/*

    Copyright (C) 2018 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Creates an extension for the String class.

*/

import Foundation

extension String {

    /// Determines whether the string is the Delete charater.

    var isDelete: Bool {

        return (self == "D")

    }

    /// Determines whether the string is a period.

    var isPeriod: Bool {

        return (self == ".")

    }

    /// Determines whether the string is the Clear charater.

    var isClear: Bool {

        return (self == "C")

    }

    /// Determines whether the string is a period or a number between 0 and 9.

    var isValidDigit: Bool {

        let digits = "0123456789."

        return digits.contains(self)

    }

    /// Determines whether the string is an operator such as +, -, *, or /.

    var isOperator: Bool {

        let operators = "+-*/"

        return operators.contains(self)

    }

    /// Determines whether the string is an equal sign.

    var isEqualSign: Bool {

        return (self == "=")

    }

    /// Determines whether a string is a valid character such as a digit, a.

    var isValidCharacter: Bool {

        return ( isValidDigit || isOperator || isDelete || isClear || isPeriod || isEqualSign)

    }

}