From a2d92dff3a8acc534daeeb3dea5edda406a6ab0d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 16 Dec 2016 12:50:28 +0100
Subject: 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.
---
 lib/stdlib/src/dict.erl | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

(limited to 'lib/stdlib/src/dict.erl')

diff --git a/lib/stdlib/src/dict.erl b/lib/stdlib/src/dict.erl
index f921e28ef6..9449ba3dc2 100644
--- a/lib/stdlib/src/dict.erl
+++ b/lib/stdlib/src/dict.erl
@@ -38,7 +38,7 @@
 
 %% 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]).
 
@@ -172,6 +172,27 @@ erase_key(Key, [E|Bkt0]) ->
     {[E|Bkt1],Dc};
 erase_key(_, []) -> {[],0}.
 
+-spec take(Key, Dict) -> {Value, Dict1} | error when
+      Dict :: dict(Key, Value),
+      Dict1 :: dict(Key, Value),
+      Key :: term(),
+      Value :: term().
+
+take(Key, D0) ->
+    Slot = get_slot(D0, Key),
+    case on_bucket(fun (B0) -> take_key(Key, B0) end, D0, Slot) of
+	{D1,{Value,Dc}} ->
+            {Value, maybe_contract(D1, Dc)};
+	{_,error} -> error
+    end.
+
+take_key(Key, [?kv(Key,Val)|Bkt]) ->
+    {Bkt,{Val,1}};
+take_key(Key, [E|Bkt0]) ->
+    {Bkt1,Res} = take_key(Key, Bkt0),
+    {[E|Bkt1],Res};
+take_key(_, []) -> {[],error}.
+
 -spec store(Key, Value, Dict1) -> Dict2 when
       Dict1 :: dict(Key, Value),
       Dict2 :: dict(Key, Value).
-- 
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