private static void Handle(SyntaxNodeAnalysisContext context)
{
if (!context.IsExcludedFromAnalysis() &&
context.Node is InvocationExpressionSyntax invocation &&
PropertyChanged.TryGetName(invocation, context.SemanticModel, context.CancellationToken, out _) != AnalysisResult.No)
{
if (invocation.TryFirstAncestor(out AccessorDeclarationSyntax? setter) &&
setter.IsKind(SyntaxKind.SetAccessorDeclaration))
{
if (Setter.TryFindSingleAssignment(setter, out var assignment))
{
if (IsFirstCall(invocation) &&
IncorrectOrMissingCheckIfDifferent(context, setter, invocation, assignment))
{
context.ReportDiagnostic(Diagnostic.Create(Descriptors.INPC005CheckIfDifferentBeforeNotifying, GetLocation()));
}
}
else if (Setter.TryFindSingleTrySet(setter, context.SemanticModel, context.CancellationToken, out var trySet))
{
if (IsFirstCall(invocation) &&
IncorrectOrMissingCheckIfDifferent(trySet, invocation))
{
context.ReportDiagnostic(Diagnostic.Create(Descriptors.INPC005CheckIfDifferentBeforeNotifying, GetLocation()));
}
}
}
#pragma warning restore GU0073 // Member of non-public type should be internal.
internal static bool Uses(ExpressionSyntax assigned, ExpressionSyntax returned, SyntaxNodeAnalysisContext context, PooledSet <SyntaxNode>?visited = null)
{
if (assigned is null ||
returned is null)
{
return(false);
}
using (var assignedPath = MemberPath.PathWalker.Borrow(assigned))
{
var containingType = context.ContainingSymbol.ContainingType;
if (UsedMemberWalker.Uses(returned, assignedPath, Search.TopLevel, containingType, context.SemanticModel, context.CancellationToken))
{
return(true);
}
if (assignedPath.Tokens.TrySingle(out var candidate) &&
containingType.TryFindPropertyRecursive(candidate.ValueText, out var property) &&
property.TrySingleDeclaration(context.CancellationToken, out var declaration) &&
declaration.TryGetSetter(out var setter) &&
Setter.TryFindSingleAssignment(setter, out var assignment))
{
using var set = visited.IncrementUsage();
if (set.Add(candidate.Parent))
{
return(Uses(assignment.Left, returned, context, set));
}
}
}
return(false);
}
protected override async Task RegisterCodeFixesAsync(DocumentEditorCodeFixContext context)
{
var syntaxRoot = await context.Document.GetSyntaxRootAsync(context.CancellationToken)
.ConfigureAwait(false);
var semanticModel = await context.Document.GetSemanticModelAsync(context.CancellationToken)
.ConfigureAwait(false);
foreach (var diagnostic in context.Diagnostics)
{
if (syntaxRoot.TryFindNodeOrAncestor(diagnostic, out ExpressionStatementSyntax? onPropertyChangedStatement) &&
onPropertyChangedStatement.TryFirstAncestor(out AccessorDeclarationSyntax? setter) &&
setter.IsKind(SyntaxKind.SetAccessorDeclaration) &&
setter.Body is { } body)
{
if (Setter.TryFindSingleAssignment(setter, out var assignment) &&
assignment.Parent is ExpressionStatementSyntax assignmentStatement &&
body.Statements.IndexOf(assignmentStatement) == 0)
{
if (semanticModel.TryGetSymbol(assignment.Left, CancellationToken.None, out var assignedSymbol) &&
assignedSymbol.Kind == SymbolKind.Field &&
semanticModel.TryGetSymbol(setter, context.CancellationToken, out IMethodSymbol? setterSymbol) &&
TrySet.TryFind(setterSymbol.ContainingType, semanticModel, context.CancellationToken, out var trySetMethod) &&
TrySet.CanCreateInvocation(trySetMethod, out _) &&
setter.TryFirstAncestor(out PropertyDeclarationSyntax? property))
{
if (setter.Body.Statements.Count == 2)
{
context.RegisterCodeFix(
trySetMethod.DisplaySignature(),
async(editor, cancellationToken) =>
{
var trySet = await editor.TrySetInvocationAsync(trySetMethod, assignment.Left, assignment.Right, property, cancellationToken)
.ConfigureAwait(false);
_ = editor.ReplaceNode(
setter,
x => x.AsExpressionBody(trySet));
},
trySetMethod.MetadataName,
diagnostic);
}
}
context.RegisterCodeFix(
"Check that value is different before notifying.",
(editor, cancellationToken) => editor.InsertBefore(
assignmentStatement,
InpcFactory.IfReturn(
InpcFactory.Equals(
assignment.Right,
assignment.Left,
editor.SemanticModel,
cancellationToken))),
nameof(CheckIfDifferentBeforeNotifyFix),
diagnostic);
}
