private async static Task<Document> UseVarAsync(Document document, Diagnostic diagnostic, CancellationToken cancellationToken)
{
var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
var diagnosticSpan = diagnostic.Location.SourceSpan;
var localDeclaration = root.FindToken(diagnosticSpan.Start).Parent.AncestorsAndSelf().OfType<LocalDeclarationStatementSyntax>().First();
var variableDeclaration = localDeclaration.Declaration;
var numVariables = variableDeclaration.Variables.Count;
var newVariableDeclarations = new VariableDeclarationSyntax[numVariables];
var varSyntax = SyntaxFactory.IdentifierName("var");
//Create a new var declaration for each variable.
for (var i = 0; i < numVariables; i++)
{
var originalVariable = variableDeclaration.Variables[i];
var newLeadingTrivia = originalVariable.GetLeadingTrivia();
//Get the trivia from the separator as well
if (i != 0)
{
newLeadingTrivia = newLeadingTrivia.InsertRange(0,
variableDeclaration.Variables.GetSeparator(i-1).GetAllTrivia());
}
newVariableDeclarations[i] = SyntaxFactory.VariableDeclaration(varSyntax)
.AddVariables(originalVariable.WithLeadingTrivia(newLeadingTrivia));
}
//ensure trivia for leading type node is preserved
var originalTypeSyntax = variableDeclaration.Type;
newVariableDeclarations[0] = newVariableDeclarations[0]
.WithType((TypeSyntax) varSyntax.WithSameTriviaAs(originalTypeSyntax));
var newLocalDeclarationStatements = newVariableDeclarations.Select(SyntaxFactory.LocalDeclarationStatement).ToList();
//Preserve the trivia for the entire statement at the start and at the end
newLocalDeclarationStatements[0] =
newLocalDeclarationStatements[0].WithLeadingTrivia(variableDeclaration.GetLeadingTrivia());
var lastIndex = numVariables -1;
newLocalDeclarationStatements[lastIndex] =
newLocalDeclarationStatements[lastIndex].WithTrailingTrivia(localDeclaration.GetTrailingTrivia());
var newRoot = root.ReplaceNode(localDeclaration, newLocalDeclarationStatements);
var newDocument = document.WithSyntaxRoot(newRoot);
return newDocument;
}
