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

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

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

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

	proto.addOperand = function addOperand(expr) {
		this.checkArgLimit(1);
		base.addOperand(expr);
	};

	/** Takes a single string and converts that string to lowercase, returning the result. All uppercase letters become lowercase. **/
	proto.evaluate = function evaluate(doc) {
		this.checkArgCount(1);
		var val = this.operands[0].evaluate(doc),
			str = Value.coerceToString(val);
		return str.toUpperCase();
	};

	return klass;
})();