/* Copyright 2002-2004 by Aidant Systems, Inc., and by Jason Smith. */
using System;
using System.Collections;
namespace Iesi_NTS.Collections{
/// <summary>
/// <p>Implements an immutable (read-only) <c>Set</c> wrapper.</p>
/// <p>Although this is advertised as immutable, it really isn't. Anyone with access to the
/// <c>basisSet</c> can still change the data-set. So <c>GetHashCode()</c> is not implemented
/// for this <c>Set</c>, as is the case for all <c>Set</c> implementations in this library.
/// This design decision was based on the efficiency of not having to <c>Clone()</c> the
/// <c>basisSet</c> every time you wrap a mutable <c>Set</c>.</p>
/// </summary>
#if !SILVERLIGHT
[Serializable]
#endif
public sealed class ImmutableSet : Set
{
private const string ERROR_MESSAGE = "Object is immutable.";
private ISet mBasisSet;
internal ISet BasisSet
{
get
{
return mBasisSet;
}
}
/// <summary>
/// Constructs an immutable (read-only) <c>Set</c> wrapper.
/// </summary>
/// <param name="basisSet">The <c>Set</c> that is wrapped.</param>
public ImmutableSet(ISet basisSet)
{
mBasisSet = basisSet;
}
/// <summary>
/// Adds the specified element to this set if it is not already present.
/// </summary>
/// <param name="o">The object to add to the set.</param>
/// <returns><c>true</c> is the object was added, <c>false</c> if it was already present.</returns>
public sealed override bool Add(object o)
{
throw new NotSupportedException(ERROR_MESSAGE);
}
/// <summary>
/// Adds all the elements in the specified collection to the set if they are not already present.
/// </summary>
/// <param name="c">A collection of objects to add to the set.</param>
/// <returns><c>true</c> is the set changed as a result of this operation, <c>false</c> if not.</returns>
public sealed override bool AddAll(ICollection c)
{
throw new NotSupportedException(ERROR_MESSAGE);
}
/// <summary>
/// Removes all objects from the set.
/// </summary>
public sealed override void Clear()
{
throw new NotSupportedException(ERROR_MESSAGE);
}
/// <summary>
/// Returns <c>true</c> if this set contains the specified element.
/// </summary>
/// <param name="o">The element to look for.</param>
/// <returns><c>true</c> if this set contains the specified element, <c>false</c> otherwise.</returns>
public sealed override bool Contains(object o)
{
return mBasisSet.Contains(o);
}
/// <summary>
/// Returns <c>true</c> if the set contains all the elements in the specified collection.
/// </summary>
/// <param name="c">A collection of objects.</param>
/// <returns><c>true</c> if the set contains all the elements in the specified collection, <c>false</c> otherwise.</returns>
public sealed override bool ContainsAll(ICollection c)
{
return mBasisSet.ContainsAll(c);
}
/// <summary>
/// Returns <c>true</c> if this set contains no elements.
/// </summary>
public sealed override bool IsEmpty
{
get{return mBasisSet.IsEmpty;}
}
/// <summary>
/// Removes the specified element from the set.
/// </summary>
/// <param name="o">The element to be removed.</param>
/// <returns><c>true</c> if the set contained the specified element, <c>false</c> otherwise.</returns>
public sealed override bool Remove(object o)
{
throw new NotSupportedException(ERROR_MESSAGE);
}
/// <summary>
/// Remove all the specified elements from this set, if they exist in this set.
/// </summary>
/// <param name="c">A collection of elements to remove.</param>
/// <returns><c>true</c> if the set was modified as a result of this operation.</returns>
public sealed override bool RemoveAll(ICollection c)
{
throw new NotSupportedException(ERROR_MESSAGE);
}
/// <summary>
/// Retains only the elements in this set that are contained in the specified collection.
/// </summary>
/// <param name="c">Collection that defines the set of elements to be retained.</param>
/// <returns><c>true</c> if this set changed as a result of this operation.</returns>
public sealed override bool RetainAll(ICollection c)
{
throw new NotSupportedException(ERROR_MESSAGE);
}
/// <summary>
/// Copies the elements in the <c>Set</c> to an array. The type of array needs
/// to be compatible with the objects in the <c>Set</c>, obviously.
/// </summary>
/// <param name="array">An array that will be the target of the copy operation.</param>
/// <param name="index">The zero-based index where copying will start.</param>
public sealed override void CopyTo(Array array, int index)
{
mBasisSet.CopyTo(array, index);
}
/// <summary>
/// The number of elements contained in this collection.
/// </summary>
public sealed override int Count
{
get{return mBasisSet.Count;}
}
/// <summary>
/// Returns an object that can be used to synchronize use of the <c>Set</c> across threads.
/// </summary>
public sealed override bool IsSynchronized
{
get{return mBasisSet.IsSynchronized;}
}
/// <summary>
/// Returns an object that can be used to synchronize the <c>Set</c> between threads.
/// </summary>
public sealed override object SyncRoot
{
get{return mBasisSet.SyncRoot;}
}
/// <summary>
/// Gets an enumerator for the elements in the <c>Set</c>.
/// </summary>
/// <returns>An <c>IEnumerator</c> over the elements in the <c>Set</c>.</returns>
public sealed override IEnumerator GetEnumerator()
{
return mBasisSet.GetEnumerator();
}
/// <summary>
/// Returns a clone of the <c>Set</c> instance.
/// </summary>
/// <returns>A clone of this object.</returns>
public sealed override object Clone()
{
return new ImmutableSet(mBasisSet);
}
/// <summary>
/// Performs a "union" of the two sets, where all the elements
/// in both sets are present. That is, the element is included if it is in either <c>a</c> or <c>b</c>.
/// Neither this set nor the input set are modified during the operation. The return value
/// is a <c>Clone()</c> of this set with the extra elements added in.
/// </summary>
/// <param name="a">A collection of elements.</param>
/// <returns>A new <c>Set</c> containing the union of this <c>Set</c> with the specified collection.
/// Neither of the input objects is modified by the union.</returns>
public sealed override ISet Union(ISet a)
{
ISet m = this;
while(m is ImmutableSet)
m = ((ImmutableSet)m).BasisSet;
return new ImmutableSet(m.Union(a));
}
/// <summary>
/// Performs an "intersection" of the two sets, where only the elements
/// that are present in both sets remain. That is, the element is included if it exists in
/// both sets. The <c>Intersect()</c> operation does not modify the input sets. It returns
/// a <c>Clone()</c> of this set with the appropriate elements removed.
/// </summary>
/// <param name="a">A set of elements.</param>
/// <returns>The intersection of this set with <c>a</c>.</returns>
public sealed override ISet Intersect(ISet a)
{
ISet m = this;
while(m is ImmutableSet)
m = ((ImmutableSet)m).BasisSet;
return new ImmutableSet(m.Intersect(a));
}
/// <summary>
/// Performs a "minus" of set <c>b</c> from set <c>a</c>. This returns a set of all
/// the elements in set <c>a</c>, removing the elements that are also in set <c>b</c>.
/// The original sets are not modified during this operation. The result set is a <c>Clone()</c>
/// of this <c>Set</c> containing the elements from the operation.
/// </summary>
/// <param name="a">A set of elements.</param>
/// <returns>A set containing the elements from this set with the elements in <c>a</c> removed.</returns>
public sealed override ISet Minus(ISet a)
{
ISet m = this;
while(m is ImmutableSet)
m = ((ImmutableSet)m).BasisSet;
return new ImmutableSet(m.Minus(a));
}
/// <summary>
/// Performs an "exclusive-or" of the two sets, keeping only the elements that
/// are in one of the sets, but not in both. The original sets are not modified
/// during this operation. The result set is a <c>Clone()</c> of this set containing
/// the elements from the exclusive-or operation.
/// </summary>
/// <param name="a">A set of elements.</param>
/// <returns>A set containing the result of <c>a ^ b</c>.</returns>
public sealed override ISet ExclusiveOr(ISet a)
{
ISet m = this;
while(m is ImmutableSet)
m = ((ImmutableSet)m).BasisSet;
return new ImmutableSet(m.ExclusiveOr(a));
}
}
}
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