/// <summary>
/// Two HashableView matrices are equal if they are MatrixEquals, that is, they have the same
/// RowKeys and ColKeys (in the same order), the same special MissingValue, and the same values.
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public override bool Equals(object obj)
{
HashableView<TRowKey, TColKey, TValue> other = obj as HashableView<TRowKey, TColKey, TValue>;
if (other == null)
{
return false;
}
else
{
return _hashCode == other._hashCode && this.MatrixEquals(other);
}
}
/// <summary>
/// Creates a view of the parent matrix which is hashable. For example, it can be used as the key of a dictionary.
/// This is a 'view' in the sense that no copying an every little extra memory is used.
///
/// Two HashableView matricies are equal if their RowKeys and ColKeys (in order), MissingValue, and values are equal.
/// They will have the same hashcode if they are equal.
///
/// The hashcode is computed only once when the the HashableView is contructed, so a HashableView does not allow
/// its values to be changed. Also, changing values of the parent will give unexpected results.
///
/// When used by Dictionary or HashSet, a full call of MatrixEquals (which looks at every value) is needed to confirm
/// that two matrices with the same hashcode are really equal.
///</summary>
/// <typeparam name="TRowKey">The type of the row key. Usually "String"</typeparam>
/// <typeparam name="TColKey">The type of the col key. Usually "String"</typeparam>
/// <typeparam name="TValue">The type of the value, for example, double, int, char, etc.</typeparam>
/// <param name="parentMatrix">The matrix to wrap.</param>
/// <returns>A hashable matrix</returns>
static public Matrix<TRowKey, TColKey, TValue> HashableView<TRowKey, TColKey, TValue>(
this Matrix<TRowKey, TColKey, TValue> parentMatrix)
{
//If this is a HashableView of a HashableView, simplify
HashableView<TRowKey, TColKey, TValue> parentHashableViewOrNull = parentMatrix as HashableView<TRowKey, TColKey, TValue>;
if (null != parentHashableViewOrNull)
{
return parentHashableViewOrNull.ParentMatrix;
}
var hashableView = new HashableView<TRowKey, TColKey, TValue>();
hashableView.ParentMatrix = parentMatrix;
return hashableView;
}