public RelValueST <Ttup> While <Trel>(Func <Trel, RelValueST <Ttup> > func)
where Trel : RelValueST <Ttup>, new()
{
var newbody = RelOpsST.While <Ttup, Trel>(this, func);
return(RelValueST <Ttup> .Create <RelValueST <Ttup> >(newbody));
}
// generate a new relation with one attribute renamed
public RelValueST <T> Rename <T>()
where T : TupBase, new()
{
var newbody = RelOpsST.Rename <Ttup, T>(this);
return(RelValueST <T> .Create <RelValueST <T> >(newbody));
}
public RelValueST <T> Transform <T>(Func <Ttup, T> func)
where T : TupBase, new()
{
var newbody = RelOpsST.Transform <Ttup, T>(this, func);
return(RelValueST <T> .Create <RelValueST <T> >(newbody));
}
public RelValueST <T> Extend <T>(Func <Ttup, object> func)
where T : TupBase, new()
{
var newbody = RelOpsST.Extend <Ttup, T>(this, func);
return(RelValueST <T> .Create <RelValueST <T> >(newbody));
}
public RelValueST <T> AntiJoin <T1, T>(RelValueST <T1> other)
where T : TupBase, new()
where T1 : TupBase, new()
{
var newbody = RelOpsST.AntiJoin <T, Ttup, T1>(this, other);
return(RelValueST <T> .Create <RelValueST <T> >(newbody));
}
public RelValueST <T> Aggregate <T, T1>(Func <Ttup, T1, T1> func)
where T : TupBase, new()
where T1 : new()
{
var newbody = RelOpsST.Aggregate <Ttup, T, T1>(this, func);
return(RelValueST <T> .Create <RelValueST <T> >(newbody));
}
// fixed point recursion
internal static HashSet <T> While <T, TR>(IEnumerable <T> body, Func <TR, RelValueST <T> > func)
where T : TupBase, new()
where TR : RelValueST <T>, new()
{
var stack = new Stack <T>(body);
var newbody = new HashSet <T>();
while (stack.Count > 0)
{
var top = stack.Pop();
if (!newbody.Contains(top))
{
newbody.Add(top);
var rel = RelValueST <T> .Create <TR>(Enumerable.Repeat(top, 1));
foreach (var t in func(rel))
{
stack.Push(t);
}
}
}
return(newbody);
}
public static new Rel Create(IEnumerable <T> tuples)
{
return(RelValueST <T> .Create <Rel>(tuples));
}
