private static bool CanCastParamTo(this ParameterizedType thisType, TypeDesc paramType, StackOverflowProtect protect)
{
// While boxed value classes inherit from object their
// unboxed versions do not. Parameterized types have the
// unboxed version, thus, if the from type parameter is value
// class then only an exact match/equivalence works.
if (thisType.ParameterType == paramType)
{
return(true);
}
TypeDesc curTypesParm = thisType.ParameterType;
// Object parameters don't need an exact match but only inheritance, check for that
TypeDesc fromParamUnderlyingType = curTypesParm.UnderlyingType;
if (fromParamUnderlyingType.IsGCPointer)
{
return(curTypesParm.CanCastToInternal(paramType, protect));
}
else if (curTypesParm.IsGenericParameter)
{
var genericVariableFromParam = (GenericParameterDesc)curTypesParm;
if (genericVariableFromParam.HasReferenceTypeConstraint)
{
return(genericVariableFromParam.CanCastToInternal(paramType, protect));
}
}
else if (fromParamUnderlyingType.IsPrimitive)
{
TypeDesc toParamUnderlyingType = paramType.UnderlyingType;
if (toParamUnderlyingType.IsPrimitive)
{
if (toParamUnderlyingType == fromParamUnderlyingType)
{
return(true);
}
if (ArePrimitveTypesEquivalentSize(fromParamUnderlyingType, toParamUnderlyingType))
{
return(true);
}
}
}
// Anything else is not a match
return(false);
}
private static bool IsBoxedAndCanCastTo(this TypeDesc thisType, TypeDesc otherType, StackOverflowProtect protect)
{
TypeDesc fromUnderlyingType = thisType.UnderlyingType;
if (fromUnderlyingType.IsGCPointer)
{
return(thisType.CanCastToInternal(otherType, protect));
}
else if (thisType.IsGenericParameter)
{
var genericVariableFromParam = (GenericParameterDesc)thisType;
if (genericVariableFromParam.HasReferenceTypeConstraint)
{
return(genericVariableFromParam.CanCastToInternal(otherType, protect));
}
}
return(false);
}
/// <summary>
/// Returns true if '<paramref name="thisType"/>' can be cast to '<paramref name="otherType"/>'.
/// Assumes '<paramref name="thisType"/>' is in it's boxed form if it's a value type (i.e.
/// [System.Int32].CanCastTo([System.Object]) will return true).
/// </summary>
public static bool CanCastTo(this TypeDesc thisType, TypeDesc otherType)
{
return(thisType.CanCastToInternal(otherType, null));
}
