egroupware/api/js/etemplate/et2_core_inheritance.ts

/**
 * EGroupware eTemplate2 - JS code for implementing inheritance with attributes
 *
 * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
 * @package etemplate
 * @subpackage api
 * @link: https://www.egroupware.org
 * @author Andreas Stöckel
 */

/*egw:uses
	et2_core_common;
*/

import {egw} from "../jsapi/egw_global";
import {et2_checkType, et2_no_init, et2_validateAttrib} from "./et2_core_common";
import {et2_implements_registry} from "./et2_core_interfaces";

// Needed for mixin
export function mix (superclass)
{
	return new MixinBuilder(superclass);
}
export class MixinBuilder {
	constructor(superclass) {
		this.superclass = superclass;
	}

	with(...mixins) {
		return mixins.reduce(this.applyMixins, this.superclass);
	}
	applyMixins(derivedConstructor: any, baseConstructor: any) {
		Object.getOwnPropertyNames(baseConstructor.prototype)
			.forEach(name => {
				Object.defineProperty(derivedConstructor.prototype,
					name,
					Object.
					getOwnPropertyDescriptor(
						baseConstructor.prototype,
						name
					)
				);
			});
	}
	 copyProperties(target, source) {
		for (let key of Reflect.ownKeys(source)) {
			if (key !== "constructor" && key !== "prototype" && key !== "name") {
				let desc = Object.getOwnPropertyDescriptor(source, key);
				Object.defineProperty(target, key, desc);
			}
		}
	}
}

// This one from Typescript docs
export function applyMixins(derivedCtor: any, constructors: any[]) {
  constructors.forEach((baseCtor) => {
    Object.getOwnPropertyNames(baseCtor.prototype).forEach((name) => {
      Object.defineProperty(
        derivedCtor.prototype,
        name,
        Object.getOwnPropertyDescriptor(baseCtor.prototype, name) ||
          Object.create(null)
      );
    });
  });
}

/*
Experiments in using mixins to combine et2_widget & LitElement
Note that this "works", in that it mixes the code properly.
It does not work in that the resulting class does not work with et2's inheritance & class checking stuff

// This one to make TypeScript happy?
interface et2_textbox extends et2_textbox, LitElement {}
// This one to make the inheritance magic happen
applyMixins(et2_textbox, [et2_textbox,LitElement]);
// Make it a real WebComponent
customElements.define("et2-textbox",et2_textbox);

 */
export class ClassWithInterfaces
{
	/**
	 * The implements function can be used to check whether the object
	 * implements the given interface.
	 *
	 * As TypeScript can not (yet) check if an objects implements an interface on runtime,
	 * we currently implements with each interface a function called 'implements_'+interfacename
	 * to be able to check here.
	 *
	 * @param _iface name of interface to check
	 */
	implements (_iface_name : string)
	{
		if (typeof et2_implements_registry[_iface_name] === 'function' &&
			et2_implements_registry[_iface_name](this))
		{
			return true
		}
		return false;
	}

	/**
	 * Check if object is an instance of a class or implements an interface (specified by the interfaces name)
	 *
	 * @param _class_or_interfacename class(-name) or string with name of interface
	 */
	instanceOf(_class_or_interfacename: any) : boolean
	{
		if (typeof _class_or_interfacename === 'string')
		{
			return this.implements(_class_or_interfacename);
		}
		return this instanceof _class_or_interfacename;
	}
}

export class ClassWithAttributes extends ClassWithInterfaces
{
	/**
	 * Object to collect the attributes we operate on
	 */
	attributes: object;

	/**
	 * Returns the value of the given attribute. If the property does not
	 * exist, an error message is issued.
	 *
	 * @param {string} _name
	 * @return {*}
	 */
	getAttribute(_name)
	{
		if (typeof this.attributes[_name] != "undefined" &&
			!this.attributes[_name].ignore) {
			if (typeof this["get_" + _name] == "function") {
				return this["get_" + _name]();
			} else {
				return this[_name];
			}
		} else {
			egw.debug("error", this, "Attribute '" + _name + "' does not exist!");
		}
	}

	/**
	 * The setAttribute function sets the attribute with the given name to
	 * the given value. _override defines, whether this[_name] will be set,
	 * if this key already exists. _override defaults to true. A warning
	 * is issued if the attribute does not exist.
	 *
	 * @param {string} _name
	 * @param {*} _value
	 * @param {boolean} _override
	 */
	setAttribute(_name, _value, _override)
	{
		if (typeof this.attributes[_name] != "undefined") {
			if (!this.attributes[_name].ignore) {
				if (typeof _override == "undefined") {
					_override = true;
				}

				var val = et2_checkType(_value, this.attributes[_name].type,
					_name, this);

				if (typeof this["set_" + _name] == "function") {
					this["set_" + _name](val);
				} else if (_override || typeof this[_name] == "undefined") {
					this[_name] = val;
				}
			}
		} else {
			egw.debug("warn", this, "Attribute '" + _name + "' does not exist!");
		}
	}

	/**
	 * generateAttributeSet sanitizes the given associative array of attributes
	 * (by passing each entry to "et2_checkType" and checking for existance of
	 * the attribute) and adds the default values to the associative array.
	 *
	 * @param {object} _attrs is the associative array containing the attributes.
	 */
	static generateAttributeSet(widget, _attrs)
	{
		// Sanity check and validation
		for (var key in _attrs) {
			if (typeof widget[key] != "undefined") {
				if (!widget[key].ignore) {
					_attrs[key] = et2_checkType(_attrs[key], widget[key].type,
						key, this);
				}
			} else {
				// Key does not exist - delete it and issue a warning
				delete (_attrs[key]);
				egw.debug("warn", this, "Attribute '" + key +
					"' does not exist in " + _attrs.type + "!");
			}
		}

		// Include default values or already set values for this attribute
		for (var key in widget) {
			if (typeof _attrs[key] == "undefined") {
				var _default = widget[key]["default"];
				if (_default == et2_no_init) {
					_default = undefined;
				}

				_attrs[key] = _default;
			}
		}

		return _attrs;
	}

	/**
	 * The initAttributes function sets the attributes to their default
	 * values. The attributes are not overwritten, which means, that the
	 * default is only set, if either a setter exists or this[propName] does
	 * not exist yet.
	 *
	 * @param {object} _attrs is the associative array containing the attributes.
	 */
	initAttributes(_attrs)
	{
		for (var key in _attrs) {
			if (typeof this.attributes[key] != "undefined" && !this.attributes[key].ignore && !(_attrs[key] == undefined)) {
				this.setAttribute(key, _attrs[key], false);
			}
		}
	}

	static buildAttributes(class_prototype: object)
	{
		let class_tree = [];
		let attributes = {};
		let n = 0;
		do {
			n++;
			class_tree.push(class_prototype);
			class_prototype = Object.getPrototypeOf(class_prototype);
		} while (class_prototype !== ClassWithAttributes && n < 50);

		for (let i = class_tree.length - 1; i >= 0; i--) {
			attributes = ClassWithAttributes.extendAttributes(attributes, class_tree[i]._attributes);
		}
		return attributes;
	}

	/**
	 * Extend current _attributes with the one from the parent class
	 *
	 * This gives inheritance from the parent plus the ability to override in the current class.
	 *
	 * @param _attributes
	 * @param _parent
	 */
	static extendAttributes(_parent: object, _attributes: object): object
	{
		function _copyMerge(_new, _old)
		{
			var result = {};

			// Copy the new object
			if (typeof _new != "undefined") {
				for (var key in _new) {
					result[key] = _new[key];
				}
			}

			// Merge the old object
			for (var key in _old) {
				if (typeof result[key] == "undefined") {
					result[key] = _old[key];
				}
			}

			return result;
		}

		var attributes = {};

		// Copy the old attributes
		for (var key in _attributes) {
			attributes[key] = _copyMerge({}, _attributes[key]);
		}

		// Add the old attributes to the new ones. If the attributes already
		// exist, they are merged.
		for (var key in _parent) {
			var _old = _parent[key];

			attributes[key] = _copyMerge(attributes[key], _old);
		}

		// Validate the attributes
		for (var key in attributes) {
			et2_validateAttrib(key, attributes[key]);
		}

		return attributes;
	}
}