Refactor DataUri parsing and improve HTML entity handling

Directory.Build.props

@@ -2,7 +2,7 @@
     <PropertyGroup>
         <Copyright>Copyright 2009-$([System.DateTime]::Today.Year) Olivier Nizet</Copyright>
         <Nullable>enable</Nullable>
-        <LangVersion>latest</LangVersion>
+        <LangVersion>preview</LangVersion>
         <ImplicitUsings>enable</ImplicitUsings>
         <Version>4.0.0</Version>
     </PropertyGroup>

src/Html2OpenXml/Collections/HtmlAttributeCollection.cs

@@ -19,7 +19,7 @@ namespace HtmlToOpenXml;
 readonly struct HtmlAttributeCollection
 {
     // Style key associated with a pointer to rawValue.
-    private readonly Dictionary<string, Range> attributes = [];
+    private readonly Dictionary<string, Range> attributes = [with(comparer: StringComparer.OrdinalIgnoreCase)];
     private readonly string rawValue;
 
 
@@ -38,67 +38,35 @@ public static HtmlAttributeCollection ParseStyle(string? htmlStyles)
         var collection = new HtmlAttributeCollection(htmlStyles!);
         if (string.IsNullOrWhiteSpace(htmlStyles)) return collection;
 
-        var span = htmlStyles.AsSpan();
-        int startIndex = 0;
-        bool foundKey = false;
-        string? key = null;
+        var stylesSpan = htmlStyles.AsSpan();
 
-        while (span.Length > 0)
+        Span<Range> tokens = stackalloc Range[20];
+        var tokenCount = stylesSpan.SplitCompositeAttribute(tokens, ';');
+        if (tokenCount == 0)
+            return collection;
+
+        for (int i = 0; i < tokenCount; i++)
         {
             // Encoded ':' and ';' characters are valid for browser
             // <span style="text-decoration&#58;underline&#59;color:red">
-            int index = span.IndexOfAny(';', '&', ':');
+            var segmentSpan = stylesSpan[tokens[i]];
+            int index = segmentSpan.IndexOfAny('&', ':');
+            int charsConsumed = 0;
+
             if (index == -1)
-            {
-                if (foundKey)
-                {
-                    // process the last value
-                    collection.attributes[key!] = new Range(startIndex, startIndex + span.Length);
-                }
-                break;
-            }
+                continue; // no key:value -> ignore this style
 
-            var separator = span[index];
-            if (separator == ';' && foundKey)
+            if ((charsConsumed = HtmlEntities.IsColon(segmentSpan.Slice(index))) > 0)
             {
-                if (index > 0)
-                    collection.attributes[key!] = new Range(startIndex, startIndex + index);
-                foundKey = false;
-                index++;
-            }
-            else if (separator == ';' && !foundKey)
-            {
-                // unexpected semicolon (ie, key with no value) -> ignore this style
-                index++;
-            }
-            else if (separator == ':' && !foundKey)
-            {
-                key = span.Slice(0, index).Trim().ToString().ToLowerInvariant();
-                foundKey = true;
-                index++;
-            }
-            // html-encoded semicolon
-            else if (foundKey && span.Slice(index).StartsWith(['&','#','5','9',';']))
-            {
-                if (index > 0)
-                    collection.attributes[key!] = new Range(startIndex, startIndex + index);
-                foundKey = false;
-                index += 5; // length of "&#58;"
-            }
-            else if (!foundKey && span.Slice(index).StartsWith(['&','#','5','8',';']))
-            {
-                key = span.Slice(0, index).Trim().ToString().ToLowerInvariant();
-                foundKey = true;
-                index += 5; // length of "&#58;"
-            }
-            else
-            {
-                span = span.Slice(index + 1);
-                continue;
-            }
+                var key = segmentSpan.Slice(0, index).Trim();
+                var startIndex = index + charsConsumed;
 
-            span = span.Slice(index);
-            startIndex += index;
+                if (key.Length == 0) continue; // empty key
+                if (segmentSpan.Length <= startIndex + 1) continue; // empty value
+
+                var rng = new Range(tokens[i].Start.Value + startIndex, tokens[i].End);
+                collection.attributes[key.ToString()] = rng;
+            }
         }
 
         return collection;

src/Html2OpenXml/Expressions/HyperlinkExpression.cs

@@ -112,7 +112,7 @@ public override IEnumerable<OpenXmlElement> Interpret (ParsingContext context)
         // ensure the links does not start with javascript:
         else if (AngleSharpExtensions.TryParseUrl(att, UriKind.Absolute, out var uri))
         {
-            var extLink = context.HostingPart.AddHyperlinkRelationship(uri!, true);
+            var extLink = context.HostingPart.AddHyperlinkRelationship(uri, true);
 
             h = new Hyperlink(
                 ) { History = true, Id = extLink.Id };

src/Html2OpenXml/Expressions/Image/ImageExpression.cs

@@ -37,8 +37,12 @@ class ImageExpression(IHtmlImageElement node) : ImageExpressionBase(node)
 
         // Bug reported by Erik2014. Inline 64 bit images can be too big and Uri.TryCreate will fail silently with a SizeLimit error.
         // To circumvent this buffer size, we will work either on the Uri, either on the original src.
-        if (src == null || 
-            (!DataUri.IsWellFormed(src) && !AngleSharpExtensions.TryParseUrl(src, UriKind.RelativeOrAbsolute, out var _)))
+        if (src == null)
+            return null;
+
+        var isDataUri = DataUri.IsDataUri(src);
+        if (!isDataUri &&
+            !AngleSharpExtensions.TryParseUrl(src, UriKind.RelativeOrAbsolute, out var _))
         {
             return null;
         }
@@ -118,10 +122,9 @@ class ImageExpression(IHtmlImageElement node) : ImageExpressionBase(node)
                         new pic.Picture(
                             new pic.NonVisualPictureProperties
                             {
-                                NonVisualDrawingProperties = new pic.NonVisualDrawingProperties()
-                                {
+                                NonVisualDrawingProperties = new pic.NonVisualDrawingProperties() {
                                     Id = imageObjId,
-                                    Name = DataUri.IsWellFormed(src) ? string.Empty : src,
+                                    Name = isDataUri ? string.Empty : src,
                                     Description = alt
                                 },
                                 NonVisualPictureDrawingProperties = new pic.NonVisualPictureDrawingProperties(

src/Html2OpenXml/HtmlConverter.cs

@@ -335,9 +335,13 @@ private static async Task PreloadImages(AngleSharp.Dom.IDocument htmlDocument,
         if (!imageUris.Any())
             return;
 
+#if NET5_0_OR_GREATER
+        await Parallel.ForEachAsync(imageUris,
+#else
         await imageUris.ForEachAsync(
-            async (img, cts) => await imageLoader.Download(img, cts),
-            parallelOptions).ConfigureAwait(false);
+#endif
+            parallelOptions,
+            async (img, cts) => await imageLoader.Download(img, cts)).ConfigureAwait(false);
     }
 
     /// <summary>

src/Html2OpenXml/HtmlToOpenXml.csproj

@@ -31,6 +31,9 @@
   <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net5.0'))">
     <DefineConstants>$(DefineConstants);NET5_0_OR_GREATER</DefineConstants>
   </PropertyGroup>
+  <PropertyGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net9.0'))">
+    <DefineConstants>$(DefineConstants);NET9_0_OR_GREATER</DefineConstants>
+  </PropertyGroup>
 
   <ItemGroup>
     <PackageReference Include="AngleSharp" Version="1.8.0" />