PowerToys/Wox/Converters/ConvertorBase.cs

using System;
using System.Globalization;
using System.Windows.Data;
using System.Windows.Markup;

namespace Wox.Converters
{
    public abstract class ConvertorBase<T> : MarkupExtension, IValueConverter where T : class, new()
    {
        private static T converter;

        /// <summary>
        /// Must be implemented in inheritor.
        /// </summary>
        public abstract object Convert(object value, Type targetType, object parameter, CultureInfo culture);

        /// <summary>
        /// Override if needed.
        /// </summary>
        public virtual object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }

        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            return converter ?? (converter = new T());
        }
    }
}