Add deep_update_with/4

CHANGELOG.md

@@ -3,10 +3,19 @@
 All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
-and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+and this project adheres to
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+## [2.1.0] - 2020-07-02
+
+### Added
+
+- New [`deep_update_with/4`][deep_update_with-4] function
+
+[deep_update_with-4]: https://hexdocs.pm/mapz/mapz.html#deep_update_with-4
+
 ## [2.0.0] - 2019-11-27
 
 ### Added
@@ -41,7 +50,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 Initial release
 
-[unreleased]: https://github.com/eproxus/mapz/compare/v2.0.0...HEAD
+[unreleased]: https://github.com/eproxus/mapz/compare/v2.1.0...HEAD
+[2.1.0]: https://github.com/eproxus/mapz/compare/v2.0.0...v2.1.0
 [2.0.0]: https://github.com/eproxus/mapz/compare/v1.0.0...v2.0.0
 [1.0.0]: https://github.com/eproxus/mapz/compare/v0.3.0...v1.0.0
 [0.3.0]: https://github.com/eproxus/mapz/releases/tag/v0.3.0

src/mapz.app.src

@@ -1,6 +1,6 @@
 {application, mapz, [
     {description, "Extensions to the Erlang maps module"},
-    {vsn, "2.0.0"},
+    {vsn, "2.1.0"},
     {applications, [kernel, stdlib]},
 
     {licenses, ["MIT"]},

src/mapz.erl

@@ -7,6 +7,7 @@
 -export([deep_put/3]).
 -export([deep_update/3]).
 -export([deep_update_with/3]).
+-export([deep_update_with/4]).
 -export([deep_remove/2]).
 -export([deep_merge/1]).
 -export([deep_merge/2]).
@@ -88,15 +89,9 @@ deep_get(Path, Map, Default) ->
 -spec deep_put(path(), term(), map()) -> map().
 deep_put(Path, Value, Map1)  ->
     check(Path, Map1),
-    update(Map1, Path,
-        fun(_Existing) -> Value end,
-        fun
-            (P, _Rest, {ok, _Existing}) ->
-                error({badvalue, P});
-            (_P, Rest, error) ->
-                lists:foldr(fun(Key, Acc) -> #{Key => Acc} end, Value, Rest)
-        end
-    ).
+    update(Map1, Path, fun(_Existing) -> Value end, fun(P, Rest, V) ->
+        badvalue_and_create(P, Rest, V, Value)
+    end).
 
 % @doc If `Path' exists in `Map1', the old associated value is replaced by value
 % `Value'. The function returns a new map `Map2' containing the new associated
@@ -113,13 +108,7 @@ deep_put(Path, Value, Map1)  ->
 -spec deep_update(path(), term(), map()) -> map().
 deep_update(Path, Value, Map1) ->
     check(Path, Map1),
-    update(Map1, Path,
-        fun(_Existing) -> Value end,
-        fun
-            (P, _Rest, {ok, _Existing}) -> error({badvalue, P});
-            (P, _Rest, error)           -> error({badkey, P})
-        end
-    ).
+    update(Map1, Path, fun(_Existing) -> Value end, fun badvalue_and_badkey/3).
 
 % @doc Update a value in a `Map1' associated with `Path' by calling `Fun' on the
 % old value to get a new value.
@@ -135,14 +124,32 @@ deep_update(Path, Value, Map1) ->
 % </ul>
 -spec deep_update_with(path(), fun((term()) -> term()), map()) -> map().
 deep_update_with(Path, Fun, Map1) ->
+    deep_update_with_1(Path, Fun, Map1, fun badvalue_and_badkey/3).
+
+% @doc Update a value in a `Map1' associated with `Path' by calling `Fun' on the
+% old value to get a new value.  If `Path' is not present in `Map1' then `Init'
+% will be associated with `Path'.
+%
+% The call can raise the following exceptions:
+% <ul>
+% <li>`{badmap,Map}' if `Map1' is not a map</li>
+% <li>`{badpath,Path}' if `Path' is not a path</li>
+% <li>`{badvalue,P}' if a term that is not a map exists as a intermediate key at
+%     the path `P'</li>
+% <li>`badarg' if `Fun' is not a function of arity 1</li>
+% </ul>
+-spec deep_update_with(path(), fun((term()) -> term()), any(), map()) -> map().
+deep_update_with(Path, Fun, Init, Map1) ->
+    deep_update_with_1(Path, Fun, Map1, fun(P, Rest, Value) ->
+        badvalue_and_create(P, Rest, Value, Init)
+    end).
+
+deep_update_with_1(Path, Fun, Map1, Default) ->
     check(Path, Map1),
     check_fun(Fun, 1),
     update(Map1, Path,
         fun(Value) -> Fun(Value) end,
-        fun
-            (P, _Rest, {ok, _Existing}) -> error({badvalue, P});
-            (P, _Rest, error)           -> error({badkey, P})
-        end
+        Default
     ).
 
 % @doc Removes the last existing key of `Path', and its associated value from
@@ -287,3 +294,12 @@ remove(Map, [First, Second|Path]) when is_map(Map) ->
         error ->
             Map
     end.
+
+create(Path, Value) ->
+    lists:foldr(fun(Key, Acc) -> #{Key => Acc} end, Value, Path).
+
+badvalue_and_badkey(P, _Rest, {ok, _Existing}) -> error({badvalue, P});
+badvalue_and_badkey(P, _Rest, error)           -> error({badkey, P}).
+
+badvalue_and_create(P, _Rest, {ok, _Existing}, _Init) -> error({badvalue, P});
+badvalue_and_create(_P, Rest, error, Init)            -> create(Rest, Init).

test/mapz_tests.erl

@@ -23,6 +23,7 @@
     deep_put/3,
     deep_update/3,
     deep_update_with/3,
+    deep_update_with/4,
     deep_remove/2,
     deep_merge/1,
     deep_merge/2,
@@ -84,14 +85,34 @@ deep_update_with_test_() ->
         ?_assertExit(badarg, deep_update_with([a], fun() -> foo end, ?STRUCT))
     ] ++ error_(fun(P, M) -> deep_update_with(P, Incr, M) end)}.
 
-error_(Function) ->
+deep_update_with_init_test_() ->
+    Incr = fun(V) -> V + 1 end,
     {inparallel, [
+        ?_assertEqual(#{a => 2}, deep_update_with([a], Incr, 0, #{a => 1})),
+        ?_assertEqual(
+            deep_put([a, a, a], 2, ?STRUCT),
+            deep_update_with([a, a, a], Incr, 0, ?STRUCT)
+        ),
+        ?_assertEqual(
+            deep_put([a, a, x, y], 0, ?STRUCT),
+            deep_update_with([a, a, x, y], Incr, 0, ?STRUCT)
+        ),
+        ?_assertExit(badarg, deep_update_with([a], x, 0, ?STRUCT)),
+        ?_assertExit(badarg, deep_update_with([a], fun() -> foo end, 0, ?STRUCT))
+    ] ++ error_init_(fun(P, M) -> deep_update_with(P, Incr, 0, M) end)}.
+
+error_(Function) ->
+    [
+        ?_assertError({badkey, [b]},     Function([b], #{a => 1})),
+        ?_assertError({badkey, [b, x]},  Function([b, x], ?STRUCT))
+    ] ++ error_init_(Function).
+
+error_init_(Function) ->
+    [
         ?_assertError({badmap, foobar},  Function([a], foobar)),
         ?_assertError({badpath, foobar}, Function(foobar, #{a => 1})),
-        ?_assertError({badkey, [b]},     Function([b], #{a => 1})),
-        ?_assertError({badkey, [b, x]},  Function([b, x], ?STRUCT)),
         ?_assertError({badvalue, [d]},   Function([d, x], ?STRUCT))
-    ]}.
+    ].
 
 deep_remove_test_() ->
     {inparallel, [