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perf: optimise SyntaxNodeComparer #1730

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Merged
belav merged 2 commits into from
Dec 25, 2025
Merged

perf: optimise SyntaxNodeComparer #1730

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38fd2ec
perf: optimise `SyntaxNodeComparer`
TimothyMakkison Nov 1, 2025
c6cbd9a
Merge branch 'main' into optimise_compare
belav Dec 25, 2025
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81 changes: 66 additions & 15 deletions Src/CSharpier.Core/CSharp/SyntaxNodeComparer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@ CancellationToken cancellationToken
cSharpParseOptions,
cancellationToken: cancellationToken
);
this.CompareFunc = Compare;
}

public string CompareSource()
Expand Down Expand Up @@ -148,14 +149,16 @@ SyntaxNode formattedStart
return Equal;
}

#pragma warning disable CA1822
private CompareResult CompareLists<T>(
IReadOnlyList<T> originalList,
IReadOnlyList<T> formattedList,
Func<T, T, CompareResult> comparer,
Func<T, TextSpan> getSpan,
T originalList,
T formattedList,
Func<SyntaxToken, SyntaxToken, CompareResult> comparer,
Func<SyntaxToken, TextSpan> getSpan,
TextSpan originalParentSpan,
TextSpan newParentSpan
)
where T : IReadOnlyList<SyntaxToken>
{
for (var x = 0; x < originalList.Count || x < formattedList.Count; x++)
{
Expand All @@ -169,25 +172,71 @@ TextSpan newParentSpan
return NotEqual(getSpan(originalList[x]), newParentSpan);
}

if (
originalList[x] is SyntaxNode originalNode
&& formattedList[x] is SyntaxNode formattedNode
)
var result = comparer(originalList[x], formattedList[x]);
if (result.IsInvalid)
{
return result;
}
}

return Equal;
}
#pragma warning restore CA1822

private CompareResult CompareLists<T>(
T originalList,
T formattedList,
Func<SyntaxNode, SyntaxNode, CompareResult> comparer,
Func<SyntaxNode, TextSpan> getSpan,
TextSpan originalParentSpan,
TextSpan newParentSpan
)
where T : IReadOnlyList<SyntaxNode>
{
for (var x = 0; x < originalList.Count || x < formattedList.Count; x++)
{
if (x == originalList.Count)
{
return NotEqual(originalParentSpan, getSpan(formattedList[x]));
}

if (x == formattedList.Count)
{
this.originalStack.Push((originalNode, originalNode.Parent));
this.formattedStack.Push((formattedNode, formattedNode.Parent));
return NotEqual(getSpan(originalList[x]), newParentSpan);
}
else

var originalNode = originalList[x];
var formattedNode = formattedList[x];
this.originalStack.Push((originalNode, originalNode.Parent));
this.formattedStack.Push((formattedNode, formattedNode.Parent));
}

return Equal;
}

private static SyntaxToken[] AllSeparatorsButLast(in SeparatedSyntaxList<SyntaxNode> list)
{
if (list.Count <= 1)
{
return [];
}

var tokens = new SyntaxToken[list.Count - 1];
var tokenIndex = 0;

foreach (var element in list.GetWithSeparators())
{
if (element.IsToken)
{
var result = comparer(originalList[x], formattedList[x]);
if (result.IsInvalid)
tokens[tokenIndex++] = element.AsToken();
if (tokenIndex == tokens.Length)
{
return result;
break;
}
}
}

return Equal;
return tokens;
}

private static CompareResult NotEqual(SyntaxNode? originalNode, SyntaxNode? formattedNode)
Expand All @@ -210,6 +259,8 @@ private static CompareResult NotEqual(TextSpan? originalSpan, TextSpan? formatte
};
}

private Func<SyntaxToken, SyntaxToken, CompareResult> CompareFunc { get; }

private CompareResult Compare(SyntaxToken originalToken, SyntaxToken formattedToken)
{
return this.Compare(originalToken, formattedToken, null, null);
Expand Down
13 changes: 8 additions & 5 deletions Src/CSharpier.Generators/SyntaxNodeComparerGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ private static void GenerateMethod(StringBuilder sourceBuilder, INamedTypeSymbol
$$"""
private CompareResult Compare{{type.Name}}({{type.Name}} originalNode, {{type.Name}} formattedNode)
{
CompareResult result;
CompareResult result;
"""
);

Expand Down Expand Up @@ -228,10 +228,13 @@ private static void GenerateMethod(StringBuilder sourceBuilder, INamedTypeSymbol
}
else
{
var compare = propertyType.Name == nameof(SyntaxTokenList) ? "Compare" : "null";
var compare =
propertyType.Name == nameof(SyntaxTokenList)
? "CompareFunc"
: "static (_, _) => default";
if (propertyName == "Modifiers")
{
propertyName += ".OrderBy(o => o.Text).ToList()";
propertyName += ".OrderBy(o => o.Text).ToArray()";
}

sourceBuilder.AppendLine(
Expand All @@ -249,13 +252,13 @@ private static void GenerateMethod(StringBuilder sourceBuilder, INamedTypeSymbol
)
{
sourceBuilder.AppendLine(
$" result = this.CompareLists(originalNode.{propertyName}, formattedNode.{propertyName}, null, o => o.Span, originalNode.Span, formattedNode.Span);"
$" result = this.CompareLists(originalNode.{propertyName}, formattedNode.{propertyName}, static (_, _) => default, o => o.Span, originalNode.Span, formattedNode.Span);"
);
sourceBuilder.AppendLine(" if (result.IsInvalid) return result;");

// Omit the last separator when comparing the original node with the formatted node, as it legitimately may be added or removed
sourceBuilder.AppendLine(
$" result = this.CompareLists(originalNode.{propertyName}.GetSeparators().Take(originalNode.{propertyName}.Count() - 1).ToList(), formattedNode.{propertyName}.GetSeparators().Take(formattedNode.{propertyName}.Count() - 1).ToList(), Compare, o => o.Span, originalNode.Span, formattedNode.Span);"
$" result = this.CompareLists(AllSeparatorsButLast(originalNode.{propertyName}), AllSeparatorsButLast(formattedNode.{propertyName}), CompareFunc, o => o.Span, originalNode.Span, formattedNode.Span);"
);
sourceBuilder.AppendLine(" if (result.IsInvalid) return result;");
}
Expand Down