public override void VisitInvocationExpression(InvocationExpression invocationExpression)
{
InvocationExpression outerInvocationExpression = invocationExpression;
//Note the invocations are in reverse order, so x.Foo().Bar() will have [0] be the Bar() and [1] be the Foo()
List <InvocationExpression> invocations = new List <InvocationExpression>();
LinqMethod outerMethod = null;
Expression target = null;
for (;;)
{
var resolveResult = ctx.Resolve(invocationExpression) as MemberResolveResult;
if (resolveResult == null || !(resolveResult.Member is IMethod))
{
break;
}
var method = LinqMethods.FirstOrDefault(candidate => candidate.FullName == resolveResult.Member.FullName &&
candidate.ParameterCount == ((IMethod)resolveResult.Member.MemberDefinition).Parameters.Count);
if (method == null || (invocations.Any() && method.IsLast))
{
break;
}
var mre = invocationExpression.Target as MemberReferenceExpression;
if (mre == null)
{
break;
}
if (outerMethod == null)
{
outerMethod = method;
}
invocations.Add(invocationExpression);
target = mre.Target;
var newInvocation = target as InvocationExpression;
if (newInvocation == null)
{
break;
}
invocationExpression = newInvocation;
}
if (target == null)
{
base.VisitInvocationExpression(invocationExpression);
return;
}
if (!outerMethod.IsPoorStyleAlone && invocations.Count == 1)
{
base.VisitInvocationExpression(invocationExpression);
return;
}
var currentTypeDeclaration = outerInvocationExpression.GetParent <TypeDeclaration>();
var currentTypeResolveResult = ctx.Resolve(currentTypeDeclaration) as TypeResolveResult;
if (currentTypeResolveResult == null)
{
base.VisitInvocationExpression(invocationExpression);
return;
}
var currentTypeDefinition = currentTypeResolveResult.Type.GetDefinition();
var targetResolveResult = ctx.Resolve(target);
if (!CanIndex(currentTypeDefinition, targetResolveResult))
{
base.VisitInvocationExpression(invocationExpression);
return;
}
string countPropertyName = GetCountProperty(currentTypeDefinition, targetResolveResult);
string lastInvocationName = ((MemberReferenceExpression)invocations[0].Target).MemberName;
bool endsReversed = invocations.Count(invocation => ((MemberReferenceExpression)invocation.Target).MemberName == "Reverse") % 2 != 0;
bool requiresCount = lastInvocationName == "Count" || lastInvocationName == "Any" ||
(endsReversed ? lastInvocationName == "First" || lastInvocationName == "ElementAt" : lastInvocationName == "Last");
if (countPropertyName == null && requiresCount)
{
base.VisitInvocationExpression(invocationExpression);
return;
}
AddIssue(new CodeIssue(invocations.Last().LParToken.StartLocation,
invocations.First().RParToken.EndLocation,
ctx.TranslateString("Use of Linq method when there's a better alternative"),
ctx.TranslateString("Replace method by simpler version"),
script => {
Expression startOffset = null;
Expression endOffset = null;
Expression expression = null;
bool reversed = false;
foreach (var invocation in invocations.AsEnumerable().Reverse())
{
string invocationName = ((MemberReferenceExpression)invocation.Target).MemberName;
switch (invocationName)
{
case "Skip":
Expression offset = reversed ? endOffset : startOffset;
if (offset == null)
{
offset = invocation.Arguments.Last().Clone();
}
else
{
offset = new BinaryOperatorExpression(offset,
BinaryOperatorType.Add,
invocation.Arguments.Last().Clone());
}
if (reversed)
{
endOffset = offset;
}
else
{
startOffset = offset;
}
break;
case "Reverse":
reversed = !reversed;
break;
case "First":
case "ElementAt":
case "Last":
{
bool fromEnd = (invocationName == "Last") ^ reversed;
Expression index = invocationName == "ElementAt" ? invocation.Arguments.Last().Clone() : null;
Expression baseOffset = fromEnd ? endOffset : startOffset;
//Our indexWithOffset is baseOffset + index
//A baseOffset/index of null is considered "0".
Expression indexWithOffset = baseOffset == null ? index :
index == null ? baseOffset :
new BinaryOperatorExpression(baseOffset, BinaryOperatorType.Add, index);
Expression indexerExpression = indexWithOffset;
if (fromEnd)
{
var endExpression = new BinaryOperatorExpression(new MemberReferenceExpression(target.Clone(), countPropertyName),
BinaryOperatorType.Subtract,
new PrimitiveExpression(1));
if (indexerExpression == null)
{
indexerExpression = endExpression;
}
else
{
indexerExpression = new BinaryOperatorExpression(endExpression,
BinaryOperatorType.Subtract,
new ParenthesizedExpression(indexerExpression));
}
}
indexerExpression = indexerExpression ?? new PrimitiveExpression(0);
var newExpression = new IndexerExpression(target.Clone(),
indexerExpression);
script.Replace(outerInvocationExpression, newExpression);
break;
}
case "Count":
case "Any":
{
Expression takenMembers;
if (startOffset == null)
{
takenMembers = endOffset;
}
else if (endOffset == null)
{
takenMembers = startOffset;
}
else
{
takenMembers = new BinaryOperatorExpression(startOffset,
BinaryOperatorType.Add,
endOffset);
}
var countExpression = new MemberReferenceExpression(target.Clone(), countPropertyName);
Expression newExpression;
if (invocationName == "Count")
{
if (takenMembers == null)
{
newExpression = countExpression;
}
else
{
newExpression = new BinaryOperatorExpression(countExpression,
BinaryOperatorType.Subtract,
new ParenthesizedExpression(takenMembers));
}
}
else
{
newExpression = new BinaryOperatorExpression(countExpression,
BinaryOperatorType.GreaterThan,
new ParenthesizedExpression(takenMembers));
}
script.Replace(outerInvocationExpression, newExpression);
break;
}
}
}
}));
base.VisitInvocationExpression(invocationExpression);
}