From 6bc276e65e89764968f3058bd281f6825d3182ba Mon Sep 17 00:00:00 2001
From: Linus Nordberg <linus@nordberg.se>
Date: Sun, 14 Sep 2014 21:44:11 +0200
Subject: Add reset_tree/1 and change new() and init().

---
 src/ht.erl | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/ht.erl b/src/ht.erl
index 7915e78..462dfa2 100644
--- a/src/ht.erl
+++ b/src/ht.erl
@@ -22,7 +22,7 @@
 -module(ht).
 -behaviour(gen_server).
 
--export([size/0, add/1, tree_hash/0, tree_hash/1]).
+-export([reset_tree/1, size/0, add/1, tree_hash/0, tree_hash/1]).
 -export([path/2, consistency/2]).
 -export([start_link/0, start_link/1, stop/0]).
 -export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
@@ -45,6 +45,8 @@ start_link() ->
     gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
 start_link(NEntries) ->
     gen_server:start_link({local, ?MODULE}, ?MODULE, [NEntries], []).
+reset_tree(Arg) ->
+    gen_server:call(?MODULE, {reset_tree, Arg}).
 stop() ->
     gen_server:call(?MODULE, stop).
 size() ->
@@ -67,8 +69,6 @@ print_tree(HashOutputLen) ->
     gen_server:call(?MODULE, {print_tree, HashOutputLen}).
 
 %% gen_server callbacks
-init([]) ->
-    {ok, new()};
 init(Args) ->
     {ok, new(Args)}.
 handle_cast(_Request, State) ->
@@ -79,6 +79,11 @@ code_change(_OldVersion, State, _Extra) ->
     {ok, State}.
 terminate(_Reason, _State) ->
     ok.
+
+% public api
+handle_call({reset_tree, Arg}, _From, _State) ->
+    NewTree = new(Arg),
+    {reply, NewTree, NewTree};
 handle_call(stop, _From, State) ->
     {stop, normal, stopped, State};
 handle_call(size, _From, State) ->
@@ -245,22 +250,25 @@ add(Tree = #tree{version = V, store = Store}, Entry) ->
     Tree#tree{version = NewVersion,
               store = ts:store(Store, {LeafIndex, 0}, LeafHash)}.
 
--spec new() -> tree().
-new() ->
+%% @doc Return a new tree.
+-spec new(list()) -> tree().
+new([]) ->
     #tree{version = -1,
           evaluated = -1,
-          store = ts:new()}.
-
--spec new([non_neg_integer()]) -> tree().
+          store = ts:new()};
+new([-1]) ->
+    new([]);
+%% Initialise tree from db.
 new([Version]) when is_integer(Version) ->
     foldl(fun(#mtl{entry = E}, Tree) ->
                   D = (E#timestamped_entry.entry)#plop_entry.data,
                   add(Tree, D) % Return value -> Tree in next invocation.
-          end, new(), db:get_by_index_sorted(0, Version));
+          end, new([]), db:get_by_index_sorted(0, Version));
+%% Initialise tree from List.
 new([List]) when is_list(List) ->
     foldl(fun(D, Tree) ->
                   add(Tree, D) % Return value -> Tree in next invocation.
-          end, new(), List).
+          end, new([]), List).
 
 update(Tree) ->
     update(Tree, Tree#tree.version).
-- 
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