relu-core/modules/rp/lib/element.js

Core for bot

var base = require("./base");

module.exports = function rpElement(array, index) {
	if(array.elements && array.elements[index])
		return array.elements[index].temporary();

	var p = base();
	p.constructor = rpElement;
	p.index = index;
	p.parent = array;

	p._info = function() { return "[" + index + "]" };

	p._actionsList = function() {
		if(index < 0) return null;
		var al = array._actionsList();
		if(!al) return null;
		return al.atPath([index]);
	};

	p._actionsTarget = function() {
		if(index < 0) return null;
		var at = array._actionsTarget();
		if(!at) return null;
		return at(index);
	};

	p._get = function() {
		p.depend();
		return p._getUndependend();
	};

	p._getUndependend = function() {
		var a = array._getUndependend();
		return getValue(a);
	};

	function getValue(a) {
		if(index < 0) return undefined;
		if(!Array.isArray(a)) return undefined;
		if(a.length <= index) return undefined;
		return a[index];
	}

	if(!array.elements)
		array.elements = {};
	array.elements[index] = p;
	array.onUpdated(onUpdated, true);
	array.onAdded(onAdded, true);
	array.onRemoved(onRemoved, true);
	array.onNested(onNested);
	array.ref(p);

	p.onceDisposed(function() {
		if(index >= 0) disconnect();
		p.index = index = -1;
	});

	p.isConst = function() {
		return array.isConst();
	};

	p.writable = function() {
		return array.writable();
	};

	function disconnect() {
		array.removeUpdatedListener(onUpdated);
		array.removeAddedListener(onAdded);
		array.removeRemovedListener(onRemoved);
		array.removeNestedListener(onNested);
		if(array.elements[index] === p)
			delete array.elements[index];
		array.unref(p);
	};

	p.remove = function() {
		if(index < 0) throw new Error("Item is already removed");
		if(!Array.isArray(p.parent._getUndependend())) throw new Error("Parent is not an array");
		if(index >= p.parent._getUndependend().length) throw new Error("Item is out of range (weird)");
		array.spliceBefore(index, 1);
	};

	function onUpdated(newValue, oldValue) {
		if(index < 0) return;
		disconnect();
		p.index = index = -1;
		var old = getValue(oldValue);
		if(old !== undefined) {
			p._updated(undefined, old);
			p._changed()
		}
	}

	function onAdded(idx) {
		if(index < 0) return;
		if(idx <= index) {
			if(array.elements[index] === p)
				delete array.elements[index];
			p.index = ++index;
			array.elements[index] = p;
		}
	}

	function onRemoved(idx, oldValue) {
		if(index < 0) return;
		if(idx < index) {
			if(array.elements[index] === p)
				delete array.elements[index];
			p.index = --index;
			array.elements[index] = p;
		} else if(idx === index) {
			disconnect();
			p.index = index = -1;
			var value = getValue(oldValue);
			if(value !== undefined) {
				p._updated(undefined, value);
				p._changed();
			}
		}
	}

	function onNested(type, path, a, b) {
		if(path[0] === index) {
			if(path.length > 1)
				p._nested(type, path.slice(1), a, b);
			else {
				switch(type) {
				case "updated":
					p._updated(a, b);
					break;
				case "added":
					p._added(a, b);
					break;
				case "removed":
					p._removed(a, b);
					break;
				case "changed":
					p._changed();
					break;
				}
			}
		}
	}

	return p;
};