|
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.CompilerServices;
namespace System.Collections.Immutable
{
/// <summary>
/// An immutable unordered hash set implementation.
/// </summary>
/// <typeparam name="T">The type of elements in the set.</typeparam>
[CollectionBuilder(typeof(ImmutableHashSet), nameof(ImmutableHashSet.Create))]
[DebuggerDisplay("Count = {Count}")]
[DebuggerTypeProxy(typeof(ImmutableEnumerableDebuggerProxy<>))]
#if NET
public sealed partial class ImmutableHashSet<T> : IImmutableSet<T>, IHashKeyCollection<T>, IReadOnlyCollection<T>, ICollection<T>, ISet<T>, IReadOnlySet<T>, ICollection, IStrongEnumerable<T, ImmutableHashSet<T>.Enumerator>
#else
public sealed partial class ImmutableHashSet<T> : IImmutableSet<T>, IHashKeyCollection<T>, IReadOnlyCollection<T>, ICollection<T>, ISet<T>, ICollection, IStrongEnumerable<T, ImmutableHashSet<T>.Enumerator>
#endif
{
/// <summary>
/// An empty immutable hash set with the default comparer for <typeparamref name="T"/>.
/// </summary>
public static readonly ImmutableHashSet<T> Empty = new ImmutableHashSet<T>(SortedInt32KeyNode<HashBucket>.EmptyNode, EqualityComparer<T>.Default, 0);
/// <summary>
/// The singleton delegate that freezes the contents of hash buckets when the root of the data structure is frozen.
/// </summary>
private static readonly Action<KeyValuePair<int, HashBucket>> s_FreezeBucketAction = (kv) => kv.Value.Freeze();
/// <summary>
/// The equality comparer used to hash the elements in the collection.
/// </summary>
private readonly IEqualityComparer<T> _equalityComparer;
/// <summary>
/// The number of elements in this collection.
/// </summary>
private readonly int _count;
/// <summary>
/// The sorted dictionary that this hash set wraps. The key is the hash code and the value is the bucket of all items that hashed to it.
/// </summary>
private readonly SortedInt32KeyNode<HashBucket> _root;
/// <summary>
/// The equality comparer to use when balancing the tree of hash buckets.
/// </summary>
private readonly IEqualityComparer<HashBucket> _hashBucketEqualityComparer;
/// <summary>
/// Initializes a new instance of the <see cref="ImmutableHashSet{T}"/> class.
/// </summary>
/// <param name="equalityComparer">The equality comparer.</param>
internal ImmutableHashSet(IEqualityComparer<T> equalityComparer)
: this(SortedInt32KeyNode<HashBucket>.EmptyNode, equalityComparer, 0)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="ImmutableHashSet{T}"/> class.
/// </summary>
/// <param name="root">The sorted set that this set wraps.</param>
/// <param name="equalityComparer">The equality comparer used by this instance.</param>
/// <param name="count">The number of elements in this collection.</param>
private ImmutableHashSet(SortedInt32KeyNode<HashBucket> root, IEqualityComparer<T> equalityComparer, int count)
{
Requires.NotNull(root, nameof(root));
Requires.NotNull(equalityComparer, nameof(equalityComparer));
root.Freeze(s_FreezeBucketAction);
_root = root;
_count = count;
_equalityComparer = equalityComparer;
_hashBucketEqualityComparer = GetHashBucketEqualityComparer(equalityComparer);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> Clear()
{
return this.IsEmpty ? this : ImmutableHashSet<T>.Empty.WithComparer(_equalityComparer);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public int Count
{
get { return _count; }
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public bool IsEmpty
{
get { return this.Count == 0; }
}
#region IHashKeyCollection<T> Properties
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public IEqualityComparer<T> KeyComparer
{
get { return _equalityComparer; }
}
#endregion
#region IImmutableSet<T> Properties
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
IImmutableSet<T> IImmutableSet<T>.Clear()
{
return this.Clear();
}
#endregion
#region ICollection Properties
/// <summary>
/// See <see cref="ICollection"/>.
/// </summary>
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
object ICollection.SyncRoot
{
get { return this; }
}
/// <summary>
/// See the <see cref="ICollection"/> interface.
/// </summary>
[DebuggerBrowsable(DebuggerBrowsableState.Never)]
bool ICollection.IsSynchronized
{
get
{
// This is immutable, so it is always thread-safe.
return true;
}
}
#endregion
/// <summary>
/// Gets the root node (for testing purposes).
/// </summary>
internal IBinaryTree Root
{
get { return _root; }
}
/// <summary>
/// Gets a data structure that captures the current state of this map, as an input into a query or mutating function.
/// </summary>
private MutationInput Origin
{
get { return new MutationInput(this); }
}
#region Public methods
/// <summary>
/// Creates a collection with the same contents as this collection that
/// can be efficiently mutated across multiple operations using standard
/// mutable interfaces.
/// </summary>
/// <remarks>
/// This is an O(1) operation and results in only a single (small) memory allocation.
/// The mutable collection that is returned is *not* thread-safe.
/// </remarks>
public Builder ToBuilder()
{
// We must not cache the instance created here and return it to various callers.
// Those who request a mutable collection must get references to the collection
// that version independently of each other.
return new Builder(this);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> Add(T item)
{
ImmutableHashSet<T>.MutationResult result = Add(item, this.Origin);
return result.Finalize(this);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> Remove(T item)
{
ImmutableHashSet<T>.MutationResult result = Remove(item, this.Origin);
return result.Finalize(this);
}
/// <summary>
/// Searches the set for a given value and returns the equal value it finds, if any.
/// </summary>
/// <param name="equalValue">The value to search for.</param>
/// <param name="actualValue">The value from the set that the search found, or the original value if the search yielded no match.</param>
/// <returns>A value indicating whether the search was successful.</returns>
/// <remarks>
/// This can be useful when you want to reuse a previously stored reference instead of
/// a newly constructed one (so that more sharing of references can occur) or to look up
/// a value that has more complete data than the value you currently have, although their
/// comparer functions indicate they are equal.
/// </remarks>
public bool TryGetValue(T equalValue, out T actualValue)
{
int hashCode = equalValue != null ? _equalityComparer.GetHashCode(equalValue) : 0;
HashBucket bucket;
if (_root.TryGetValue(hashCode, out bucket))
{
return bucket.TryExchange(equalValue, _equalityComparer, out actualValue);
}
actualValue = equalValue;
return false;
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> Union(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
return this.Union(other, avoidWithComparer: false);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
internal ImmutableHashSet<T> Union(ReadOnlySpan<T> other)
{
return Union(other, this.Origin).Finalize(this);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> Intersect(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
ImmutableHashSet<T>.MutationResult result = Intersect(other, this.Origin);
return result.Finalize(this);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> Except(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
ImmutableHashSet<T>.MutationResult result = Except(other, _equalityComparer, _hashBucketEqualityComparer, _root);
return result.Finalize(this);
}
/// <summary>
/// Produces a set that contains elements either in this set or a given sequence, but not both.
/// </summary>
/// <param name="other">The other sequence of items.</param>
/// <returns>The new set.</returns>
public ImmutableHashSet<T> SymmetricExcept(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
ImmutableHashSet<T>.MutationResult result = SymmetricExcept(other, this.Origin);
return result.Finalize(this);
}
/// <summary>
/// Checks whether a given sequence of items entirely describe the contents of this set.
/// </summary>
/// <param name="other">The sequence of items to check against this set.</param>
/// <returns>A value indicating whether the sets are equal.</returns>
public bool SetEquals(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
if (object.ReferenceEquals(this, other))
{
return true;
}
return SetEquals(other, this.Origin);
}
/// <summary>
/// Determines whether the current set is a property (strict) subset of a specified collection.
/// </summary>
/// <param name="other">The collection to compare to the current set.</param>
/// <returns>true if the current set is a correct subset of <paramref name="other"/>; otherwise, false.</returns>
public bool IsProperSubsetOf(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
return IsProperSubsetOf(other, this.Origin);
}
/// <summary>
/// Determines whether the current set is a correct superset of a specified collection.
/// </summary>
/// <param name="other">The collection to compare to the current set.</param>
/// <returns>true if the current set is a correct superset of <paramref name="other"/>; otherwise, false.</returns>
public bool IsProperSupersetOf(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
return IsProperSupersetOf(other, this.Origin);
}
/// <summary>
/// Determines whether a set is a subset of a specified collection.
/// </summary>
/// <param name="other">The collection to compare to the current set.</param>
/// <returns>true if the current set is a subset of <paramref name="other"/>; otherwise, false.</returns>
public bool IsSubsetOf(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
return IsSubsetOf(other, this.Origin);
}
/// <summary>
/// Determines whether the current set is a superset of a specified collection.
/// </summary>
/// <param name="other">The collection to compare to the current set.</param>
/// <returns>true if the current set is a superset of <paramref name="other"/>; otherwise, false.</returns>
public bool IsSupersetOf(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
return IsSupersetOf(other, this.Origin);
}
/// <summary>
/// Determines whether the current set overlaps with the specified collection.
/// </summary>
/// <param name="other">The collection to compare to the current set.</param>
/// <returns>true if the current set and <paramref name="other"/> share at least one common element; otherwise, false.</returns>
public bool Overlaps(IEnumerable<T> other)
{
Requires.NotNull(other, nameof(other));
return Overlaps(other, this.Origin);
}
#endregion
#region IImmutableSet<T> Methods
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
IImmutableSet<T> IImmutableSet<T>.Add(T item)
{
return this.Add(item);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
IImmutableSet<T> IImmutableSet<T>.Remove(T item)
{
return this.Remove(item);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
IImmutableSet<T> IImmutableSet<T>.Union(IEnumerable<T> other)
{
return this.Union(other);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
IImmutableSet<T> IImmutableSet<T>.Intersect(IEnumerable<T> other)
{
return this.Intersect(other);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
IImmutableSet<T> IImmutableSet<T>.Except(IEnumerable<T> other)
{
return this.Except(other);
}
/// <summary>
/// Produces a set that contains elements either in this set or a given sequence, but not both.
/// </summary>
/// <param name="other">The other sequence of items.</param>
/// <returns>The new set.</returns>
IImmutableSet<T> IImmutableSet<T>.SymmetricExcept(IEnumerable<T> other)
{
return this.SymmetricExcept(other);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public bool Contains(T item)
{
return Contains(item, this.Origin);
}
/// <summary>
/// See the <see cref="IImmutableSet{T}"/> interface.
/// </summary>
public ImmutableHashSet<T> WithComparer(IEqualityComparer<T>? equalityComparer)
{
equalityComparer ??= EqualityComparer<T>.Default;
if (equalityComparer == _equalityComparer)
{
return this;
}
else
{
var result = new ImmutableHashSet<T>(equalityComparer);
result = result.Union(this, avoidWithComparer: true);
Debug.Assert(result != null);
return result;
}
}
#endregion
#region ISet<T> Members
/// <summary>
/// See <see cref="ISet{T}"/>
/// </summary>
bool ISet<T>.Add(T item)
{
throw new NotSupportedException();
}
/// <summary>
/// See <see cref="ISet{T}"/>
/// </summary>
void ISet<T>.ExceptWith(IEnumerable<T> other)
{
throw new NotSupportedException();
}
/// <summary>
/// See <see cref="ISet{T}"/>
/// </summary>
void ISet<T>.IntersectWith(IEnumerable<T> other)
{
throw new NotSupportedException();
}
/// <summary>
/// See <see cref="ISet{T}"/>
/// </summary>
void ISet<T>.SymmetricExceptWith(IEnumerable<T> other)
{
throw new NotSupportedException();
}
/// <summary>
/// See <see cref="ISet{T}"/>
/// </summary>
void ISet<T>.UnionWith(IEnumerable<T> other)
{
throw new NotSupportedException();
}
#endregion
#region ICollection<T> members
/// <summary>
/// See the <see cref="ICollection{T}"/> interface.
/// </summary>
bool ICollection<T>.IsReadOnly
{
get { return true; }
}
/// <summary>
/// See the <see cref="ICollection{T}"/> interface.
/// </summary>
void ICollection<T>.CopyTo(T[] array, int arrayIndex)
{
Requires.NotNull(array, nameof(array));
Requires.Range(arrayIndex >= 0, nameof(arrayIndex));
Requires.Range(array.Length >= arrayIndex + this.Count, nameof(arrayIndex));
foreach (T item in this)
{
array[arrayIndex++] = item;
}
}
/// <summary>
/// See the <see cref="IList{T}"/> interface.
/// </summary>
void ICollection<T>.Add(T item)
{
throw new NotSupportedException();
}
/// <summary>
/// See the <see cref="ICollection{T}"/> interface.
/// </summary>
void ICollection<T>.Clear()
{
throw new NotSupportedException();
}
/// <summary>
/// See the <see cref="IList{T}"/> interface.
/// </summary>
bool ICollection<T>.Remove(T item)
{
throw new NotSupportedException();
}
#endregion
#region ICollection Methods
/// <summary>
/// Copies the elements of the <see cref="ICollection"/> to an <see cref="Array"/>, starting at a particular <see cref="Array"/> index.
/// </summary>
/// <param name="array">The one-dimensional <see cref="Array"/> that is the destination of the elements copied from <see cref="ICollection"/>. The <see cref="Array"/> must have zero-based indexing.</param>
/// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
void ICollection.CopyTo(Array array, int arrayIndex)
{
Requires.NotNull(array, nameof(array));
Requires.Range(arrayIndex >= 0, nameof(arrayIndex));
Requires.Range(array.Length >= arrayIndex + this.Count, nameof(arrayIndex));
foreach (T item in this)
{
array.SetValue(item, arrayIndex++);
}
}
#endregion
#region IEnumerable<T> Members
/// <summary>
/// Returns an enumerator that iterates through the collection.
/// </summary>
/// <returns>
/// A <see cref="IEnumerator{T}"/> that can be used to iterate through the collection.
/// </returns>
public Enumerator GetEnumerator()
{
return new Enumerator(_root);
}
/// <summary>
/// Returns an enumerator that iterates through the collection.
/// </summary>
IEnumerator<T> IEnumerable<T>.GetEnumerator()
{
return this.IsEmpty ?
Enumerable.Empty<T>().GetEnumerator() :
this.GetEnumerator();
}
#endregion
#region IEnumerable Members
/// <summary>
/// Returns an enumerator that iterates through a collection.
/// </summary>
/// <returns>
/// An <see cref="IEnumerator"/> object that can be used to iterate through the collection.
/// </returns>
IEnumerator IEnumerable.GetEnumerator()
{
return this.GetEnumerator();
}
#endregion
#region Static query and manipulator methods
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool IsSupersetOf(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
foreach (T item in other.GetEnumerableDisposable<T, Enumerator>())
{
if (!Contains(item, origin))
{
return false;
}
}
return true;
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult Add(T item, MutationInput origin)
{
OperationResult result;
int hashCode = item != null ? origin.EqualityComparer.GetHashCode(item) : 0;
HashBucket bucket = origin.Root.GetValueOrDefault(hashCode);
ImmutableHashSet<T>.HashBucket newBucket = bucket.Add(item, origin.EqualityComparer, out result);
if (result == OperationResult.NoChangeRequired)
{
return new MutationResult(origin.Root, 0);
}
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> newRoot = UpdateRoot(origin.Root, hashCode, origin.HashBucketEqualityComparer, newBucket);
Debug.Assert(result == OperationResult.SizeChanged);
return new MutationResult(newRoot, 1 /*result == OperationResult.SizeChanged ? 1 : 0*/);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult Remove(T item, MutationInput origin)
{
ImmutableHashSet<T>.OperationResult result = OperationResult.NoChangeRequired;
int hashCode = item != null ? origin.EqualityComparer.GetHashCode(item) : 0;
HashBucket bucket;
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> newRoot = origin.Root;
if (origin.Root.TryGetValue(hashCode, out bucket))
{
ImmutableHashSet<T>.HashBucket newBucket = bucket.Remove(item, origin.EqualityComparer, out result);
if (result == OperationResult.NoChangeRequired)
{
return new MutationResult(origin.Root, 0);
}
newRoot = UpdateRoot(origin.Root, hashCode, origin.HashBucketEqualityComparer, newBucket);
}
return new MutationResult(newRoot, result == OperationResult.SizeChanged ? -1 : 0);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool Contains(T item, MutationInput origin)
{
int hashCode = item != null ? origin.EqualityComparer.GetHashCode(item) : 0;
HashBucket bucket;
if (origin.Root.TryGetValue(hashCode, out bucket))
{
return bucket.Contains(item, origin.EqualityComparer);
}
return false;
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult Union(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
int count = 0;
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> newRoot = origin.Root;
foreach (T item in other.GetEnumerableDisposable<T, Enumerator>())
{
int hashCode = item != null ? origin.EqualityComparer.GetHashCode(item) : 0;
HashBucket bucket = newRoot.GetValueOrDefault(hashCode);
OperationResult result;
ImmutableHashSet<T>.HashBucket newBucket = bucket.Add(item, origin.EqualityComparer, out result);
if (result == OperationResult.SizeChanged)
{
newRoot = UpdateRoot(newRoot, hashCode, origin.HashBucketEqualityComparer, newBucket);
count++;
}
}
return new MutationResult(newRoot, count);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult Union(ReadOnlySpan<T> other, MutationInput origin)
{
int count = 0;
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> newRoot = origin.Root;
foreach (T item in other)
{
int hashCode = item != null ? origin.EqualityComparer.GetHashCode(item) : 0;
HashBucket bucket = newRoot.GetValueOrDefault(hashCode);
OperationResult result;
ImmutableHashSet<T>.HashBucket newBucket = bucket.Add(item, origin.EqualityComparer, out result);
if (result == OperationResult.SizeChanged)
{
newRoot = UpdateRoot(newRoot, hashCode, origin.HashBucketEqualityComparer, newBucket);
count++;
}
}
return new MutationResult(newRoot, count);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool Overlaps(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
if (origin.Root.IsEmpty)
{
return false;
}
foreach (T item in other.GetEnumerableDisposable<T, Enumerator>())
{
if (Contains(item, origin))
{
return true;
}
}
return false;
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool SetEquals(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
var otherSet = new HashSet<T>(other, origin.EqualityComparer);
if (origin.Count != otherSet.Count)
{
return false;
}
foreach (T item in otherSet)
{
if (!Contains(item, origin))
{
return false;
}
}
return true;
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static SortedInt32KeyNode<HashBucket> UpdateRoot(SortedInt32KeyNode<HashBucket> root, int hashCode, IEqualityComparer<HashBucket> hashBucketEqualityComparer, HashBucket newBucket)
{
if (newBucket.IsEmpty)
{
return root.Remove(hashCode, out _);
}
else
{
return root.SetItem(hashCode, newBucket, hashBucketEqualityComparer, out _, out _);
}
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult Intersect(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> newSet = SortedInt32KeyNode<HashBucket>.EmptyNode;
int count = 0;
foreach (T item in other.GetEnumerableDisposable<T, Enumerator>())
{
if (Contains(item, origin))
{
ImmutableHashSet<T>.MutationResult result = Add(item, new MutationInput(newSet, origin.EqualityComparer, origin.HashBucketEqualityComparer, count));
newSet = result.Root;
count += result.Count;
}
}
return new MutationResult(newSet, count, CountType.FinalValue);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult Except(IEnumerable<T> other, IEqualityComparer<T> equalityComparer, IEqualityComparer<HashBucket> hashBucketEqualityComparer, SortedInt32KeyNode<HashBucket> root)
{
Requires.NotNull(other, nameof(other));
Requires.NotNull(equalityComparer, nameof(equalityComparer));
Requires.NotNull(root, nameof(root));
int count = 0;
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> newRoot = root;
foreach (T item in other.GetEnumerableDisposable<T, Enumerator>())
{
int hashCode = item != null ? equalityComparer.GetHashCode(item) : 0;
HashBucket bucket;
if (newRoot.TryGetValue(hashCode, out bucket))
{
OperationResult result;
HashBucket newBucket = bucket.Remove(item, equalityComparer, out result);
if (result == OperationResult.SizeChanged)
{
count--;
newRoot = UpdateRoot(newRoot, hashCode, hashBucketEqualityComparer, newBucket);
}
}
}
return new MutationResult(newRoot, count);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static MutationResult SymmetricExcept(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
ImmutableHashSet<T> otherAsSet = ImmutableHashSet.CreateRange(origin.EqualityComparer, other);
int count = 0;
SortedInt32KeyNode<ImmutableHashSet<T>.HashBucket> result = SortedInt32KeyNode<HashBucket>.EmptyNode;
foreach (T item in new NodeEnumerable(origin.Root))
{
if (!otherAsSet.Contains(item))
{
ImmutableHashSet<T>.MutationResult mutationResult = Add(item, new MutationInput(result, origin.EqualityComparer, origin.HashBucketEqualityComparer, count));
result = mutationResult.Root;
count += mutationResult.Count;
}
}
foreach (T item in otherAsSet)
{
if (!Contains(item, origin))
{
ImmutableHashSet<T>.MutationResult mutationResult = Add(item, new MutationInput(result, origin.EqualityComparer, origin.HashBucketEqualityComparer, count));
result = mutationResult.Root;
count += mutationResult.Count;
}
}
return new MutationResult(result, count, CountType.FinalValue);
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool IsProperSubsetOf(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
if (origin.Root.IsEmpty)
{
return other.Any();
}
// To determine whether everything we have is also in another sequence,
// we enumerate the sequence and "tag" whether it's in this collection,
// then consider whether every element in this collection was tagged.
// Since this collection is immutable we cannot directly tag. So instead
// we simply count how many "hits" we have and ensure it's equal to the
// size of this collection. Of course for this to work we need to ensure
// the uniqueness of items in the given sequence, so we create a set based
// on the sequence first.
var otherSet = new HashSet<T>(other, origin.EqualityComparer);
if (origin.Count >= otherSet.Count)
{
return false;
}
int matches = 0;
bool extraFound = false;
foreach (T item in otherSet)
{
if (Contains(item, origin))
{
matches++;
}
else
{
extraFound = true;
}
if (matches == origin.Count && extraFound)
{
return true;
}
}
return false;
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool IsProperSupersetOf(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
if (origin.Root.IsEmpty)
{
return false;
}
int matchCount = 0;
foreach (T item in other.GetEnumerableDisposable<T, Enumerator>())
{
matchCount++;
if (!Contains(item, origin))
{
return false;
}
}
return origin.Count > matchCount;
}
/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static bool IsSubsetOf(IEnumerable<T> other, MutationInput origin)
{
Requires.NotNull(other, nameof(other));
if (origin.Root.IsEmpty)
{
return true;
}
// To determine whether everything we have is also in another sequence,
// we enumerate the sequence and "tag" whether it's in this collection,
// then consider whether every element in this collection was tagged.
// Since this collection is immutable we cannot directly tag. So instead
// we simply count how many "hits" we have and ensure it's equal to the
// size of this collection. Of course for this to work we need to ensure
// the uniqueness of items in the given sequence, so we create a set based
// on the sequence first.
var otherSet = new HashSet<T>(other, origin.EqualityComparer);
int matches = 0;
foreach (T item in otherSet)
{
if (Contains(item, origin))
{
matches++;
}
}
return matches == origin.Count;
}
#endregion
/// <summary>
/// Wraps the specified data structure with an immutable collection wrapper.
/// </summary>
/// <param name="root">The root of the data structure.</param>
/// <param name="equalityComparer">The equality comparer.</param>
/// <param name="count">The number of elements in the data structure.</param>
/// <returns>The immutable collection.</returns>
private static ImmutableHashSet<T> Wrap(SortedInt32KeyNode<HashBucket> root, IEqualityComparer<T> equalityComparer, int count)
{
Requires.NotNull(root, nameof(root));
Requires.NotNull(equalityComparer, nameof(equalityComparer));
Requires.Range(count >= 0, nameof(count));
return new ImmutableHashSet<T>(root, equalityComparer, count);
}
/// <summary>
/// Gets the <see cref="IEqualityComparer{HashBucket}"/> to use.
/// </summary>
/// <param name="valueComparer">The value comparer for T.</param>
/// <returns>The equality comparer to use.</returns>
private static IEqualityComparer<HashBucket> GetHashBucketEqualityComparer(IEqualityComparer<T> valueComparer)
{
if (!ImmutableExtensions.IsValueType<T>())
{
return HashBucketByRefEqualityComparer.DefaultInstance;
}
else if (valueComparer == EqualityComparer<T>.Default)
{
return HashBucketByValueEqualityComparer.DefaultInstance;
}
else
{
return new HashBucketByValueEqualityComparer(valueComparer);
}
}
/// <summary>
/// Wraps the specified data structure with an immutable collection wrapper.
/// </summary>
/// <param name="root">The root of the data structure.</param>
/// <param name="adjustedCountIfDifferentRoot">The adjusted count if the root has changed.</param>
/// <returns>The immutable collection.</returns>
private ImmutableHashSet<T> Wrap(SortedInt32KeyNode<HashBucket> root, int adjustedCountIfDifferentRoot)
{
return (root != _root) ? new ImmutableHashSet<T>(root, _equalityComparer, adjustedCountIfDifferentRoot) : this;
}
/// <summary>
/// Bulk adds entries to the set.
/// </summary>
/// <param name="items">The entries to add.</param>
/// <param name="avoidWithComparer"><c>true</c> when being called from <see cref="WithComparer"/> to avoid a stack overflow.</param>
private ImmutableHashSet<T> Union(IEnumerable<T> items, bool avoidWithComparer)
{
Requires.NotNull(items, nameof(items));
// Some optimizations may apply if we're an empty set.
if (this.IsEmpty && !avoidWithComparer)
{
// If the items being added actually come from an ImmutableHashSet<T>,
// reuse that instance if possible.
if (items is ImmutableHashSet<T> other)
{
return other.WithComparer(this.KeyComparer);
}
}
ImmutableHashSet<T>.MutationResult result = Union(items, this.Origin);
return result.Finalize(this);
}
}
}
|