Refactor code generation for decoding SEQUENCE/SET

In order to optimize the generated code, we will need data structures
that can be traversed in several passes before the actual code is
generated.

Refactor the code so that if first builds (essentially) a list of
funs that do the actual code generation, and a second function
that will call the funs one at the time.

1 files changed, 466 insertions, 333 deletions

diff --git a/lib/asn1/src/asn1ct_constructed_per.erl b/lib/asn1/src/asn1ct_constructed_per.erl
index 1558047e8f..d5afd20954 100644
--- a/lib/asn1/src/asn1ct_constructed_per.erl
+++ b/lib/asn1/src/asn1ct_constructed_per.erl
@@ -217,9 +217,44 @@ gen_decode_set(Erules,Typename,D) ->
 gen_decode_sequence(Erules,Typename,D) ->
     gen_decode_constructed(Erules,Typename,D).
 
-gen_decode_constructed(Erules,Typename,D) when is_record(D,type) ->
+gen_decode_constructed(Erule, Typename, #type{}=D) ->
+    Imm = gen_dec_constructed_imm(Erule, Typename, #type{}=D),
     asn1ct_name:start(),
     asn1ct_name:clear(),
+    emit_gen_dec_imm(Imm),
+    emit([".",nl,nl]).
+
+emit_gen_dec_imm(L) ->
+    emit_gen_dec_imm(L, "", []).
+
+emit_gen_dec_imm([ignore|T], Sep, St) ->
+    emit_gen_dec_imm(T, Sep, St);
+emit_gen_dec_imm([{ignore,Fun}|T], Sep, St0) ->
+    St = Fun(St0),
+    emit_gen_dec_imm(T, Sep, St);
+emit_gen_dec_imm([{group,L}|T], Sep, St0) ->
+    emit(Sep),
+    St = emit_gen_dec_imm_group(L, St0),
+    emit_gen_dec_imm(T, [com,nl], St);
+emit_gen_dec_imm([Emit|T], Sep, St0) ->
+    emit(Sep),
+    St = Emit(St0),
+    emit_gen_dec_imm(T, [com,nl], St);
+emit_gen_dec_imm([], _, _) -> ok.
+
+emit_gen_dec_imm_group([H|T], St0) ->
+    St = emit_gen_dec_group_item(H, St0),
+    emit_gen_dec_imm_group(T, St);
+emit_gen_dec_imm_group([], St) -> St.
+
+emit_gen_dec_group_item(ignore, St) ->
+    St;
+emit_gen_dec_group_item({ignore,Fun}, St) ->
+    Fun(St);
+emit_gen_dec_group_item(Emit, St) ->
+    Emit(St).
+
+gen_dec_constructed_imm(Erule, Typename, #type{}=D) ->
     {CompList,TableConsInfo} = 
 	case D#type.def of
 	    #'SEQUENCE'{tablecinf=TCI,components=CL} ->
@@ -229,27 +264,29 @@ gen_decode_constructed(Erules,Typename,D) when is_record(D,type) ->
 		{CL,TCI} % the textual order is already taken care of
 	end,
     Ext = extensible_dec(CompList),
-    MaybeComma1 = case Ext of
-		      {ext,_Pos,_NumExt} -> 
-			  gen_dec_extension_value("Bytes"),
-			  {",",nl};
-		      _ -> 
-			  ""
-		  end,
+    EmitExt = case Ext of
+		  {ext,_Pos,_NumExt} ->
+		      fun(_) ->
+			      gen_dec_extension_value("Bytes")
+		      end;
+		  _ -> ignore
+	      end,
     Optionals = optionals(CompList),
-    MaybeComma2 = case Optionals of
-		      [] -> MaybeComma1;
-		      _ -> 
-			  Bcurr = asn1ct_name:curr(bytes),
-			  Bnext = asn1ct_name:next(bytes),
-			  emit(MaybeComma1),
-			  GetoptCall = "} = ?RT_PER:getoptionals2(",
-			  emit({"{Opt,",{var,Bnext},GetoptCall,
-				{var,Bcurr},",",{asis,length(Optionals)},")"}),
-			  asn1ct_name:new(bytes),
-			  ", "    
-		  end,
-    {DecObjInf,UniqueFName,ValueIndex} = 
+    EmitOpt = case Optionals of
+		  [] ->
+		      ignore;
+		  [_|_] ->
+		      fun(_) ->
+			      Bcurr = asn1ct_name:curr(bytes),
+			      Bnext = asn1ct_name:next(bytes),
+			      GetoptCall = "} = ?RT_PER:getoptionals2(",
+			      emit({"{Opt,",{var,Bnext},GetoptCall,
+				    {var,Bcurr},",",
+				    {asis,length(Optionals)},")"}),
+			      asn1ct_name:new(bytes)
+		      end
+	      end,
+    ObjSetInfo =
 	case TableConsInfo of
 %%	    {ObjectSet,AttrN,N,UniqueFieldName} ->%% N is index of attribute that determines constraint
 	    #simpletableattributes{objectsetname=ObjectSet,
@@ -281,13 +318,19 @@ gen_decode_constructed(Erules,Typename,D) when is_record(D,type) ->
 			{false,false,false}
 		end
 	end,
-%%    NewCompList = wrap_compList(CompList),
-    {AccTerm,AccBytes} =
-	gen_dec_components_call(Erules,Typename,CompList,MaybeComma2,DecObjInf,Ext,length(Optionals)),
-    case asn1ct_name:all(term) of
-	[] -> emit(MaybeComma2); % no components at all
-	_ -> emit({com,nl})
-    end,
+    {DecObjInf,_,_} = ObjSetInfo,
+    EmitComp = gen_dec_components_call(Erule, Typename, CompList,
+				       DecObjInf, Ext, length(Optionals)),
+    EmitRest = fun({AccTerm,AccBytes}) ->
+		       gen_dec_constructed_imm_2(Typename, CompList,
+						 ObjSetInfo,
+						 AccTerm, AccBytes)
+	       end,
+    [EmitExt,EmitOpt|EmitComp++[EmitRest]].
+
+gen_dec_constructed_imm_2(Typename, CompList,
+			  ObjSetInfo, AccTerm, AccBytes) ->
+    {_,UniqueFName,ValueIndex} = ObjSetInfo,
     case {AccTerm,AccBytes} of
 	{[],[]} ->
 	    ok;
@@ -329,8 +372,7 @@ gen_decode_constructed(Erules,Typename,D) when is_record(D,type) ->
 	    mkvlist(textual_order(to_encoding_order(CompList),asn1ct_name:all(term))),
 	    emit("},")
     end,
-    emit({{curr,bytes},"}"}),
-    emit({".",nl,nl}).
+    emit({{curr,bytes},"}"}).
 
 textual_order([#'ComponentType'{textual_order=undefined}|_],TermList) ->
     TermList;
@@ -1002,53 +1044,66 @@ gen_enc_line(Erule,TopType,Cname,Type,Element, _Pos,DynamicEnc,Ext) ->
 	    emit("))");
 	_ -> true
     end.
-gen_dec_components_call(Erule,TopType,{Root,ExtList},MaybeComma,
+
+gen_dec_components_call(Erule, TopType, {Root,ExtList},
+			DecInfObj, Ext, NumberOfOptionals) ->
+    gen_dec_components_call(Erule,TopType,{Root,ExtList,[]},
+			    DecInfObj,Ext,NumberOfOptionals);
+gen_dec_components_call(Erule,TopType,CL={Root1,ExtList,Root2},
 			DecInfObj,Ext,NumberOfOptionals) ->
-    gen_dec_components_call(Erule,TopType,{Root,ExtList,[]},MaybeComma,DecInfObj,Ext,NumberOfOptionals);
-gen_dec_components_call(Erule,TopType,CL={Root1,ExtList,Root2},MaybeComma,DecInfObj,Ext,NumberOfOptionals) ->
     %% The type has extensionmarker
-
     OptTable = create_optionality_table(Root1++Root2),
-    {Rpos,AccTerm,AccBytes} = 
-	gen_dec_components_call1(Erule,TopType, Root1++Root2, 1, OptTable, 
-				 MaybeComma,DecInfObj,noext,[],[],
-				 NumberOfOptionals),
-    emit([",",nl,"{Extensions,",{next,bytes},"} = "]),
-    emit(["?RT_PER:getextension(Ext,",{curr,bytes},"),",nl]),
-    asn1ct_name:new(bytes),
+    Init = {ignore,fun(_) -> {[],[]} end},
+    {EmitRoot,Tpos} =
+	gen_dec_comp_calls(Root1++Root2, Erule, TopType, OptTable,
+			   DecInfObj, noext, NumberOfOptionals,
+			   1, []),
+    EmitGetExt = fun(St) ->
+			 emit(["{Extensions,",{next,bytes},"} = "]),
+			 emit(["?RT_PER:getextension(Ext,",
+			       {curr,bytes},")"]),
+			 asn1ct_name:new(bytes),
+			 St
+		 end,
     {extgrouppos,ExtGroupPosLen}  = extgroup_pos_and_length(CL),
-    NewExtList = wrap_extensionAdditionGroups(ExtList,ExtGroupPosLen),
-    {_Epos,AccTermE,AccBytesE} = 
-	gen_dec_components_call1(Erule,TopType,NewExtList,Rpos, OptTable,
-				 "",DecInfObj,Ext,[],[],NumberOfOptionals),
-    case ExtList of
-	[] -> true;
-	_ -> emit([",",nl])
-    end,
-    emit([{next,bytes},"= ?RT_PER:skipextensions(",{curr,bytes},",",
-	  length(ExtList)+1,",Extensions)",nl]),
-    asn1ct_name:new(bytes),
-    {AccTerm++AccTermE,AccBytes++AccBytesE};
-
-gen_dec_components_call(Erule,TopType,CompList,MaybeComma,DecInfObj,
-			Ext,NumberOfOptionals) ->
+    NewExtList = wrap_extensionAdditionGroups(ExtList, ExtGroupPosLen),
+    {EmitExts,_} = gen_dec_comp_calls(NewExtList, Erule, TopType, OptTable,
+				      DecInfObj, Ext, NumberOfOptionals,
+				      Tpos, []),
+    Finish =
+	fun(St) ->
+		emit([{next,bytes},"= ?RT_PER:skipextensions(",{curr,bytes},",",
+		      length(ExtList)+1,",Extensions)"]),
+		asn1ct_name:new(bytes),
+		St
+	end,
+    [Init] ++ EmitRoot ++ [EmitGetExt|EmitExts] ++ [Finish];
+gen_dec_components_call(Erule, TopType, CompList, DecInfObj,
+			Ext, NumberOfOptionals) ->
     %% The type has no extensionmarker
     OptTable = create_optionality_table(CompList),
-    {_,AccTerm,AccBytes} =
-	gen_dec_components_call1(Erule,TopType, CompList, 1, OptTable,
-				 MaybeComma,DecInfObj,Ext,[],[],
-				 NumberOfOptionals),
-    {AccTerm,AccBytes}.
-
-
-gen_dec_components_call1(Erule,TopType,
-			 [C=#'ComponentType'{name=Cname,typespec=Type,prop=Prop,textual_order=TextPos}|Rest],
-			 Tpos,OptTable,MaybeComma,DecInfObj,Ext,AccTerm,AccBytes,NumberOfOptionals) ->
+    Init = {ignore,fun(_) -> {[],[]} end},
+    {Cs,_} = gen_dec_comp_calls(CompList, Erule, TopType, OptTable,
+				DecInfObj, Ext, NumberOfOptionals,
+				1, []),
+    [Init|Cs].
+
+gen_dec_comp_calls([C|Cs], Erule, TopType, OptTable, DecInfObj,
+		   Ext, NumberOfOptionals, Tpos, Acc) ->
+    L = gen_dec_comp_call(C, Erule, TopType, Tpos, OptTable, DecInfObj,
+			  Ext, NumberOfOptionals),
+    gen_dec_comp_calls(Cs, Erule, TopType, OptTable, DecInfObj,
+		       Ext, NumberOfOptionals, Tpos+1, [L|Acc]);
+gen_dec_comp_calls([], _, _, _, _, _, _, Tpos, Acc) ->
+    {lists:append(lists:reverse(Acc)),Tpos}.
+
+gen_dec_comp_call(Comp, Erule, TopType, Tpos, OptTable, DecInfObj,
+		  Ext, NumberOfOptionals) ->
+    #'ComponentType'{typespec=Type,prop=Prop,textual_order=TextPos} = Comp,
     Pos = case Ext of
 	      noext -> Tpos;
 	      {ext,Epos,_Enum} -> Tpos - Epos + 1
 	  end,
-    emit(MaybeComma),
     InnerType = 
 	case Type#type.def of
 	    #'ObjectClassFieldType'{type=InType} ->
@@ -1057,109 +1112,134 @@ gen_dec_components_call1(Erule,TopType,
 		asn1ct_gen:get_inner(Def)
 	end,
 
-    case InnerType of
-	#'Externaltypereference'{type=T} ->
-	    emit({nl,"%%  attribute number ",TextPos," with type ",
-		  T,nl});
-	IT when is_tuple(IT) ->
-	    emit({nl,"%%  attribute number ",TextPos," with type ",
-		  element(2,IT),nl});
-	_ ->
-	    emit({nl,"%% attribute number ",TextPos," with type ",
-		  InnerType,nl})
-    end,
-
-    IsMandatoryAndPredefinedTableC =
-	fun(noext,mandatory,{"got objfun through args","ObjFun"}) ->
-		true;
-	   (_,_,{"got objfun through args","ObjFun"}) ->
-		false;
-	   (_,_,_) ->
-		true
-	end,
-    case {InnerType,IsMandatoryAndPredefinedTableC(Ext,Prop,DecInfObj)} of
-%%	{typefield,_} when Ext == noext, Prop == mandatory ->
-	{{typefield,_},true}  ->
-	    %% DecInfObj /= {"got objfun through args","ObjFun"} |
-	    %% (DecInfObj == {"got objfun through args","ObjFun"} &
-	    %% Ext == noext & Prop == mandatory)
-	    asn1ct_name:new(term),
-	    asn1ct_name:new(tmpterm),
-	    emit({"{",{curr,tmpterm},", ",{next,bytes},"} = "});
+    DispType = case InnerType of
+		   #'Externaltypereference'{type=T} -> T;
+		   IT when is_tuple(IT) -> element(2,IT);
+		   _ -> InnerType
+	       end,
+    Comment = fun(St) ->
+		      emit([nl,"%% attribute number ",TextPos,
+			    " with type ",DispType,nl]),
+		      St
+	      end,
+
+    Preamble =
+	case {InnerType,is_mandatory_predef_tab_c(Ext, Prop, DecInfObj)} of
+	    {{typefield,_},true}  ->
+		%% DecInfObj /= {"got objfun through args","ObjFun"} |
+		%% (DecInfObj == {"got objfun through args","ObjFun"} &
+		%% Ext == noext & Prop == mandatory)
+		fun(St) ->
+			asn1ct_name:new(term),
+			asn1ct_name:new(tmpterm),
+			emit(["{",{curr,tmpterm},", ",{next,bytes},"} = "]),
+			St
+		end;
 	%%{objectfield,_,_} when Ext == noext, Prop == mandatory ->
-	{{objectfield,_,_},true} ->
-	    asn1ct_name:new(term),
-	    asn1ct_name:new(tmpterm),
-	    emit({"{",{curr,tmpterm},", ",{next,bytes},"} = "});
+	    {{objectfield,_,_},true} ->
+		fun(St) ->
+			asn1ct_name:new(term),
+			asn1ct_name:new(tmpterm),
+			emit(["{",{curr,tmpterm},", ",{next,bytes},"} = "]),
+			St
+		end;
 	_ ->
 	    case Type of
 		#type{def=#'SEQUENCE'{
 			extaddgroup=Number1,
 			components=ExtGroupCompList1}} when is_integer(Number1)->
-		    emit({"{{_,"}),
-		    emit_extaddgroupTerms(term,ExtGroupCompList1),
-		    emit({"}"});
+		    fun(St) ->
+			    emit(["{{_,"]),
+			    emit_extaddgroupTerms(term,ExtGroupCompList1),
+			    emit(["}"]),
+			    emit([",",{next,bytes},"} = "]),
+			    St
+		    end;
 		_ ->
-		    asn1ct_name:new(term),
-		    emit({"{",{curr,term}})
-	    end,
-	    emit({",",{next,bytes},"} = "})
-    end,
+		    fun(St) ->
+			    asn1ct_name:new(term),
+			    emit(["{",{curr,term}]),
+			    emit([",",{next,bytes},"} = "]),
+			    St
+		    end
+	    end
+	end,
 
-    case {Ext,Prop,is_optimized(Erule)} of
-	{noext,mandatory,_} -> ok; % generate nothing
-	{noext,_,_} -> %% OPTIONAL or DEFAULT
-	    OptPos = get_optionality_pos(TextPos,OptTable),
-	    Element = io_lib:format("Opt band (1 bsl ~w)",[NumberOfOptionals - OptPos]),
-	    emit(["case ",Element," of",nl]),
-	    emit(["  _Opt",TextPos," when _Opt",TextPos," > 0 ->"]);
+    OptOrDef =
+	case {Ext,Prop,is_optimized(Erule)} of
+	    {noext,mandatory,_} ->
+		ignore;
+	    {noext,_,_} -> %% OPTIONAL or DEFAULT
+		OptPos = get_optionality_pos(TextPos, OptTable),
+		Element = io_lib:format("Opt band (1 bsl ~w)",
+					[NumberOfOptionals - OptPos]),
+		fun(St) ->
+			emit(["case ",Element," of",nl]),
+			emit(["  _Opt",TextPos," when _Opt",TextPos," > 0 ->"]),
+			St
+		end;
 	{_,_,false} -> %% extension element, not bitstring
-	    emit(["case Extensions of",nl]),
-	    emit(["  _ when size(Extensions) >= ",Pos,",element(",Pos,",Extensions) == 1 ->",nl]);
-	_ ->
-	    emit(["case Extensions of",nl]),
-	    emit(["  <<_:",Pos-1,",1:1,_/bitstring>> when bit_size(Extensions) >= ",Pos," ->",nl])
-    end,
-    put(component_type,{true,C}),
-    {TermVar,BytesVar} = gen_dec_line(Erule,TopType,Cname,Type,Tpos,DecInfObj,Ext,Prop),
-    erase(component_type),
-    case {Ext,Prop} of
-	{noext,mandatory} -> true; % generate nothing
-	{noext,_} ->
-	    emit([";",nl,"0 ->"]),
-	    emit(["{"]),
-	    gen_dec_component_no_val(Ext,Prop),
-	    emit({",",{curr,bytes},"}",nl}),
-	    emit([nl,"end"]);
-	_ ->
-	    emit([";",nl,"_  ->",nl]),
-	    emit(["{"]),
-	    case Type of
-		#type{def=#'SEQUENCE'{
-			extaddgroup=Number2,
-			components=ExtGroupCompList2}} when is_integer(Number2)->
-		    emit({"{extAddGroup,"}),
-		    gen_dec_extaddGroup_no_val(Ext,ExtGroupCompList2),
-		    emit({"}"});
-		_ ->
-		    gen_dec_component_no_val(Ext,Prop)
-	    end,
-	    emit({",",{curr,bytes},"}",nl}),
-	    emit([nl,"end"])
-    end,    
-    asn1ct_name:new(bytes),
-    case Rest of
-	[] ->
-	    {Tpos+1,AccTerm++TermVar,AccBytes++BytesVar};
-	_ ->
-	    emit({com,nl}),
-	    gen_dec_components_call1(Erule,TopType,Rest,Tpos+1,OptTable,
-				     "",DecInfObj,Ext, AccTerm++TermVar,
-				     AccBytes++BytesVar,NumberOfOptionals)
-    end;
-
-gen_dec_components_call1(_,_TopType,[],Pos,_OptTable,_,_,_,AccTerm,AccBytes,_NumberOfOptionals) ->
-    {Pos,AccTerm,AccBytes}.
+		fun(St) ->
+			emit(["case Extensions of",nl]),
+			emit(["  _ when size(Extensions) >= ",Pos,
+			      ",element(",Pos,",Extensions) == 1 ->",nl]),
+			St
+		end;
+	    _ ->
+		fun(St) ->
+			emit(["case Extensions of",nl]),
+			emit(["  <<_:",Pos-1,",1:1,_/bitstring>> "
+			      "when bit_size(Extensions) >= ",Pos," ->",nl]),
+			St
+		end
+	end,
+    Lines = gen_dec_line_imm(Erule, TopType, Comp, Tpos, DecInfObj, Ext),
+    Postamble =
+	case {Ext,Prop} of
+	    {noext,mandatory} ->
+		ignore;
+	    {noext,_} ->
+		fun(St) ->
+			emit([";",nl,"0 ->"]),
+			emit(["{"]),
+			gen_dec_component_no_val(Ext,Prop),
+			emit({",",{curr,bytes},"}",nl}),
+			emit([nl,"end"]),
+			St
+		end;
+	    _ ->
+		fun(St) ->
+			emit([";",nl,"_  ->",nl]),
+			emit(["{"]),
+			case Type of
+			    #type{def=#'SEQUENCE'{
+					 extaddgroup=Number2,
+					 components=ExtGroupCompList2}}
+			      when is_integer(Number2)->
+				emit({"{extAddGroup,"}),
+				gen_dec_extaddGroup_no_val(Ext,ExtGroupCompList2),
+				emit({"}"});
+			    _ ->
+				gen_dec_component_no_val(Ext, Prop)
+			end,
+			emit({",",{curr,bytes},"}",nl}),
+			emit([nl,"end"]),
+			St
+		end
+	end,
+    AdvBuffer = {ignore,fun(St) ->
+				asn1ct_name:new(bytes),
+				St
+			end},
+    [{group,[Comment,Preamble,OptOrDef|Lines]++[Postamble,AdvBuffer]}].
+
+is_mandatory_predef_tab_c(noext, mandatory,
+			  {"got objfun through args","ObjFun"}) ->
+    true;
+is_mandatory_predef_tab_c(_, _, {"got objfun through args","ObjFun"}) ->
+    false;
+is_mandatory_predef_tab_c(_,_,_) ->
+    true.
 
 gen_dec_extaddGroup_no_val(Ext,[#'ComponentType'{prop=Prop}])->
     gen_dec_component_no_val(Ext,Prop),
@@ -1179,8 +1259,14 @@ gen_dec_component_no_val({ext,_,_},mandatory) ->
     emit({"asn1_NOVALUE"}).
     
 
-gen_dec_line(Erule,TopType,Cname,Type,Pos,DecInfObj,Ext,Prop)  ->
-    Ctgenmod = asn1ct_gen:ct_gen_module(Erule),
+gen_dec_line(Erule, TopType, Comp, Pos, DecInfObj, Ext) ->
+    Imm0 = gen_dec_line_imm(Erule, TopType, Comp, Pos, DecInfObj, Ext),
+    Init = {ignore,fun(_) -> {[],[]} end},
+    Imm = [{group,[Init|Imm0]}],
+    emit_gen_dec_imm(Imm).
+
+gen_dec_line_imm(Erule, TopType, Comp, Pos, DecInfObj, Ext) ->
+    #'ComponentType'{name=Cname,typespec=Type} = Comp,
     Atype = 
 	case Type of
 	    #type{def=#'ObjectClassFieldType'{type=InnerType}} ->
@@ -1189,177 +1275,230 @@ gen_dec_line(Erule,TopType,Cname,Type,Pos,DecInfObj,Ext,Prop)  ->
 		asn1ct_gen:get_inner(Type#type.def)
 	end,
 
-    BytesVar0 = asn1ct_gen:mk_var(asn1ct_name:curr(bytes)),
-    BytesVar = case Ext of
-		   {ext,Ep,_} when Pos >= Ep ->
-		       emit(["begin",nl,"{TmpVal",Pos,",Trem",Pos,
-			     "}=?RT_PER:decode_open_type(",
-			     {curr,bytes},",[]),",nl,
-			     "{TmpValx",Pos,",_}="]),
-		       io_lib:format("TmpVal~p",[Pos]);
-		   _ -> BytesVar0
-	       end,
-    SaveBytes = 
-	case Atype of
-	    {typefield,_} ->
+    Pre = gen_dec_line_open_type(Ext, Pos),
+    Decode = gen_dec_line_special(Erule, Atype, TopType, Comp, DecInfObj, Ext),
+    Post =
+	fun({SaveBytes,Finish}) ->
+		{AccTerm,AccBytes} = Finish(),
+		#'ComponentType'{name=Cname} = Comp,
 		case DecInfObj of
-		    false -> % This is in a choice with typefield components
-			{Name,RestFieldNames} = 
-			    (Type#type.def)#'ObjectClassFieldType'.fieldname,
-
-			asn1ct_name:new(tmpterm),
-			asn1ct_name:new(reason),
-			emit([indent(2),"{",{curr,tmpterm},", ",{next,bytes},
-			      "} = ?RT_PER:decode_open_type(",{curr,bytes},
-			      ", []),",nl]),
-			emit([indent(2),"case (catch ObjFun(",
-			      {asis,Name},",",{curr,tmpterm},",telltype,",
-			      {asis,RestFieldNames},")) of", nl]),
-			emit([indent(4),"{'EXIT',",{curr,reason},"} ->",nl]),
-			emit([indent(6),"exit({'Type not ",
-			      "compatible with table constraint', ",
-			      {curr,reason},"});",nl]),
-			asn1ct_name:new(tmpterm),
-			emit([indent(4),"{",{curr,tmpterm},", _} ->",nl]),
-			emit([indent(6),"{",{asis,Cname},", {",{curr,tmpterm},", ",
-			      {next,bytes},"}}",nl]),
-			emit([indent(2),"end"]),
-			[];
-		    {"got objfun through args","ObjFun"} ->
-			%% this is when the generated code gots the
-			%% objfun though arguments on function
-			%% invocation.
-			if
-			    Ext == noext andalso Prop == mandatory ->
-				ok;
-			    true ->
-				asn1ct_name:new(tmpterm),
-				asn1ct_name:new(tmpbytes),
-				emit([nl,"    {",{curr,tmpterm},", ",{curr,tmpbytes},"} ="])
-			end,
-			{Name,RestFieldNames} = 
-			    (Type#type.def)#'ObjectClassFieldType'.fieldname,
-			emit(["?RT_PER:decode_open_type(",{curr,bytes},
-			      ", []),",nl]),
-			if
-			   Ext == noext andalso Prop == mandatory -> 
-				emit([{curr,term}," =",nl,"      "]);
-			    true ->
-				emit(["     {"])
-			end,
-			emit(["case (catch ObjFun(",{asis,Name},",",
-			      {curr,tmpterm},",telltype,",
-			      {asis,RestFieldNames},")) of", nl]),
-			emit(["    {'EXIT',",{curr,reason},"} ->",nl]),
-			emit([indent(6),"exit({'Type not ",
-			      "compatible with table constraint', ",
-			      {curr,reason},"});",nl]),
-			asn1ct_name:new(tmpterm),
-			emit([indent(4),"{",{curr,tmpterm},", _} ->",nl]),
-			emit([indent(6),{curr,tmpterm},nl]),
-			emit([indent(2),"end"]),
-			if
-			    Ext == noext andalso Prop == mandatory ->
-				ok;
-			    true ->
-				emit([",",nl,{curr,tmpbytes},"}"])
-			end,
-			[];
+		    {Cname,ObjSet} ->
+			ObjSetRef =
+			    case ObjSet of
+				{deep,OSName,_,_} ->
+				    OSName;
+				_ -> ObjSet
+			    end,
+			{AccTerm++[{ObjSetRef,Cname,
+				    asn1ct_gen:mk_var(asn1ct_name:curr(term))}],
+			 AccBytes++SaveBytes};
 		    _ ->
-			emit(["?RT_PER:decode_open_type(",{curr,bytes},
-			      ", [])"]),
-			RefedFieldName = 
-			    (Type#type.def)#'ObjectClassFieldType'.fieldname,
+			{AccTerm,AccBytes++SaveBytes}
+		end
+	end,
+    [Pre,Decode,Post].
+
+gen_dec_line_open_type({ext,Ep,_}, Pos) when Pos >= Ep ->
+    fun(St) ->
+	    emit(["begin",nl,"{TmpVal",Pos,",Trem",Pos,"} = ",
+		  "?RT_PER:decode_open_type(",
+		  {curr,bytes},", []),",nl,
+		  "{TmpValx",Pos,",_}="]),
+	    {"TmpVal" ++ integer_to_list(Pos),
+	     fun() ->
+		     emit([", {TmpValx",Pos,",Trem",Pos,"}",nl,"end"]),
+		     St
+	     end}
+    end;
+gen_dec_line_open_type(_, _) ->
+    fun(St) ->
+	    {asn1ct_gen:mk_var(asn1ct_name:curr(bytes)),
+	     fun() -> St end}
+    end.
 
-			[{Cname,RefedFieldName,
+gen_dec_line_special(_, {typefield,_}, _TopType, Comp,
+		     DecInfObj, Ext) ->
+    #'ComponentType'{name=Cname,typespec=Type,prop=Prop} = Comp,
+    fun({_BytesVar,PrevSt}) ->
+	    case DecInfObj of
+		false -> % This is in a choice with typefield components
+		    {Name,RestFieldNames} =
+			(Type#type.def)#'ObjectClassFieldType'.fieldname,
+
+		    asn1ct_name:new(tmpterm),
+		    asn1ct_name:new(reason),
+		    emit([indent(2),"{",{curr,tmpterm},", ",{next,bytes},
+			  "} = ?RT_PER:decode_open_type(",{curr,bytes},
+			  ", []),",nl]),
+		    emit([indent(2),"case (catch ObjFun(",
+			  {asis,Name},",",{curr,tmpterm},",telltype,",
+			  {asis,RestFieldNames},")) of", nl]),
+		    emit([indent(4),"{'EXIT',",{curr,reason},"} ->",nl]),
+		    emit([indent(6),"exit({'Type not ",
+			  "compatible with table constraint', ",
+			  {curr,reason},"});",nl]),
+		    asn1ct_name:new(tmpterm),
+		    emit([indent(4),"{",{curr,tmpterm},", _} ->",nl]),
+		    emit([indent(6),"{",{asis,Cname},", {",{curr,tmpterm},", ",
+			  {next,bytes},"}}",nl]),
+		    emit([indent(2),"end"]),
+		    {[],PrevSt};
+		{"got objfun through args","ObjFun"} ->
+		    %% this is when the generated code gots the
+		    %% objfun though arguments on function
+		    %% invocation.
+		    if
+			Ext == noext andalso Prop == mandatory ->
+			    ok;
+			true ->
+			    asn1ct_name:new(tmpterm),
+			    asn1ct_name:new(tmpbytes),
+			    emit([nl,"    {",{curr,tmpterm},", ",{curr,tmpbytes},"} ="])
+		    end,
+		    {Name,RestFieldNames} =
+			(Type#type.def)#'ObjectClassFieldType'.fieldname,
+		    emit(["?RT_PER:decode_open_type(",{curr,bytes},
+			  ", []),",nl]),
+		    if
+			Ext == noext andalso Prop == mandatory ->
+			    emit([{curr,term}," =",nl,"      "]);
+			true ->
+			    emit(["     {"])
+		    end,
+		    emit(["case (catch ObjFun(",{asis,Name},",",
+			  {curr,tmpterm},",telltype,",
+			  {asis,RestFieldNames},")) of", nl]),
+		    emit(["    {'EXIT',",{curr,reason},"} ->",nl]),
+		    emit([indent(6),"exit({'Type not ",
+			  "compatible with table constraint', ",
+			  {curr,reason},"});",nl]),
+		    asn1ct_name:new(tmpterm),
+		    emit([indent(4),"{",{curr,tmpterm},", _} ->",nl]),
+		    emit([indent(6),{curr,tmpterm},nl]),
+		    emit([indent(2),"end"]),
+		    if
+			Ext == noext andalso Prop == mandatory ->
+			    ok;
+			true ->
+			    emit([",",nl,{curr,tmpbytes},"}"])
+		    end,
+		    {[],PrevSt};
+		_ ->
+		    emit(["?RT_PER:decode_open_type(",{curr,bytes},
+			  ", [])"]),
+		    RefedFieldName =
+			(Type#type.def)#'ObjectClassFieldType'.fieldname,
+
+		    {[{Cname,RefedFieldName,
+		       asn1ct_gen:mk_var(asn1ct_name:curr(term)),
+		       asn1ct_gen:mk_var(asn1ct_name:curr(tmpterm)),
+		       Prop}],PrevSt}
+	    end
+    end;
+gen_dec_line_special(_, {objectfield,PrimFieldName1,PFNList}, _TopType,
+		     Comp, _DecInfObj, _Ext) ->
+    fun({_BytesVar,PrevSt}) ->
+	    emit(["?RT_PER:decode_open_type(",{curr,bytes},", [])"]),
+	    #'ComponentType'{name=Cname,prop=Prop} = Comp,
+	    SaveBytes = [{Cname,{PrimFieldName1,PFNList},
 			  asn1ct_gen:mk_var(asn1ct_name:curr(term)),
 			  asn1ct_gen:mk_var(asn1ct_name:curr(tmpterm)),
-			  get_components_prop()}]
-		end;
-	    {objectfield,PrimFieldName1,PFNList} ->
-		emit(["?RT_PER:decode_open_type(",{curr,bytes},", [])"]),
-		[{Cname,{PrimFieldName1,PFNList},
-		  asn1ct_gen:mk_var(asn1ct_name:curr(term)),
-		  asn1ct_gen:mk_var(asn1ct_name:curr(tmpterm)),
-		  get_components_prop()}];
-	    _ ->
-		CurrMod = get(currmod),
-		case asn1ct_gen:type(Atype) of
-		    #'Externaltypereference'{module=CurrMod,type=EType} ->
-			emit({"'dec_",EType,"'(",BytesVar,",telltype)"});
-		    #'Externaltypereference'{module=Mod,type=EType} ->
-			emit({"'",Mod,"':'dec_",EType,"'(",BytesVar,
-			      ",telltype)"});
-		    {primitive,bif} ->
-			case Atype of
-			   {fixedtypevaluefield,_,Btype} ->
-				Ctgenmod:gen_dec_prim(Erule,Btype,
-						      BytesVar);
-			    _ ->
-				Ctgenmod:gen_dec_prim(Erule,Type,
-						      BytesVar)
-			end;
-		    'ASN1_OPEN_TYPE' ->
-			case Type#type.def of
-			    #'ObjectClassFieldType'{type=OpenType} ->
-				Ctgenmod:gen_dec_prim(Erule,#type{def=OpenType},
-						      BytesVar);
-			    _ ->
-				Ctgenmod:gen_dec_prim(Erule,Type,
-						      BytesVar)
-			end;
-		    #typereference{val=Dname} ->
-			emit({"'dec_",Dname,"'(",BytesVar,",telltype)"});
-		    {notype,_} ->
-			emit({"'dec_",Atype,"'(",BytesVar,",telltype)"});
-		    {constructed,bif} ->
-			NewTypename = [Cname|TopType],
-			case Type#type.tablecinf of
-			    [{objfun,_}|_R] ->
-				emit({"'dec_",asn1ct_gen:list2name(NewTypename),
-				      "'(",BytesVar,", telltype, ObjFun)"});
-			    _ ->
-				emit({"'dec_",asn1ct_gen:list2name(NewTypename),
-				      "'(",BytesVar,", telltype)"})
-			end
-		end,
-		case DecInfObj of
-		    {Cname,{_,OSet,UniqueFName,ValIndex}} ->
-			Term = asn1ct_gen:mk_var(asn1ct_name:curr(term)),
-			ValueMatch = value_match(ValIndex,Term),
-			{ObjSetMod,ObjSetName} =
-			    case OSet of
-				{M,O} -> {{asis,M},O};
-				_ -> {"?MODULE",OSet}
-			    end,
-			emit({",",nl,"ObjFun = ",ObjSetMod,
-			      ":'getdec_",ObjSetName,"'(",
-			      {asis,UniqueFName},", ",ValueMatch,")"});
-		    _ ->
-			ok
-		end,
-		[]
-	end,
-    case Ext of 
-	{ext,Ep2,_} when Pos >= Ep2 ->
-	    emit([", {TmpValx",Pos,",Trem",Pos,"}",nl,"end"]);
-	_ -> true
-    end,
-    %% Prepare return value
+			  Prop}],
+	    {SaveBytes,PrevSt}
+    end;
+gen_dec_line_special(Erule, Atype, TopType, Comp, DecInfObj, _Ext) ->
+    case gen_dec_line_other(Erule, Atype, TopType, Comp) of
+	Fun when is_function(Fun, 1) ->
+	    fun({BytesVar,PrevSt}) ->
+		    Fun(BytesVar),
+		    gen_dec_line_dec_inf(Comp, DecInfObj),
+		    {[],PrevSt}
+	    end
+    end.
+
+gen_dec_line_dec_inf(Comp, DecInfObj) ->
+    #'ComponentType'{name=Cname} = Comp,
     case DecInfObj of
-	{Cname,ObjSet} ->
-	    ObjSetRef =
-		case ObjSet of
-		    {deep,OSName,_,_} ->
-			OSName;
-		    _ -> ObjSet
+	{Cname,{_,OSet,UniqueFName,ValIndex}} ->
+	    Term = asn1ct_gen:mk_var(asn1ct_name:curr(term)),
+	    ValueMatch = value_match(ValIndex,Term),
+	    {ObjSetMod,ObjSetName} =
+		case OSet of
+		    {M,O} -> {{asis,M},O};
+		    _ -> {"?MODULE",OSet}
 		end,
-	    {[{ObjSetRef,Cname,asn1ct_gen:mk_var(asn1ct_name:curr(term))}],
-	     SaveBytes};
+	    emit({",",nl,"ObjFun = ",ObjSetMod,
+		  ":'getdec_",ObjSetName,"'(",
+		  {asis,UniqueFName},", ",ValueMatch,")"});
 	_ ->
-	    {[],SaveBytes}
+	    ok
+    end.
+
+gen_dec_line_other(Erule, Atype, TopType, Comp) ->
+    #'ComponentType'{name=Cname,typespec=Type} = Comp,
+    CurrMod = get(currmod),
+    Ctgenmod = asn1ct_gen:ct_gen_module(Erule),
+    case asn1ct_gen:type(Atype) of
+	#'Externaltypereference'{module=CurrMod,type=EType} ->
+	    fun(BytesVar) ->
+		    emit({"'dec_",EType,"'(",BytesVar,",telltype)"})
+	    end;
+	#'Externaltypereference'{module=Mod,type=EType} ->
+	    fun(BytesVar) ->
+		    emit({"'",Mod,"':'dec_",EType,"'(",BytesVar,
+			  ",telltype)"})
+	    end;
+	{primitive,bif} ->
+	    case Atype of
+		{fixedtypevaluefield,_,Btype} ->
+		    fun(BytesVar) ->
+			    Ctgenmod:gen_dec_prim(Erule, Btype,
+						  BytesVar)
+		    end;
+		_ ->
+		    fun(BytesVar) ->
+			    Ctgenmod:gen_dec_prim(Erule, Type,
+						  BytesVar)
+		    end
+	    end;
+	'ASN1_OPEN_TYPE' ->
+	    case Type#type.def of
+		#'ObjectClassFieldType'{type=OpenType} ->
+		    fun(BytesVar) ->
+			    Ctgenmod:gen_dec_prim(Erule,#type{def=OpenType},
+						  BytesVar)
+		    end;
+		_ ->
+		    fun(BytesVar) ->
+			    Ctgenmod:gen_dec_prim(Erule, Type,
+						  BytesVar)
+		    end
+	    end;
+	#typereference{val=Dname} ->
+	    fun(BytesVar) ->
+		    emit({"'dec_",Dname,"'(",BytesVar,",telltype)"})
+	    end;
+	{notype,_} ->
+	    fun(BytesVar) ->
+		    emit({"'dec_",Atype,"'(",BytesVar,",telltype)"})
+	    end;
+	{constructed,bif} ->
+	    NewTypename = [Cname|TopType],
+	    case Type#type.tablecinf of
+		[{objfun,_}|_R] ->
+		    fun(BytesVar) ->
+			    emit({"'dec_",asn1ct_gen:list2name(NewTypename),
+				  "'(",BytesVar,", telltype, ObjFun)"})
+		    end;
+		_ ->
+		    fun(BytesVar) ->
+			    emit({"'dec_",asn1ct_gen:list2name(NewTypename),
+				  "'(",BytesVar,", telltype)"})
+		    end
+	    end
     end.
 
+
 gen_enc_choice(Erule,TopType,CompList,Ext) ->
     gen_enc_choice_tag(CompList, [], Ext),
     emit({com,nl}),
@@ -1611,18 +1750,12 @@ wrap_extensionAdditionGroups([],_,Acc,_,_) ->
     lists:reverse(Acc).
 
 
-wrap_gen_dec_line(Erule,C,TopType,Cname,Type,Pos,DIO,Ext) ->
+wrap_gen_dec_line(Erule,C,TopType,_Cname,_Type,Pos,DIO,Ext) ->
     put(component_type,{true,C}),
-    gen_dec_line(Erule,TopType,Cname,Type,Pos,DIO,Ext,mandatory),
+    gen_dec_line(Erule, TopType, C#'ComponentType'{prop=mandatory},
+		 Pos, DIO, Ext),
     erase(component_type).
 
-get_components_prop() ->
-    case get(component_type) of
-	undefined ->
-	    mandatory;
-	{true,#'ComponentType'{prop=Prop}} -> Prop
-    end.
-
 			  
 value_match(Index,Value) when is_atom(Value) ->
     value_match(Index,atom_to_list(Value));