[inherit ('NaryTree'), environment ('NaryTreeSet')]

module NaryTreeSet;

type  NaryTreeSet = ^NaryTreeSetRecord;
      NaryTreeSetRecord = record
         Member: NaryTree;
         Next: NaryTreeSet;
         end;

procedure NullNaryTreeSet (var Result: NaryTreeSet);
begin new (Result);
Result^.Member := (- MaxInt)::NaryTree;
Result^.Next := nil end;

function IsNullNaryTreeSet (S: NaryTreeSet): boolean;
begin IsNullNaryTreeSet := S^.Member::integer = - MaxInt end;

procedure ForEachNaryTree (S: NaryTreeSet; procedure DoIt (i: NaryTree));
var   ThisS, NextS: NaryTreeSet;
begin ThisS := S;
while ThisS^.Member::integer <> - MaxInt do
   begin NextS := ThisS^.Next;
   DoIt (ThisS^.Member);
   ThisS := NextS end;
end;

function FirstNaryTree (S: NaryTreeSet): NaryTree;
begin FirstNaryTree := S^.Member end;

function IsNaryTreeInSet (i: NaryTree; S: NaryTreeSet): boolean;
   procedure TestEquals (j: NaryTree);
   begin if EqualNaryTree (i, j) then IsNaryTreeInSet := true; end;
begin IsNaryTreeInSet := false; ForEachNaryTree (S, TestEquals); end;

function IncludesNaryTreeSet (S1, S2: NaryTreeSet): boolean;
var Result: boolean;
   procedure TestIfInS1 (i: NaryTree);
   begin if Result then if not IsNaryTreeInSet (i, S1) then Result := false; end;
begin Result := true;
ForEachNaryTree (S2, TestIfInS1);
IncludesNaryTreeSet := Result end;

function DisjointNaryTreeSets (S1, S2: NaryTreeSet): boolean;
var Result: boolean;
   procedure TestIfInS1 (i: NaryTree);
   begin if Result then if IsNaryTreeInSet (i, S1) then Result := false; end;
begin Result := true;
ForEachNaryTree (S2, TestIfInS1);
DisjointNaryTreeSets := Result end;

function EqualNaryTreeSet (S1, S2: NaryTreeSet): boolean;
begin
EqualNaryTreeSet := IncludesNaryTreeSet (S1, S2) and IncludesNaryTreeSet (S2, S1);
end;

procedure InsertNaryTree (i: NaryTree; var S: NaryTreeSet);
var   This, Pred, Succ: NaryTreeSet;
begin
if not IsNaryTreeInSet (i, S) then
   begin
   Pred := nil; Succ := S;
   while Succ^.Member::integer > i::integer do begin
      Pred := Succ; Succ := Succ^.Next end;
   if Succ^.Member::integer < i::integer then begin
      new (This); This^.Next := Succ; This^.Member := i;
      if Pred <> nil then Pred^.Next := This else S := This;
      end;
   end;
end;

procedure InsertNaryTrees (S1: NaryTreeSet; var S2: NaryTreeSet);
var   This, Pred, Succ: NaryTreeSet;
   procedure AddNaryTree (i: NaryTree);
   begin InsertNaryTree (i, S2) end;
begin
ForEachNaryTree (S1, AddNaryTree);
end;

procedure RemoveNaryTree (i: NaryTree; var S: NaryTreeSet);
var   Pred, This: NaryTreeSet;
begin
Pred := nil; This := S;
while not EqualNaryTree (This^.Member, i) do begin
   Pred := This; This := This^.Next end;
if Pred <> nil then Pred^.Next := This^.Next else S := This^.Next;
Dispose (This);
end;

procedure DisposeNaryTreeSet (var S: NaryTreeSet);
var   Old: NaryTreeSet;
begin
while S <> nil do begin Old := S; S := S^.Next; Dispose (Old) end;
end;

end.