public CheckNullVisitor(ParameterDeclaration parameter)
{
pattern = PatternHelper.CommutativeOperator(new IdentifierExpression(parameter.Name), BinaryOperatorType.Any, new NullReferenceExpression());
}
protected override CodeAction GetAction(RefactoringContext context, IfElseStatement node)
{
var match = ActionPattern.Match(node.Condition);
if (!match.Success)
{
return(null);
}
var conditionExpression = match.Get <BinaryOperatorExpression>(expressionGroupName).Single();
bool isEqualityComparison = conditionExpression.Operator == BinaryOperatorType.Equality;
Expression comparedNode = match.Get <Expression>(comparedNodeGroupName).Single();
Statement contentStatement;
if (isEqualityComparison)
{
contentStatement = node.TrueStatement;
if (!IsEmpty(node.FalseStatement))
{
return(null);
}
}
else
{
contentStatement = node.FalseStatement;
if (!IsEmpty(node.TrueStatement))
{
return(null);
}
}
contentStatement = GetSimpleStatement(contentStatement);
if (contentStatement == null)
{
return(null);
}
var leftExpressionPattern = PatternHelper.OptionalParentheses(comparedNode);
var expressionPattern = new AssignmentExpression(leftExpressionPattern, AssignmentOperatorType.Assign, new AnyNode(valueOnNullGroupName));
var statementPattern = new ExpressionStatement(PatternHelper.OptionalParentheses(expressionPattern));
var statementMatch = statementPattern.Match(contentStatement);
if (!statementMatch.Success)
{
return(null);
}
var rightSide = statementMatch.Get <Expression>(valueOnNullGroupName).Single();
return(new CodeAction(context.TranslateString("Convert if statement to ?? expression"),
script => {
var previousNode = node.GetPrevSibling(sibling => sibling is Statement);
var previousDeclaration = previousNode as VariableDeclarationStatement;
if (previousDeclaration != null && previousDeclaration.Variables.Count() == 1)
{
var variable = previousDeclaration.Variables.First();
var comparedNodeIdentifierExpression = comparedNode as IdentifierExpression;
if (comparedNodeIdentifierExpression != null &&
comparedNodeIdentifierExpression.Identifier == variable.Name)
{
script.Replace(variable.Initializer, new BinaryOperatorExpression(variable.Initializer.Clone(),
BinaryOperatorType.NullCoalescing,
rightSide.Clone()));
script.Remove(node);
return;
}
}
var previousExpressionStatement = previousNode as ExpressionStatement;
if (previousExpressionStatement != null)
{
var previousAssignment = previousExpressionStatement.Expression as AssignmentExpression;
if (previousAssignment != null &&
comparedNode.IsMatch(previousAssignment.Left))
{
var newExpression = new BinaryOperatorExpression(previousAssignment.Right.Clone(),
BinaryOperatorType.NullCoalescing,
rightSide.Clone());
script.Replace(previousAssignment.Right, newExpression);
script.Remove(node);
return;
}
}
var coalescedExpression = new BinaryOperatorExpression(comparedNode.Clone(),
BinaryOperatorType.NullCoalescing,
rightSide.Clone());
var newAssignment = new ExpressionStatement(new AssignmentExpression(comparedNode.Clone(), coalescedExpression));
script.Replace(node, newAssignment);
}, node));
}
