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treap.erl was moved to p1_utils

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Paweł Chmielowski 2014-07-17 11:57:23 +02:00
parent 0456b78d87
commit e0c9242dcf
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src/treap.erl
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%%%----------------------------------------------------------------------
%%% File : treap.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Treaps implementation
%%% Created : 22 Apr 2008 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2014 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%----------------------------------------------------------------------
-module(treap).
-export([empty/0, insert/4, delete/2, delete_root/1,
get_root/1, lookup/2, is_empty/1, fold/3, from_list/1,
to_list/1]).
-type hashkey() :: {non_neg_integer(), any()}.
-type treap() :: {hashkey(), any(), any(), treap(), treap()} | nil.
-export_type([treap/0]).
empty() -> nil.
insert(Key, Priority, Value, Tree) ->
HashKey = {erlang:phash2(Key), Key},
insert1(Tree, HashKey, Priority, Value).
insert1(nil, HashKey, Priority, Value) ->
{HashKey, Priority, Value, nil, nil};
insert1({HashKey1, Priority1, Value1, Left, Right} =
Tree,
HashKey, Priority, Value) ->
if HashKey < HashKey1 ->
heapify({HashKey1, Priority1, Value1,
insert1(Left, HashKey, Priority, Value), Right});
HashKey > HashKey1 ->
heapify({HashKey1, Priority1, Value1, Left,
insert1(Right, HashKey, Priority, Value)});
Priority == Priority1 ->
{HashKey, Priority, Value, Left, Right};
true ->
insert1(delete_root(Tree), HashKey, Priority, Value)
end.
heapify({_HashKey, _Priority, _Value, nil, nil} =
Tree) ->
Tree;
heapify({HashKey, Priority, Value, nil = Left,
{HashKeyR, PriorityR, ValueR, LeftR, RightR}} =
Tree) ->
if PriorityR > Priority ->
{HashKeyR, PriorityR, ValueR,
{HashKey, Priority, Value, Left, LeftR}, RightR};
true -> Tree
end;
heapify({HashKey, Priority, Value,
{HashKeyL, PriorityL, ValueL, LeftL, RightL},
nil = Right} =
Tree) ->
if PriorityL > Priority ->
{HashKeyL, PriorityL, ValueL, LeftL,
{HashKey, Priority, Value, RightL, Right}};
true -> Tree
end;
heapify({HashKey, Priority, Value,
{HashKeyL, PriorityL, ValueL, LeftL, RightL} = Left,
{HashKeyR, PriorityR, ValueR, LeftR, RightR} = Right} =
Tree) ->
if PriorityR > Priority ->
{HashKeyR, PriorityR, ValueR,
{HashKey, Priority, Value, Left, LeftR}, RightR};
PriorityL > Priority ->
{HashKeyL, PriorityL, ValueL, LeftL,
{HashKey, Priority, Value, RightL, Right}};
true -> Tree
end.
delete(Key, Tree) ->
HashKey = {erlang:phash2(Key), Key},
delete1(HashKey, Tree).
delete1(_HashKey, nil) -> nil;
delete1(HashKey,
{HashKey1, Priority1, Value1, Left, Right} = Tree) ->
if HashKey < HashKey1 ->
{HashKey1, Priority1, Value1, delete1(HashKey, Left),
Right};
HashKey > HashKey1 ->
{HashKey1, Priority1, Value1, Left,
delete1(HashKey, Right)};
true -> delete_root(Tree)
end.
delete_root({HashKey, Priority, Value, Left, Right}) ->
case {Left, Right} of
{nil, nil} -> nil;
{_, nil} -> Left;
{nil, _} -> Right;
{{HashKeyL, PriorityL, ValueL, LeftL, RightL},
{HashKeyR, PriorityR, ValueR, LeftR, RightR}} ->
if PriorityL > PriorityR ->
{HashKeyL, PriorityL, ValueL, LeftL,
delete_root({HashKey, Priority, Value, RightL, Right})};
true ->
{HashKeyR, PriorityR, ValueR,
delete_root({HashKey, Priority, Value, Left, LeftR}),
RightR}
end
end.
is_empty(nil) -> true;
is_empty({_HashKey, _Priority, _Value, _Left,
_Right}) ->
false.
get_root({{_Hash, Key}, Priority, Value, _Left,
_Right}) ->
{Key, Priority, Value}.
lookup(Key, Tree) ->
HashKey = {erlang:phash2(Key), Key},
lookup1(Tree, HashKey).
lookup1(nil, _HashKey) -> error;
lookup1({HashKey1, Priority1, Value1, Left, Right},
HashKey) ->
if HashKey < HashKey1 -> lookup1(Left, HashKey);
HashKey > HashKey1 -> lookup1(Right, HashKey);
true -> {ok, Priority1, Value1}
end.
fold(_F, Acc, nil) -> Acc;
fold(F, Acc,
{{_Hash, Key}, Priority, Value, Left, Right}) ->
Acc1 = F({Key, Priority, Value}, Acc),
Acc2 = fold(F, Acc1, Left),
fold(F, Acc2, Right).
to_list(Tree) -> to_list(Tree, []).
to_list(nil, Acc) -> Acc;
to_list(Tree, Acc) ->
Root = get_root(Tree),
to_list(delete_root(Tree), [Root | Acc]).
from_list(List) -> from_list(List, nil).
from_list([{Key, Priority, Value} | Tail], Tree) ->
from_list(Tail, insert(Key, Priority, Value, Tree));
from_list([], Tree) -> Tree.