@fontoxml/fontoxml-development-tools/src/request/VariableSyntaxPart.js

Development tools for Fonto.

import InputError from './InputError.js';
import NamedSyntaxPart from './NamedSyntaxPart.js';
import symbols from './symbols.js';

export default class VariableSyntaxPart extends NamedSyntaxPart {
	/**
	 * @param {string} name
	 */
	constructor(name) {
		super(name);

		this.validators = [];
	}

	/**
	 * @param {boolean|function(Type, Type): Type} required - If this is a function, acts as a short-hand for addValidator() as well
	 * @return {VariableSyntaxPart}
	 */
	isRequired(required) {
		this.required = !!required;

		return typeof required === 'function'
			? this.addValidator(required)
			: this;
	}

	/**
	 * Add a validator function that would check the resolved value and is expected to throw if something's awry.
	 * @param {function(Type, Type): Type} validator
	 * @return {VariableSyntaxPart}
	 */
	addValidator(validator) {
		this.validators.push(validator);
		return this;
	}

	/**
	 * Define a callback that can (asynchronously) resolve user input to a value. `resolver` can return any value
	 * synchronously or a Promise for that value.
	 * @param {function(Type, Type): Type} resolver
	 * @return {VariableSyntaxPart}
	 */
	setResolver(resolver) {
		this.resolver = resolver;
		return this;
	}

	/**
	 * Set a value to fall back to in case VariableSyntaxPart was not defined (and not required)
	 * @param {*} value
	 * @return {VariableSyntaxPart}
	 */
	setDefault(value) {
		this.default = value;
		return this;
	}

	[symbols.applyDefault](value, isUndefined) {
		return isUndefined ? this.cloneDefault() : value;
	}

	// @TODO: Find a better way to clone objects, since Object.assign does not seem to do the job
	// If clone is not done properly, actual usage of a default property could overwrite it for later usages
	cloneDefault() {
		return this.default &&
			typeof this.default === 'object' &&
			!Array.isArray(this.default)
			? JSON.parse(JSON.stringify(this.default))
			: this.default;
	}

	[symbols.validateInput](input) {
		if (this.required && input === undefined) {
			throw new InputError(
				`The ${this.getType()} "${this.name}" can not be undefined.`,
				null,
				'EINVAL'
			);
		}
	}

	validateValue(value) {
		this.validators.forEach((validator) => validator(value));
	}
}