/// <summary>
/// Matches an 'ldflda' instruction accessing a tuple element.
///
/// E.g. matches:
/// <c>ldflda Item1(ldflda Rest(target))</c>
/// </summary>
public static bool MatchTupleFieldAccess(LdFlda inst, out IType tupleType, out ILInstruction target, out int position)
{
tupleType = inst.Field.DeclaringType;
target = inst.Target;
if (!inst.Field.Name.StartsWith("Item", StringComparison.Ordinal))
{
position = 0;
return(false);
}
if (!int.TryParse(inst.Field.Name.Substring(4), out position))
{
return(false);
}
if (!TupleType.IsTupleCompatible(tupleType, out _))
{
return(false);
}
while (target is LdFlda ldflda && ldflda.Field.Name == "Rest" && TupleType.IsTupleCompatible(ldflda.Field.DeclaringType, out _))
{
tupleType = ldflda.Field.DeclaringType;
target = ldflda.Target;
position += TupleType.RestPosition - 1;
}
return(true);
}
/// <summary>
/// Matches 'newobj TupleType(...)'.
/// Takes care of flattening long tuples.
/// </summary>
public static bool MatchTupleConstruction(NewObj newobj, out ILInstruction[] arguments)
{
arguments = null;
if (newobj == null)
{
return(false);
}
if (!TupleType.IsTupleCompatible(newobj.Method.DeclaringType, out int elementCount))
{
return(false);
}
arguments = new ILInstruction[elementCount];
int outIndex = 0;
while (elementCount >= TupleType.RestPosition)
{
if (newobj.Arguments.Count != TupleType.RestPosition)
{
return(false);
}
for (int pos = 1; pos < TupleType.RestPosition; pos++)
{
arguments[outIndex++] = newobj.Arguments[pos - 1];
}
elementCount -= TupleType.RestPosition - 1;
Debug.Assert(outIndex + elementCount == arguments.Length);
newobj = newobj.Arguments.Last() as NewObj;
if (newobj == null)
{
return(false);
}
if (!TupleType.IsTupleCompatible(newobj.Method.DeclaringType, out int restElementCount))
{
return(false);
}
if (restElementCount != elementCount)
{
return(false);
}
}
Debug.Assert(outIndex + elementCount == arguments.Length);
if (newobj.Arguments.Count != elementCount)
{
return(false);
}
for (int i = 0; i < elementCount; i++)
{
arguments[outIndex++] = newobj.Arguments[i];
}
return(true);
}