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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
// These helper methods are known to a NUTC intrinsic used to implement the Comparer<T> class.
// the compiler will instead replace the IL code within get_Default to call one of GetUnknownComparer, GetKnownGenericComparer,
// GetKnownNullableComparer, GetKnownEnumComparer or GetKnownObjectComparer based on what sort of
// type is being compared.
using System;
using System.Collections.Generic;
using System.Runtime;
using Internal.IntrinsicSupport;
using Internal.Runtime.Augments;
namespace Internal.IntrinsicSupport
{
internal static class ComparerHelpers
{
private static bool ImplementsIComparable(RuntimeTypeHandle t)
{
EETypePtr objectType = t.ToEETypePtr();
EETypePtr icomparableType = typeof(IComparable<>).TypeHandle.ToEETypePtr();
int interfaceCount = objectType.Interfaces.Count;
for (int i = 0; i < interfaceCount; i++)
{
EETypePtr interfaceType = objectType.Interfaces[i];
if (!interfaceType.IsGeneric)
continue;
if (interfaceType.GenericDefinition == icomparableType)
{
var instantiation = interfaceType.Instantiation;
if (instantiation.Length != 1)
continue;
if (objectType.IsValueType)
{
if (instantiation[0] == objectType)
{
return true;
}
}
else if (RuntimeImports.AreTypesAssignable(objectType, instantiation[0]))
{
return true;
}
}
}
return false;
}
private static object GetComparer(RuntimeTypeHandle t)
{
RuntimeTypeHandle comparerType;
RuntimeTypeHandle openComparerType = default(RuntimeTypeHandle);
RuntimeTypeHandle comparerTypeArgument = default(RuntimeTypeHandle);
if (RuntimeAugments.IsNullable(t))
{
RuntimeTypeHandle nullableType = RuntimeAugments.GetNullableType(t);
if (ImplementsIComparable(nullableType))
{
openComparerType = typeof(NullableComparer<>).TypeHandle;
comparerTypeArgument = nullableType;
}
}
if (openComparerType.Equals(default(RuntimeTypeHandle)))
{
if (ImplementsIComparable(t))
{
openComparerType = typeof(GenericComparer<>).TypeHandle;
comparerTypeArgument = t;
}
else
{
openComparerType = typeof(ObjectComparer<>).TypeHandle;
comparerTypeArgument = t;
}
}
bool success = RuntimeAugments.TypeLoaderCallbacks.TryGetConstructedGenericTypeForComponents(openComparerType, new RuntimeTypeHandle[] { comparerTypeArgument }, out comparerType);
if (!success)
{
Environment.FailFast("Unable to create comparer");
}
return RuntimeAugments.NewObject(comparerType);
}
internal static Comparer<T> GetUnknownComparer<T>()
{
return (Comparer<T>)GetComparer(typeof(T).TypeHandle);
}
private static Comparer<T> GetKnownGenericComparer<T>() where T : IComparable<T>
{
return new GenericComparer<T>();
}
private static Comparer<Nullable<U>> GetKnownNullableComparer<U>() where U : struct, IComparable<U>
{
return new NullableComparer<U>();
}
private static Comparer<T> GetKnownObjectComparer<T>()
{
return new ObjectComparer<T>();
}
// This routine emulates System.Collection.Comparer.Default.Compare(), which lives in the System.Collections.NonGenerics contract.
// To avoid adding a reference to that contract just for this hack, we'll replicate the implementation here.
internal static int CompareObjects(object x, object y)
{
if (x == y)
return 0;
if (x == null)
return -1;
if (y == null)
return 1;
{
// System.Collection.Comparer.Default.Compare() compares strings using the CurrentCulture.
string sx = x as string;
string sy = y as string;
if (sx != null && sy != null)
return string.Compare(sx, sy, StringComparison.CurrentCulture);
}
IComparable ix = x as IComparable;
if (ix != null)
return ix.CompareTo(y);
IComparable iy = y as IComparable;
if (iy != null)
return -iy.CompareTo(x);
throw new ArgumentException(SR.Argument_ImplementIComparable);
}
}
}
namespace System.Collections.Generic
{
//-----------------------------------------------------------------------
// Implementations of EqualityComparer<T> for the various possible scenarios
// Because these are serializable, they must not be renamed
//-----------------------------------------------------------------------
[Serializable]
[System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
public sealed class GenericComparer<T> : Comparer<T> where T : IComparable<T>
{
public sealed override int Compare(T x, T y)
{
if (x != null)
{
if (y != null)
return x.CompareTo(y);
return 1;
}
if (y != null)
return -1;
return 0;
}
// Equals method for the comparer itself.
public sealed override bool Equals(object obj) => obj != null && GetType() == obj.GetType();
public sealed override int GetHashCode() => GetType().GetHashCode();
}
[Serializable]
[System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
public sealed class NullableComparer<T> : Comparer<Nullable<T>> where T : struct, IComparable<T>
{
public sealed override int Compare(Nullable<T> x, Nullable<T> y)
{
if (x.HasValue)
{
if (y.HasValue)
return x.Value.CompareTo(y.Value);
return 1;
}
if (y.HasValue)
return -1;
return 0;
}
// Equals method for the comparer itself.
public sealed override bool Equals(object obj) => obj != null && GetType() == obj.GetType();
public sealed override int GetHashCode() => GetType().GetHashCode();
}
[Serializable]
[System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
public sealed class ObjectComparer<T> : Comparer<T>
{
public sealed override int Compare(T x, T y)
{
return ComparerHelpers.CompareObjects(x, y);
}
// Equals method for the comparer itself.
public sealed override bool Equals(object obj) => obj != null && GetType() == obj.GetType();
public sealed override int GetHashCode() => GetType().GetHashCode();
}
}
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