1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(couch_key_tree).
-export([merge/2, find_missing/2, get_key_leafs/2, get_full_key_paths/2, get/2]).
-export([map/2, get_all_leafs/1, get_leaf_keys/1, count_leafs/1, remove_leafs/2,get_all_leafs_full/1]).
% a key tree looks like this:
% Tree -> [] or [{Key, Value, ChildTree} | SiblingTree]
% ChildTree -> Tree
% SiblingTree -> [] or [{SiblingKey, Value, Tree} | Tree]
% And each Key < SiblingKey
% key tree functions
% When the same key is found in the trees, the value in tree B is discarded.
merge([], B) ->
B;
merge(A, []) ->
A;
merge([ATree | ANextTree], [BTree | BNextTree]) ->
{AKey, AValue, ASubTree} = ATree,
{BKey, _BValue, BSubTree} = BTree,
if
AKey == BKey ->
%same key
MergedSubTree = merge(ASubTree, BSubTree),
MergedNextTree = merge(ANextTree, BNextTree),
[{AKey, AValue, MergedSubTree} | MergedNextTree];
AKey < BKey ->
[ATree | merge(ANextTree, [BTree | BNextTree])];
true ->
[BTree | merge([ATree | ANextTree], BNextTree)]
end.
find_missing(_Tree, []) ->
[];
find_missing([], Keys) ->
Keys;
find_missing([{Key, _, SubTree} | RestTree], Keys) ->
SrcKeys2 = Keys -- [Key],
SrcKeys3 = find_missing(SubTree, SrcKeys2),
find_missing(RestTree, SrcKeys3).
get_all_key_paths_rev([], KeyPathAcc) ->
KeyPathAcc;
get_all_key_paths_rev([{Key, Value, SubTree} | RestTree], KeyPathAcc) ->
get_all_key_paths_rev(SubTree, [{Key, Value} | KeyPathAcc]) ++
get_all_key_paths_rev(RestTree, KeyPathAcc).
% Removes any branches from the tree whose leaf node(s) are in the Keys
remove_leafs(Tree, Keys) ->
% flatten each branch in a tree into a tree path
Paths = get_all_key_paths_rev(Tree, []),
% filter out any that are in the keys list.
{FoundKeys, FilteredPaths} = lists:mapfoldl(
fun(Key, PathsAcc) ->
case [Path || [{LeafKey,_}|_]=Path <- PathsAcc, LeafKey /= Key] of
PathsAcc ->
{nil, PathsAcc};
PathsAcc2 ->
{Key, PathsAcc2}
end
end, Paths, Keys),
% convert paths back to trees
NewTree = lists:foldl(
fun(Path,TreeAcc) ->
SingleTree = lists:foldl(
fun({K,V},NewTreeAcc) -> [{K,V,NewTreeAcc}] end, [], Path),
merge(TreeAcc, SingleTree)
end, [], FilteredPaths),
{NewTree, FoundKeys}.
% get the leafs in the tree matching the keys. The matching key nodes can be
% leafs or an inner nodes. If an inner node, then the leafs for that node
% are returned.
get_key_leafs(Tree, Keys) ->
get_key_leafs(Tree, Keys, []).
get_key_leafs(_Tree, [], _KeyPathAcc) ->
{[], []};
get_key_leafs([], KeysToGet, _KeyPathAcc) ->
{[], KeysToGet};
get_key_leafs([{Key, _Value, SubTree}=Tree | RestTree], KeysToGet, KeyPathAcc) ->
case KeysToGet -- [Key] of
KeysToGet -> % same list, key not found
{LeafsFound, KeysToGet2} = get_key_leafs(SubTree, KeysToGet, [Key | KeyPathAcc]),
{RestLeafsFound, KeysRemaining} = get_key_leafs(RestTree, KeysToGet2, KeyPathAcc),
{LeafsFound ++ RestLeafsFound, KeysRemaining};
KeysToGet2 ->
LeafsFound = get_all_leafs([Tree], KeyPathAcc),
LeafKeysFound = [LeafKeyFound || {LeafKeyFound, _, _} <- LeafsFound],
KeysToGet2 = KeysToGet2 -- LeafKeysFound,
{RestLeafsFound, KeysRemaining} = get_key_leafs(RestTree, KeysToGet2, KeyPathAcc),
{LeafsFound ++ RestLeafsFound, KeysRemaining}
end.
get(Tree, KeysToGet) ->
{KeyPaths, KeysNotFound} = get_full_key_paths(Tree, KeysToGet),
FixedResults = [ {Key, Value, [Key0 || {Key0, _} <- Path]} || [{Key, Value}|_] = Path <- KeyPaths],
{FixedResults, KeysNotFound}.
get_full_key_paths(Tree, Keys) ->
get_full_key_paths(Tree, Keys, []).
get_full_key_paths(_Tree, [], _KeyPathAcc) ->
{[], []};
get_full_key_paths([], KeysToGet, _KeyPathAcc) ->
{[], KeysToGet};
get_full_key_paths([{KeyId, Value, SubTree} | RestTree], KeysToGet, KeyPathAcc) ->
KeysToGet2 = KeysToGet -- [KeyId],
CurrentNodeResult =
case length(KeysToGet2) == length(KeysToGet) of
true -> % not in the key list.
[];
false -> % this node is the key list. return it
[[{KeyId, Value} | KeyPathAcc]]
end,
{KeysGotten, KeysRemaining} = get_full_key_paths(SubTree, KeysToGet2, [{KeyId, Value} | KeyPathAcc]),
{KeysGotten2, KeysRemaining2} = get_full_key_paths(RestTree, KeysRemaining, KeyPathAcc),
{CurrentNodeResult ++ KeysGotten ++ KeysGotten2, KeysRemaining2}.
get_all_leafs_full(Tree) ->
get_all_leafs_full(Tree, []).
get_all_leafs_full([], _KeyPathAcc) ->
[];
get_all_leafs_full([{KeyId, Value, []} | RestTree], KeyPathAcc) ->
[[{KeyId, Value} | KeyPathAcc] | get_all_leafs_full(RestTree, KeyPathAcc)];
get_all_leafs_full([{KeyId, Value, SubTree} | RestTree], KeyPathAcc) ->
get_all_leafs_full(SubTree, [{KeyId, Value} | KeyPathAcc]) ++ get_all_leafs_full(RestTree, KeyPathAcc).
get_all_leafs(Tree) ->
get_all_leafs(Tree, []).
get_all_leafs([], _KeyPathAcc) ->
[];
get_all_leafs([{KeyId, Value, []} | RestTree], KeyPathAcc) ->
[{KeyId, Value, [KeyId | KeyPathAcc]} | get_all_leafs(RestTree, KeyPathAcc)];
get_all_leafs([{KeyId, _Value, SubTree} | RestTree], KeyPathAcc) ->
get_all_leafs(SubTree, [KeyId | KeyPathAcc]) ++ get_all_leafs(RestTree, KeyPathAcc).
get_leaf_keys([]) ->
[];
get_leaf_keys([{Key, _Value, []} | RestTree]) ->
[Key | get_leaf_keys(RestTree)];
get_leaf_keys([{_Key, _Value, SubTree} | RestTree]) ->
get_leaf_keys(SubTree) ++ get_leaf_keys(RestTree).
count_leafs([]) ->
0;
count_leafs([{_Key, _Value, []} | RestTree]) ->
1 + count_leafs(RestTree);
count_leafs([{_Key, _Value, SubTree} | RestTree]) ->
count_leafs(SubTree) + count_leafs(RestTree).
map(_Fun, []) ->
[];
map(Fun, [{Key, Value, SubTree} | RestTree]) ->
Value2 = Fun(Key, Value),
[{Key, Value2, map(Fun, SubTree)} | map(Fun, RestTree)].
|
