public static Bamboo.DataStructures.Table Evaluate(Database database, object statement)
{
if (statement is SelectStatement)
{
Iterators.Iterator iterator = CreateIterator(database, (SelectStatement)statement);
if (iterator == null)
{
return(null);
}
return(iterator.ToTable());
}
else if (statement is UnionStatement)
{
Iterators.Iterator iterator = CreateIterator(database, (UnionStatement)statement);
if (iterator == null)
{
return(null);
}
return(iterator.ToTable());
}
else
{
throw new System.Exception("Invalid statement.");
}
}
private static Predicates.Predicate CreatePredicate(Predicate predicate, Iterators.Iterator iterator)
{
switch (predicate.Operator.ToUpper())
{
case "AND":
{
return(new Predicates.AndPredicate(CreatePredicate((Predicate)predicate.A, iterator), CreatePredicate((Predicate)predicate.B, iterator)));
}
case "=":
{
return(new Predicates.EqualsPredicate(GetOrdinal(predicate.A, iterator.Columns()), predicate.B));
}
case "!=":
case "<>":
{
return(new Predicates.NotEqualsPredicate(GetOrdinal(predicate.A, iterator.Columns()), predicate.B));
}
case "NOT":
{
return(new Predicates.NotPredicate(CreatePredicate((Predicate)predicate.A, iterator)));
}
case "OR":
{
return(new Predicates.OrPredicate(CreatePredicate((Predicate)predicate.A, iterator), CreatePredicate((Predicate)predicate.B, iterator)));
}
default:
{
throw new System.Exception("Invalid predicate: " + predicate.Operator);
}
}
}
private static Iterators.ColumnIterator CreateColumnIterator(object column, Iterators.Iterator iterator)
{
if (column is Identifier)
{
return(new Iterators.ColumnIterator(GetOrdinal(column, iterator.Columns()), ((Identifier)column).Value));
}
else if (column is Alias)
{
Alias alias = (Alias)column;
return(new Iterators.AliasIterator(CreateColumnIterator(alias.Name, iterator), alias.As.Value));
}
else if (column is Function)
{
Function function = (Function)column;
System.Text.StringBuilder stringBuilder = new System.Text.StringBuilder();
stringBuilder.Append(function.Name);
stringBuilder.Append("(");
for (int i = 0; i < function.Operands.Count; i++)
{
if (i > 0)
{
stringBuilder.Append(", ");
}
stringBuilder.Append(function.Operands[i].ToString());
}
stringBuilder.Append(")");
Functions.Function fn = Functions.Function.Create(function.Name.Value, cdr(function.Operands));
return(new Iterators.FunctionIterator(GetOrdinal(function.Operands[0], iterator.Columns()), stringBuilder.ToString(), fn));
}
else
{
throw new System.Exception();
}
}