/Mercurial.Net/Attributes/NullableArgumentAttribute.cs

using System;



namespace Mercurial.Attributes

{

    /// <summary>

    /// This attribute can be applied to nullable properties in option classes,

    /// to specify the option to pass to the executable in case

    /// of a <c>null</c> value, or the option to pass before the property

    /// value itself.

    /// </summary>

    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]

    public sealed class NullableArgumentAttribute : ArgumentAttribute

    {

        /// <summary>

        /// Gets or sets the option to pass to the Mercurial executable if the

        /// property value is <c>null</c>. If <see cref="string.Empty"/>,

        /// no option will be passed in this case.

        /// </summary>

        public string NullOption

        {

            get;

            set;

        }



        /// <summary>

        /// Gets or sets the option to specify before the property value when

        /// passing it to the Mercurial executable. If <see cref="string.Empty"/>,

        /// only the property value itself will be passed.

        /// </summary>

        public string NonNullOption

        {

            get;

            set;

        }



        /// <summary>

        /// Gets a collection of options or arguments to pass to the Mercurial

        /// executable, based on the property value from the options class.

        /// </summary>

        /// <param name="propertyValue">

        /// The property value from the tagged property of the options class.

        /// </param>

        /// <returns>

        /// A collection of options or arguments, or an empty array or <c>null</c>

        /// for no options for the specified property value.

        /// </returns>

        public override string[] GetOptions(object propertyValue)

        {

            string result;

            if (propertyValue == null)

                result = null;

            else

                result = propertyValue.ToString().Trim();



            if (StringEx.IsNullOrWhiteSpace(result))

            {

                if (StringEx.IsNullOrWhiteSpace(NullOption))

                    return null;

                return new[]

                {

                    NullOption

                };

            }



            if (!StringEx.IsNullOrWhiteSpace(NonNullOption))

                return new[]

                {

                    NonNullOption, "\"" + result + "\""

                };



            return new[]

            {

                "\"" + result + "\""

            };

        }

    }

}