Move IsSpacingToken perf optimizations down to base class (#22555)

This gives the HtmlMarkupParser the same non-allocating behavior for it's IsSpacing* method invocations. Profile from following feedback ticket showed ~100ms time spent doing these allocations: https://developercommunity.visualstudio.com/content/problem/1006207/vs-2019-constant-freezing-please-wait-for-an-edito.html?childToView=1065769

Author: ToddGrun

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs

@@ -16,27 +16,6 @@ internal class CSharpCodeParser : TokenizerBackedParser<CSharpTokenizer>
             '@', '!', '<', '/', '?', '[', '>', ']', '=', '"', '\'', '*'
         });
 
-        // Following four high traffic methods cached as using method groups would cause allocation on every invocation.
-        protected static readonly Func<SyntaxToken, bool> IsSpacingToken = (token) =>
-        {
-            return token.Kind == SyntaxKind.Whitespace;
-        };
-
-        protected static readonly Func<SyntaxToken, bool> IsSpacingTokenIncludingNewLines = (token) =>
-        {
-            return IsSpacingToken(token) || token.Kind == SyntaxKind.NewLine;
-        };
-
-        protected static readonly Func<SyntaxToken, bool> IsSpacingTokenIncludingComments = (token) =>
-        {
-            return IsSpacingToken(token) || token.Kind == SyntaxKind.CSharpComment;
-        };
-
-        protected static readonly Func<SyntaxToken, bool> IsSpacingTokenIncludingNewLinesAndComments = (token) =>
-        {
-            return IsSpacingTokenIncludingNewLines(token) || token.Kind == SyntaxKind.CSharpComment;
-        };
-
         private static readonly Func<SyntaxToken, bool> IsValidStatementSpacingToken =
             IsSpacingTokenIncludingNewLinesAndComments;
 

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/HtmlMarkupParser.cs

@@ -128,7 +128,7 @@ public MarkupBlockSyntax ParseBlock()
                         return null;
                     }
 
-                    AcceptWhile(IsSpacingToken(includeNewLines: true));
+                    AcceptWhile(IsSpacingTokenIncludingNewLines);
                     builder.Add(OutputAsMarkupLiteral());
 
                     if (At(SyntaxKind.OpenAngle))
@@ -683,7 +683,7 @@ private MarkupStartTagSyntax ParseStartTag(
                         var bookmark = CurrentStart.AbsoluteIndex;
 
                         // Skip whitespace
-                        ReadWhile(IsSpacingToken(includeNewLines: true));
+                        ReadWhile(IsSpacingTokenIncludingNewLines);
 
                         // Open Angle
                         if (At(SyntaxKind.OpenAngle) && NextIs(SyntaxKind.ForwardSlash))
@@ -754,7 +754,7 @@ private MarkupStartTagSyntax ParseStartTextTag(SyntaxToken openAngleToken, out M
                 SyntaxToken forwardSlashToken = null;
                 SyntaxToken closeAngleToken = null;
 
-                AcceptWhile(IsSpacingToken(includeNewLines: false));
+                AcceptWhile(IsSpacingToken);
                 miscAttributeContentBuilder.Add(OutputAsMarkupLiteral());
 
                 if (At(SyntaxKind.CloseAngle) ||
@@ -1442,7 +1442,7 @@ private bool ParseCData(in SyntaxListBuilder<RazorSyntaxNode> builder)
 
         private void ParseDoubleTransition(in SyntaxListBuilder<RazorSyntaxNode> builder)
         {
-            AcceptWhile(IsSpacingToken(includeNewLines: true));
+            AcceptWhile(IsSpacingTokenIncludingNewLines);
             builder.Add(OutputAsMarkupLiteral());
 
             // First transition
@@ -1463,7 +1463,7 @@ private void ParseCodeTransition(in SyntaxListBuilder<RazorSyntaxNode> builder)
                 // We don't want to write it to output.
                 Context.NullGenerateWhitespaceAndNewLine = false;
                 SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
-                AcceptWhile(IsSpacingToken(includeNewLines: false));
+                AcceptWhile(IsSpacingToken);
                 if (At(SyntaxKind.NewLine))
                 {
                     AcceptAndMoveNext();
@@ -1549,7 +1549,7 @@ private void ParseRazorCommentWithLeadingAndTrailingWhitespace(in SyntaxListBuil
                 // We don't want to write it to output.
                 Context.NullGenerateWhitespaceAndNewLine = false;
                 SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
-                AcceptWhile(IsSpacingToken(includeNewLines: false));
+                AcceptWhile(IsSpacingToken);
                 if (At(SyntaxKind.NewLine))
                 {
                     AcceptAndMoveNext();
@@ -1596,7 +1596,7 @@ private void ParseRazorCommentWithLeadingAndTrailingWhitespace(in SyntaxListBuil
                 (At(SyntaxKind.NewLine) ||
                 (At(SyntaxKind.Whitespace) && NextIs(SyntaxKind.NewLine))))
             {
-                AcceptWhile(IsSpacingToken(includeNewLines: false));
+                AcceptWhile(IsSpacingToken);
                 AcceptAndMoveNext();
                 SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
                 builder.Add(OutputAsMarkupEphemeralLiteral());
@@ -1611,7 +1611,7 @@ private void ParseMisc(in SyntaxListBuilder<RazorSyntaxNode> builder)
                 // We don't want to write it to output.
                 Context.NullGenerateWhitespaceAndNewLine = false;
                 SpanContext.ChunkGenerator = SpanChunkGenerator.Null;
-                AcceptWhile(IsSpacingToken(includeNewLines: false));
+                AcceptWhile(IsSpacingToken);
                 if (At(SyntaxKind.NewLine))
                 {
                     AcceptAndMoveNext();
@@ -1620,7 +1620,7 @@ private void ParseMisc(in SyntaxListBuilder<RazorSyntaxNode> builder)
                 builder.Add(OutputAsMarkupEphemeralLiteral());
             }
 
-            AcceptWhile(IsSpacingToken(includeNewLines: true));
+            AcceptWhile(IsSpacingTokenIncludingNewLines);
         }
 
         private bool ScriptTagExpectsHtml(MarkupStartTagSyntax tagBlock)
@@ -2111,11 +2111,6 @@ internal static bool IsCommentContentEndingInvalid(IEnumerable<SyntaxToken> sequ
             return false;
         }
 
-        protected static Func<SyntaxToken, bool> IsSpacingToken(bool includeNewLines)
-        {
-            return token => token.Kind == SyntaxKind.Whitespace || (includeNewLines && token.Kind == SyntaxKind.NewLine);
-        }
-
         internal static bool IsHyphen(SyntaxToken token)
         {
             return token.Kind == SyntaxKind.Text && token.Content == "-";

src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/TokenizerBackedParser.cs

@@ -16,6 +16,27 @@ internal abstract class TokenizerBackedParser<TTokenizer> : ParserBase
         private readonly TokenizerView<TTokenizer> _tokenizer;
         private SyntaxListBuilder<SyntaxToken>? _tokenBuilder;
 
+        // Following four high traffic methods cached as using method groups would cause allocation on every invocation.
+        protected static readonly Func<SyntaxToken, bool> IsSpacingToken = (token) =>
+        {
+            return token.Kind == SyntaxKind.Whitespace;
+        };
+
+        protected static readonly Func<SyntaxToken, bool> IsSpacingTokenIncludingNewLines = (token) =>
+        {
+            return IsSpacingToken(token) || token.Kind == SyntaxKind.NewLine;
+        };
+
+        protected static readonly Func<SyntaxToken, bool> IsSpacingTokenIncludingComments = (token) =>
+        {
+            return IsSpacingToken(token) || token.Kind == SyntaxKind.CSharpComment;
+        };
+
+        protected static readonly Func<SyntaxToken, bool> IsSpacingTokenIncludingNewLinesAndComments = (token) =>
+        {
+            return IsSpacingTokenIncludingNewLines(token) || token.Kind == SyntaxKind.CSharpComment;
+        };
+        
         protected TokenizerBackedParser(LanguageCharacteristics<TTokenizer> language, ParserContext context)
             : base(context)
         {