IType[] OutputTypes(ResolveResult e, IType t)
{
// C# 4.0 spec: §7.5.2.4 Output types
LambdaResolveResult lrr = e as LambdaResolveResult;
if (lrr != null || e is MethodGroupResolveResult)
{
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m != null)
{
return(new[] { m.ReturnType });
}
}
return(emptyTypeArray);
}
void MakeExplicitParameterTypeInference(LambdaResolveResult e, IType t)
{
// C# 4.0 spec: §7.5.2.7 Explicit parameter type inferences
if (e.IsImplicitlyTyped || !e.HasParameterList)
{
return;
}
Log.WriteLine(" MakeExplicitParameterTypeInference from " + e + " to " + t);
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m == null)
{
return;
}
for (int i = 0; i < e.Parameters.Count && i < m.Parameters.Count; i++)
{
MakeExactInference(e.Parameters[i].Type, m.Parameters[i].Type);
}
}
IType[] InputTypes(ResolveResult e, IType t)
{
// C# 4.0 spec: §7.5.2.3 Input types
LambdaResolveResult lrr = e as LambdaResolveResult;
if (lrr != null && lrr.IsImplicitlyTyped || e is MethodGroupResolveResult)
{
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m != null)
{
IType[] inputTypes = new IType[m.Parameters.Count];
for (int i = 0; i < inputTypes.Length; i++)
{
inputTypes[i] = m.Parameters[i].Type;
}
return(inputTypes);
}
}
return(emptyTypeArray);
}
void PhaseOne()
{
// C# 4.0 spec: §7.5.2.1 The first phase
Log.WriteLine("Phase One");
for (int i = 0; i < arguments.Length; i++)
{
ResolveResult Ei = arguments[i];
IType Ti = parameterTypes[i];
LambdaResolveResult lrr = Ei as LambdaResolveResult;
if (lrr != null)
{
MakeExplicitParameterTypeInference(lrr, Ti);
}
if (lrr != null || Ei is MethodGroupResolveResult)
{
// this is not in the spec???
if (OutputTypeContainsUnfixed(Ei, Ti) && !InputTypesContainsUnfixed(Ei, Ti))
{
MakeOutputTypeInference(Ei, Ti);
}
}
if (IsValidType(Ei.Type))
{
if (Ti is ByReferenceType)
{
MakeExactInference(Ei.Type, Ti);
}
else
{
MakeLowerBoundInference(Ei.Type, Ti);
}
}
}
}
void MakeOutputTypeInference(ResolveResult e, IType t)
{
Log.WriteLine(" MakeOutputTypeInference from " + e + " to " + t);
// If E is an anonymous function with inferred return type U (§7.5.2.12) and T is a delegate type or expression
// tree type with return type Tb, then a lower-bound inference (§7.5.2.9) is made from U to Tb.
LambdaResolveResult lrr = e as LambdaResolveResult;
if (lrr != null)
{
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m != null)
{
IType inferredReturnType;
if (lrr.IsImplicitlyTyped)
{
if (m.Parameters.Count != lrr.Parameters.Count)
{
return; // cannot infer due to mismatched parameter lists
}
TypeParameterSubstitution substitution = GetSubstitutionForFixedTPs();
IType[] inferredParameterTypes = new IType[m.Parameters.Count];
for (int i = 0; i < inferredParameterTypes.Length; i++)
{
IType parameterType = m.Parameters[i].Type;
inferredParameterTypes[i] = parameterType.AcceptVisitor(substitution);
}
inferredReturnType = lrr.GetInferredReturnType(inferredParameterTypes);
}
else
{
inferredReturnType = lrr.GetInferredReturnType(null);
}
MakeLowerBoundInference(inferredReturnType, m.ReturnType);
return;
}
}
// Otherwise, if E is a method group and T is a delegate type or expression tree type
// with parameter types T1…Tk and return type Tb, and overload resolution
// of E with the types T1…Tk yields a single method with return type U, then a lower-bound
// inference is made from U to Tb.
MethodGroupResolveResult mgrr = e as MethodGroupResolveResult;
if (mgrr != null)
{
IMethod m = GetDelegateOrExpressionTreeSignature(t);
if (m != null)
{
ResolveResult[] args = new ResolveResult[m.Parameters.Count];
TypeParameterSubstitution substitution = GetSubstitutionForFixedTPs();
for (int i = 0; i < args.Length; i++)
{
IParameter param = m.Parameters[i];
IType parameterType = param.Type.AcceptVisitor(substitution);
if ((param.IsRef || param.IsOut) && parameterType.Kind == TypeKind.ByReference)
{
parameterType = ((ByReferenceType)parameterType).ElementType;
args[i] = new ByReferenceResolveResult(parameterType, param.IsOut);
}
else
{
args[i] = new ResolveResult(parameterType);
}
}
var or = mgrr.PerformOverloadResolution(compilation,
args,
allowExpandingParams: false, allowOptionalParameters: false);
if (or.FoundApplicableCandidate && or.BestCandidateAmbiguousWith == null)
{
IType returnType = or.GetBestCandidateWithSubstitutedTypeArguments().ReturnType;
MakeLowerBoundInference(returnType, m.ReturnType);
}
}
return;
}
// Otherwise, if E is an expression with type U, then a lower-bound inference is made from U to T.
if (IsValidType(e.Type))
{
MakeLowerBoundInference(e.Type, t);
}
}
