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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.
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
namespace Microsoft.Interop
{
internal static class Comparers
{
/// <summary>
/// Comparer for an individual generated stub source as a syntax tree and the generated diagnostics for the stub.
/// </summary>
public static readonly IEqualityComparer<(MemberDeclarationSyntax Syntax, ImmutableArray<DiagnosticInfo> Diagnostics)> GeneratedSyntax = new CustomValueTupleElementComparer<MemberDeclarationSyntax, ImmutableArray<DiagnosticInfo>>(SyntaxEquivalentComparer.Instance, new ImmutableArraySequenceEqualComparer<DiagnosticInfo>(EqualityComparer<DiagnosticInfo>.Default));
}
/// <summary>
/// Generic comparer to compare two <see cref="ImmutableArray{T}"/> instances element by element.
/// </summary>
/// <typeparam name="T">The type of immutable array element.</typeparam>
internal sealed class ImmutableArraySequenceEqualComparer<T> : IEqualityComparer<ImmutableArray<T>>
{
private readonly IEqualityComparer<T> _elementComparer;
/// <summary>
/// Creates an <see cref="ImmutableArraySequenceEqualComparer{T}"/> with a custom comparer for the elements of the collection.
/// </summary>
/// <param name="elementComparer">The comparer instance for the collection elements.</param>
public ImmutableArraySequenceEqualComparer(IEqualityComparer<T> elementComparer)
{
_elementComparer = elementComparer;
}
public bool Equals(ImmutableArray<T> x, ImmutableArray<T> y)
{
return x.SequenceEqual(y, _elementComparer);
}
public int GetHashCode(ImmutableArray<T> obj)
{
throw new UnreachableException();
}
}
internal sealed class CustomValueTupleElementComparer<T, U> : IEqualityComparer<(T, U)>
{
private readonly IEqualityComparer<T> _item1Comparer;
private readonly IEqualityComparer<U> _item2Comparer;
public CustomValueTupleElementComparer(IEqualityComparer<T> item1Comparer, IEqualityComparer<U> item2Comparer)
{
_item1Comparer = item1Comparer;
_item2Comparer = item2Comparer;
}
public bool Equals((T, U) x, (T, U) y)
{
return _item1Comparer.Equals(x.Item1, y.Item1) && _item2Comparer.Equals(x.Item2, y.Item2);
}
public int GetHashCode((T, U) obj)
{
throw new UnreachableException();
}
}
}
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