Use collection expressions

src/Markdig/Extensions/Abbreviations/AbbreviationParser.cs

@@ -20,7 +20,7 @@ public class AbbreviationParser : BlockParser
     /// </summary>
     public AbbreviationParser()
     {
-        OpeningCharacters = new[] { '*' };
+        OpeningCharacters = ['*'];
     }
 
     public override BlockState TryOpen(BlockProcessor processor)

src/Markdig/Extensions/Emoji/EmojiMapping.cs

@@ -1786,6 +1786,6 @@ public class EmojiMapping
                 ThrowHelper.ArgumentException(string.Format("Smiley {0} is already present in the emoji mapping", smiley.Key));
         }
 
-        OpeningCharacters = new List<char>(firstChars).ToArray();
+        OpeningCharacters = [.. firstChars];
     }
 }

src/Markdig/Extensions/Figures/FigureBlockParser.cs

@@ -18,7 +18,7 @@ public class FigureBlockParser : BlockParser
     /// </summary>
     public FigureBlockParser()
     {
-        OpeningCharacters = new[] { '^' };
+        OpeningCharacters = ['^'];
     }
 
     public override BlockState TryOpen(BlockProcessor processor)

src/Markdig/Extensions/Footers/FooterBlockParser.cs

@@ -19,7 +19,7 @@ public class FooterBlockParser : BlockParser
     /// </summary>
     public FooterBlockParser()
     {
-        OpeningCharacters = new[] {'^'};
+        OpeningCharacters = ['^'];
     }
 
     public override BlockState TryOpen(BlockProcessor processor)

src/Markdig/Extensions/GenericAttributes/GenericAttributesParser.cs

@@ -23,7 +23,7 @@ public class GenericAttributesParser : InlineParser
     /// </summary>
     public GenericAttributesParser()
     {
-        OpeningCharacters = new[] { '{' };
+        OpeningCharacters = ['{'];
     }
 
     public override bool Match(InlineProcessor processor, ref StringSlice slice)
@@ -136,10 +136,7 @@ public class GenericAttributesParser : InlineParser
                 var text = slice.Text.Substring(start, end - start + 1);
                 if (isClass)
                 {
-                    if (classes is null)
-                    {
-                        classes = new List<string>();
-                    }
+                    classes ??= new List<string>();
                     classes.Add(text);
                 }
                 else

src/Markdig/Extensions/Mathematics/MathInlineParser.cs

@@ -21,7 +21,7 @@ public class MathInlineParser : InlineParser
     /// </summary>
     public MathInlineParser()
     {
-        OpeningCharacters = new[] { '$' };
+        OpeningCharacters = ['$'];
         DefaultClass = "math";
     }
 

src/Markdig/Extensions/NoRefLinks/NoFollowLinksExtension.cs

@@ -17,7 +17,7 @@ public class NoFollowLinksExtension : IMarkdownExtension
 
     public NoFollowLinksExtension()
     {
-        _referralLinksExtension = new ReferralLinksExtension(new[] { "nofollow" });
+        _referralLinksExtension = new ReferralLinksExtension(["nofollow"]);
     }
 
     public void Setup(MarkdownPipelineBuilder pipeline)

src/Markdig/Extensions/Tables/GridTableParser.cs

@@ -12,7 +12,7 @@ public class GridTableParser : BlockParser
 {
     public GridTableParser()
     {
-        OpeningCharacters = new[] { '+' };
+        OpeningCharacters = ['+'];
     }
 
     public override BlockState TryOpen(BlockProcessor processor)

src/Markdig/Extensions/Tables/PipeTableBlockParser.cs

@@ -22,7 +22,7 @@ public class PipeTableBlockParser : BlockParser
     /// </summary>
     public PipeTableBlockParser()
     {
-        OpeningCharacters = new[] {'-'};
+        OpeningCharacters = ['-'];
     }
 
     public override BlockState TryOpen(BlockProcessor processor)

src/Markdig/Extensions/TaskLists/TaskListInlineParser.cs

@@ -19,7 +19,7 @@ public class TaskListInlineParser : InlineParser
     /// </summary>
     public TaskListInlineParser()
     {
-        OpeningCharacters = new[] {'['};
+        OpeningCharacters = ['['];
         ListClass = "contains-task-list";
         ListItemClass = "task-list-item";
     }

src/Markdig/Parsers/HeadingBlockParser.cs

@@ -20,7 +20,7 @@ public class HeadingBlockParser : BlockParser, IAttributesParseable
     /// </summary>
     public HeadingBlockParser()
     {
-        OpeningCharacters = new[] {'#'};
+        OpeningCharacters = ['#'];
     }
 
     /// <summary>

src/Markdig/Parsers/HtmlBlockParser.cs

@@ -18,7 +18,7 @@ public class HtmlBlockParser : BlockParser
     /// </summary>
     public HtmlBlockParser()
     {
-        OpeningCharacters = new[] { '<' };
+        OpeningCharacters = ['<'];
     }
        
     public override BlockState TryOpen(BlockProcessor processor)

src/Markdig/Parsers/Inlines/EmphasisInlineParser.cs

@@ -20,7 +20,7 @@ namespace Markdig.Parsers.Inlines;
 public class EmphasisInlineParser : InlineParser, IPostInlineProcessor
 {
     private CharacterMap<EmphasisDescriptor>? emphasisMap;
-    private readonly DelimitersObjectCache inlinesCache = new DelimitersObjectCache();
+    private readonly DelimitersObjectCache inlinesCache = new();
 
     [Obsolete("Use TryCreateEmphasisInlineDelegate instead", error: false)]
     public delegate EmphasisInline CreateEmphasisInlineDelegate(char emphasisChar, bool isStrong);
@@ -31,11 +31,11 @@ public class EmphasisInlineParser : InlineParser, IPostInlineProcessor
     /// </summary>
     public EmphasisInlineParser()
     {
-        EmphasisDescriptors = new List<EmphasisDescriptor>()
-        {
+        EmphasisDescriptors =
+        [
             new EmphasisDescriptor('*', 1, 2, true),
             new EmphasisDescriptor('_', 1, 2, false)
-        };
+        ];
     }
 
     /// <summary>
@@ -65,7 +65,7 @@ public class EmphasisInlineParser : InlineParser, IPostInlineProcessor
     /// </summary>
     [Obsolete("Use TryCreateEmphasisInlineList instead", error: false)]
     public CreateEmphasisInlineDelegate? CreateEmphasisInline { get; set; }
-    public readonly List<TryCreateEmphasisInlineDelegate> TryCreateEmphasisInlineList = new List<TryCreateEmphasisInlineDelegate>();
+    public readonly List<TryCreateEmphasisInlineDelegate> TryCreateEmphasisInlineList = [];
 
     public override void Initialize()
     {

src/Markdig/Parsers/Inlines/EscapeInlineParser.cs

@@ -15,7 +15,7 @@ public class EscapeInlineParser : InlineParser
 {
     public EscapeInlineParser()
     {
-        OpeningCharacters = new[] {'\\'};
+        OpeningCharacters = ['\\'];
     }
 
     public override bool Match(InlineProcessor processor, ref StringSlice slice)

src/Markdig/Parsers/Inlines/HtmlEntityParser.cs

@@ -21,7 +21,7 @@ public class HtmlEntityParser : InlineParser
     /// </summary>
     public HtmlEntityParser()
     {
-        OpeningCharacters = new[] {'&'};
+        OpeningCharacters = ['&'];
     }
 
     public static bool TryParse(ref StringSlice slice, [NotNullWhen(true)] out string? literal, out int match)

src/Markdig/Parsers/Inlines/LineBreakInlineParser.cs

@@ -18,7 +18,7 @@ public class LineBreakInlineParser : InlineParser
     /// </summary>
     public LineBreakInlineParser()
     {
-        OpeningCharacters = new[] { '\n', '\r' };
+        OpeningCharacters = ['\n', '\r'];
     }
 
     /// <summary>

src/Markdig/Parsers/Inlines/LinkInlineParser.cs

@@ -19,7 +19,7 @@ public class LinkInlineParser : InlineParser
     /// </summary>
     public LinkInlineParser()
     {
-        OpeningCharacters = new[] {'[', ']', '!'};
+        OpeningCharacters = ['[', ']', '!'];
     }
 
     public override bool Match(InlineProcessor processor, ref StringSlice slice)
@@ -322,7 +322,7 @@ public class LinkInlineParser : InlineParser
 
         if (label != null || LinkHelper.TryParseLabelTrivia(ref text, true, out label, out labelSpan))
         {
-            SourceSpan labelWithTrivia = new SourceSpan(labelSpan.Start, labelSpan.End);
+            var labelWithTrivia = new SourceSpan(labelSpan.Start, labelSpan.End);
             if (isLabelSpanLocal)
             {
                 labelSpan = inlineState.GetSourcePositionFromLocalSpan(labelSpan);

src/Markdig/Polyfills/NullableAttributes.cs

@@ -23,7 +23,7 @@ internal sealed class AllowNullAttribute : Attribute { }
 #if !NET5_0_OR_GREATER
 internal sealed class MemberNotNullAttribute : Attribute
 {
-    public MemberNotNullAttribute(string member) => Members = new[] { member };
+    public MemberNotNullAttribute(string member) => Members = [member];
 
     public MemberNotNullAttribute(params string[] members) => Members = members;
 

src/Markdig/Syntax/CodeBlock.cs

@@ -21,7 +21,7 @@ public class CodeBlock : LeafBlock
     }
 
     private List<CodeBlockLine>? _codeBlockLines;
-    public List<CodeBlockLine> CodeBlockLines => _codeBlockLines ??= new();
+    public List<CodeBlockLine> CodeBlockLines => _codeBlockLines ??= [];
 
     /// <summary>
     /// Initializes a new instance of the <see cref="CodeBlock"/> class.

src/Markdig/Syntax/ContainerBlock.cs

@@ -27,7 +27,7 @@ public abstract class ContainerBlock : Block, IList<Block>, IReadOnlyList<Block>
     /// <param name="parser">The parser used to create this block.</param>
     protected ContainerBlock(BlockParser? parser) : base(parser)
     {
-        _children = Array.Empty<BlockWrapper>();
+        _children = [];
         SetTypeKind(isInline: false, isContainer: true);
     }