public StringExpressionSet Union( StringExpressionSet ses )
{
// If either set is empty, the union represents a copy of the other.
if (ses == null || ses.IsEmpty())
return this.Copy();
if (this.IsEmpty())
return ses.Copy();
CheckList();
ses.CheckList();
// Perform the union
// note: insert smaller set into bigger set to reduce needed comparisons
StringExpressionSet bigger = ses.m_list.Count > this.m_list.Count ? ses : this;
StringExpressionSet smaller = ses.m_list.Count <= this.m_list.Count ? ses : this;
StringExpressionSet unionSet = bigger.Copy();
unionSet.Reduce();
for (int index = 0; index < smaller.m_list.Count; ++index)
{
unionSet.AddSingleExpressionNoDuplicates( (String)smaller.m_list[index] );
}
unionSet.GenerateString();
return unionSet;
}