Refactor opacity parsing and add percent/number converters

src/ExCSS.Tests/PropertyTests/OpacityPropertyTests.cs

@@ -25,16 +25,20 @@ public void OpacityVarianceTests()
         var result = (OpacityProperty)property;
         Assert.Equal("50%", result.Value);
 
+        property = ParseDeclaration("opacity: 0.4");
+        result = (OpacityProperty)property;
+        Assert.Equal("0.4", result.Value);
+
         property = ParseDeclaration("opacity: .50");
         result = (OpacityProperty)property;
-        Assert.Equal("50%", result.Value);
+        Assert.Equal("0.5", result.Value);
 
         property = ParseDeclaration("opacity: 1");
         result = (OpacityProperty)property;
-        Assert.Equal("100%", result.Value);
+        Assert.Equal("1", result.Value);
 
         property = ParseDeclaration("opacity: 0");
         result = (OpacityProperty)property;
-        Assert.Equal("0%", result.Value);
+        Assert.Equal("0", result.Value);
     }
 }

src/ExCSS/Extensions/ValueExtensions.cs

@@ -120,6 +120,32 @@ public static Length ToLength(this FontSize fontSize)
             }
         }
 
+        public static Number? ToPercentOrNumber(this IEnumerable<Token> value)
+        {
+            var enumerable = value as Token[] ?? value.ToArray();
+            var percent = ToPercent(enumerable);
+
+            if (percent is not null)
+            {
+                return new Number(percent.Value.Value, Number.Unit.Percent);
+            }
+
+            var element = value.OnlyOrDefault();
+            if (element is not NumberToken token)
+            {
+                return null;
+            }
+
+            try
+            {
+                return new Number(token.Value, Number.Unit.Float);
+            }
+            catch
+            {
+                return null;
+            }
+        }
+
         public static string ToCssString(this IEnumerable<Token> value)
         {
             var element = value.OnlyOrDefault();

src/ExCSS/Model/Converters.cs

@@ -70,6 +70,9 @@ public static readonly IValueConverter
         public static readonly IValueConverter PercentOrFractionConverter =
             new StructValueConverter<Percent>(ValueExtensions.ToPercentOrFraction);
 
+        public static readonly IValueConverter PercentOrNumberConverter =
+            new StructValueConverter<Number>(ValueExtensions.ToPercentOrNumber);
+
         public static readonly IValueConverter AngleNumberConverter =
             new StructValueConverter<Angle>(ValueExtensions.ToAngleNumber);
 
@@ -323,6 +326,7 @@ public static readonly IValueConverter
         public static readonly IValueConverter OptionalLengthOrPercentConverter = LengthOrPercentConverter.OrNone();
         public static readonly IValueConverter AutoLengthOrPercentConverter = LengthOrPercentConverter.OrAuto();
         public static readonly IValueConverter OptionalPercentOrFractionConverter = PercentOrFractionConverter.OrDefault(1f);
+        public static readonly IValueConverter OptionalPercentOrNumberConverter = PercentOrNumberConverter.OrDefault(1f);
 
         public static readonly IValueConverter FontSizeConverter =
             LengthOrPercentConverter.Or(Map.FontSizes.ToConverter());

src/ExCSS/StyleProperties/Visibility/OpacityProperty.cs

@@ -2,7 +2,7 @@
 {
     internal sealed class OpacityProperty : Property
     {
-        private static readonly IValueConverter StyleConverter = Converters.OptionalPercentOrFractionConverter;
+        private static readonly IValueConverter StyleConverter = Converters.OptionalPercentOrNumberConverter;
 
         internal OpacityProperty() : base(PropertyNames.Opacity, PropertyFlags.Animatable)
         {

src/ExCSS/Values/Number.cs

@@ -65,7 +65,8 @@ public bool Equals(Number other)
         public enum Unit : byte
         {
             Integer,
-            Float
+            Float,
+            Percent
         }
 
         public static bool operator ==(Number a, Number b)
@@ -90,12 +91,12 @@ public override int GetHashCode()
 
         public override string ToString()
         {
-            return Value.ToString();
+            return Value.ToString() + (_unit == Unit.Percent ? "%" : string.Empty);
         }
 
         public string ToString(string format, IFormatProvider formatProvider)
         {
-            return Value.ToString(format, formatProvider);
+            return Value.ToString(format, formatProvider) + (_unit == Unit.Percent ? "%" : string.Empty);
         }
     }
 }