private static Task <Document> RefactorAsync(
Document document,
LocalDeclarationStatementSyntax localDeclaration,
CancellationToken cancellationToken)
{
VariableDeclaratorSyntax variableDeclarator = localDeclaration
.Declaration
.Variables
.Single();
ExpressionSyntax expression = variableDeclarator
.Initializer
.Value
.WalkDownParentheses();
AsExpressionInfo asExpressionInfo = SyntaxInfo.AsExpressionInfo(expression);
PrefixUnaryExpressionSyntax newCondition = LogicalNotExpression(
ParenthesizedExpression(
IsPatternExpression(
asExpressionInfo.Expression,
DeclarationPattern(
asExpressionInfo.Type,
SingleVariableDesignation(variableDeclarator.Identifier)))));
StatementListInfo statements = SyntaxInfo.StatementListInfo(localDeclaration);
int index = statements.IndexOf(localDeclaration);
var ifStatement = (IfStatementSyntax)statements[index + 1];
SyntaxTriviaList leadingTrivia = localDeclaration
.DescendantTrivia(TextSpan.FromBounds(localDeclaration.SpanStart, ifStatement.SpanStart))
.ToSyntaxTriviaList()
.EmptyIfWhitespace();
leadingTrivia = localDeclaration.GetLeadingTrivia().AddRange(leadingTrivia);
StatementSyntax newStatement = ifStatement.Statement;
if (ifStatement.SingleNonBlockStatementOrDefault() is ReturnStatementSyntax returnStatement &&
returnStatement.Expression?.WalkDownParentheses() is IdentifierNameSyntax identifierName &&
string.Equals(identifierName.Identifier.ValueText, variableDeclarator.Identifier.ValueText, System.StringComparison.Ordinal))
{
newStatement = newStatement.ReplaceNode(returnStatement.Expression, NullLiteralExpression().WithTriviaFrom(returnStatement.Expression));
}
IfStatementSyntax newIfStatement = ifStatement
.WithCondition(newCondition.WithTriviaFrom(ifStatement.Condition))
.WithStatement(newStatement)
.WithLeadingTrivia(leadingTrivia)
.WithFormatterAnnotation();
StatementListInfo newStatements = statements.RemoveAt(index).ReplaceAt(index, newIfStatement);
return(document.ReplaceStatementsAsync(statements, newStatements, cancellationToken));
}
private static Task <Document> RefactorAsync(
Document document,
LocalDeclarationStatementSyntax localDeclaration,
CancellationToken cancellationToken)
{
VariableDeclaratorSyntax variableDeclarator = localDeclaration
.Declaration
.Variables
.Single();
ExpressionSyntax expression = variableDeclarator
.Initializer
.Value
.WalkDownParentheses();
AsExpressionInfo asExpressionInfo = SyntaxInfo.AsExpressionInfo(expression);
PrefixUnaryExpressionSyntax newCondition = LogicalNotExpression(
ParenthesizedExpression(
IsPatternExpression(
asExpressionInfo.Expression,
DeclarationPattern(
asExpressionInfo.Type,
SingleVariableDesignation(variableDeclarator.Identifier)))));
StatementListInfo statements = SyntaxInfo.StatementListInfo(localDeclaration);
int index = statements.IndexOf(localDeclaration);
var ifStatement = (IfStatementSyntax)statements[index + 1];
SyntaxTriviaList leadingTrivia = localDeclaration
.DescendantTrivia(TextSpan.FromBounds(localDeclaration.SpanStart, ifStatement.SpanStart))
.ToSyntaxTriviaList()
.EmptyIfWhitespace();
leadingTrivia = localDeclaration.GetLeadingTrivia().AddRange(leadingTrivia);
IfStatementSyntax newIfStatement = ifStatement
.WithCondition(newCondition.WithTriviaFrom(ifStatement.Condition))
.WithLeadingTrivia(leadingTrivia);
StatementListInfo newStatements = statements.RemoveAt(index).ReplaceAt(index, newIfStatement);
return(document.ReplaceStatementsAsync(statements, newStatements, cancellationToken));
}