maps support and downward compatibility

.travis.yml

@@ -2,6 +2,7 @@ language: erlang
 otp_release:
 # Test on all supported releases accepted by the `require_otp_vsn` in rebar.config
 #  - 17.0 not yet available on travis!
+  - 17.3
   - R16B03-1
 #  - R16B03 this version is broken!
   - R16B02

rebar.config

@@ -4,7 +4,10 @@
 %% also accept OTP v17, altough it may not work properly on that release yet..
 {require_otp_vsn, "R15B0[^1]|R16B$|R16B[^0]|R16B0[^3]|R16B03-1|17"}.
 
-{erl_opts, [debug_info]}.
+{erl_opts, [
+            debug_info,
+            {platform_define, "^[0-9]+", maps_available} 
+           ]}.
 {yrl_opts, [{includefile, "include/erlydtl_preparser.hrl"}]}.
 
 {eunit_opts,

src/erlydtl_runtime.erl

@@ -49,6 +49,84 @@ adjust_index(Key, Off, Opt, Options) when is_list(Options) ->
     end;
 adjust_index(Key, _Off, _Opt, _Options) -> Key.
 
+-ifdef(maps_available).
+find_value(_, undefined) ->
+    undefined;
+find_value(Key, Fun) when is_function(Fun, 1) ->
+    Fun(Key);
+find_value(Key, Map) when is_atom(Key), is_map(Map) ->
+    case maps:find(Key, Map) of
+        error           -> find_value(atom_to_list(Key), Map);
+        {ok, Value}     -> Value
+    end;
+find_value(Key, Map) when is_list(Key), is_map(Map) ->
+    case maps:find(Key, Map) of
+        error           -> find_value(list_to_binary(Key), Map);
+        {ok, Value}     -> Value
+    end;
+find_value(Key, Map) when is_binary(Key), is_map(Map) ->
+    case maps:find(Key, Map) of
+        error           -> undefined;
+        {ok, Value}     -> Value
+    end;
+find_value(Key, L) when is_atom(Key), is_list(L) ->
+    case lists:keyfind(Key, 1, L) of
+        false           -> find_value(atom_to_list(Key), L);
+        {Key, Value}    -> Value
+    end;
+find_value(Key, L) when is_list(Key), is_list(L) ->
+    case lists:keyfind(Key, 1, L) of
+        false           -> find_value(list_to_binary(Key), L);
+        {Key, Value}    -> Value
+    end;
+find_value(Key, L) when is_binary(Key), is_list(L) ->
+    case lists:keyfind(Key, 1, L) of
+        false           -> undefined;
+        {Key, Value}    -> Value
+    end;
+find_value(Key, L) when is_integer(Key), is_list(L) ->
+    if Key =< length(L) -> lists:nth(Key, L);
+       true -> undefined
+    end;
+find_value(Key, {GBSize, GBData}) when is_integer(GBSize) ->
+    case gb_trees:lookup(Key, {GBSize, GBData}) of
+        {value, Val} ->
+            Val;
+        _ ->
+            undefined
+    end;
+find_value(Key, Tuple) when is_tuple(Tuple) ->
+    case element(1, Tuple) of
+        dict ->
+            case dict:find(Key, Tuple) of
+                {ok, Val} ->
+                    Val;
+                _ ->
+                    undefined
+            end;
+        _ when is_integer(Key) ->
+            if Key =< size(Tuple) -> element(Key, Tuple);
+               true -> undefined
+            end;
+        Module ->
+            case lists:member({Key, 1}, Module:module_info(exports)) of
+                true ->
+                    case Tuple:Key() of
+                        Val when is_tuple(Val) ->
+                            case element(1, Val) of
+                                'Elixir.Ecto.Associations.BelongsTo' -> Val:get();
+                                'Elixir.Ecto.Associations.HasOne' -> Val:get();
+                                _ -> Val
+                            end;
+                        Val -> Val
+                    end;
+                _ ->
+                    undefined
+            end
+    end;
+find_value(_, _) ->
+    undefined.
+-else.
 find_value(_, undefined) ->
     undefined;
 find_value(Key, Fun) when is_function(Fun, 1) ->
@@ -110,6 +188,7 @@ find_value(Key, Tuple) when is_tuple(Tuple) ->
     end;
 find_value(_, _) ->
     undefined.
+-endif.
 
 fetch_value(Key, Data, Options) ->
     fetch_value(Key, Data, Options, []).