private static ExpressionSyntax SimplifyCast(CastExpressionSyntax node, SemanticModel semanticModel, OptionSet optionSet, CancellationToken cancellationToken)
{
if (!CastSimplifier.IsUnnecessaryCast(node, semanticModel, cancellationToken))
{
return(node);
}
return(node.Uncast());
}
/// <summary>
/// Adds to <paramref name="targetType"/> if it does not contain an anonymous
/// type and binds to the same type at the given <paramref name="position"/>.
/// </summary>
public static ExpressionSyntax CastIfPossible(
this ExpressionSyntax expression,
ITypeSymbol targetType,
int position,
SemanticModel semanticModel,
CancellationToken cancellationToken)
{
if (targetType.ContainsAnonymousType())
{
return(expression);
}
if (targetType.IsSystemVoid())
{
return(expression);
}
if (targetType.Kind == SymbolKind.DynamicType)
{
targetType = semanticModel.Compilation.GetSpecialType(SpecialType.System_Object);
}
var typeSyntax = targetType.GenerateTypeSyntax();
var type = semanticModel.GetSpeculativeTypeInfo(
position,
typeSyntax,
SpeculativeBindingOption.BindAsTypeOrNamespace).Type;
if (!targetType.Equals(type))
{
return(expression);
}
var castExpression = expression.Cast(targetType);
// Ensure that inserting the cast doesn't change the semantics.
var specAnalyzer = new SpeculationAnalyzer(expression, castExpression, semanticModel, cancellationToken);
var speculativeSemanticModel = specAnalyzer.SpeculativeSemanticModel;
if (speculativeSemanticModel == null)
{
return(expression);
}
var speculatedCastExpression = (CastExpressionSyntax)specAnalyzer.ReplacedExpression;
if (!CastSimplifier.IsUnnecessaryCast(speculatedCastExpression, speculativeSemanticModel, cancellationToken))
{
return(expression);
}
return(castExpression);
}
protected override async Task FixAllAsync(
Document document, ImmutableArray <Diagnostic> diagnostics,
SyntaxEditor editor, CodeActionOptionsProvider options, CancellationToken cancellationToken)
{
var castNodes = diagnostics.SelectAsArray(
d => (ExpressionSyntax)d.AdditionalLocations[0].FindNode(getInnermostNodeForTie: true, cancellationToken));
await editor.ApplyExpressionLevelSemanticEditsAsync(
document, castNodes,
(semanticModel, castExpression) => CastSimplifier.IsUnnecessaryCast(castExpression, semanticModel, cancellationToken),
(_, currentRoot, castExpression) =>
{
var oldParent = castExpression.WalkUpParentheses();
var newParent = Recurse(oldParent);
return(currentRoot.ReplaceNode(oldParent, newParent));
},
cancellationToken).ConfigureAwait(false);
}
protected override bool IsUnnecessaryCast(SemanticModel model, ExpressionSyntax cast, CancellationToken cancellationToken) => CastSimplifier.IsUnnecessaryCast(cast, model, cancellationToken);
