/// <summary>
///
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <param name="mask"></param>
/// <returns></returns>
public static bool EqualsWithMask(this Edge a, Edge b, TripleMask mask)
{
return((!mask.HasFlag(TripleMask.Subject) || a.Subject.Equals(b.Subject)) &&
(!mask.HasFlag(TripleMask.Predicate) || a.Predicate.Equals(b.Predicate)) &&
(!mask.HasFlag(TripleMask.Object) || a.Object.Equals(b.Object)) &&
(!mask.HasFlag(TripleMask.Context) || a.Context.Equals(b.Context)));
}
public static IndexKey Create(Edge triple, TripleMask index)
{
return(new IndexKey
(
index.HasFlag(IndexCoverage.Subject) ? triple.Subject : null,
index.HasFlag(IndexCoverage.Predicate) ? triple.Predicate : null,
index.HasFlag(IndexCoverage.Object) ? triple.Object : null,
index.HasFlag(IndexCoverage.Context) ? triple.Context : null
));
}
// Selects the best index in the supplied IndexCoverage for the given set.
// Returns a tuple<index, remaining bitfield>
/// <summary>
///
/// </summary>
/// <param name="coverage"></param>
/// <param name="mask"></param>
/// <returns></returns>
public static Tuple <IndexCoverage, TripleMask> SelectIndex(this IndexCoverage coverage, TripleMask mask)
{
if (mask == TripleMask.None)
{
return(Tuple.Create(IndexCoverage.None, TripleMask.None));
}
// The prefered order of indices.
byte[] pref = { 10, 13, 12, 11, 5, 4, 7, 6, 8, 9, 0, 2, 1, 3 };
// The bitmask for each index.
byte[] table = { 1, 2, 4, 8, 3, 5, 9, 6, 10, 12, 7, 11, 13, 14 };
int i;
for (i = 0; i < 14; i++)
{
if (((int)mask & table[pref[i]]) == table[pref[i]] && coverage.HasFlag((IndexCoverage)(1 << pref[i])))
{
break;
}
}
return(Tuple.Create((IndexCoverage)(1 << pref[i]), (TripleMask)((int)mask & ~table[pref[i]])));
}
