lama_byterun/stdlib/Collection.expr
2019-12-26 00:17:34 +03:00

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-- MNode (key, list of values, balance factor, left subtree, right subtree)
-- balance factor = height (left subtree) - height (right subtree)
fun insert (m, k, v) {
fun rot (left, node) {
return
if left
then case node of
MNode (k, v, _, l, MNode (rk, rv, _, ll, rr)) ->
MNode (rk, rv, 0, MNode (k, v, 0, l, ll), rr)
esac
else case node of
MNode (k, v, _, MNode (lk, lv, _, ll, rr), r) ->
MNode (lk, lv, 0, ll, MNode (k, v, 0, rr, r))
esac
fi
}
fun factor (x) {
return x [2]
}
fun inner (m, k, v) {
return
case m of
{} -> [true, MNode (k, {v}, 0, {}, {})]
| MNode (kk, vv, bf, l, r) ->
local c = compare (k, kk);
if c == 0
then [false, MNode (kk, v : vv, bf, l, r)]
else if c < 0
then
case inner (l, k, v) of
[true, ll] -> if bf < 0
then [false, MNode (kk, vv, bf + 1, ll, r)]
elif bf == 1
then if ll.factor > 0
then [false, rot (false, MNode (kk, vv, bf, ll, r))]
else [false, rot (false, MNode (kk, vv, bf, rot (true, ll), r))]
fi
else [true, MNode (kk, vv, bf + 1, ll, r)]
fi
| [false, ll] -> [false, MNode (kk, vv, bf, ll, r)]
esac
else
case inner (r, k, v) of
[true, rr] -> if bf > 0
then [false, MNode (kk, vv, bf - 1, l, rr)]
elif bf == -1
then if rr.factor < 0
then [false, rot (true, MNode (kk, vv, bf, l, rr))]
else [false, rot (true, MNode (kk, vv, bf, l, rot (false, rr)))]
fi
else [true, MNode (kk, vv, bf - 1, l, rr)]
fi
| [false, rr] -> [false, MNode (kk, vv, bf, l, rr)]
esac
fi
fi
esac
}
return inner (m, k, v).snd
}
fun find (m, k) {
return
case m of
{} -> None
| MNode (kk, vv, _, l, r) ->
local c = compare (k, kk);
if c == 0
then case vv of v : _ -> Some (v) | _ -> None esac
else find (if c < 0 then l else r fi, k)
fi
esac
}
fun remove (m, k) {
return
case m of
{} -> m
| MNode (kk, vv, bf, l, r) ->
local c = compare (k, kk);
if c == 0
then case vv of {} -> m | _ : vt -> MNode (kk, vt, l, r) esac
else if c < 0
then MNode (kk, vv, bf, remove (l, k), r)
else MNode (kk, vv, bf, l, remove (r, k))
fi
fi
esac
}
fun validate (t) {
fun inner (t, verify) {
return
case t of
{} -> 0
| MNode (k, _, bf, l, r) ->
if verify (k)
then
local lh = validate (l, fun (x) {return x < k}),
rh = validate (r, fun (x) {return x > k});
if bf == lh - rh
then 1 + if lh > rh then lh else rh fi
else failure ("Balance violation on key %s\n", k.string)
fi
else failure ("Order violation on key %s\n", k.string)
fi
esac
}
inner (t, fun (x) {return true})
}
local tree = {}, i;
for i := 1, i <= 100, i := i+1 do
validate (tree);
tree := insert (tree, i, i);
printf ("Inserting: %s\n", i.string);
printf ("Result : %s\n", tree.string)
od