public static ISignature FromBuiltinSpec([NotNull] BuiltinSpec spec)
{
var pis = spec.Method.GetParameters();
var parts = pis
.Skip(spec.Attr.Data == null ? 1 : 2)
.Select(ConvertBuiltinParam)
.ToArray();
var returnPart = ConvertBuiltinParam(
spec.Method.ReturnParameter ??
throw new InvalidOperationException($"Missing {nameof(spec.Method.ReturnParameter)}"));
return(new ZBuiltinSignature(
spec.MinArgs, spec.MaxArgs,
spec.Attr.MinVersion, spec.Attr.MaxVersion,
parts,
returnPart));
// helper
SignaturePart ConvertBuiltinParam(ParameterInfo pi)
{
var type = pi.ParameterType;
if (type == typeof(void))
{
if (spec.CallType == typeof(VoidCall))
{
return(LiteralPart.From("T"));
}
var part = SignatureBuilder.Constrained(
SignatureBuilder.Identifier("$return"),
spec.CallType == typeof(PredCall) ? Constraint.Boolean : Constraint.AnyObject);
return(ApplyParamAttributes(part, pi));
}
if (ParameterTypeHandler.Handlers.TryGetValue(type, out var handler))
{
return(ConvertWithHandler(handler, pi));
}
// ReSharper disable once PatternAlwaysOfType
if (type.IsArray && type.GetElementType() is Type t &&
ParameterTypeHandler.Handlers.TryGetValue(t, out handler))
{
var part = ConvertWithHandler(handler, pi);
return(SignatureBuilder.VarArgs(part, false));
}
throw new InvalidOperationException("Unexpected builtin param type");
}
}
static SignaturePart ConstrainByType([NotNull] SignaturePart part, [NotNull] Type elementType)
{
System.Diagnostics.Debug.Assert(!elementType.IsArray);
// treat Nullable<Foo> as an optional Foo
bool isOptional = false;
var nullableUnderlyingType = Nullable.GetUnderlyingType(elementType);
if (nullableUnderlyingType != null)
{
isOptional = true;
elementType = nullableUnderlyingType;
}
// treat LocalEnvironment as an optional ZilEnvironment
if (elementType == typeof(LocalEnvironment))
{
isOptional = true;
elementType = typeof(ZilEnvironment);
}
// find an appropriate type or primtype constraint for the element type
if (!StandardTypeConstraints.TryGetValue(elementType, out var constraint))
{
BuiltinPrimTypeAttribute primTypeAttr;
if ((primTypeAttr = elementType.GetCustomAttribute <BuiltinPrimTypeAttribute>(false)) != null)
{
constraint = Constraint.OfPrimType(primTypeAttr.PrimType);
}
else
{
BuiltinTypeAttribute typeAttr;
if ((typeAttr = elementType.GetCustomAttribute <BuiltinTypeAttribute>(false)) != null)
{
constraint = Constraint.OfType(typeAttr.Name);
}
else
{
throw new UnhandledCaseException(elementType.Name);
}
}
}
part = SignatureBuilder.Constrained(part, constraint);
return(isOptional ? SignatureBuilder.Optional(part) : part);
}
static SignaturePart ApplyParamAttributes([NotNull] SignaturePart part, [NotNull] ParameterInfo pi)
{
// TODO: also handle VariableAttribute?
if (pi.IsDefined(typeof(TableAttribute), false))
{
part = SignatureBuilder.Constrained(part, Constraint.OfPrimType(PrimType.TABLE));
}
if (pi.IsDefined(typeof(ObjectAttribute), false))
{
part = SignatureBuilder.Constrained(part, Constraint.OfType(StdAtom.OBJECT));
}
if (pi.IsOptional)
{
part = SignatureBuilder.Optional(part);
}
return(part);
}