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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
using System;
using ICSharpCode.NRefactory.TypeSystem.Implementation;
namespace ICSharpCode.NRefactory.TypeSystem
{
/// <summary>
/// Static helper methods for working with nullable types.
/// </summary>
public static class NullableType
{
/// <summary>
/// Gets whether the specified type is a nullable type.
/// </summary>
public static bool IsNullable(IType type)
{
if (type == null)
throw new ArgumentNullException("type");
ParameterizedType pt = type as ParameterizedType;
return pt != null && pt.TypeParameterCount == 1 && pt.GetDefinition().KnownTypeCode == KnownTypeCode.NullableOfT;
}
public static bool IsNonNullableValueType(IType type)
{
return type.IsReferenceType == false && !IsNullable(type);
}
/// <summary>
/// Returns the element type, if <paramref name="type"/> is a nullable type.
/// Otherwise, returns the type itself.
/// </summary>
public static IType GetUnderlyingType(IType type)
{
if (type == null)
throw new ArgumentNullException("type");
ParameterizedType pt = type as ParameterizedType;
if (pt != null && pt.TypeParameterCount == 1 && pt.FullName == "System.Nullable")
return pt.GetTypeArgument(0);
else
return type;
}
/// <summary>
/// Creates a nullable type.
/// </summary>
public static IType Create(ICompilation compilation, IType elementType)
{
if (compilation == null)
throw new ArgumentNullException("compilation");
if (elementType == null)
throw new ArgumentNullException("elementType");
IType nullableType = compilation.FindType(KnownTypeCode.NullableOfT);
ITypeDefinition nullableTypeDef = nullableType.GetDefinition();
if (nullableTypeDef != null)
return new ParameterizedType(nullableTypeDef, new [] { elementType });
else
return nullableType;
}
/// <summary>
/// Creates a nullable type reference.
/// </summary>
public static ITypeReference Create(ITypeReference elementType)
{
if (elementType == null)
throw new ArgumentNullException("elementType");
return new ParameterizedTypeReference(KnownTypeReference.NullableOfT, new [] { elementType });
}
}
}
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