Add option to override the coded callback (#87)

src/euneus_encoder.erl

@@ -7,6 +7,7 @@
 
 -export([encode/2]).
 -export([continue/2]).
+-export([codec_callback/2]).
 -export([key_to_binary/1]).
 -export([escape/1]).
 -export([encode_integer/2]).
@@ -23,6 +24,7 @@
 %
 
 -ignore_xref([continue/2]).
+-ignore_xref([codec_callback/2]).
 -ignore_xref([key_to_binary/1]).
 -ignore_xref([escape/1]).
 -ignore_xref([encode_integer/2]).
@@ -48,6 +50,8 @@
 %% --------------------------------------------------------------------
 
 -export_type([options/0]).
+-export_type([codec_fun/0]).
+-export_type([codec_result/0]).
 -export_type([codec_callback/0]).
 -export_type([is_proplist/0]).
 -export_type([encode/1]).
@@ -75,6 +79,7 @@
 
 -type options() :: #{
     codecs => [codec()],
+    codec_callback => codec_callback(),
     nulls => [term()],
     skip_values => [term()],
     key_to_binary => fun((term()) -> binary()),
@@ -99,17 +104,25 @@
     | ipv4
     | ipv6
     | {records, #{Name :: atom() := {Fields :: [atom()], Size :: pos_integer()}}}
-    | codec_callback().
+    | codec_fun()
+    | custom_codec().
 -export_type([codec/0]).
 
--type codec_callback() :: fun((tuple()) -> next | {halt, term()}).
+-type codec_fun() :: fun((tuple()) -> codec_result()).
+
+-type codec_result() :: next | {halt, term()}.
+
+-type custom_codec() :: term().
+
+-type codec_callback() :: fun((codec(), tuple()) -> codec_result()).
 
 -type is_proplist() :: fun((list()) -> boolean()).
 
 -type encode(Type) :: fun((Type, state()) -> iodata()).
 
 -record(state, {
     codecs :: [codec()],
+    codec_callback :: codec_callback(),
     nulls :: #{term() := null},
     skip_values :: #{term() := skip},
     key_to_binary :: fun((term()) -> binary()),
@@ -264,6 +277,11 @@
 %% '''
 %%   </li>
 %%   <li>
+%%     `codec_callback' - Overrides the default codec resolver.
+%%
+%%     Default is `codec_callback/2'.
+%%   </li>
+%%   <li>
 %%     `nulls' - Defines which values should be encoded as null.
 %%
 %%     Default is `[null]'.
@@ -413,7 +431,7 @@ continue(List, State) when is_list(List) ->
 continue(Map, State) when is_map(Map) ->
     (State#state.encode_map)(Map, State);
 continue(Tuple, State) when is_tuple(Tuple) ->
-    case traverse_codecs(State#state.codecs, Tuple) of
+    case traverse_codecs(State#state.codecs, State#state.codec_callback, Tuple) of
         NewTuple when is_tuple(NewTuple) ->
             (State#state.encode_tuple)(NewTuple, State);
         NewTerm ->
@@ -428,6 +446,20 @@ continue(Ref, State) when is_reference(Ref) ->
 continue(Term, State) ->
     (State#state.encode_term)(Term, State).
 
+-spec codec_callback(codec(), tuple()) -> codec_result().
+codec_callback(timestamp, Tuple) ->
+    timestamp_codec_callback(Tuple);
+codec_callback(datetime, Tuple) ->
+    datetime_codec_callback(Tuple);
+codec_callback(ipv4, Tuple) ->
+    ipv4_codec_callback(Tuple);
+codec_callback(ipv6, Tuple) ->
+    ipv6_codec_callback(Tuple);
+codec_callback({records, Records}, Tuple) ->
+    records_codec_callback(Tuple, Records);
+codec_callback(CodecFun, Tuple) ->
+    CodecFun(Tuple).
+
 -spec key_to_binary(Term) -> binary() when
     Term :: binary() | string() | atom() | integer().
 key_to_binary(Bin) when is_binary(Bin) ->
@@ -551,6 +583,7 @@ encode_term(Term, State) ->
 new_state(Opts) ->
     #state{
         codecs = maps:get(codecs, Opts, []),
+        codec_callback = maps:get(codec_callback, Opts, fun codec_callback/2),
         nulls = maps:from_keys(maps:get(nulls, Opts, [null]), null),
         skip_values = maps:from_keys(maps:get(skip_values, Opts, [undefined]), skip),
         key_to_binary = maps:get(key_to_binary, Opts, fun key_to_binary/1),
@@ -571,29 +604,16 @@ new_state(Opts) ->
 
 % Codecs
 
-traverse_codecs([Codec | Codecs], Tuple) ->
-    case codec_callback(Codec, Tuple) of
+traverse_codecs([Codec | Codecs], CodecCallback, Tuple) ->
+    case CodecCallback(Codec, Tuple) of
         next ->
-            traverse_codecs(Codecs, Tuple);
+            traverse_codecs(Codecs, CodecCallback, Tuple);
         {halt, NewTerm} ->
             NewTerm
     end;
-traverse_codecs([], Tuple) ->
+traverse_codecs([], _CodecCallback, Tuple) ->
     Tuple.
 
-codec_callback(timestamp, Tuple) ->
-    timestamp_codec_callback(Tuple);
-codec_callback(datetime, Tuple) ->
-    datetime_codec_callback(Tuple);
-codec_callback(ipv4, Tuple) ->
-    ipv4_codec_callback(Tuple);
-codec_callback(ipv6, Tuple) ->
-    ipv6_codec_callback(Tuple);
-codec_callback({records, Records}, Tuple) ->
-    records_codec_callback(Tuple, Records);
-codec_callback(Callback, Tuple) ->
-    Callback(Tuple).
-
 timestamp_codec_callback({MegaSecs, Secs, MicroSecs} = Timestamp) when
     ?IS_MIN(MegaSecs, 0), ?IS_MIN(Secs, 0), ?IS_MIN(MicroSecs, 0)
 ->

test/euneus_encoder_SUITE.erl

@@ -64,6 +64,17 @@ codecs_test(Config) when is_list(Config) ->
         )
     ].
 
+codec_callback_test(Config) when is_list(Config) ->
+    ?assertEqual(
+        <<"[\"foo\"]">>,
+        encode({foo}, #{
+            codecs => [tuple_to_list],
+            codec_callback => fun(tuple_to_list, Tuple) ->
+                {halt, erlang:tuple_to_list(Tuple)}
+            end
+        })
+    ).
+
 timestamp_codec_test(Config) when is_list(Config) ->
     ?assertEqual(<<"\"1970-01-01T00:00:00.000Z\"">>, encode({0, 0, 0}, #{codecs => [timestamp]})).