mungedb-aggregate/lib/pipeline/expressions/SetIntersectionExpression.js

"use strict";

/**
 * A $setintersection pipeline expression.
 * @see evaluateInternal
 * @class SetIntersectionExpression
 * @namespace mungedb-aggregate.pipeline.expressions
 * @module mungedb-aggregate
 * @constructor
 **/
var SetIntersectionExpression = module.exports = function SetIntersectionExpression() {
		this.fixedArity(2);
		if (arguments.length !== 2) throw new Error("two args expected");
		base.call(this);
}, klass = SetIntersectionExpression,
		base = require("./NaryExpression"),
		proto = klass.prototype = Object.create(base.prototype, {
				constructor: {
						value: klass
				}
		});

// DEPENDENCIES
var Value = require("../Value"),
		Expression = require("./Expression");

// PROTOTYPE MEMBERS
proto.getOpName = function getOpName() {
		return "$setintersection";
};

/**
 * Takes 2 objects. Returns the intersects of the objects.
 * @method evaluateInternal
 **/
proto.evaluateInternal = function evaluateInternal(vars) {
		var object1 = this.operands[0].evaluateInternal(vars),
				object2 = this.operands[1].evaluateInternal(vars);
		if (object1 instanceof Array) throw new Error(this.getOpName() + ": object 1 must be an object");
		if (object2 instanceof Array) throw new Error(this.getOpName() + ": object 2 must be an object");

		var result = object1.filter(function(n) {
		  return object2.indexOf(n) > -1;
		});
};

/** Register Expression */
Expression.registerExpression("$setintersection", SetIntersectionExpression.parse);