Further optimisation on Memory Span

src/Html2OpenXml/Collections/HtmlAttributeCollection.cs

@@ -107,16 +107,37 @@ public static HtmlAttributeCollection ParseStyle(string? htmlStyles)
     /// <summary>
     /// Gets the named attribute.
     /// </summary>
-    public string? this[string name]
+    public ReadOnlySpan<char> this[string name]
     {
         get 
         {
             if (attributes.TryGetValue(name, out var range))
-                return rawValue.AsSpan().Slice(range).ToString().Trim();
-            return null;
+                return rawValue.AsSpan().Slice(range).Trim();
+            return [];
         }
     }
 
+    /// <summary>
+    /// Determines whether the collection contains the specified key.
+    /// </summary>
+    public bool ContainsKey(string name)
+    {
+        return attributes.ContainsKey(name);
+    }
+
+    /// <summary>
+    /// Efficient way to determine if a style is equals to a value.
+    /// </summary>
+    public bool HasKeyEqualsTo(string name, string value)
+    {
+        if (attributes.TryGetValue(name, out var range))
+        {
+            var span = rawValue.AsSpan().Slice(range).Trim();
+            return span.Equals(value.AsSpan(), StringComparison.InvariantCultureIgnoreCase);
+        }
+        return false;
+    }
+
     /// <summary>
     /// Gets an attribute representing a color (named color, hexadecimal or hexadecimal 
     /// without the preceding # character).
@@ -147,6 +168,8 @@ public Unit GetUnit(string name, UnitMetric defaultMetric = UnitMetric.Unitless)
     public Margin GetMargin(string name)
     {
         Margin margin = Margin.Empty;
+        if (IsEmpty) return margin;
+
         if (attributes.TryGetValue(name, out var range))
             margin = Margin.Parse(rawValue.AsSpan().Slice(range));
 
@@ -194,6 +217,8 @@ public HtmlBorder GetBorders()
     public SideBorder GetSideBorder(string name)
     {
         SideBorder border = SideBorder.Empty;
+        if (IsEmpty) return border;
+
         if (attributes.TryGetValue(name, out Range range))
             border = SideBorder.Parse(rawValue.AsSpan().Slice(range));
 
@@ -224,6 +249,8 @@ public SideBorder GetSideBorder(string name)
     public HtmlFont GetFont(string name)
     {
         HtmlFont font = HtmlFont.Empty;
+        if (IsEmpty) return font;
+
         if (attributes.TryGetValue(name, out Range range))
             font = HtmlFont.Parse(rawValue.AsSpan().Slice(range));
 

src/Html2OpenXml/Expressions/BlockElementExpression.cs

@@ -90,7 +90,7 @@ protected override IEnumerable<OpenXmlElement> Interpret (
     {
         return ComposeChildren(context, childNodes, paraProperties,
             (runs) => {
-                if ("always".Equals(styleAttributes!["page-break-before"], StringComparison.OrdinalIgnoreCase))
+                if (styleAttributes.HasKeyEqualsTo("page-break-before", "always"))
                 {
                     runs.Add(
                         new Run(
@@ -102,7 +102,7 @@ protected override IEnumerable<OpenXmlElement> Interpret (
                 }
             },
             (runs) => {
-                if ("always".Equals(styleAttributes!["page-break-after"], StringComparison.OrdinalIgnoreCase))
+                if (styleAttributes.HasKeyEqualsTo("page-break-after", "always"))
                 {
                     runs.Add(new Run(
                         new Break() { Type = BreakValues.Page }));
@@ -186,8 +186,8 @@ protected override void ComposeStyles (ParsingContext context)
             };
         }
 
-        JustificationValues? align = Converter.ToParagraphAlign(styleAttributes!["text-align"]);
-        if (!align.HasValue) align = Converter.ToParagraphAlign(node.GetAttribute("align"));
+        JustificationValues? align = Converter.ToParagraphAlign(styleAttributes["text-align"]);
+        if (!align.HasValue) align = Converter.ToParagraphAlign(node.GetAttribute("align").AsSpan());
         if (!align.HasValue) align = Converter.ToParagraphAlign(styleAttributes["justify-content"]);
         if (align.HasValue)
         {
@@ -256,7 +256,7 @@ protected override void ComposeStyles (ParsingContext context)
 
         var lineHeight = styleAttributes.GetUnit("line-height");
         if (!lineHeight.IsValid 
-            && "normal".Equals(styleAttributes["line-height"], StringComparison.OrdinalIgnoreCase))
+            && styleAttributes.HasKeyEqualsTo("line-height", "normal"))
         {
             // if `normal` is specified, reset any values
             lineHeight = new Unit(UnitMetric.Unitless, 1);

src/Html2OpenXml/Expressions/BodyExpression.cs

@@ -69,10 +69,11 @@ protected override void ComposeStyles(ParsingContext context)
 
         // Unsupported W3C attribute but claimed by users. Specified at <body> level, the page
         // orientation is applied on the whole document
-        string? attr = styleAttributes!["page-orientation"];
-        if (attr != null)
+        if (styleAttributes.ContainsKey("page-orientation"))
         {
-            PageOrientationValues orientation = Converter.ToPageOrientation(attr);
+            PageOrientationValues orientation = PageOrientationValues.Portrait;
+            if (styleAttributes.HasKeyEqualsTo("page-orientation", "landscape"))
+                orientation = PageOrientationValues.Landscape;
 
             var sectionProperties = mainPart.Document.Body!.GetFirstChild<SectionProperties>();
             if (sectionProperties == null || sectionProperties.GetFirstChild<PageSize>() == null)

src/Html2OpenXml/Expressions/Numbering/ListExpression.cs

@@ -214,7 +214,7 @@ private static string GetListName(IElement listNode, string? parentName = null)
     {
         var styleAttributes = listNode.GetStyles();
         bool orderedList = listNode.NodeName.Equals("ol", StringComparison.OrdinalIgnoreCase);
-        string? type = styleAttributes["list-style-type"];
+        string? type = styleAttributes["list-style-type"].ToString();
 
         if(orderedList && string.IsNullOrEmpty(type))
         {

src/Html2OpenXml/Expressions/Table/TableCaptionExpression.cs

@@ -54,8 +54,9 @@ public override IEnumerable<OpenXmlElement> Interpret (ParsingContext context)
         }
         p.Append(childElements);
 
-        string? att = styleAttributes!["text-align"] ?? node.GetAttribute("align");
-        if (!string.IsNullOrEmpty(att))
+        var att = styleAttributes["text-align"];
+        if (att.IsEmpty) att = node.GetAttribute("align").AsSpan();
+        if (!att.IsEmpty)
         {
             JustificationValues? align = Converter.ToParagraphAlign(att);
             if (align.HasValue)

src/Html2OpenXml/Expressions/Table/TableCellExpression.cs

@@ -62,7 +62,7 @@ protected override void ComposeStyles(ParsingContext context)
     {
         base.ComposeStyles(context);
 
-        Unit width = styleAttributes!.GetUnit("width");
+        Unit width = styleAttributes.GetUnit("width");
         if (!width.IsValid)
         {
             var widthValue = cellNode.GetAttribute("width");
@@ -84,23 +84,22 @@ protected override void ComposeStyles(ParsingContext context)
         }
 
         // Manage vertical text (only for table cell)
-        string? direction = styleAttributes!["writing-mode"];
-        if (direction != null)
+        var direction = styleAttributes["writing-mode"];
+        if (!direction.IsEmpty)
         {
-            switch (direction)
+            if (direction.Equals("tb-lr".AsSpan(), StringComparison.InvariantCultureIgnoreCase) ||
+                direction.Equals("vertical-lr".AsSpan(), StringComparison.InvariantCultureIgnoreCase))
             {
-                case "tb-lr":
-                case "vertical-lr":
-                    cellProperties.TextDirection = new() { Val = TextDirectionValues.BottomToTopLeftToRight };
-                    cellProperties.TableCellVerticalAlignment = new() { Val = TableVerticalAlignmentValues.Center };
-                    paraProperties.Justification = new() { Val = JustificationValues.Center };
-                    break;
-                case "tb-rl":
-                case "vertical-rl":
-                    cellProperties.TextDirection = new() { Val = TextDirectionValues.TopToBottomRightToLeft };
-                    cellProperties.TableCellVerticalAlignment = new() { Val = TableVerticalAlignmentValues.Center };
-                    paraProperties.Justification = new() { Val = JustificationValues.Center };
-                    break;
+                cellProperties.TextDirection = new() { Val = TextDirectionValues.BottomToTopLeftToRight };
+                cellProperties.TableCellVerticalAlignment = new() { Val = TableVerticalAlignmentValues.Center };
+                paraProperties.Justification = new() { Val = JustificationValues.Center };
+            }
+            else if (direction.Equals("tb-rl".AsSpan(), StringComparison.InvariantCultureIgnoreCase) ||
+                direction.Equals("vertical-rl".AsSpan(), StringComparison.InvariantCultureIgnoreCase))
+            {
+                cellProperties.TextDirection = new() { Val = TextDirectionValues.TopToBottomRightToLeft };
+                cellProperties.TableCellVerticalAlignment = new() { Val = TableVerticalAlignmentValues.Center };
+                paraProperties.Justification = new() { Val = JustificationValues.Center };
             }
         }
     }

src/Html2OpenXml/Expressions/Table/TableColExpression.cs

@@ -35,7 +35,7 @@ public override IEnumerable<OpenXmlElement> Interpret(ParsingContext context)
         ComposeStyles(context);
 
         var column = new GridColumn();
-        var width = styleAttributes!.GetUnit("width");
+        var width = styleAttributes.GetUnit("width");
         if (width.IsValid)
         {
             if (width.IsFixed)

src/Html2OpenXml/Expressions/Table/TableElementExpressionBase.cs

@@ -71,8 +71,8 @@ protected override void ComposeStyles(ParsingContext context)
     {
         base.ComposeStyles(context);
 
-        var valign = Converter.ToVAlign(styleAttributes!["vertical-align"]);
-        if (!valign.HasValue) valign = Converter.ToVAlign(node.GetAttribute("valign"));
+        var valign = Converter.ToVAlign(styleAttributes["vertical-align"]);
+        if (!valign.HasValue) valign = Converter.ToVAlign(node.GetAttribute("valign").AsSpan());
         if (!valign.HasValue)
         {
             // in Html, table cell are vertically centered by default
@@ -92,7 +92,7 @@ protected override void ComposeStyles(ParsingContext context)
         }
 
         var halign = Converter.ToParagraphAlign(styleAttributes["text-align"]);
-        if (!halign.HasValue) halign = Converter.ToParagraphAlign(node.GetAttribute("align"));
+        if (!halign.HasValue) halign = Converter.ToParagraphAlign(node.GetAttribute("align").AsSpan());
         if (halign.HasValue)
         {
             paraProperties.KeepNext = new();

src/Html2OpenXml/Expressions/Table/TableExpression.cs

@@ -278,7 +278,7 @@ protected override void ComposeStyles (ParsingContext context)
             }
         }
 
-        var align = Converter.ToParagraphAlign(tableNode.GetAttribute("align"))
+        var align = Converter.ToParagraphAlign(tableNode.GetAttribute("align").AsSpan())
             ?? Converter.ToParagraphAlign(styleAttributes["justify-self"]);
         if (!align.HasValue)
         {

src/Html2OpenXml/Expressions/Table/TableRowExpression.cs

@@ -101,7 +101,7 @@ protected override void ComposeStyles(ParsingContext context)
     {
         base.ComposeStyles(context);
 
-        Unit unit = styleAttributes!.GetUnit("height", UnitMetric.Pixel);
+        Unit unit = styleAttributes.GetUnit("height", UnitMetric.Pixel);
         if (!unit.IsValid) unit = Unit.Parse(rowNode.GetAttribute("height").AsSpan(), UnitMetric.Pixel);
 
         switch (unit.Metric)

src/Html2OpenXml/Primitives/HtmlColor.Named.cs

@@ -15,7 +15,6 @@ private static HtmlColor GetNamedColor (ReadOnlySpan<char> name)
     {
         // the longest built-in Color's name is much lower than this check, so we should not allocate here in a typical usage
         Span<char> loweredValue = name.Length <= 128 ? stackalloc char[name.Length] : new char[name.Length];
-
         name.ToLowerInvariant(loweredValue);
 
         namedColors.TryGetValue(loweredValue.ToString(), out var color);

src/Html2OpenXml/Utilities/AngleSharpExtensions.cs

@@ -156,9 +156,11 @@ public static string CollapseLineBreaks(this string str)
     /// Determines whether the layout mode is inline vs block or flex.
     /// </summary>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static bool IsInlineLayout(string? displayMode, string defaultLayout)
+    public static bool IsInlineLayout(ReadOnlySpan<char> displayMode, string defaultLayout)
     {
-        return (displayMode ?? defaultLayout)
-            .StartsWith("inline", StringComparison.OrdinalIgnoreCase) == true;
+        if (displayMode.IsEmpty)
+            displayMode = defaultLayout.AsSpan();
+
+        return displayMode.StartsWith("inline".AsSpan(), StringComparison.InvariantCultureIgnoreCase);
     }
 }

src/Html2OpenXml/Utilities/Converter.cs

@@ -22,12 +22,13 @@ static class Converter
     /// <summary>
     /// Convert the Html text align attribute (horizontal alignement) to its corresponding OpenXml value.
     /// </summary>
-    public static JustificationValues? ToParagraphAlign(string? htmlAlign)
+    public static JustificationValues? ToParagraphAlign(ReadOnlySpan<char> span)
     {
-        if (htmlAlign == null) return null;
-        return htmlAlign.ToLowerInvariant() switch
+        Span<char> loweredValue = span.Length <= 128 ? stackalloc char[span.Length] : new char[span.Length];
+        span.ToLowerInvariant(loweredValue);
+        return loweredValue switch
         {
-            "left" => JustificationValues.Left,
+           "left" => JustificationValues.Left,
             "right" => JustificationValues.Right,
             "center" => JustificationValues.Center,
             "justify" => JustificationValues.Both,
@@ -38,10 +39,11 @@ static class Converter
     /// <summary>
     /// Convert the Html vertical-align attribute to its corresponding OpenXml value.
     /// </summary>
-    public static TableVerticalAlignmentValues? ToVAlign(string? htmlAlign)
+    public static TableVerticalAlignmentValues? ToVAlign(ReadOnlySpan<char> span)
     {
-        if (htmlAlign == null) return null;
-        return htmlAlign.ToLowerInvariant() switch
+        Span<char> loweredValue = span.Length <= 128 ? stackalloc char[span.Length] : new char[span.Length];
+        span.ToLowerInvariant(loweredValue);
+        return loweredValue switch
         {
             "top" => TableVerticalAlignmentValues.Top,
             "middle" => TableVerticalAlignmentValues.Center,
@@ -159,14 +161,6 @@ public static BorderValues ToBorderStyle(ReadOnlySpan<char> span)
         };
     }
 
-    public static PageOrientationValues ToPageOrientation(string? orientation)
-    {
-        if ( "landscape".Equals(orientation,StringComparison.OrdinalIgnoreCase))
-            return PageOrientationValues.Landscape;
-
-        return PageOrientationValues.Portrait;
-    }
-
     public static ICollection<TextDecoration> ToTextDecoration(ReadOnlySpan<char> values)
     {
         // this style could take multiple values separated by a space

test/HtmlToOpenXml.Tests/Primitives/StyleParserTests.cs

@@ -9,21 +9,22 @@ namespace HtmlToOpenXml.Tests.Primitives
     public class StyleParserTests
     {
         [TestCase("text-decoration:underline; color: red ")]
-        [TestCase("text-decoration:underline&#59;color:red")]
+        [TestCase("text-decoration : underline &#59;color :red")]
         public void ParseStyle_ShouldSucceed(string htmlStyle)
         {
             var styles = HtmlAttributeCollection.ParseStyle(htmlStyle);
             Assert.Multiple(() => {
-                Assert.That(styles["text-decoration"], Is.EqualTo("underline"));
-                Assert.That(styles["color"], Is.EqualTo("red"));
+                Assert.That(styles.HasKeyEqualsTo("text-decoration", "underline"), Is.True);
+                Assert.That(styles.HasKeyEqualsTo("color", "red"), Is.True);
+                Assert.That(styles["color"].ToString(), Is.EqualTo("red"));
             });
         }
 
         [Test(Description = "Parser should consider the last occurence of a style")]
         public void DuplicateStyle_ReturnsLatter()
         {
-            var styleAttributes = HtmlAttributeCollection.ParseStyle("color:red;color:blue");
-            Assert.That(styleAttributes["color"], Is.EqualTo("blue"));
+            var styleAttributes = HtmlAttributeCollection.ParseStyle("color:red;color:BLUE");
+            Assert.That(styleAttributes.HasKeyEqualsTo("color", "blue"), Is.True);
         }
 
         [TestCase("color;color;")]
@@ -33,7 +34,7 @@ public void InvalidStyle_ShouldBeEmpty(string htmlStyle)
         {
             var styles = HtmlAttributeCollection.ParseStyle(htmlStyle);
             Assert.That(styles.IsEmpty, Is.True);
-            Assert.That(styles["color"], Is.Null);
+            Assert.That(styles.ContainsKey("color"), Is.False);
         }
 
         [Test]

test/HtmlToOpenXml.Tests/StyleTests.cs

@@ -163,23 +163,23 @@ public void ManualAddStyle_ThenRefreshStyles_ShouldSucceed()
         public void DuplicateStyle_ReturnsLatter()
         {
             var styleAttributes = HtmlAttributeCollection.ParseStyle("color:red;color:blue");
-            Assert.That(styleAttributes["color"], Is.EqualTo("blue"));
+            Assert.That(styleAttributes["color"].ToString(), Is.EqualTo("blue"));
         }
 
         [Test(Description = "Encoded ':' and ';' characters are valid")]
         public void EncodedStyle_ShouldSucceed()
         {
             var styleAttributes = HtmlAttributeCollection.ParseStyle("text-decoration:underline&#59;color:red");
-            Assert.That(styleAttributes["text-decoration"], Is.EqualTo("underline"));
-            Assert.That(styleAttributes["color"], Is.EqualTo("red"));
+            Assert.That(styleAttributes["text-decoration"].ToString(), Is.EqualTo("underline"));
+            Assert.That(styleAttributes["color"].ToString(), Is.EqualTo("red"));
         }
 
         [Test(Description = "Key style with no value should be ignored")]
         public void EmptyStyle_ShouldBeIgnored()
         {
             var styleAttributes = HtmlAttributeCollection.ParseStyle("text-decoration;color:red");
-            Assert.That(styleAttributes["text-decoration"], Is.Null);
-            Assert.That(styleAttributes["color"], Is.EqualTo("red"));
+            Assert.That(styleAttributes.ContainsKey("text-decoration"), Is.False);
+            Assert.That(styleAttributes["color"].ToString(), Is.EqualTo("red"));
         }
     }
 }