-- public domain 20080407 lua@ztact.com


require 'ztact'


-- tree manipulation ---------------------------------------- tree manipulation


-- adding a node...

-- without ztact.set
a = a or {}
a.b = a.b or {}
a.b.c = a.b.c or {}
a.b.c.d = 1

-- with ztact.set:
a = a or {}
ztact.set (a, 'b', 'c', 'd', 1)


-- determining if a node exists...

-- without ztact.get
if a and a.b and a.b.c and a.b.c.d == 1 then
  -- do something
end

-- with ztact.get
if ztact.get (a, 'b', 'c', 'd') == 1 then
  -- do something
end


-- clearing a node (that may not exist!)

-- without ztact.set
-- Note that the below does not collapse the now empty branch
-- a.b.c, it only -- removes the leaf 'd'.
if a and a.b and a.b.c then
  a.b.c.d = nil
end

-- with ztact.set
-- Note that the below will also collapse the empty branch a.b.c, so
-- that a will again be an empty table.
ztact.set (a, 'b', 'c', 'd', nil)