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authorBjörn Gustavsson <[email protected]>2016-12-16 12:50:28 +0100
committerBjörn Gustavsson <[email protected]>2016-12-19 11:54:06 +0100
commita2d92dff3a8acc534daeeb3dea5edda406a6ab0d (patch)
treea61765af69f9cca94879083422571be3c959bd8c /lib/stdlib/src/orddict.erl
parent8362491325db87bd7d561399f8ef8c849df22d33 (diff)
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Add take/2 to all dictionary modules
Similar to maps:take/2, add take/2 to the other dictionary modules in STDLIB: orddict:take(Key, Dict) -> {Val,NewDict} | 'error'. dict:take(Key, Dict) -> {Val,NewDict} | 'error'. gb_trees:take(Key, Dict) -> {Val,NewDict}. For gb_trees also add: gb_trees:take_any(Key, Dict) -> {Val,NewDict} | 'error'. gb_trees already has delete() and delete_any(), so we will follow that design pattern. Suggested by Boris Bochkaryov in https://github.com/erlang/otp/pull/1209.
Diffstat (limited to 'lib/stdlib/src/orddict.erl')
-rw-r--r--lib/stdlib/src/orddict.erl19
1 files changed, 18 insertions, 1 deletions
diff --git a/lib/stdlib/src/orddict.erl b/lib/stdlib/src/orddict.erl
index 37cf0084f0..caa59099af 100644
--- a/lib/stdlib/src/orddict.erl
+++ b/lib/stdlib/src/orddict.erl
@@ -22,7 +22,7 @@
%% Standard interface.
-export([new/0,is_key/2,to_list/1,from_list/1,size/1,is_empty/1]).
--export([fetch/2,find/2,fetch_keys/1,erase/2]).
+-export([fetch/2,find/2,fetch_keys/1,erase/2,take/2]).
-export([store/3,append/3,append_list/3,update/3,update/4,update_counter/3]).
-export([fold/3,map/2,filter/2,merge/3]).
@@ -106,6 +106,23 @@ erase(Key, [{K,_}=E|Dict]) when Key > K ->
erase(_Key, [{_K,_Val}|Dict]) -> Dict; %Key == K
erase(_, []) -> [].
+-spec take(Key, Orddict) -> {Value, Orddict1} | error when
+ Orddict :: orddict(Key, Value),
+ Orddict1 :: orddict(Key, Value),
+ Key :: term(),
+ Value :: term().
+
+take(Key, Dict) ->
+ take_1(Key, Dict, []).
+
+take_1(Key, [{K,_}|_], _Acc) when Key < K ->
+ error;
+take_1(Key, [{K,_}=P|D], Acc) when Key > K ->
+ take_1(Key, D, [P|Acc]);
+take_1(_Key, [{_K,Value}|D], Acc) ->
+ {Value,lists:reverse(Acc, D)};
+take_1(_, [], _) -> error.
+
-spec store(Key, Value, Orddict1) -> Orddict2 when
Orddict1 :: orddict(Key, Value),
Orddict2 :: orddict(Key, Value).