"use strict";

/**
 * A $toUpper pipeline expression.
 * @see evaluateInternal
 * @class ToUpperExpression
 * @namespace mungedb-aggregate.pipeline.expressions
 * @module mungedb-aggregate
 * @constructor
 **/
var ToUpperExpression = module.exports = function ToUpperExpression() {
	base.call(this);
}, klass = ToUpperExpression, base = require("./FixedArityExpressionT")(ToUpperExpression, 1), proto = klass.prototype = Object.create(base.prototype, {constructor: {value: klass }});

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

klass.opName = "$toUpper";

// PROTOTYPE MEMBERS
proto.getOpName = function getOpName() {
	return klass.opName;
};

/**
 * Takes a single string and converts that string to lowercase, returning the result. All uppercase letters become lowercase.
 **/
proto.evaluateInternal = function evaluateInternal(vars) {
	var val = this.operands[0].evaluateInternal(vars),
		str = Value.coerceToString(val);
	return str.toUpperCase();
};

/** Register Expression */
Expression.registerExpression(klass.opName, base.parse);