Teach the ASN.1 compiler the 'maps' option

When the 'maps' option is given, the SEQUENCE and SET types are
represented as maps instead of as records. Optional and default values
must be not be given as asn1_NOVALUE or asn1_DEFAULT in a map passed
to the M:encode/2 function; they must be omitted from the
map. Similarly, when decoding missing values will be omitted from the
map.

No .hrl files will be generated when the 'maps' options is used.
That means values in an ASN.1 module must be retrieved by calling the
appropriate function in generated module.

Since we one day hope to get rid of the options 'compact_bit_string',
'legacy_bit_string', and 'legacy_erlang_types', we will not allow them
to be combined with the 'maps' option.

1 files changed, 61 insertions, 1 deletions

diff --git a/lib/asn1/src/asn1rtt_ext.erl b/lib/asn1/src/asn1rtt_ext.erl
index 3bf01823db..161b2db691 100644
--- a/lib/asn1/src/asn1rtt_ext.erl
+++ b/lib/asn1/src/asn1rtt_ext.erl
@@ -19,7 +19,8 @@
 %%
 
 -module(asn1rtt_ext).
--export([transform_to_EXTERNAL1990/1,transform_to_EXTERNAL1994/1]).
+-export([transform_to_EXTERNAL1990/1,transform_to_EXTERNAL1990_maps/1,
+         transform_to_EXTERNAL1994/1,transform_to_EXTERNAL1994_maps/1]).
 
 transform_to_EXTERNAL1990({_,_,_,_}=Val) ->
     transform_to_EXTERNAL1990(tuple_to_list(Val), []);
@@ -51,6 +52,30 @@ transform_to_EXTERNAL1990([Data_value], Acc)
     list_to_tuple(lists:reverse([{'octet-aligned',Data_value}|Acc])).
 
 
+transform_to_EXTERNAL1990_maps(#{identification:=Id,'data-value':=Value}=V) ->
+    M0 = case Id of
+             {syntax,DRef} ->
+                 #{'direct-reference'=>DRef};
+             {'presentation-context-id',IndRef} ->
+                 #{'indirect-reference'=>IndRef};
+             {'context-negotiation',
+              #{'presentation-context-id':=IndRef,
+                'transfer-syntax':=DRef}} ->
+                 #{'direct-reference'=>DRef,
+                   'indirect-reference'=>IndRef}
+         end,
+    M = case V of
+            #{'data-value-descriptor':=Dvd} ->
+                M0#{'data-value-descriptor'=>Dvd};
+            #{} ->
+                M0
+        end,
+    M#{encoding=>{'octet-aligned',Value}};
+transform_to_EXTERNAL1990_maps(#{encoding:=_}=V) ->
+    %% Already in the EXTERNAL 1990 format.
+    V.
+
+
 transform_to_EXTERNAL1994({'EXTERNAL',DRef,IndRef,Data_v_desc,Encoding}=V) ->
     Identification =
 	case {DRef,IndRef} of
@@ -71,3 +96,38 @@ transform_to_EXTERNAL1994({'EXTERNAL',DRef,IndRef,Data_v_desc,Encoding}=V) ->
 	    %% information.
 	    V
     end.
+
+transform_to_EXTERNAL1994_maps(V0) ->
+    Identification =
+        case V0 of
+            #{'direct-reference':=DRef,
+              'indirect-reference':=asn1_NOVALUE} ->
+		{syntax,DRef};
+            #{'direct-reference':=asn1_NOVALUE,
+              'indirect-reference':=IndRef} ->
+		{'presentation-context-id',IndRef};
+            #{'direct-reference':=DRef,
+              'indirect-reference':=IndRef} ->
+		{'context-negotiation',
+                 #{'transfer-syntax'=>DRef,
+                   'presentation-context-id'=>IndRef}}
+	end,
+    case V0 of
+        #{encoding:={'octet-aligned',Val}}
+          when is_list(Val); is_binary(Val) ->
+	    %% Transform to the EXTERNAL 1994 definition.
+            V = #{identification=>Identification,
+                  'data-value'=>Val},
+            case V0 of
+                #{'data-value-descriptor':=asn1_NOVALUE} ->
+                    V;
+                #{'data-value-descriptor':=Dvd} ->
+                    V#{'data-value-descriptor'=>Dvd}
+            end;
+	_  ->
+	    %% Keep the EXTERNAL 1990 definition to avoid losing
+	    %% information.
+	    V = [{K,V} || {K,V} <- maps:to_list(V0),
+                          V =/= asn1_NOVALUE],
+            maps:from_list(V)
+    end.