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using System;
using System.Collections;
using System.Collections.Generic;
namespace System.Collections.Generic {
/// <summary>
/// Equality comparer for hashsets of hashsets
/// </summary>
/// <typeparam name="T"></typeparam>
#if !FEATURE_NETCORE
[Serializable()]
#endif
internal class HashSetEqualityComparer<T> : IEqualityComparer<HashSet<T>> {
private IEqualityComparer<T> m_comparer;
public HashSetEqualityComparer() {
m_comparer = EqualityComparer<T>.Default;
}
public HashSetEqualityComparer(IEqualityComparer<T> comparer) {
if (comparer == null) {
m_comparer = EqualityComparer<T>.Default;
}
else {
m_comparer = comparer;
}
}
// using m_comparer to keep equals properties in tact; don't want to choose one of the comparers
public bool Equals(HashSet<T> x, HashSet<T> y) {
return HashSet<T>.HashSetEquals(x, y, m_comparer);
}
public int GetHashCode(HashSet<T> obj) {
int hashCode = 0;
if (obj != null) {
foreach (T t in obj) {
hashCode = hashCode ^ (m_comparer.GetHashCode(t) & 0x7FFFFFFF);
}
} // else returns hashcode of 0 for null hashsets
return hashCode;
}
// Equals method for the comparer itself.
public override bool Equals(Object obj){
HashSetEqualityComparer<T> comparer = obj as HashSetEqualityComparer<T>;
if (comparer == null) {
return false;
}
return (this.m_comparer == comparer.m_comparer);
}
public override int GetHashCode() {
return m_comparer.GetHashCode();
}
}
}
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