public static Task <Document> RefactorAsync(
Document document,
BlockSyntax block,
CancellationToken cancellationToken)
{
SyntaxList <StatementSyntax> statements = block.Statements;
var ifStatement = (IfStatementSyntax)statements[0];
var returnStatement = (ReturnStatementSyntax)statements[1];
var expressionStatement = (ExpressionStatementSyntax)ifStatement.GetSingleStatementOrDefault();
var assignment = (AssignmentExpressionSyntax)expressionStatement.Expression;
ExpressionSyntax expression = returnStatement.Expression.WithoutTrivia();
BinaryExpressionSyntax coalesceExpression = CSharpFactory.CoalesceExpression(
expression,
CSharpFactory.SimpleAssignmentExpression(expression, assignment.Right.WithoutTrivia()).Parenthesize());
ReturnStatementSyntax newReturnStatement = returnStatement
.WithExpression(coalesceExpression)
.WithLeadingTrivia(ifStatement.GetLeadingTrivia());
SyntaxList <StatementSyntax> newStatements = statements
.Replace(returnStatement, newReturnStatement)
.RemoveAt(0);
BlockSyntax newBlock = block.WithStatements(newStatements);
return(document.ReplaceNodeAsync(block, newBlock, cancellationToken));
}