diff options
Diffstat (limited to 'lib/stdlib/src/maps.erl')
| -rw-r--r-- | lib/stdlib/src/maps.erl | 76 |
1 files changed, 62 insertions, 14 deletions
diff --git a/lib/stdlib/src/maps.erl b/lib/stdlib/src/maps.erl index 5dafdb282a..7ed32a3988 100644 --- a/lib/stdlib/src/maps.erl +++ b/lib/stdlib/src/maps.erl @@ -23,7 +23,8 @@ -export([get/3, filter/2,fold/3, map/2, size/1, update_with/3, update_with/4, - without/2, with/2]). + without/2, with/2, + iterator/1, next/1]). %% BIFs -export([get/2, find/2, from_list/1, @@ -31,6 +32,10 @@ new/0, put/3, remove/2, take/2, to_list/1, update/3, values/1]). +-opaque iterator() :: [{term(), term()}]. + +-export_type([iterator/0]). + %% Shadowed by erl_bif_types: maps:get/2 -spec get(Key,Map) -> Value when Key :: term(), @@ -200,10 +205,22 @@ get(Key,Map,Default) -> Map2 :: map(). filter(Pred,Map) when is_function(Pred,2), is_map(Map) -> - maps:from_list([{K,V}||{K,V}<-maps:to_list(Map),Pred(K,V)]); + maps:from_list(filter_1(Pred, iterator(Map))); filter(Pred,Map) -> erlang:error(error_type(Map),[Pred,Map]). +filter_1(Pred, Iter) -> + case next(Iter) of + {K, V, NextIter} -> + case Pred(K,V) of + true -> + [{K,V} | filter_1(Pred, NextIter)]; + false -> + filter_1(Pred, NextIter) + end; + none -> + [] + end. -spec fold(Fun,Init,Map) -> Acc when Fun :: fun((K, V, AccIn) -> AccOut), @@ -216,10 +233,18 @@ filter(Pred,Map) -> V :: term(). fold(Fun,Init,Map) when is_function(Fun,3), is_map(Map) -> - lists:foldl(fun({K,V},A) -> Fun(K,V,A) end,Init,maps:to_list(Map)); + fold_1(Fun, Init, iterator(Map)); fold(Fun,Init,Map) -> erlang:error(error_type(Map),[Fun,Init,Map]). +fold_1(Fun, Acc, Iter) -> + case next(Iter) of + {K, V, NextIter} -> + fold_1(Fun, Fun(K,V,Acc), NextIter); + none -> + Acc + end. + -spec map(Fun,Map1) -> Map2 when Fun :: fun((K, V1) -> V2), Map1 :: map(), @@ -229,10 +254,17 @@ fold(Fun,Init,Map) -> V2 :: term(). map(Fun,Map) when is_function(Fun, 2), is_map(Map) -> - maps:from_list([{K,Fun(K,V)}||{K,V}<-maps:to_list(Map)]); + maps:from_list(map_1(Fun, iterator(Map))); map(Fun,Map) -> erlang:error(error_type(Map),[Fun,Map]). +map_1(Fun, Iter) -> + case next(Iter) of + {K, V, NextIter} -> + [{K, Fun(K, V)} | map_1(Fun, NextIter)]; + none -> + [] + end. -spec size(Map) -> non_neg_integer() when Map :: map(). @@ -242,6 +274,23 @@ size(Map) when is_map(Map) -> size(Val) -> erlang:error({badmap,Val},[Val]). +-spec iterator(Map) -> Iterator when + Map :: map(), + Iterator :: iterator(). + +iterator(Map) when is_map(Map) -> + maps:to_list(Map); +iterator(M) -> + erlang:error(error_type(M),[M]). + +-spec next(Iterator) -> {K,V,NextIterator} | 'none' when + Iterator :: iterator(), + K :: term(), + V :: term(), + NextIterator :: iterator(). +next([]) -> none; +next([{K, V} | I]) -> + {K, V, I}. -spec without(Ks,Map1) -> Map2 when Ks :: [K], @@ -250,11 +299,10 @@ size(Val) -> K :: term(). without(Ks,M) when is_list(Ks), is_map(M) -> - lists:foldl(fun(K, M1) -> ?MODULE:remove(K, M1) end, M, Ks); + lists:foldl(fun(K, M1) -> maps:remove(K, M1) end, M, Ks); without(Ks,M) -> erlang:error(error_type(M),[Ks,M]). - -spec with(Ks, Map1) -> Map2 when Ks :: [K], Map1 :: map(), @@ -263,14 +311,14 @@ without(Ks,M) -> with(Ks,Map1) when is_list(Ks), is_map(Map1) -> Fun = fun(K, List) -> - case ?MODULE:find(K, Map1) of - {ok, V} -> - [{K, V} | List]; - error -> - List - end - end, - ?MODULE:from_list(lists:foldl(Fun, [], Ks)); + case maps:find(K, Map1) of + {ok, V} -> + [{K, V} | List]; + error -> + List + end + end, + maps:from_list(lists:foldl(Fun, [], Ks)); with(Ks,M) -> erlang:error(error_type(M),[Ks,M]). |