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C#: Preserve NullSafe marker through CSharpTemplate.Rewrite() #7140

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knutwannheden merged 2 commits into from
Mar 26, 2026
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C#: Preserve NullSafe marker through CSharpTemplate.Rewrite() #7140

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8a1416a
C#: Preserve NullSafe marker through CSharpTemplate.Rewrite()
knutwannheden Mar 25, 2026
86736ab
C#: Move NullSafe from ArrayDimension to ArrayAccess and add template…
knutwannheden Mar 25, 2026
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76 changes: 41 additions & 35 deletions rewrite-csharp/csharp/OpenRewrite/CSharp/CSharpParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6308,7 +6308,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
// Skip the . in the member binding (it's part of ?.)
var nullSafe = AdvancePastDotWithNullSafe(memberBinding.OperatorToken);

// Parse the method name with NullSafe marker
// Parse the method name — NullSafe marker goes on the MethodInvocation
Identifier name;
JContainer<Expression>? typeParameters = null;

Expand All @@ -6319,7 +6319,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
name = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([nullSafe]),
Markers.Empty,
[],
genericName.Identifier.Text,
null,
Expand All @@ -6334,7 +6334,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
name = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([nullSafe]),
Markers.Empty,
[],
memberBinding.Name.Identifier.Text,
null,
Expand All @@ -6347,7 +6347,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
return new MethodInvocation(
Guid.NewGuid(),
prefix,
Markers.Empty,
Markers.Build([nullSafe]),
new JRightPadded<Expression>(targetExpr, operatorSpace, Markers.Empty),
name,
typeParameters,
Expand Down Expand Up @@ -6433,7 +6433,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
var name = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([nullSafe]),
Markers.Empty,
[],
memberBinding.Name.Identifier.Text,
null,
Expand All @@ -6443,7 +6443,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
return new FieldAccess(
Guid.NewGuid(),
prefix,
Markers.Empty,
Markers.Build([nullSafe]),
targetExpr,
new JLeftPadded<Identifier>(operatorSpace, name),
null
Expand Down Expand Up @@ -6502,7 +6502,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
firstName = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([innerNullSafe]),
Markers.Empty,
[],
genericName.Identifier.Text,
null,
Expand All @@ -6517,7 +6517,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
firstName = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([innerNullSafe]),
Markers.Empty,
[],
innerMemberBinding.Name.Identifier.Text,
null,
Expand All @@ -6530,7 +6530,7 @@ public override J VisitConditionalAccessExpression(ConditionalAccessExpressionSy
firstAccess = new MethodInvocation(
Guid.NewGuid(),
Space.Empty,
Markers.Empty,
Markers.Build([innerNullSafe]),
new JRightPadded<Expression>(targetExpr, operatorSpace, Markers.Empty),
firstName,
firstTypeParams,
Expand Down Expand Up @@ -6595,19 +6595,21 @@ private ArrayAccess ParseNullConditionalElementAccess(Space prefix, Expression t
var closeBracketSpace = ExtractSpaceBefore(argList.CloseBracketToken);
_cursor = argList.CloseBracketToken.Span.End;

// Combine operatorSpace (before ?) with bracketPrefix (before [) into dimension prefix
// The NullSafe marker on dimension tells printer to print ?[
var combinedPrefix = CombineSpaces(operatorSpace, bracketPrefix);
// operatorSpace = space before ?, bracketPrefix = space between ? and [
// NullSafe.DotPrefix stores space between ? and [ (like space between ? and . in MI)
var singleDimNs = bracketPrefix.IsEmpty
? NullSafe.Instance
: new NullSafe(Guid.NewGuid(), bracketPrefix);

return new ArrayAccess(
Guid.NewGuid(),
prefix,
Markers.Empty,
Markers.Build([singleDimNs]),
target,
new ArrayDimension(
Guid.NewGuid(),
combinedPrefix,
Markers.Build([NullSafe.Instance]),
operatorSpace,
Markers.Empty,
new JRightPadded<Expression>(index, closeBracketSpace, Markers.Empty)
),
null
Expand All @@ -6633,18 +6635,20 @@ private ArrayAccess ParseNullConditionalElementAccess(Space prefix, Expression t
var currentSpaceBeforeComma = ExtractSpaceBefore(firstSeparator);
_cursor = firstSeparator.Span.End;

var combinedFirstPrefix = CombineSpaces(operatorSpace, firstBracketPrefix);
var multiDimNs = firstBracketPrefix.IsEmpty
? NullSafe.Instance
: new NullSafe(Guid.NewGuid(), firstBracketPrefix);

// Innermost ArrayAccess with NullSafe marker on dimension
// Innermost ArrayAccess with NullSafe marker on the ArrayAccess
ArrayAccess current = new ArrayAccess(
Guid.NewGuid(),
prefix,
Markers.Empty,
Markers.Build([multiDimNs]),
target,
new ArrayDimension(
Guid.NewGuid(),
combinedFirstPrefix,
Markers.Build([NullSafe.Instance]),
operatorSpace,
Markers.Empty,
new JRightPadded<Expression>(firstIndexExpr, Space.Empty, Markers.Empty)
),
null
Expand Down Expand Up @@ -6741,7 +6745,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
name = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([nullSafe]),
Markers.Empty,
[],
genericName.Identifier.Text,
null,
Expand All @@ -6756,7 +6760,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
name = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([nullSafe]),
Markers.Empty,
[],
memberBinding.Name.Identifier.Text,
null,
Expand All @@ -6769,7 +6773,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
return new MethodInvocation(
Guid.NewGuid(),
prefix,
Markers.Empty,
Markers.Build([nullSafe]),
new JRightPadded<Expression>(target, operatorSpace, Markers.Empty),
name,
typeParameters,
Expand Down Expand Up @@ -6802,7 +6806,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
var name = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([tbNullSafe]),
Markers.Empty,
[],
terminalBinding.Name.Identifier.Text,
null,
Expand All @@ -6811,7 +6815,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
return new FieldAccess(
Guid.NewGuid(),
prefix,
Markers.Empty,
Markers.Build([tbNullSafe]),
target,
new JLeftPadded<Identifier>(operatorSpace, name),
null
Expand Down Expand Up @@ -6848,7 +6852,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
firstName = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([innerNs]),
Markers.Empty,
[],
genericName.Identifier.Text,
null,
Expand All @@ -6863,7 +6867,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
firstName = new Identifier(
Guid.NewGuid(),
namePrefix,
Markers.Build([innerNs]),
Markers.Empty,
[],
innerMemberBinding.Name.Identifier.Text,
null,
Expand All @@ -6876,7 +6880,7 @@ private Expression ProcessConditionalWhenNotNull(Space prefix, Expression target
firstCall = new MethodInvocation(
Guid.NewGuid(),
Space.Empty,
Markers.Empty,
Markers.Build([innerNs]),
new JRightPadded<Expression>(target, operatorSpace, Markers.Empty),
firstName,
firstTypeParams,
Expand Down Expand Up @@ -6934,7 +6938,7 @@ private Expression ParseConditionalAccessSegment(Expression target, Space operat
var namePrefix = ExtractSpaceBefore(genericName.Identifier);
_cursor = genericName.Identifier.Span.End;
name = new Identifier(
Guid.NewGuid(), namePrefix, Markers.Build([mbNs]),
Guid.NewGuid(), namePrefix, Markers.Empty,
[],
genericName.Identifier.Text, null,
null
Expand All @@ -6946,14 +6950,14 @@ private Expression ParseConditionalAccessSegment(Expression target, Space operat
var namePrefix = ExtractSpaceBefore(memberBinding.Name.Identifier);
_cursor = memberBinding.Name.Identifier.Span.End;
name = new Identifier(
Guid.NewGuid(), namePrefix, Markers.Build([mbNs]),
Guid.NewGuid(), namePrefix, Markers.Empty,
[],
memberBinding.Name.Identifier.Text, null,
null
);
}
return new FieldAccess(
Guid.NewGuid(), Space.Empty, Markers.Empty,
Guid.NewGuid(), Space.Empty, Markers.Build([mbNs]),
target, new JLeftPadded<Identifier>(operatorSpace, name), null);
}

Expand Down Expand Up @@ -6997,16 +7001,17 @@ private Expression ParseConditionalAccessSegment(Expression target, Space operat
JRightPadded<Expression> select;
Identifier name;
JContainer<Expression>? typeParams = null;
NullSafe? nullSafeMarker = null;

if (invocation.Expression is MemberBindingExpressionSyntax binding)
{
var bNs = AdvancePastDotWithNullSafe(binding.OperatorToken);
nullSafeMarker = AdvancePastDotWithNullSafe(binding.OperatorToken);
if (binding.Name is GenericNameSyntax gn)
{
var np = ExtractSpaceBefore(gn.Identifier);
_cursor = gn.Identifier.Span.End;
name = new Identifier(
Guid.NewGuid(), np, Markers.Build([bNs]),
Guid.NewGuid(), np, Markers.Empty,
[],
gn.Identifier.Text, null,
null
Expand All @@ -7018,7 +7023,7 @@ private Expression ParseConditionalAccessSegment(Expression target, Space operat
var np = ExtractSpaceBefore(binding.Name.Identifier);
_cursor = binding.Name.Identifier.Span.End;
name = new Identifier(
Guid.NewGuid(), np, Markers.Build([bNs]),
Guid.NewGuid(), np, Markers.Empty,
[],
binding.Name.Identifier.Text, null,
null
Expand Down Expand Up @@ -7064,7 +7069,8 @@ private Expression ParseConditionalAccessSegment(Expression target, Space operat

var args = ParseArgumentList(invocation.ArgumentList);
return new MethodInvocation(
Guid.NewGuid(), Space.Empty, Markers.Empty,
Guid.NewGuid(), Space.Empty,
nullSafeMarker != null ? Markers.Build([nullSafeMarker]) : Markers.Empty,
select, name, typeParams, args, null);
}

Expand Down
31 changes: 21 additions & 10 deletions rewrite-csharp/csharp/OpenRewrite/CSharp/CSharpPrinter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -250,8 +250,8 @@ public override J VisitFieldAccess(FieldAccess fieldAccess, PrintOutputCapture<P
// Check for PointerMemberAccess marker on target PointerDereference - if present, print -> instead of .
var isPointerMemberAccess = fieldAccess.Target is PointerDereference pd
&& pd.Markers.FindFirst<PointerMemberAccess>() != null;
// Check for NullSafe marker on the name - if present, print ?. instead of .
var nullSafe = fieldAccess.Name.Element.Markers.FindFirst<NullSafe>();
// Check for NullSafe marker on the FieldAccess - if present, print ?. instead of .
var nullSafe = fieldAccess.Markers.FindFirst<NullSafe>();
if (isPointerMemberAccess)
{
p.Append("->");
Expand Down Expand Up @@ -356,9 +356,13 @@ private void PrintArrayAccessWithoutClosingBracket(ArrayAccess aa, PrintOutputCa
VisitSpace(aa.Prefix, p);
Visit(aa.Indexed, p);
VisitSpace(aa.Dimension.Prefix, p);
// Check for NullSafe marker - if present, print ?[ instead of [
var isNullSafe = aa.Dimension.Markers.FindFirst<NullSafe>() != null;
p.Append(isNullSafe ? "?[" : "[");
var nullSafe = aa.Markers.FindFirst<NullSafe>();
if (nullSafe != null)
{
p.Append('?');
VisitSpace(nullSafe.DotPrefix, p);
}
p.Append('[');
Visit(aa.Dimension.Index.Element, p);
VisitSpace(aa.Dimension.Index.After, p);
// Don't print ] - parent will
Expand All @@ -368,9 +372,16 @@ private void PrintArrayAccessWithoutClosingBracket(ArrayAccess aa, PrintOutputCa
public override J VisitArrayDimension(ArrayDimension dimension, PrintOutputCapture<P> p)
{
BeforeSyntax(dimension, p);
// Check for NullSafe marker - if present, print ?[ instead of [
var isNullSafe = dimension.Markers.FindFirst<NullSafe>() != null;
p.Append(isNullSafe ? "?[" : "[");
// NullSafe marker lives on the parent ArrayAccess — check via cursor
// Dimension prefix holds space before ?, NullSafe.DotPrefix holds space between ? and [
var nullSafe = Cursor.Value is ArrayAccess aa
? aa.Markers.FindFirst<NullSafe>() : null;
if (nullSafe != null)
{
p.Append('?');
VisitSpace(nullSafe.DotPrefix, p);
}
p.Append('[');
Visit(dimension.Index.Element, p);
VisitSpace(dimension.Index.After, p);
p.Append(']');
Expand All @@ -393,9 +404,9 @@ public override J VisitMethodInvocation(MethodInvocation mi, PrintOutputCapture<
// For delegate invocation, skip the dot and name (it's syntactic sugar for .Invoke())
if (!isDelegateInvocation)
{
// Check for NullSafe marker on the name - if present, print ?. instead of .
// Check for NullSafe marker on the MethodInvocation - if present, print ?. instead of .
// Check for PointerMemberAccess marker on select PointerDereference - if present, print -> instead of .
var nullSafe = mi.Name.Markers.FindFirst<NullSafe>();
var nullSafe = mi.Markers.FindFirst<NullSafe>();
var isPointerDeref = mi.Select.Element is PointerDereference selectPd
&& selectPd.Markers.FindFirst<PointerMemberAccess>() != null;
if (isPointerDeref)
Expand Down
4 changes: 3 additions & 1 deletion rewrite-csharp/csharp/OpenRewrite/CSharp/Template/CSharpPattern.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -177,7 +177,9 @@ public J GetTree()

var comparator = new PatternMatchingComparator(_captures);
var captured = comparator.Match(patternTree, tree, cursor);
return captured != null ? new MatchResult(captured) : null;
if (captured == null) return null;
var nullSafe = comparator.NullSafeBindings;
return new MatchResult(captured, nullSafe.Count > 0 ? nullSafe : null);
}

private bool IsCapturePlaceholder(J node)
Expand Down
12 changes: 11 additions & 1 deletion rewrite-csharp/csharp/OpenRewrite/CSharp/Template/MatchResult.cs
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Expand Up @@ -24,10 +24,13 @@ namespace OpenRewrite.CSharp.Template;
public sealed class MatchResult
{
private readonly Dictionary<string, object> _captures;
private readonly IReadOnlyDictionary<string, NullSafe>? _nullSafeCaptures;

internal MatchResult(Dictionary<string, object> captures)
internal MatchResult(Dictionary<string, object> captures,
IReadOnlyDictionary<string, NullSafe>? nullSafeCaptures = null)
{
_captures = captures;
_nullSafeCaptures = nullSafeCaptures;
}

/// <summary>
Expand Down Expand Up @@ -121,5 +124,12 @@ public IReadOnlyList<T> GetList<T>(string name) where T : class, J
/// </summary>
public bool Has(ICapture capture) => _captures.ContainsKey(capture.Name);

/// <summary>
/// Get the NullSafe marker associated with a capture, if any.
/// Present when the capture was the Select of a null-conditional MI/FA in the matched tree.
/// </summary>
internal NullSafe? GetNullSafe(string name) =>
_nullSafeCaptures != null && _nullSafeCaptures.TryGetValue(name, out var ns) ? ns : null;

internal Dictionary<string, object> AsDict() => _captures;
}
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