protected override async Task <SemanticDocument> ExpandAsync(
SelectionResult selection,
CancellationToken cancellationToken
)
{
var lastExpression = selection
.GetFirstTokenInSelection()
.GetCommonRoot(selection.GetLastTokenInSelection())
.GetAncestors <ExpressionSyntax>()
.LastOrDefault();
if (lastExpression == null)
{
return(selection.SemanticDocument);
}
var newExpression = await Simplifier
.ExpandAsync(
lastExpression,
selection.SemanticDocument.Document,
n => n != selection.GetContainingScope(),
expandParameter : false,
cancellationToken : cancellationToken
)
.ConfigureAwait(false);
return(await selection.SemanticDocument
.WithSyntaxRootAsync(
selection.SemanticDocument.Root.ReplaceNode(lastExpression, newExpression),
cancellationToken
)
.ConfigureAwait(false));
}
protected override ITypeSymbol GetSymbolType(
SemanticModel semanticModel,
ISymbol symbol
)
{
var selectionOperation = semanticModel.GetOperation(
SelectionResult.GetContainingScope()
);
switch (symbol)
{
case ILocalSymbol localSymbol
when localSymbol.NullableAnnotation == NullableAnnotation.Annotated:
case IParameterSymbol parameterSymbol
when parameterSymbol.NullableAnnotation == NullableAnnotation.Annotated:
// For local symbols and parameters, we can check what the flow state
// for refences to the symbols are and determine if we can change
// the nullability to a less permissive state.
var references = selectionOperation
.DescendantsAndSelf()
.Where(IsSymbolReferencedByOperation);
if (AreAllReferencesNotNull(references))
{
return(base.GetSymbolType(semanticModel, symbol)
.WithNullableAnnotation(NullableAnnotation.NotAnnotated));
}
return(base.GetSymbolType(semanticModel, symbol));
default:
return(base.GetSymbolType(semanticModel, symbol));
}
bool AreAllReferencesNotNull(IEnumerable <IOperation> references) =>
references.All(
r =>
semanticModel.GetTypeInfo(r.Syntax).Nullability.FlowState
== NullableFlowState.NotNull
);
bool IsSymbolReferencedByOperation(IOperation operation) =>
operation switch
{
ILocalReferenceOperation localReference
=> localReference.Local.Equals(symbol),
IParameterReferenceOperation parameterReference
=> parameterReference.Parameter.Equals(symbol),
IAssignmentOperation assignment
=> IsSymbolReferencedByOperation(assignment.Target),
_ => false
};
}
}
protected override async Task<SemanticDocument> ExpandAsync(SelectionResult selection, CancellationToken cancellationToken)
{
var lastExpression = selection.GetFirstTokenInSelection().GetCommonRoot(selection.GetLastTokenInSelection()).GetAncestors<ExpressionSyntax>().LastOrDefault();
if (lastExpression == null)
{
return selection.SemanticDocument;
}
var newExpression = await Simplifier.ExpandAsync(lastExpression, selection.SemanticDocument.Document, n => n != selection.GetContainingScope(), expandParameter: false, cancellationToken: cancellationToken).ConfigureAwait(false);
return await selection.SemanticDocument.WithSyntaxRootAsync(selection.SemanticDocument.Root.ReplaceNode(lastExpression, newExpression), cancellationToken).ConfigureAwait(false);
}
protected override ITypeSymbol GetSymbolType(SemanticModel semanticModel, ISymbol symbol)
{
var selectionOperation = semanticModel.GetOperation(SelectionResult.GetContainingScope());
// Check if null is possibly assigned to the symbol. If it is, leave nullable annotation as is, otherwise
// we can modify the annotation to be NotAnnotated to code that more likely matches the user's intent.
if (selectionOperation is not null &&
NullableHelpers.IsSymbolAssignedPossiblyNullValue(semanticModel, selectionOperation, symbol) == false)
{
return(base.GetSymbolType(semanticModel, symbol).WithNullableAnnotation(NullableAnnotation.NotAnnotated));
}
return(base.GetSymbolType(semanticModel, symbol));
}
