Add support for TimeSpan

Fluid.Tests/MiscFiltersTests.cs

@@ -409,6 +409,23 @@ public async Task DateNumberIsParsedAsSeconds(long number, string expected)
             Assert.Equal(expected, result.ToStringValue());
         }
 
+        [Theory]
+        [InlineData("0", "00:00:00.000")]
+        [InlineData("1:2", "01:02:00.000")]
+        [InlineData("1:2:3.1", "01:02:03.100")]
+        public async Task DateTimeSpan(string timespan, string expected)
+        {
+            // Converting to Unix time should not vary by TimeSone
+
+            var input = FluidValue.Create(TimeSpan.Parse(timespan), new TemplateOptions());
+            var format = new FilterArguments(new StringValue("%H:%M:%S.%L"));
+            var context = new TemplateContext { TimeZone = Eastern };
+
+            var result = await MiscFilters.Date(input, format, context);
+
+            Assert.Equal(expected, result.ToStringValue());
+        }
+
         [Fact]
         public async Task NoTimeZoneIsParsedAsLocal()
         {

Fluid/MemberAccessStrategyExtensions.cs

@@ -80,7 +80,7 @@ internal static IMemberAccessor GetNamedAccessor(Type type, string name, MemberN
         /// </summary>
         /// <typeparam name="T">The type to register.</typeparam>
         /// <param name="strategy">The <see cref="MemberAccessStrategy"/>.</param>
-        public static void Register<T>(this MemberAccessStrategy strategy)
+        public static void Register<T>(this MemberAccessStrategy strategy) where T : class
         {
             Register(strategy, typeof(T));
         }
@@ -101,7 +101,7 @@ public static void Register(this MemberAccessStrategy strategy, Type type)
         /// <typeparam name="T">The type to register.</typeparam>
         /// <param name="strategy">The <see cref="MemberAccessStrategy"/>.</param>
         /// <param name="names">The names of the properties in the type to register.</param>
-        public static void Register<T>(this MemberAccessStrategy strategy, params string[] names)
+        public static void Register<T>(this MemberAccessStrategy strategy, params string[] names) where T : class
         {
             strategy.Register(typeof(T), names);
         }
@@ -112,7 +112,7 @@ public static void Register<T>(this MemberAccessStrategy strategy, params string
         /// <typeparam name="T">The type to register.</typeparam>
         /// <param name="strategy">The <see cref="MemberAccessStrategy"/>.</param>
         /// <param name="names">The property's expressions in the type to register.</param>
-        public static void Register<T>(this MemberAccessStrategy strategy, params Expression<Func<T, object>>[] names)
+        public static void Register<T>(this MemberAccessStrategy strategy, params Expression<Func<T, object>>[] names) where T : class
         {
             strategy.Register<T>(names.Select(ExpressionHelper.GetPropertyName).ToArray());
         }

Fluid/Values/FluidValue.cs

@@ -166,6 +166,9 @@ public static FluidValue Create(object value, TemplateOptions options)
                         case DateTimeOffset dateTimeOffset:
                             return new DateTimeValue(dateTimeOffset);
 
+                        case TimeSpan timeSpan:
+                            return new DateTimeValue(new DateTime(timeSpan.Ticks));
+
                         case IFormattable formattable:
                             return new StringValue(formattable.ToString(null, options.CultureInfo));