	 * @param {CommandoMessage} originalMsg - Message that triggered the command
	 * @param {Argument} arg - Argument the value was obtained from
	 * @param {?CommandoMessage} [currentMsg=originalMsg] - Current response message
	 * @return {boolean} Whether the value is empty
	 */
	isEmpty(val, originalMsg, arg, currentMsg = originalMsg) { // eslint-disable-line no-unused-vars
		if(Array.isArray(val)) return val.length === 0;
		return !val;
	}
}

module.exports = ArgumentType;