private static void ExpandInvocationOperation(
IInvocationOperation invocationOperation,
WellKnownSymbolsInfo wellKnownSymbolsInfo,
Queue <IOperation> queue)
{
// Check the arguments of this invocation to see if this is a deferred executing method.
// e.g.
// var a = b.Concat(c);
// When we looking at the creation of 'a', we want to find both 'b' and 'c'
foreach (var argument in invocationOperation.Arguments)
{
if (IsLinqChainInvocation(invocationOperation, argument, wellKnownSymbolsInfo, out _))
{
queue.Enqueue(argument.Value);
}
}
// Also check it's invocation instance if the extension method could be used in reduced form.
// e.g.
// Dim a = b.Concat(c)
// We need enqueue the invocation instance (which is 'b') if the target method is a reduced extension method
if (IsLinqChainInvocation(invocationOperation, wellKnownSymbolsInfo, out _))
{
queue.Enqueue(invocationOperation.Instance);
}
}
private static void ExpandConversionOperation(
IConversionOperation conversionOperation,
WellKnownSymbolsInfo wellKnownSymbolsInfo,
Queue <IOperation> queue)
{
if (IsValidImplicitConversion(conversionOperation, wellKnownSymbolsInfo))
{
queue.Enqueue(conversionOperation.Operand);
}
}
static (IOperation linqChainTailOperation, EnumerationCount enumerationCount) VisitLinqChainAndCoversionMethod(
IOperation operation,
EnumerationCount enumerationCount,
WellKnownSymbolsInfo wellKnownSymbolsInfo)
{
if (IsValidImplicitConversion(operation.Parent, wellKnownSymbolsInfo))
{
// Go to the implicit conversion if needed
// e.g.
// void Bar (IOrderedEnumerable<T> c)
// {
// c.First();
// }
// here 'c' would be converted to IEnumerable<T>
return(VisitLinqChainAndCoversionMethod(operation.Parent, enumerationCount, wellKnownSymbolsInfo));
}
if (IsOperationIsArgumentOfLinqChainInvocation(operation.Parent, wellKnownSymbolsInfo, out var enumerateArgument))
{
// This operation is used as an argument of a deferred execution method.
// Check if the invocation of the deferred execution method is used in another deferred execution method.
return(VisitLinqChainAndCoversionMethod(
operation.Parent.Parent,
enumerateArgument
? InvocationSetHelpers.AddInvocationCount(enumerationCount, EnumerationCount.One)
: enumerationCount,
wellKnownSymbolsInfo));
}
if (IsInstanceOfLinqChainInvocation(operation, wellKnownSymbolsInfo, out var enumerateInstance))
{
// If the extension method could be used as reduced method, also check its invocation instance.
// Like in VB,
// 'i.Select(Function(a) a)', 'i' is the invocation instance of 'Select'
return(VisitLinqChainAndCoversionMethod(
operation.Parent,
enumerateInstance
? InvocationSetHelpers.AddInvocationCount(enumerationCount, EnumerationCount.One)
: enumerationCount,
wellKnownSymbolsInfo));
}
return(operation, enumerationCount);
}
private EnumerationCount GetEnumerationCount(IOperation parameterOrLocalReferenceOperation, WellKnownSymbolsInfo wellKnownSymbolsInfo)
{
var(linqChainTailOperation, linqChainEnumerationCount) = SkipLinqChainAndConversionMethod(
parameterOrLocalReferenceOperation,
wellKnownSymbolsInfo);
if (IsOperationEnumeratedByInvocation(linqChainTailOperation, wellKnownSymbolsInfo) ||
IsGetEnumeratorOfForEachLoopInvoked(linqChainTailOperation))
{
return(InvocationSetHelpers.AddInvocationCount(linqChainEnumerationCount, EnumerationCount.One));
}
return(linqChainEnumerationCount);
}
protected AvoidMultipleEnumerationsFlowStateDictionaryFlowOperationVisitor(
GlobalFlowStateDictionaryAnalysisContext analysisContext,
WellKnownSymbolsInfo wellKnownSymbolsInfo) : base(analysisContext)
{
_wellKnownSymbolsInfo = wellKnownSymbolsInfo;
}
/// <summary>
/// Skip the deferred method call and conversion operation in Linq methods call chain.
/// Return the tail of the Linq chain operation, and possible enumerationCount by the Linq Chain Method.
/// </summary>
public static (IOperation linqChainTailOperation, EnumerationCount linqChainEnumerationCount) SkipLinqChainAndConversionMethod(
IOperation operation,
WellKnownSymbolsInfo wellKnownSymbolsInfo)
{
RoslynDebug.Assert(operation is IParameterReferenceOperation or ILocalReferenceOperation);
return(VisitLinqChainAndCoversionMethod(operation, EnumerationCount.Zero, wellKnownSymbolsInfo));
