strict-oop.js

"use strict";
/* @description     Stric OOP for Javascript									    *
 * @author          Tom Butler tom@r.je                                             *
 * @copyright       2016 Tom Butler <tom@r.je> | https://r.je/                      *
 * @license         http://www.opensource.org/licenses/bsd-license.php  BSD License *
 * @version         1.0                                                             */
var StrictOOP = class {
	constructor(obj) {
		this.obj = obj;
		this.properties = [];
		this.methods = [];
	}

	property(name) {
		if (!this.properties[name])	this.properties[name] = new StrictOOP.Property(this, name);
		return this.properties[name];
	}

	method(name) {
		if (!this.methods[name]) this.methods[name] = new StrictOOP.Method(this, name);
		return this.methods[name];
	}

	getCallerName(n) {
		try {
			throw new Error('Generating a stack trace');
		}
		catch (e) {
			return e.stack.split('\n')[n].split('at ')[1].split(' (')[0];
		}
	}

	checkVisibility(visibility, error) {
		if (this.getCallerName(4).indexOf(this.obj.constructor.name) == -1 && visibility == 'private') {
			throw new Error(error);
		}
	}

	checktype(expected, actual, error) {
		if (expected != null && !(typeof actual == expected || this.obj.constructor.name == expected)) {
				throw new Error(error);
		}
	}
};

StrictOOP.Method = class {
	constructor(parent, name) {
		this.parent = parent;
		var oldFunc = parent.obj[name];
		var self = this;

		parent.obj[name] = function() {	
			parent.checkVisibility(self.visibility, 'Cannot call private method ' + name);
			
 			var result = oldFunc.apply(parent.obj, arguments);

 			parent.checktype(self.otype, result, 'Method ' + name + ' must return a ' + self.otype);
			
			return result;			
		};
	}

	is(visibility) {
		this.visibility = visibility;
		return this;
	}

	returns(type) {
		this.otype = type;
		return this;
	}
};

StrictOOP.Property = class {
	constructor(parent, name) {
		this.value = parent.obj[name];
		delete parent.obj[name];
		this.visibility = 'public';
		this.otype = null;

		var self = this;

		Object.defineProperty(parent.obj, name, {
			get: function() {
				parent.checkVisibility(self.visibility, 'Cannot read private property ' + parent.obj.constructor.name + '.' + name);
				
				return self.value;
			},
			set: function(value) {
				parent.checkVisibility(self.visibility, 'Cannot set private property ' + parent.obj.constructor.name + '.' + name);
				parent.checktype(self.otype, value, 'Cannot set property ' + name + ' to ' + value + ', expecting ' + self.otype);

				self.value = value;
			}
		});
	}

	is(visibility) {
		this.visibility = visibility;
		return this;
	}

	type(type) {
		this.otype = type;
		return this;
	}
}

module.exports = StrictOOP;