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

"use strict";

/** 
 * A $strcasecmp pipeline expression.
 * @see evaluate 
 * @class StrcasecmpExpression
 * @namespace mungedb-aggregate.pipeline.expressions
 * @module mungedb-aggregate
 * @constructor
 **/
var StrcasecmpExpression = module.exports = function StrcasecmpExpression(){
	if (arguments.length !== 0) throw new Error("zero args expected");
	base.call(this);
}, klass = StrcasecmpExpression, base = require("./NaryExpression"), proto = klass.prototype = Object.create(base.prototype, {constructor:{value:klass}});

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

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

proto.addOperand = function addOperand(expr) {
	this.checkArgLimit(2);
	base.prototype.addOperand.call(this, expr);
};

/** 
 * Takes in two strings. Returns a number. $strcasecmp is positive if the first string is “greater than” the second and negative if the first string is “less than” the second. $strcasecmp returns 0 if the strings are identical. 
 * @method evaluate
 **/
proto.evaluate = function evaluate(doc){
	this.checkArgCount(2);
	var val1 = this.operands[0].evaluate(doc),
		val2 = this.operands[1].evaluate(doc),
		str1 = Value.coerceToString(val1).toUpperCase(),
		str2 = Value.coerceToString(val2).toUpperCase(),
		cmp = Value.compare(str1, str2);
	return cmp;
};