Let messages and grouped AVPs be encoded/decoded from/to maps

With {record_decode, map}. The option name is arguably a bit misleading
now, but not too objectionable given that the encode/decode in question
has historically only been of records.

One advantage of the map decode is that the map only contains values for
those AVPs existing in the message or grouped AVP in question. The name
of the message or grouped AVP is stored in with key ':name', the leading
colon ensuring that the key isn't a diameter-name.

Decoding to maps makes the hrl files generated from dictionary files
largely irrelevant. There are value defines generated into these, but
they're typically so long as to be unusable.

1 files changed, 27 insertions, 1 deletions

diff --git a/lib/diameter/src/base/diameter_gen.erl b/lib/diameter/src/base/diameter_gen.erl
index 4879ad8f6c..be2e221b7e 100644
--- a/lib/diameter/src/base/diameter_gen.erl
+++ b/lib/diameter/src/base/diameter_gen.erl
@@ -50,7 +50,9 @@
 %% # encode_avps/3
 %% ---------------------------------------------------------------------------
 
--spec encode_avps(parent_name(), parent_record() | avp_values(), map())
+-spec encode_avps(parent_name(),
+                  parent_record() | avp_values() | map(),
+                  map())
    -> iolist()
     | no_return().
 
@@ -83,6 +85,11 @@ encode(Name, Vals, Opts, Mod)
   when is_list(Vals) ->
     encode(Name, Mod:'#set-'(Vals, newrec(Mod, Name)), Opts, Mod);
 
+encode(Name, Map, Opts, Mod)
+  when is_map(Map) ->
+    [enc(Name, F, A, V, Opts, Mod) || {F,A} <- Mod:avp_arity(Name),
+                                      V <- [maps:get(F, Map, def(A))]];
+
 encode(Name, Rec, Opts, Mod) ->
     [encode(Name, F, V, Opts, Mod) || {F,V} <- Mod:'#get-'(Rec)].
 
@@ -627,6 +634,14 @@ too_many(FieldName, M, Map) ->
 set(_, _, _, _, undefined = No) ->
     No;
 
+set(1, F, Value, _, Map)
+  when is_map(Map) ->
+    maps:put(F, Value, Map);
+
+set(_, F, V, _, Map)
+  when is_map(Map) ->
+    maps:update_with(F, fun(Vs) -> [V|Vs] end, [V], Map);
+
 set(1, F, Value, Mod, Rec) ->
     Mod:'#set-'({F, Value}, Rec);
 
@@ -731,6 +746,9 @@ empty(Name, #{module := Mod} = Opts) ->
 newrec(_, _, #{record_decode := false}) ->
     undefined;
 
+newrec(_, Name, #{record_decode := map}) ->
+    #{':name' => Name};
+
 newrec(Mod, Name, _) ->
     newrec(Mod, Name).
 
@@ -738,3 +756,11 @@ newrec(Mod, Name, _) ->
 
 newrec(Mod, Name) ->
     Mod:'#new-'(Mod:name2rec(Name)).
+
+%% def/1
+
+def(1) ->
+    undefined;
+
+def(_) ->
+    [].