Add JSON Schema draft discrimination

Track the declared JSON Schema dialect in the validator state and validate
dialect-sensitive constructs before applying a schema.

Recognize draft-04, draft-06, draft-07, 2019-09, and 2020-12, while preserving
the existing compatibility behavior for schemas without a $schema declaration.
Reject unknown dialects and known keywords or forms that do not belong to the
declared draft.

Implement draft-specific exclusive bound semantics, boolean-schema rules, and
array vocabulary differences. Document the behavior and add coverage for all
supported drafts.

The generated Gajumaru draft-04 configuration schema passes the new checks.

README.md

@@ -11,6 +11,9 @@ management subsystem. It is based on JSON-Schema, and includes, among other thin
 * Caching of the user config (and schema) as persistent terms
 * Fast config lookups using key paths
 * Lookups can handle both schema defaults and user-provided defaults
+* Optional type coercion during validation
+* Optional conversion of enums to atoms
+* Optional extensions with custom validator funs
 
 ## JSON-Schema validator
 
@@ -22,6 +25,19 @@ is still incomplete. `"definitions"` and `"$ref"` properties are recognized.
 As almost anything is theoretically possible with JSON-Schema,
 there are surely other things that are unsupported.
 
+### Schema dialects
+
+If a schema declares `"$schema"`, the validator recognizes draft-04,
+draft-06, draft-07, 2019-09 and 2020-12. It rejects unknown dialects and
+known constructs that do not belong to the declared draft. This currently
+includes boolean-schema availability, keyword introduction dates,
+draft-specific exclusive-bound syntax and the 2020-12 array vocabulary.
+
+Schemas without `"$schema"` retain the historical compatibility behavior,
+which accepts the supported keyword subset without assigning it to one
+particular JSON-Schema draft. Dialect recognition does not yet imply full
+conformance with every keyword in that draft.
+
 ### All standard data types
 
 * `"null"`
@@ -78,3 +94,63 @@ there are surely other things that are unsupported.
 * `"merge"`   (for objects, keeps and/or updates existing values)
 * `"suggest"` (adds value if not already present)
 
+### Custom validation options
+
+Using `gmconfig_schema_utils:validate(Json, Schema, Opts)`, a few options are supported
+to further enhance the validation (`Opts` is of type `map()`):
+
+`coerce => boolean()` converts strings to integers, null and booleans when needed.
+`enums_to_atoms => boolean()` converts enum strings to atoms
+`extensions => map()` supports mapping `x-...` properties to custom validators.
+
+#### Validator extensions
+
+See the following test case:
+```erlang
+t_nested_refs() ->
+    S = read("data/nested_refs_schema.json"),
+    F = fun(Str, #{<<"tags">> := Tags}) ->
+                true = lists:any(
+                         fun(T) ->
+                                 nomatch =/= string:prefix(Str, T)
+                         end, Tags)
+        end,
+    Opts = #{extensions => #{<<"x-serialization">> => F}},
+    Vs = #{<<"tx">> => #{<<"from">> => <<"ak_good">>}},
+    Vf = #{<<"tx">> => #{<<"from">> => <<"ac_bad">>}},
+    validate(Vs, S, Opts),
+    fails(Vf, S, Opts, #{e => failing_schemas}),
+    ok.
+```
+This simulates an encoding extension, where the example fun here simply checks
+if tags specified under the `x-serialization` property are prefixes of the 
+given string value.
+
+In the test schema, we can see the following definition:
+```json
+        "properties": {
+            "from": {
+                "allOf": [
+                    { "$ref": "#/components/schemas/Pubkey" },
+                    { "x-serialization": {
+                        "tags": ["ak"]
+                    }}
+                ]
+            }
+        }
+...
+    "Pubkey": {
+        "type": "string",
+        "x-serialization": {
+            "tags": ["ak", "ct"]
+        }
+```
+
+Whenever the validator encounters an `x-...` property mapped to a validator fun,
+this fun is called with the value and the schema part of the property. The return
+value of the fun is ignored, and any normal return is treated as a validation success.
+
+The example illustrates a common pattern in OpenAPI specs, where entity references are
+used extensively. The `Pubkey` data type can have a more general `x-serialization`
+definition, where multiple key types are accepted, whereas a specialized use of the
+type can narrow the scope by accepting only a subset of the possible types.

ebin/gmconfig.app

@@ -1,6 +1,6 @@
 {application,gmconfig,
              [{description,"Configuration management support"},
-              {vsn,"0.1.0"},
+              {vsn,"0.2.0"},
               {registered,[]},
               {applications,[kernel,stdlib,setup]},
               {env,[]},

src/gmconfig.app.src

@@ -1,7 +1,7 @@
 %% -*- mode: erlang; erlang-indent-level: 4; indent-tabs-mode: nil -*-
 {application, gmconfig,
  [{description, "Gajumaru configuration management support"},
-  {vsn, "0.1.0"},
+  {vsn, "zomp"},
   {registered, []},
   {applications,
    [

src/gmconfig.app.src.script

@@ -0,0 +1,14 @@
+%% -*- erlang-mode; erlang-indent-level: 4; indent-tabs-mode: nil -*-
+
+[{application, Name, Opts}] = CONFIG.
+case lists:keyfind(vsn, 1, Opts) of
+    {vsn, "zomp"} ->
+        ZompMetaF = filename:join(filename:dirname(filename:dirname(SCRIPT)), "zomp.meta"),
+        {ok, ZMeta} = file:consult(ZompMetaF),
+        {_, {_, _, {Vmaj,Vmin,Vpatch}}} = lists:keyfind(package_id, 1, ZMeta),
+        VsnStr = unicode:characters_to_list(io_lib:fwrite("~w.~w.~w", [Vmaj, Vmin, Vpatch])),
+        Opts1 = lists:keyreplace(vsn, 1, Opts, {vsn, VsnStr}),
+        [{application, Name, Opts1}];
+    _ ->
+        CONFIG
+end.

src/gmconfig.erl

@@ -7,6 +7,7 @@
 %%% @end
 %%%-------------------------------------------------------------------
 -module(gmconfig).
+-vsn("0.2.0").
 
 -export([get_env/2, get_env/3]).
 
@@ -38,6 +39,7 @@
 -export([update_config/1,
          update_config/2,
          update_config/3,
+         pure_update_config/3,
          silent_update_config/1,
          delete_config_value/1,
          suggest_config/2,
@@ -99,7 +101,7 @@ mock_config() ->
 
 mock_config(Cfg) ->
     ensure_schema_loaded(),
-    store(Cfg, _Notify = false, _Mode = silent).
+    store(Cfg, _Mode = silent).
 
 unmock_config() ->
     gmconfig_schema_utils:clear(),
@@ -443,7 +445,20 @@ just_schema_keys(_) ->
 schema_default(Path) when is_list(Path) ->
     schema_default(Path, schema()).
 
-schema_default(Path, Schema) ->
+schema_default(Path0, Schema) ->
+    %% There is a way to navigate through an array of objects
+    %% essentially locating the desired object in the array, and then
+    %% continuing into one of its properties. This is specified in
+    %% a path exression as `{PropName, Value, ThenProp}`.
+    %% If the query expects us to fall back to the schema default, then
+    %% we must adapt the path accordingly.
+    %%
+    %% find_config([<<"system">>, <<"plugins">>,
+    %%              {<<"name">>, PluginName, <<"config">>} | Key],
+    %%             [user_config, schema_default]);
+    Path = lists:flatmap(fun({_, _,P}) -> [<<"items">>, P];
+                            (P) -> [P]
+                         end, Path0),
     case schema(Path, Schema) of
         undefined -> undefined;
         {ok, Tree} ->
@@ -878,6 +893,12 @@ update_config(Map, ConfigMap, Mode) ->
     pt_set_config(ConfigMap1),
     ok.
 
+pure_update_config(Map, ConfigMap, Schema) ->
+    NewCfg = gmconfig_schema_utils:merge(Map, ConfigMap, Schema),
+    check_validation([validate_(NewCfg, Schema)],
+                     [NewCfg], pure_update_config, silent),
+    NewCfg.
+
 export_config() ->
     Config = pt_get_config(),
     JSON = json:format(Config, #{indent => 2}),

src/gmconfig_schema_helpers.erl

@@ -1,4 +1,5 @@
 -module(gmconfig_schema_helpers).
+-vsn("0.2.0").
 
 -export(
    [

src/gmconfig_schema_utils.erl

@@ -1,5 +1,6 @@
 %% -*- mode: erlang; erlang-indent-level: 4; indent-tabs-mode: nil -*-
 -module(gmconfig_schema_utils).
+-vsn("0.2.0").
 
 
 -export([get_config/0,
@@ -7,20 +8,28 @@
          get_schema/0,
          get_schema/1,   %% (Default)
          set_schema/1,
+         use_schema/1,
+         use_schema/2,
          schema/1,       %% (Path)
          schema/2,       %% (Path, Schema)
          schema/3,       %% (Path, Schema, Opts)
          clear/0,
-         expand_schema/1]).
+         expand_ref/2,
+         expand_schema/1,    %% (Schema)                 %% expand whole schema
+         expand_schema/2]).  %% (SubSchema, RootSchema)
 
 -export([ update_config/1  %% (Map) -> ok
         , merge/2          %% (Item1, Item2) -> Item3
         , merge/3          %% (Item1, Item2, Schema) -> Item3
         , valid/1          %% (Item) -> Item | error()
         , valid/2          %% (Item, Schema) -> Item | error()
+        , validate/3       %% (Item, Schema, Opts) -> Item | error().
         ]).
 -export([in_properties/2]).
 
+-export([normalize/0,
+         normalize/1]).
+
 -type json_string() :: binary().
 -type json_int() :: integer().
 -type json_num() :: number().
@@ -37,15 +46,34 @@
 
 -type schema() :: json().
 
+-type draft() :: compatibility
+               | draft4
+               | draft6
+               | draft7
+               | draft2019_09
+               | draft2020_12.
+
+-type ext_fun() :: fun( (json(), schema()) -> any() | no_return() ).
+-type extensions() :: #{ binary() => ext_fun() }.
+-type options() :: #{coerce => boolean(),
+                     enum_to_atom => boolean(),
+                     extensions => extensions() }.
+
 -record(st, { s :: schema()  %% schema
             , r :: schema()  %% root schema
+            , draft = compatibility :: draft()
             , p = []
             , a = []         %% annotations
             , v :: json() | undefined  %% value
+            , d = undefined :: list() | 'undefined'  %% dynamic eval
+            , opts = #{} :: options()
             }).
 
 -type st() :: #st{}.
 
+-export_type([ schema/0, json/0 ]).
+
+-include_lib("kernel/include/logger.hrl").
 
 -spec set_schema(schema()) -> ok.
 set_schema(Schema) ->
@@ -67,6 +95,313 @@ get_schema() ->
 get_schema(Default) ->
     persistent_term:get({?MODULE, '$schema'}, Default).
 
+-spec use_schema(schema() | st()) -> st().
+use_schema(#st{} = St) -> St;
+use_schema(S)          -> new_state(S, S).
+
+use_schema(Schema, RootSchema) ->
+    new_state(Schema, RootSchema).
+
+normalize() ->
+    normalize(get_schema()).
+
+normalize(S) when is_map(S) ->
+    #{bin_key(K) => normalize(V) || K := V <- S};
+normalize(S) when is_list(S) ->
+    [normalize(Sx) || Sx <- S];
+normalize(S) ->
+    S.
+
+bin_key(A) when is_atom(A)   -> atom_to_binary(A, utf8);
+bin_key(B) when is_binary(B) -> B.
+
+new_state(Schema, RootSchema) ->
+    Draft = schema_draft(RootSchema, compatibility, []),
+    case Draft of
+        compatibility -> ok;
+        _ -> check_schema(normalize(RootSchema), Draft, [])
+    end,
+    #st{s = Schema, r = RootSchema, draft = Draft}.
+
+schema_draft(Schema, Inherited, Path) when is_map(Schema) ->
+    case schema_value(<<"$schema">>, '$schema', Schema) of
+        undefined ->
+            Inherited;
+        URI ->
+            draft_from_uri(URI, Path ++ [<<"$schema">>])
+    end;
+schema_draft(_, Inherited, _) ->
+    Inherited.
+
+schema_value(BinaryKey, AtomKey, Schema) ->
+    case maps:find(BinaryKey, Schema) of
+        {ok, Value} -> Value;
+        error -> maps:get(AtomKey, Schema, undefined)
+    end.
+
+draft_from_uri(URI, _) when URI =:= <<"http://json-schema.org/draft-04/schema#">>;
+                            URI =:= <<"https://json-schema.org/draft-04/schema#">>;
+                            URI =:= <<"http://json-schema.org/draft-04/schema">>;
+                            URI =:= <<"https://json-schema.org/draft-04/schema">> ->
+    draft4;
+draft_from_uri(URI, _) when URI =:= <<"http://json-schema.org/draft-06/schema#">>;
+                            URI =:= <<"https://json-schema.org/draft-06/schema#">>;
+                            URI =:= <<"http://json-schema.org/draft-06/schema">>;
+                            URI =:= <<"https://json-schema.org/draft-06/schema">> ->
+    draft6;
+draft_from_uri(URI, _) when URI =:= <<"http://json-schema.org/draft-07/schema#">>;
+                            URI =:= <<"https://json-schema.org/draft-07/schema#">>;
+                            URI =:= <<"http://json-schema.org/draft-07/schema">>;
+                            URI =:= <<"https://json-schema.org/draft-07/schema">> ->
+    draft7;
+draft_from_uri(URI, _) when URI =:= <<"http://json-schema.org/draft/2019-09/schema#">>;
+                            URI =:= <<"https://json-schema.org/draft/2019-09/schema#">>;
+                            URI =:= <<"http://json-schema.org/draft/2019-09/schema">>;
+                            URI =:= <<"https://json-schema.org/draft/2019-09/schema">> ->
+    draft2019_09;
+draft_from_uri(URI, _) when URI =:= <<"http://json-schema.org/draft/2020-12/schema#">>;
+                            URI =:= <<"https://json-schema.org/draft/2020-12/schema#">>;
+                            URI =:= <<"http://json-schema.org/draft/2020-12/schema">>;
+                            URI =:= <<"https://json-schema.org/draft/2020-12/schema">> ->
+    draft2020_12;
+draft_from_uri(URI, Path) ->
+    schema_error(unsupported_schema_draft,
+                 #{draft_uri => URI, p => Path}).
+
+check_schema(_, compatibility, _) ->
+    ok;
+check_schema(Schema, draft4 = Draft, Path) when is_boolean(Schema) ->
+    case lists:reverse(Path) of
+        [<<"additionalProperties">> | _] -> ok;
+        [<<"additionalItems">> | _] -> ok;
+        _ ->
+            schema_error(boolean_schema_not_in_draft,
+                         #{draft => Draft, p => Path})
+    end;
+check_schema(Schema, _Draft, _Path) when is_boolean(Schema) ->
+    ok;
+check_schema(Schema, Draft0, Path) when is_map(Schema) ->
+    Draft = schema_draft(Schema, Draft0, Path),
+    maps:foreach(
+      fun(Keyword0, Value) ->
+              Keyword = bin_key(Keyword0),
+              check_keyword(Keyword, Value, Draft, Path ++ [Keyword])
+      end, Schema),
+    check_schema_shape(Schema, Draft, Path),
+    check_subschemas(Schema, Draft, Path);
+check_schema(_, Draft, Path) ->
+    schema_error(invalid_schema,
+                 #{draft => Draft, p => Path}).
+
+check_keyword(Keyword, Value, Draft, Path) ->
+    case minimum_draft(Keyword) of
+        undefined -> ok;
+        Minimum ->
+            case draft_rank(Draft) >= draft_rank(Minimum) of
+                true -> ok;
+                false ->
+                    schema_error(keyword_not_in_draft,
+                                 #{draft => Draft,
+                                   keyword => Keyword,
+                                   introduced_in => Minimum,
+                                   p => Path})
+            end
+    end,
+    case maximum_draft(Keyword) of
+        undefined -> ok;
+        Maximum ->
+            case draft_rank(Draft) =< draft_rank(Maximum) of
+                true -> ok;
+                false ->
+                    schema_error(keyword_not_in_draft,
+                                 #{draft => Draft,
+                                   keyword => Keyword,
+                                   last_supported_in => Maximum,
+                                   p => Path})
+            end
+    end,
+    check_keyword_shape(Keyword, Value, Draft, Path).
+
+minimum_draft(<<"$id">>) -> draft6;
+minimum_draft(<<"const">>) -> draft6;
+minimum_draft(<<"contains">>) -> draft6;
+minimum_draft(<<"propertyNames">>) -> draft6;
+minimum_draft(<<"examples">>) -> draft6;
+minimum_draft(<<"$comment">>) -> draft7;
+minimum_draft(<<"if">>) -> draft7;
+minimum_draft(<<"then">>) -> draft7;
+minimum_draft(<<"else">>) -> draft7;
+minimum_draft(<<"writeOnly">>) -> draft7;
+minimum_draft(<<"contentMediaType">>) -> draft7;
+minimum_draft(<<"contentEncoding">>) -> draft7;
+minimum_draft(<<"$defs">>) -> draft2019_09;
+minimum_draft(<<"$anchor">>) -> draft2019_09;
+minimum_draft(<<"$recursiveAnchor">>) -> draft2019_09;
+minimum_draft(<<"$recursiveRef">>) -> draft2019_09;
+minimum_draft(<<"dependentRequired">>) -> draft2019_09;
+minimum_draft(<<"dependentSchemas">>) -> draft2019_09;
+minimum_draft(<<"unevaluatedItems">>) -> draft2019_09;
+minimum_draft(<<"unevaluatedProperties">>) -> draft2019_09;
+minimum_draft(<<"minContains">>) -> draft2019_09;
+minimum_draft(<<"maxContains">>) -> draft2019_09;
+minimum_draft(<<"contentSchema">>) -> draft2019_09;
+minimum_draft(<<"$dynamicAnchor">>) -> draft2020_12;
+minimum_draft(<<"$dynamicRef">>) -> draft2020_12;
+minimum_draft(<<"prefixItems">>) -> draft2020_12;
+minimum_draft(_) -> undefined.
+
+maximum_draft(<<"additionalItems">>) -> draft2019_09;
+maximum_draft(_) -> undefined.
+
+draft_rank(draft4) -> 4;
+draft_rank(draft6) -> 6;
+draft_rank(draft7) -> 7;
+draft_rank(draft2019_09) -> 8;
+draft_rank(draft2020_12) -> 9.
+
+check_keyword_shape(<<"exclusiveMinimum">>, Value, draft4, Path) ->
+    require_type(fun is_boolean/1, Value, draft4, Path);
+check_keyword_shape(<<"exclusiveMaximum">>, Value, draft4, Path) ->
+    require_type(fun is_boolean/1, Value, draft4, Path);
+check_keyword_shape(<<"exclusiveMinimum">>, Value, Draft, Path) ->
+    require_type(fun is_number/1, Value, Draft, Path);
+check_keyword_shape(<<"exclusiveMaximum">>, Value, Draft, Path) ->
+    require_type(fun is_number/1, Value, Draft, Path);
+check_keyword_shape(<<"items">>, Value, draft2020_12, Path)
+  when is_list(Value) ->
+    schema_error(keyword_value_not_in_draft,
+                 #{draft => draft2020_12,
+                   keyword => <<"items">>,
+                   p => Path});
+check_keyword_shape(_, _, _, _) ->
+    ok.
+
+check_schema_shape(Schema, draft4, Path) ->
+    check_exclusive_bound(Schema, <<"exclusiveMinimum">>, <<"minimum">>,
+                          draft4, Path),
+    check_exclusive_bound(Schema, <<"exclusiveMaximum">>, <<"maximum">>,
+                          draft4, Path);
+check_schema_shape(_, _, _) ->
+    ok.
+
+check_exclusive_bound(Schema, Exclusive, Bound, Draft, Path) ->
+    case {maps:find(Exclusive, Schema), maps:is_key(Bound, Schema)} of
+        {{ok, _}, false} ->
+            schema_error(missing_keyword_for_draft,
+                         #{draft => Draft,
+                           keyword => Exclusive,
+                           required_keyword => Bound,
+                           p => Path ++ [Exclusive]});
+        _ ->
+            ok
+    end.
+
+require_type(Predicate, Value, Draft, Path) ->
+    case Predicate(Value) of
+        true -> ok;
+        false ->
+            schema_error(keyword_value_not_in_draft,
+                         #{draft => Draft, p => Path, value => Value})
+    end.
+
+check_subschemas(Schema, Draft, Path) ->
+    check_schema_values(
+      [<<"additionalProperties">>, <<"additionalItems">>, <<"contains">>,
+       <<"propertyNames">>, <<"not">>, <<"if">>, <<"then">>, <<"else">>,
+       <<"unevaluatedProperties">>, <<"unevaluatedItems">>,
+       <<"contentSchema">>],
+      Schema, Draft, Path),
+    check_schema_arrays(
+      [<<"allOf">>, <<"anyOf">>, <<"oneOf">>, <<"prefixItems">>],
+      Schema, Draft, Path),
+    check_schema_maps(
+      [<<"properties">>, <<"patternProperties">>, <<"definitions">>,
+       <<"$defs">>, <<"dependentSchemas">>],
+      Schema, Draft, Path),
+    check_schema_items(Schema, Draft, Path),
+    check_dependencies(Schema, Draft, Path).
+
+check_schema_values(Keys, Schema, Draft, Path) ->
+    lists:foreach(
+      fun(Key) ->
+              case maps:find(Key, Schema) of
+                  {ok, SubSchema} ->
+                      check_schema(SubSchema, Draft, Path ++ [Key]);
+                  error ->
+                      ok
+              end
+      end, Keys).
+
+check_schema_arrays(Keys, Schema, Draft, Path) ->
+    lists:foreach(
+      fun(Key) ->
+              case maps:find(Key, Schema) of
+                  {ok, SubSchemas} when is_list(SubSchemas) ->
+                      check_schema_list(SubSchemas, Draft, Path ++ [Key], 0);
+                  {ok, Value} ->
+                      schema_error(invalid_schema,
+                                   #{draft => Draft,
+                                     keyword => Key,
+                                     value => Value,
+                                     p => Path ++ [Key]});
+                  error ->
+                      ok
+              end
+      end, Keys).
+
+check_schema_list([Schema | Schemas], Draft, Path, Index) ->
+    check_schema(Schema, Draft, Path ++ [Index]),
+    check_schema_list(Schemas, Draft, Path, Index + 1);
+check_schema_list([], _, _, _) ->
+    ok.
+
+check_schema_maps(Keys, Schema, Draft, Path) ->
+    lists:foreach(
+      fun(Key) ->
+              case maps:find(Key, Schema) of
+                  {ok, SubSchemas} when is_map(SubSchemas) ->
+                      maps:foreach(
+                        fun(Name, SubSchema) ->
+                                check_schema(SubSchema, Draft,
+                                             Path ++ [Key, Name])
+                        end, SubSchemas);
+                  {ok, Value} ->
+                      schema_error(invalid_schema,
+                                   #{draft => Draft,
+                                     keyword => Key,
+                                     value => Value,
+                                     p => Path ++ [Key]});
+                  error ->
+                      ok
+              end
+      end, Keys).
+
+check_schema_items(Schema, Draft, Path) ->
+    case maps:find(<<"items">>, Schema) of
+        {ok, Items} when is_list(Items) ->
+            check_schema_list(Items, Draft, Path ++ [<<"items">>], 0);
+        {ok, Items} ->
+            check_schema(Items, Draft, Path ++ [<<"items">>]);
+        error ->
+            ok
+    end.
+
+check_dependencies(Schema, Draft, Path) ->
+    case maps:find(<<"dependencies">>, Schema) of
+        {ok, Dependencies} when is_map(Dependencies) ->
+            maps:foreach(
+              fun(_, Dependency) when is_list(Dependency) -> ok;
+                 (Name, Dependency) ->
+                      check_schema(Dependency, Draft,
+                                   Path ++ [<<"dependencies">>, Name])
+              end, Dependencies);
+        _ ->
+            ok
+    end.
+
+schema_error(Reason, Details) ->
+    error(Details#{e => Reason}).
+
 clear() ->
     persistent_term:erase({?MODULE,'$schema'}),
     persistent_term:erase({?MODULE,'$config'}),
@@ -76,8 +411,7 @@ clear() ->
 update_config(Cfg) ->
     OldCfg = get_config(),
     Schema = get_schema(),
-    Res = merge(Cfg, OldCfg, #st{s = Schema,
-                                 r = Schema }),
+    Res = merge(Cfg, OldCfg, Schema),
     set_config(Res),
     Res.
 
@@ -89,7 +423,7 @@ merge(A, B) ->
 merge(A, B, #st{} = St) ->
     merge_(A, B, St);
 merge(A, B, Schema) ->
-    merge_(A, B, #st{s = Schema, r = Schema}).
+    merge_(A, B, new_state(Schema, Schema)).
 
 %% Neither the JSON spec or the JSON-Schema spec are very helpful
 %% regarding what takes precedence if dynamically evaluated parts
@@ -138,12 +472,12 @@ schema_get(_, _, Default) ->
 
 %% let us pattern-match on a schema map
 %% all schemas that are not a map are converted to the empty map.
-schema_map(Map) when is_map(Map) -> Map;
-schema_map(_) -> #{}.
+schema_map(Map, _) when is_map(Map) -> Map;
+schema_map(_, _) -> #{}.
 
 -spec merge_(json(), json(), st()) -> json().
-merge_(A, B, #st{} = St) ->
-    Ss = schemas_from_dynamic_eval(A, St),
+merge_(A, B, #st{} = St0) ->
+    {Ss, St} = schemas_from_dynamic_eval(A, St0#st{d = undefined}),
     case schema_prop(<<"readOnly">>, St, Ss, false) of
         true when B == null ->
             valid(A, St);
@@ -163,7 +497,7 @@ merge_(A, B, St, Ss) ->
     end.
 
 update_semantics(A, St, Ss) ->
-    case maps:find(<<"$updateSemantics">>, schema_map(A)) of
+    case maps:find(<<"$updateSemantics">>, schema_map(A, St)) of
         {ok, _} = Ok ->
             {Ok, object};
         error ->
@@ -190,9 +524,9 @@ remove_props(O, Keys, Recurse) when is_map(O) ->
 remove_props(Other, _, _) ->
     Other.
 
-get_type(#st{} = St, Value) ->
-    Ss = schemas_from_dynamic_eval(Value, St),
-    get_type(St, Ss, Value).
+get_type(#st{} = St0, Value) ->
+    {Ss, St} = schemas_from_dynamic_eval(Value, St0),
+    {get_type(St, Ss, Value), St}.
 
 get_type(#st{} = St, Ss, Value) ->
     case any_schema_prop(<<"type">>, St, Ss) of
@@ -272,7 +606,7 @@ update_object(A0, B, St, Ss) ->
 
 update_object_(New, Old, St, Ss) ->
     Dyn = acc_props(Ss),
-    SsOld = schemas_from_dynamic_eval(Old, St),
+    {SsOld, _} = schemas_from_dynamic_eval(Old, St#st{d = undefined}),
     PropSchemas = [{P, prop_schema(P, Dyn, St)} || P <- maps:keys(New)],
     try do_update_object(New, Old, St, PropSchemas)
     catch
@@ -300,6 +634,55 @@ do_update_object(New, Old, St, PropSchemas) ->
             end, Old, PropSchemas),
     valid(Res, object, St).
 
+validate(V, Schema, Opts) when is_map(Opts) ->
+    St0 = use_schema(Schema),
+    St = St0#st{opts = Opts},
+    V1 = valid(V, St),
+    case Opts of
+        #{enum_to_atom := true} ->
+            convert_enums(V1, St);
+        _ ->
+            V1
+    end.
+
+convert_enums(V, St0) when is_binary(V) ->
+    case get_type(St0, V) of
+        {string, St} ->
+            {Ss, St1} = schemas_from_dynamic_eval(V, St),
+            case any_schema_prop(<<"enum">>, St1, Ss) of
+                {ok, _} ->
+                    binary_to_atom(V, utf8);
+                _ ->
+                    V
+            end;
+        _ ->
+            V
+    end;
+convert_enums(V, St0) when is_map(V) ->
+    {Ss, St} = schemas_from_dynamic_eval(V, St0),
+    Dyn = acc_props(Ss),
+    maps:map(
+      fun(P, Vp) ->
+              PSchema = prop_schema(P, Dyn, St),
+              convert_enums(Vp, push_path(P, s(PSchema, St)))
+      end, V);
+convert_enums(V, St0) when is_list(V) ->
+    {Ss,St} = schemas_from_dynamic_eval(V, St0),
+    case any_schema_prop(<<"items">>, St, Ss) of
+        {ok, Is} ->
+            [convert_enums(Vi, push_path(items, s(Is, St)))
+             || Vi <- V];
+        error ->
+            case any_schema_prop(<<"prefixItems">>, St, Ss) of
+                {ok, PfxIs} ->
+                    [convert_enums(Vi, push_path(prefixItems, s(PfxIs, St)))
+                     || Vi <- V];
+                error ->
+                    V
+            end
+    end;
+convert_enums(V, _) ->
+    V.
 
 valid(V) ->
     valid(V, get_schema()).
@@ -307,25 +690,25 @@ valid(V) ->
 valid(V, #st{} = St) ->
     valid_(V, St#st{v = V});
 valid(V, Schema) ->
-    valid(V, #st{p = [], s = Schema, r = Schema, v = V}).
+    valid(V, (new_state(Schema, Schema))#st{v = V}).
 
 valid_(V, #st{s = true}) -> V;
 valid_(_, #st{s = false} = St) -> fail(invalid, St);
-valid_(V, St) ->
-    Type = get_type(St, V),
+valid_(V, St0) ->
+    {Type, St} = get_type(St0, V),
     valid(V, Type, St).
 
 valid(V, _, #st{s = true}) -> V;
 valid(_, _, #st{s = false} = St) -> fail(invalid, St);
-valid(V, Type, St) ->
+valid(V, Type, St0) ->
     %% We run dynamic eval to find conditional parts of the schema.
     %% we keep these in a separate list.
-    Ss = schemas_from_dynamic_eval(V, St),
+    {Ss,St} = schemas_from_dynamic_eval(V, St0),
     valid(V, Type, St, Ss).
 
 valid(V, Type, St, Ss) ->
-    valid_const(V, Type, St, Ss),
-    valid_enum(V, Type, St, Ss),
+    _ = valid_const(V, Type, St, Ss),
+    _ = valid_enum(V, Type, St, Ss),
     %% Dynamic eval returns a list of matching schemas
     %% We pass them along as they may contain properties,
     %% but `V` has already been validated against them.
@@ -342,7 +725,7 @@ valid(V, Type, St, Ss) ->
 split_valid(V, St, Ss) ->
     split_valid(V, 0, St, Ss, [], []).
 split_valid(V, Ix, St, [S|Ss], Yes, No) ->
-    try valid(V, push_path(Ix, St#st{s = S})) of
+    try valid(V, push_path(Ix, s(S, St))) of
         _ -> split_valid(V, Ix+1, St, Ss, [{Ix,S}|Yes], No)
     catch
         error:Err ->
@@ -370,7 +753,8 @@ valid_enum(V, Type, St, Ss) ->
             case lists:any(fun(X) ->
                                     is_equal(Type, V, X)
                            end, En) of
-                true -> V;
+                true ->
+                    V;
                 false ->
                     fail(not_in_enum, push_path(enum, St))
             end
@@ -396,7 +780,7 @@ valid_object(O, St, Ss) when is_map(O) ->
     end,
     lists:foreach(
         fun({P, #st{} = S}) ->
-            valid(maps:get(P, O), push_path(P, S))
+            valid(maps:get(P, O), push_path(P, S#st{d = undefined}))
         end, PropSchemas),
     O;
 valid_object(_, St, _) ->
@@ -405,12 +789,15 @@ valid_object(_, St, _) ->
 -spec valid_boolean(json(), st(), [st()]) -> json_bool().
 valid_boolean(V, #st{s = true}, []) -> V;
 valid_boolean(_, #st{s = false} = St, []) -> fail(invalid, St);
+valid_boolean(<<"true">> , #st{opts = #{coerce := true}}, _) -> true;
+valid_boolean(<<"false">>, #st{opts = #{coerce := true}}, _) -> false;
 valid_boolean(V, St, _) ->
     assert_type(fun is_boolean/1, V, St),
     V.
 
 valid_null(N, #st{s = true}, []) -> N;
 valid_null(_, #st{s = false} = St, []) -> fail(invalid, St);
+valid_null(<<"null">>, #st{s = null, opts = #{coerce := true}}, _) -> null;
 valid_null(null, #st{s = null}, _) ->
     null;
 valid_null(_, St, _) ->
@@ -432,15 +819,28 @@ valid_string(S, St, Ss) when is_binary(S) ->
     Lmax = schema_prop(<<"maxLength">>, St, Ss, Sz),
     assert_min(Sz, Lmin, min_length, St),
     assert_max(Sz, Lmax, max_length, St),
-    S;
+    valid_enum(S, string, St, Ss);
 valid_string(_, St, _) ->
     fail(wrong_type, St).
 
 
 valid_number(N, _, #st{s = true}, []) -> N;
 valid_number(_, _, #st{s = false} = St, []) -> fail(invalid, St);
+valid_number(I, Sub, #st{opts = #{coerce := true}} = St, Ss) when is_binary(I) ->
+    try coerce_num(Sub, I) of
+        I1 ->
+            valid_number_(I1, Sub, St#st{v = I1}, Ss)
+    catch
+        error:_ ->
+            fail(wrong_type, St)
+    end;
 valid_number(I, Sub, St, Ss) when is_number(I) ->
-    [assert_type(fun is_integer/1, I, St) || Sub == integer],
+    valid_number_(I, Sub, St, Ss);
+valid_number(_, _, St, _) ->
+    fail(wrong_type, St).
+
+valid_number_(I, Sub, St, Ss) when is_number(I) ->
+        [assert_type(fun is_integer/1, I, St) || Sub == integer],
     case any_schema_prop(<<"multipleOf">>, St, Ss) of
         error -> ok;
         {ok, X} when is_integer(X), X > 0 ->
@@ -465,6 +865,19 @@ valid_number(I, Sub, St, Ss) when is_number(I) ->
                     fail(not_a_multiple, St1)
             end
     end,
+    validate_number_bounds(I, St, Ss),
+    I.
+
+validate_number_bounds(I, #st{draft = draft4} = St, Ss) ->
+    Min = schema_prop(<<"minimum">>, St, Ss, I),
+    Max = schema_prop(<<"maximum">>, St, Ss, I),
+    EMin = schema_prop(<<"exclusiveMinimum">>, St, Ss, false),
+    EMax = schema_prop(<<"exclusiveMaximum">>, St, Ss, false),
+    MinOp = case EMin of true -> '<'; false -> '=<' end,
+    MaxOp = case EMax of true -> '>'; false -> '>=' end,
+    test_range(MaxOp, Max, I, add_anno(Max, push_path(maximum, St))),
+    test_range(MinOp, Min, I, add_anno(Min, push_path(minimum, St)));
+validate_number_bounds(I, St, Ss) ->
     Min = schema_prop(<<"minimum">>, St, Ss, I),
     Max = schema_prop(<<"maximum">>, St, Ss, I),
     test_range('>=', Max, I, add_anno(Max, push_path(maximum, St))),
@@ -472,10 +885,16 @@ valid_number(I, Sub, St, Ss) when is_number(I) ->
     EMin = schema_prop(<<"exclusiveMinimum">>, St, Ss, I-1),
     EMax = schema_prop(<<"exclusiveMaximum">>, St, Ss, I+1),
     test_range('>', EMax, I, add_anno(EMax, push_path(exclusiveMaximum, St))),
-    test_range('<', EMin, I, add_anno(EMin, push_path(exclusiveMinimum, St))),
-    I;
-valid_number(_, _, St, _) ->
-    fail(wrong_type, St).
+    test_range('<', EMin, I, add_anno(EMin, push_path(exclusiveMinimum, St))).
+
+coerce_num(integer, I) when is_binary(I) ->
+    binary_to_integer(I);
+coerce_num(number, I) when is_binary(I) ->
+    try binary_to_integer(I)
+    catch
+        error:_ ->
+            binary_to_float(I)
+    end.
 
 valid_array(A, #st{s = true}, []) -> A;
 valid_array(_, #st{s = false} = St, []) -> fail(invalid, St);
@@ -497,23 +916,23 @@ valid_array(A, #st{} = St, Ss) when is_list(A) ->
                 {ok, PfxIs} ->
                     assert_schema(fun is_list/1, PfxIs, push_path(prefixItems, St)),
                     check_prefix_items(
-                      PfxIs, A, Is, push_path(prefixItems, St#st{s = PfxIs}));
+                      PfxIs, A, Is, push_path(prefixItems, s(PfxIs, St)));
                   error ->
-                      check_items(A, push_path(items, St#st{s = Is}))
+                      check_items(A, push_path(items, s(Is, St)))
               end;
         error ->
             case PfxItems of
                 {ok, PfxIs} ->
                     assert_schema(fun is_list/1, PfxIs, push_path(prefixItems, St)),
                     check_prefix_items(
-                      PfxIs, A, true, push_path(prefixItems, St#st{s = PfxIs}));
+                      PfxIs, A, true, push_path(prefixItems, s(PfxIs, St)));
                 error ->
                     ok
             end
     end,
     case any_schema_prop(<<"contains">>, St, Ss) of
         {ok, Cs} ->
-            check_contains(A, push_path(contains, St#st{s = Cs}),
+            check_contains(A, push_path(contains, s(Cs, St)),
                            schema_prop(<<"minContains">>, St, Ss, null),
                            schema_prop(<<"maxContains">>, St, Ss, null));
         error ->
@@ -540,12 +959,12 @@ check_prefix_items(_, _, _, St) ->
     fail(invalid, St).
 
 check_prefix_items([I|Is], [H|T], Ix, Items, St) ->
-    _ = valid(H, push_path(Ix, St#st{s = I})),
+    _ = valid(H, push_path(Ix, s(I, St))),
     check_prefix_items(Is, T, Ix+1, Items, St);
 check_prefix_items(_, [], _, _, _) ->
     ok;
 check_prefix_items([], Rest, Ix, Items, St) ->
-    check_items(Rest, Ix, push_path(items, St#st{s = Items})).
+    check_items(Rest, Ix, push_path(items, s(Items, St))).
 
 check_items(A, St) ->
     check_items(A, 0, St).
@@ -577,13 +996,13 @@ check_contains([], _, St, Min, Max, Yes, _No) ->
             if is_integer(Max) ->
                     _ = valid(YesLen,
                               push_path(max,
-                                        St#st{s = #{<<"maximum">> => Max}}));
+                                        s(#{<<"maximum">> => Max}, St)));
                true -> ok
             end,
             if is_integer(Min) ->
                     _ = valid(YesLen,
                               push_path(min,
-                                        St#st{s = #{<<"minimum">> => Min}}));
+                                        s(#{<<"minimum">> => Min}, St)));
                true ->
                     ok
             end
@@ -660,14 +1079,26 @@ any_pattern_({Pat, Schema, I}, P) ->
             any_pattern_(maps:next(I), P)
     end.
 
-schemas_from_dynamic_eval(Obj, #st{s = Schema} = St) ->
-    SMap = schema_map(Schema),
+maybe_expand_ref(#st{s = S} = St) ->
+    case S of
+        #{<<"$ref">> := Ref} = R when map_size(R) == 1 ->
+            St#st{s = expand_ref(Ref, St#st.r)};
+        _ ->
+            St
+    end.
+
+schemas_from_dynamic_eval(_, #st{d = Ss} = St) when Ss =/= undefined ->
+    {Ss, St};
+schemas_from_dynamic_eval(Obj, #st{s = Schema} = St0) ->
+    St = maybe_expand_ref(St0),
+    SMap = schema_map(Schema, St),
+    Ss =
     maps:fold(
       fun(<<"allOf">>, Ss, Acc) ->
               St1 = push_path(allOf, St),
               case split_valid(Obj, St, Ss) of
                   {ValidSs, []} ->
-		      Acc ++ [St1#st{s = S} || {_, S} <- ValidSs];
+		      Acc ++ [s(S, St1) || {_, S} <- ValidSs];
                   {_, FailedSs} ->
 		      fail(failing_schemas, add_anno(FailedSs, St1))
               end;
@@ -675,7 +1106,7 @@ schemas_from_dynamic_eval(Obj, #st{s = Schema} = St) ->
               St1 = push_path(anyOf, St),
               case split_valid(Obj, St1, Ss) of
                   {[_|_] = ValidSs, _} ->
-                      Acc ++ [St1#st{s = S} || {_, S} <- ValidSs];
+                      Acc ++ [s(S, St1) || {_, S} <- ValidSs];
                   {[], FailedSs} ->
                       fail(no_matching_schema, add_anno(FailedSs, St1))
               end;
@@ -683,7 +1114,7 @@ schemas_from_dynamic_eval(Obj, #st{s = Schema} = St) ->
 	      St1 = push_path(oneOf, St),
               case split_valid(Obj, St1, Ss) of
                   {[{_, S}], _} ->
-		      Acc ++ [St1#st{s = S}];
+		      Acc ++ [s(S, St1)];
 		  {[_|_] = MoreValid, _} ->
 		      ValidIxs = [I || {I,_} <- MoreValid],
 		      fail(more_than_one, add_anno({valid, ValidIxs}, St1));
@@ -692,31 +1123,49 @@ schemas_from_dynamic_eval(Obj, #st{s = Schema} = St) ->
               end;
          (<<"if">>, S, Acc) ->
 	      St1 = push_path('if', St),
-              try valid(Obj, St1#st{s = S}) of
+              try valid(Obj, s(S, St1)) of
                   _ ->
                       Sthen =
                           push_path(
-                            'then', St1#st{s = maps:get(<<"then">>, SMap, #{})}),
+                            'then', s(maps:get(<<"then">>, SMap, #{}), St1)),
                       _ = valid(Obj, Sthen),
                       Acc ++ [Sthen]
               catch
                   error:_ ->
                       Selse =
                           push_path(
-                            'else', St1#st{s = maps:get(<<"else">>, SMap, #{})}),
+                            'else', s(maps:get(<<"else">>, SMap, #{}), St1)),
                       _ = valid(Obj, Selse),
                       Acc ++ [Selse]
               end;
 	 (<<"not">>, S, Acc) ->
-              Snot = push_path('not', St#st{s = S}),
+              Snot = push_path('not', s(S, St)),
 	      try valid(Obj, Snot) of
 		  _ -> fail(invalid, Snot)
 	      catch
 		  error:_ ->
 		      Acc
 	      end;
-         (_, _, Acc) -> Acc
-      end, [], SMap).
+         (<<"x-", _/binary>> = Prop, SExt, Acc) ->
+              case St#st.opts of
+                  #{extensions := #{Prop := ExtF}} ->
+                      St1 = push_path(Prop, St),
+                      call_extension(ExtF, Obj, SExt, Prop, St1),
+                      Acc;
+                  _ ->
+                      Acc
+              end;
+         (_, _, Acc) ->
+              Acc
+      end, [], SMap),
+    {Ss, St#st{d = Ss}}.
+
+call_extension(F, Obj, S, Prop, St) ->
+    try F(Obj, S)
+    catch
+        error:E ->
+            fail(extended_check, add_anno({Prop, E}, St))
+    end.
 
 acc_props(Ss) ->
     lists:foldl(
@@ -728,6 +1177,10 @@ acc_props(Ss) ->
               end
       end, #{}, Ss).
 
+s(S, #st{} = St) ->
+    Draft = schema_draft(S, St#st.draft, lists:reverse(St#st.p)),
+    St#st{s = S, d = undefined, draft = Draft}.
+
 push_path(Ps, #st{p = P0} = St) when is_list(Ps) ->
     %% Assume Ps is in reverse order
     St#st{p = Ps ++ P0};
@@ -780,13 +1233,15 @@ uniqueItems(L) ->
     USorted = lists:usort(L),
     [] == L -- USorted.
 
-expand_schema(S0) ->
-    S = expand_definitions(S0),
+expand_schema(S) ->
+    %% S = expand_definitions(S0),
     expand_schema(S, S).
 
-expand_definitions(#{<<"definitions">> := D} = S) ->
-    S#{<<"definitions">> := expand_schema(D, S)}.
+%% expand_definitions(#{<<"definitions">> := D} = S) ->
+%%     S#{<<"definitions">> := expand_schema(D, S)}.
 
+expand_schema(#{<<"$ref">> := Path} = V, S0) when map_size(V) == 1 ->
+    expand_schema(expand_ref(Path, S0), S0);
 expand_schema(S, S0) when is_map(S) ->
     %% https://json-schema.org/understanding-json-schema/structuring#dollarref
     %% When $id is used in a subschema, it indicates an embedded schema.
@@ -802,9 +1257,9 @@ expand_schema(S, S0) when is_map(S) ->
                  S0
          end,
     maps:fold(fun(K, V, Acc) -> expand_schema_(K, V, Acc, S1) end, #{}, S);
-expand_schema([#{<<"$ref">> := Path} = V], S0) when map_size(V) == 1 ->
-    D = expand_ref(Path, S0),
-    [D];
+%% expand_schema([#{<<"$ref">> := Path} = V], S0) when map_size(V) == 1 ->
+%%     D = expand_ref(Path, S0),
+%%     [expand_schema(D, S0)];
 expand_schema(S, S0) when is_list(S) ->
     [expand_schema(E, S0) || E <- S];
 expand_schema(S, _) ->
@@ -853,8 +1308,11 @@ schema(Path) ->
 schema(Path, Schema) ->
     schema(Path, Schema, #{follow_refs => true}).
 
+schema(Path, #st{s = Schema, r = RootSchema}, Opts) ->
+    schema_(Path, Schema, RootSchema, Opts);
 schema(Path, Schema, Opts) ->
-    schema_(Path, Schema, Schema, Opts).
+    St = new_state(Schema, Schema),
+    schema(Path, St, Opts).
 
 schema_([H|T], Schema, RootSchema0, Opts) ->
     RootSchema = set_rootschema(Schema, RootSchema0),

test/data/nested_refs_schema.json

@@ -0,0 +1,29 @@
+{
+    "type": "object",
+    "properties": {
+        "tx" : { "$ref" : "#/components/schemas/Tx" }
+    },
+    "components": {
+        "schemas": {
+            "Tx": {
+                "type": "object",
+                "properties": {
+                    "from": {
+                        "allOf": [
+                            { "$ref": "#/components/schemas/Pubkey" },
+                            { "x-serialization": {
+                                "tags": ["ak"]
+                            }}
+                        ]
+                    }
+                }
+            },
+            "Pubkey": {
+                "type": "string",
+                "x-serialization": {
+                    "tags": ["ak", "ct"]
+                }
+            }
+        }
+    }
+}

test/data/recursion_data.json

@@ -0,0 +1,20 @@
+{
+  "name": "Elizabeth",
+  "children": [
+    {
+      "name": "Charles",
+      "children": [
+        {
+          "name": "William",
+          "children": [
+            { "name": "George" },
+            { "name": "Charlotte" }
+          ]
+        },
+        {
+          "name": "Harry"
+        }
+      ]
+    }
+  ]
+}

test/data/recursion_data_faulty.json

@@ -0,0 +1,20 @@
+{
+  "name": "Elizabeth",
+  "children": [
+    {
+      "name": "Charles",
+      "children": [
+        {
+          "name": "William",
+          "children": [
+            { "name": [1] },
+            { "name": "Charlotte" }
+          ]
+        },
+        {
+          "name": "Harry"
+        }
+      ]
+    }
+  ]
+}

test/data/recursion_schema.json

@@ -0,0 +1,10 @@
+{
+  "type": "object",
+  "properties": {
+    "name": { "type": "string" },
+    "children": {
+      "type": "array",
+      "items": { "$ref": "#" }
+    }
+  }
+}

test/data/ref_loop_schema.json

@@ -0,0 +1,6 @@
+{
+  "$defs": {
+    "alice": { "$ref": "#/$defs/bob" },
+    "bob": { "$ref": "#/$defs/alice" }
+  }
+}

test/gmconfig_schema_utils_tests.erl

@@ -0,0 +1,554 @@
+-module(gmconfig_schema_utils_tests).
+
+-export([tr/0]).
+
+-include_lib("eunit/include/eunit.hrl").
+
+-import(gmconfig_schema_utils, [ valid/2
+                               , validate/3 ]).
+
+%%-define(t(Expr), ?_test(?debugVal(Expr))).
+-define(t(Expr), ?_test(Expr)).
+
+tr() ->
+    dbg:tracer(),
+    dbg:tpl(?MODULE, x),
+    dbg:tpl(gmconfig_schema_utils,x),
+    dbg:p(all,[c]),
+    eunit:test(?MODULE).
+
+simple_type_test_() ->
+    {"Simple type tests",
+     [
+       ?t(t_integer())
+     , ?t(t_number())
+     , ?t(t_boolean())
+     , ?t(t_string())
+     , ?t(t_array())
+     , ?t(t_object())
+     , ?t(t_shortcut_schema())
+     ]}.
+
+update_test_() ->
+    {"Validated update tests",
+     [
+       ?t(t_update_objects())
+     ]}.
+
+schema_spec_examples_test_() ->
+    {"Examples from JSON-Schema docs",
+     [
+       ?t(t_ref_loop())
+     , ?t(t_recursive_def())
+     , ?t(t_nested_refs())
+     ]}.
+
+draft_discrimination_test_() ->
+    {"JSON Schema draft discrimination",
+     [
+       ?t(t_draft4_exclusive_bounds())
+     , ?t(t_draft4_rejects_boolean_schema())
+     , ?t(t_draft4_rejects_const())
+     , ?t(t_draft6_accepts_const())
+     , ?t(t_draft6_rejects_conditionals())
+     , ?t(t_draft7_accepts_conditionals())
+     , ?t(t_draft7_rejects_prefix_items())
+     , ?t(t_draft2020_accepts_prefix_items())
+     , ?t(t_draft2020_rejects_tuple_items())
+     , ?t(t_unspecified_draft_remains_compatible())
+     , ?t(t_unknown_draft_is_rejected())
+     ]}.
+
+-define(DRAFT4, <<"http://json-schema.org/draft-04/schema#">>).
+-define(DRAFT6, <<"http://json-schema.org/draft-06/schema#">>).
+-define(DRAFT7, <<"http://json-schema.org/draft-07/schema#">>).
+-define(DRAFT2020, <<"https://json-schema.org/draft/2020-12/schema">>).
+
+with_draft(Draft, Schema) ->
+    Schema#{<<"$schema">> => Draft}.
+
+t_draft4_exclusive_bounds() ->
+    S = with_draft(?DRAFT4,
+                   #{<<"type">> => <<"number">>,
+                     <<"minimum">> => 1,
+                     <<"exclusiveMinimum">> => true,
+                     <<"maximum">> => 3,
+                     <<"exclusiveMaximum">> => false}),
+    all_valid([2, 3], S),
+    all_fail([1, 4], S, not_in_range),
+    schema_fails(
+      with_draft(?DRAFT4,
+                 #{<<"type">> => <<"number">>,
+                   <<"exclusiveMinimum">> => 1}),
+      #{e => keyword_value_not_in_draft,
+        draft => draft4,
+        p => [<<"exclusiveMinimum">>]}),
+    schema_fails(
+      with_draft(?DRAFT4,
+                 #{<<"type">> => <<"number">>,
+                   <<"exclusiveMinimum">> => true}),
+      #{e => missing_keyword_for_draft,
+        draft => draft4,
+        keyword => <<"exclusiveMinimum">>,
+        required_keyword => <<"minimum">>}).
+
+t_draft4_rejects_boolean_schema() ->
+    S = with_draft(?DRAFT4,
+                   #{<<"properties">> => #{<<"disabled">> => false}}),
+    schema_fails(S, #{e => boolean_schema_not_in_draft,
+                      draft => draft4,
+                      p => [<<"properties">>, <<"disabled">>]}),
+    ObjectSchema = with_draft(?DRAFT4,
+                              #{<<"type">> => <<"object">>,
+                                <<"additionalProperties">> => false}),
+    is_valid(#{}, ObjectSchema),
+    fails(#{<<"unexpected">> => true}, ObjectSchema, invalid).
+
+t_draft4_rejects_const() ->
+    S = with_draft(?DRAFT4,
+                   #{<<"properties">> =>
+                         #{<<"mode">> => #{<<"const">> => <<"on">>}}}),
+    schema_fails(S, #{e => keyword_not_in_draft,
+                      draft => draft4,
+                      keyword => <<"const">>,
+                      introduced_in => draft6,
+                      p => [<<"properties">>, <<"mode">>, <<"const">>]}).
+
+t_draft6_accepts_const() ->
+    S = with_draft(?DRAFT6, #{<<"const">> => <<"on">>}),
+    is_valid(<<"on">>, S),
+    fails(<<"off">>, S, not_in_enum).
+
+t_draft6_rejects_conditionals() ->
+    S = with_draft(?DRAFT6,
+                   #{<<"if">> => #{<<"const">> => 1},
+                     <<"then">> => false}),
+    schema_fails(S, #{e => keyword_not_in_draft,
+                      draft => draft6,
+                      keyword => <<"if">>,
+                      introduced_in => draft7,
+                      p => [<<"if">>]}).
+
+t_draft7_accepts_conditionals() ->
+    S = with_draft(?DRAFT7,
+                   #{<<"if">> => #{<<"const">> => 1},
+                     <<"then">> => #{<<"minimum">> => 1},
+                     <<"else">> => #{<<"minimum">> => 2}}),
+    all_valid([1, 2], S),
+    fails(0, S, not_in_range).
+
+t_draft7_rejects_prefix_items() ->
+    S = with_draft(?DRAFT7,
+                   #{<<"type">> => <<"array">>,
+                     <<"prefixItems">> => [#{<<"type">> => <<"integer">>}]}),
+    schema_fails(S, #{e => keyword_not_in_draft,
+                      draft => draft7,
+                      keyword => <<"prefixItems">>,
+                      introduced_in => draft2020_12,
+                      p => [<<"prefixItems">>]}).
+
+t_draft2020_accepts_prefix_items() ->
+    S = with_draft(?DRAFT2020,
+                   #{<<"type">> => <<"array">>,
+                     <<"prefixItems">> => [#{<<"type">> => <<"integer">>}],
+                     <<"items">> => false}),
+    is_valid([1], S),
+    fails([1, 2], S, invalid).
+
+t_draft2020_rejects_tuple_items() ->
+    S = with_draft(?DRAFT2020,
+                   #{<<"type">> => <<"array">>,
+                     <<"items">> => [#{<<"type">> => <<"integer">>}]}),
+    schema_fails(S, #{e => keyword_value_not_in_draft,
+                      draft => draft2020_12,
+                      keyword => <<"items">>,
+                      p => [<<"items">>]}),
+    Additional = with_draft(?DRAFT2020,
+                            #{<<"type">> => <<"array">>,
+                              <<"additionalItems">> => false}),
+    schema_fails(Additional, #{e => keyword_not_in_draft,
+                               draft => draft2020_12,
+                               keyword => <<"additionalItems">>,
+                               last_supported_in => draft2019_09,
+                               p => [<<"additionalItems">>]}).
+
+t_unspecified_draft_remains_compatible() ->
+    S = #{<<"type">> => <<"array">>,
+          <<"prefixItems">> => [#{<<"type">> => <<"integer">>}]},
+    is_valid([1], S).
+
+t_unknown_draft_is_rejected() ->
+    S = with_draft(<<"https://example.test/schema-dialect">>, #{}),
+    schema_fails(S, #{e => unsupported_schema_draft,
+                      draft_uri => <<"https://example.test/schema-dialect">>,
+                      p => [<<"$schema">>]}).
+
+array() -> #{<<"type">> => <<"array">>}.
+int()   -> #{<<"type">> => <<"integer">>}.
+str()   -> #{<<"type">> => <<"string">>}.
+obj(Ps) -> #{<<"type">> => <<"object">>,
+             <<"properties">> => Ps}.
+     
+
+t_update_objects() ->
+    S0 = obj(
+           #{<<"a">> => int(),
+             <<"b">> => obj(#{<<"b1">> => array(),
+                              <<"b2">> =>
+                                  obj(#{<<"b21">> => str()})
+                             })
+             }),
+    %%
+    %% Only objects are merged; other types are replaced.
+    A0 = #{<<"a">> => 1,
+           <<"b">> => #{<<"b1">> => [1,2],
+                        <<"b2">> => #{}}},
+    B0 = #{<<"a">> => 2,
+           <<"b">> => #{<<"b1">> => [4,5],
+                        <<"b2">> => #{<<"b21">> => <<"foo">>}}},
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := #{<<"b21">> := <<"foo">>}}} =
+        gmconfig_schema_utils:merge(A0, B0, S0),
+    %%
+    %% Modified update semantics - replace instead of merge
+    S0Ps = maps:get(<<"properties">>, S0),
+    S01Ps = S0Ps#{<<"c">> => #{<<"type">> => <<"object">>,
+                               <<"updateSemantics">> => <<"replace">>,
+                               <<"properties">> =>
+                                   #{<<"c1">> => #{<<"type">> => <<"integer">>},
+                                     <<"c2">> => #{<<"type">> => <<"integer">>}
+                                    }}},
+    S01 = S0#{<<"properties">> => S01Ps},
+    A01 = A0#{<<"c">> => #{<<"c1">> => 1}},
+    B01 = B0#{<<"c">> => #{<<"c2">> => 2}},
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := #{<<"b21">> := <<"foo">>}},
+      <<"c">> := #{<<"c1">> := 1}} =
+        gmconfig_schema_utils:merge(A01, B01, S01),
+    A0r = #{<<"a">> => 1,
+            <<"b">> => #{<<"$updateSemantics">> => <<"replace">>,
+                         <<"b1">> => [1,2],
+                         <<"b2">> => #{<<"$updateSemantics">> => <<"merge">>}
+                        }},
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := B2M}} =
+        gmconfig_schema_utils:merge(A0r, B0, S0),
+    %% B2M is the empty map (updateSemantics prop removed recursively)
+    ?assertEqual(#{}, B2M),
+    A0r1 = #{<<"a">> => 1,
+             <<"b">> => #{<<"$updateSemantics">> => <<"merge">>,
+                          <<"b1">> => [1,2],
+                          <<"b2">> => #{<<"$updateSemantics">> => <<"replace">>}
+                         }},
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := B2M1}} =
+        gmconfig_schema_utils:merge(A0r1, B0, S0),
+    %% B2M is the empty map (updateSemantics prop removed recursively)
+    ?assertEqual(#{}, B2M1),
+    %%
+    %% With updateSemantics : suggest, the offered data is accepted if
+    %% the existing is missing or 'null'.
+    S02Ps = S0Ps#{<<"c">> => #{<<"type">> => <<"object">>,
+                               <<"updateSemantics">> => <<"suggest">>,
+                               <<"properties">> =>
+                                   #{<<"c1">> => #{<<"type">> => <<"integer">>},
+                                     <<"c2">> => #{<<"type">> => <<"integer">>}
+                                    }}},
+    S02 = S0#{<<"properties">> => S02Ps},
+    A02 = A0#{<<"c">> => #{<<"c1">> => 1}},
+    B02 = B0#{<<"c">> => #{<<"c2">> => 2}},
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := #{<<"b21">> := <<"foo">>}},
+      <<"c">> := #{<<"c2">> := 2}} =
+        gmconfig_schema_utils:merge(A02, B02, S02),
+    B03 = B0#{<<"c">> => null},
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := #{<<"b21">> := <<"foo">>}},
+      <<"c">> := #{<<"c1">> := 1}} =
+        gmconfig_schema_utils:merge(A02, B0, S02),
+    #{<<"a">> := 1,
+      <<"b">> := #{<<"b1">> := [1,2],
+                   <<"b2">> := #{<<"b21">> := <<"foo">>}},
+      <<"c">> := #{<<"c1">> := 1}} =
+        gmconfig_schema_utils:merge(A02, B03, S02),
+    ok.
+
+t_integer() ->
+    S0 = #{<<"type">> => <<"integer">>},
+    is_valid(17, S0),
+    all_fail([17.0, [], #{}, <<>>], S0, wrong_type),
+    S1 = S0#{<<"minimum">> => 1, <<"maximum">> => 4},
+    all_valid([1, 2, 4], S1),
+    all_fail([0, 5], S1, not_in_range),
+    S2 = S0#{<<"exclusiveMinimum">> => 1, <<"exclusiveMaximum">> => 3},
+    is_valid(2, S2),
+    all_fail([1, 3], S2, not_in_range),
+    S3 = S0#{<<"multipleOf">> => 2},
+    is_valid(4, S3),
+    fails(3, S3, not_a_multiple),
+    ok.
+
+t_number() ->
+    S0 = #{<<"type">> => <<"number">>},
+    all_valid([17, 17.0], S0),
+    all_fail([#{}, [], <<>>, true], S0, wrong_type),
+    S1 = S0#{<<"minimum">> => 1, <<"maximum">> => 4.0},
+    all_valid([1, 1.0, 2, 2.3, 3.999, 4, 4.0], S1),
+    all_fail([0, 5], S1, not_in_range),
+    S2 = S0#{<<"exclusiveMinimum">> => 1, <<"exclusiveMaximum">> => 3},
+    is_valid(2, S2),
+    all_fail([1, 3], S2, not_in_range),
+    S3 = S0#{<<"multipleOf">> => 2},
+    is_valid(4, S3),
+    all_fail([3, 4.0], S3, not_a_multiple),
+    ok.
+
+t_boolean() ->
+    S0 = #{<<"type">> => <<"boolean">>},
+    all_valid([true, false], S0),
+    %% truthy and falsy types not accepted
+    all_fail([1, 0, null, [], <<>>, #{}], S0, wrong_type),
+    ok.
+
+t_string() ->
+    S0 = #{<<"type">> => <<"string">>},
+    all_valid([<<>>, <<"foo">>], S0),
+    fails("foo", S0, wrong_type),
+    ok.
+
+t_array() ->
+    S0 = #{<<"type">> => <<"array">>},
+    all_valid([ [], [1,1], [1,2,3], [#{}] ], S0),
+    all_fail([1, false, #{}, <<"foo">>], S0, wrong_type),
+    S1 = S0#{<<"minItems">> => 2},
+    all_valid([[1,2], [1,2,3,4]], S1),
+    all_fail([[], [1]], S1, not_in_range),
+    S2 = S0#{<<"maxItems">> => 4},
+    all_valid([[], [1], [1,2], [1,2,3,4]], S2),
+    fails([1,2,3,4,5], S2, not_in_range),
+    S3 = maps:merge(S1, S2),
+    all_valid([ [1,2], [1,2,3], [1,2,3,4] ], S3),
+    all_fail([ [1], [1,2,3,4,5] ], S3, not_in_range),
+    S4 = S0#{<<"uniqueItems">> => true},
+    all_valid([ [], [1], [1,2] ], S4),
+    all_fail([ [1,1], [2,1,2] ], S4, not_unique),
+    S5 = S0#{<<"items">> => #{<<"type">> => <<"integer">>}},
+    all_valid([ [], [1], [1,2,3] ], S5),
+    fails([<<"foo">>], S5, #{e => wrong_type, p => [array,items,0,integer]}),
+    fails([1,2,false], S5, #{e => wrong_type, p => [array,items,2,integer]}),
+    S6 = S0#{<<"prefixItems">> => [#{<<"type">> => <<"string">>},
+                                   #{<<"type">> => <<"integer">>},
+                                   #{<<"type">> => <<"integer">>}]},
+    is_valid([<<"foo">>, 1], S6),
+    is_valid([<<"foo">>, 1, 2], S6),
+    is_valid([<<"foo">>, 1, 2, 3], S6),
+    fails([1,2,3], S6, #{e => wrong_type, p => [array,prefixItems,0,string]}),
+    S7 = S6#{<<"items">> => false},
+    fails([<<"foo">>, 1, 2, 3], S7, #{e => invalid,
+                                      p => [array,prefixItems,items,3]}),
+    S71 = S6#{<<"items">> => #{<<"type">> => <<"integer">>}},
+    is_valid([<<>>, 1,2,3,4,5,6], S71),
+    fails([<<>>, 1,2,3,4,5,[]], S71,
+          #{e => wrong_type,
+            p => [array,prefixItems,items,6,integer]}),
+    S8 = S0#{<<"contains">> => #{<<"type">> => <<"integer">>}},
+    is_valid([1,2,3], S8),
+    is_valid([true,true,1], S8),
+    fails([true], S8, contains),
+    fails([], S8, contains),      % not sure where specifed, but makes sense
+    S81 = S8#{<<"minContains">> => 2},
+    is_valid([1,2,3], S81),
+    is_valid([true,1,2], S81),
+    fails([1], S81, #{e => not_in_range, p => [array, contains, min,
+                                               integer, minimum]}),
+    S82 = S8#{<<"maxContains">> => 4},
+    all_valid([ [1], [1,2,3], [true,1,2,3,4] ], S82),
+    S83 = maps:merge(S81, S82),
+    is_valid([1,2,3], S83),
+    fails([1], S83, #{e => not_in_range, p => [array, contains, min,
+                                               integer, minimum]}),
+    fails([1,2,3,4,5], S83, #{e => not_in_range, p => [array, contains, max,
+                                                       integer, maximum]}),
+    is_valid([], S8#{<<"minContains">> => 0}),
+    ok.
+
+t_object() ->
+    S0 = #{<<"type">> => <<"object">>},
+    all_valid([ #{}, #{<<"a">> => 1} ], S0),
+    all_fail([ true, 17, 17.0, [], <<"foo">> ], S0, #{e => wrong_type}),
+    S1 = S0#{<<"properties">> => #{<<"a">> => #{<<"type">> => <<"integer">>}}},
+    all_valid([ #{<<"a">> => 1}, #{}, #{<<"b">> => 1} ], S1),
+    fails(#{<<"a">> => true}, S1, #{e => wrong_type,
+                                    p => [object, <<"a">>, integer]}),
+    is_valid(#{<<"b">> => 1}, S1#{<<"additionalProperties">> => true}),
+    fails(#{<<"b">> => 1}, S1#{<<"additionalProperties">> => false},
+          #{e => invalid,
+            p => [object, <<"b">>],
+            a => [additionalProperties]}),
+    fails(#{<<"b">> => 1}, S1#{<<"required">> => [<<"a">>]},
+          #{e => required, p => [object,required], a => [[<<"a">>]]}),
+    all_valid([ #{<<"a">> => 1}, #{<<"a">> => true} ],
+              S0#{<<"properties">> =>
+                      #{<<"a">> => #{<<"oneOf">> =>
+                                         [#{<<"type">> => <<"integer">>},
+                                          #{<<"type">> => <<"boolean">>}]}
+                       }}),
+    S2 = S0#{<<"properties">> =>
+                 #{<<"a">> => #{<<"type">> => <<"integer">>,
+                                <<"allOf">> =>
+                                    [#{<<"minimum">> => 2},
+                                     #{<<"maximum">> => 5},
+                                     #{<<"multipleOf">> => 2}
+                                    ]}}
+            },
+    is_valid(#{<<"a">> => 4}, S2),
+    fails(#{<<"a">> => 3}, S2, #{e => failing_schemas,
+                                 a => [[{2,'_'}]|'_'],
+                                 p => [object, <<"a">>, allOf]}),
+    ok.
+
+t_shortcut_schema() ->
+    Vs = [<<"foo">>,
+          #{<<"a">> => 1},
+          17],
+    all_valid(Vs, #{}),
+    all_valid(Vs, true),
+    all_fail(Vs, false, invalid),
+    ok.
+
+is_valid(V, S) ->
+    {V, V} = {valid(V, S), V}.
+    %% ?assertEqual(V, valid(V, S)).
+
+fails(V, S, Reason) ->
+    fails(V, S, #{}, Reason).
+
+fails(V, S, Opts, Reason) when is_atom(Reason) ->
+    fails(V, S, Opts, #{e => Reason});
+fails(V, S, Opts, Expect) ->
+    try validate(V, S, Opts) of
+        _ ->
+            error({expected_exception, #{v => V,
+                                         s => S,
+                                         e => Expect}})
+    catch
+        error:R ->
+            match_expected(Expect, R)
+    end.
+    %% ?assertError({Reason, [], V}, valid(V, S)).
+
+schema_fails(Schema, Expect) ->
+    try valid(null, Schema) of
+        _ ->
+            error({expected_schema_exception,
+                   #{s => Schema, e => Expect}})
+    catch
+        error:Reason ->
+            match_expected(Expect, Reason)
+    end.
+
+match_expected(E, R) ->
+    case maps:fold(
+           fun(K, V, Acc) ->
+                   case maps:find(K, R) of
+                       {ok, V} -> Acc;
+                       {ok, Other} ->
+                           case match_other(V, Other) of
+                               true -> Acc;
+                               false ->
+                                   Acc#{K => Other}
+                           end;
+                       error ->
+                           Acc#{K => '$not_found'}
+                   end
+           end, #{}, E) of
+        M when map_size(M) == 0 ->
+            ok;
+        Unexpected ->
+            error({expected, E, Unexpected})
+    end.
+
+match_other(V, V) -> true;
+match_other([H1|T1], [H2|T2]) ->
+    case match_other(H1, H2) of
+        true ->
+            match_other(T1, T2);
+        false ->
+            false
+    end;
+match_other(T1, T2) when tuple_size(T1) =:= tuple_size(T2) ->
+    lists:all(fun({A,B}) -> match_other(A, B) end,
+              lists:zip(tuple_to_list(T1),
+                        tuple_to_list(T2)));
+match_other('_', _) ->
+    true;
+match_other(_, _) ->
+    false.
+
+all_valid(Vs, S) ->
+    [is_valid(V, S) || V <- Vs].
+
+all_fail(Vs, S, Reason) ->
+    [fails(V, S, Reason) || V <- Vs].
+
+read(F) ->
+    FullF = filename:join(
+              filename:dirname(code:which(?MODULE)), F),
+    ?debugFmt("FullF = ~s~n", [FullF]),
+    {ok, Bin} = file:read_file(FullF),
+    dec(Bin).
+
+dec(Str) ->
+    try json:decode(Str)
+    catch
+        error:E ->
+            error(#{type => json_decode_error,
+                    error => E})
+    end.
+
+
+t_ref_loop() ->
+    S = read("data/ref_loop_schema.json"),
+    try gmconfig_schema_utils:schema([<<"$defs">>,<<"alice">>], S) of
+        Unexpected ->
+            error({unexpected, Unexpected})
+    catch
+        error:nested_references ->
+            ok
+    end.
+
+t_recursive_def() ->
+    S = read("data/recursion_schema.json"),
+    D = read("data/recursion_data.json"),
+    Df = read("data/recursion_data_faulty.json"),
+    is_valid(D, S),
+    fails(Df, S, #{e => wrong_type, p => [object, <<"children">>,
+                                          array, items, 0,
+                                          object, <<"children">>,
+                                          array, items, 0,
+                                          object,<<"children">>,
+                                          array, items, 0,
+                                          object, <<"name">>, string
+                                         ]}),
+    ok.
+
+t_nested_refs() ->
+    S = read("data/nested_refs_schema.json"),
+    F = fun(Str, #{<<"tags">> := Tags}) ->
+                true = lists:any(
+                         fun(T) ->
+                                 nomatch =/= string:prefix(Str, T)
+                         end, Tags)
+        end,
+    Opts = #{extensions => #{<<"x-serialization">> => F}},
+    Vs = #{<<"tx">> => #{<<"from">> => <<"ak_good">>}},
+    Vf = #{<<"tx">> => #{<<"from">> => <<"ac_bad">>}},
+    validate(Vs, S, Opts),
+    fails(Vf, S, Opts, #{e => failing_schemas}),
+    ok.

zomp.meta

@@ -4,7 +4,7 @@
 {prefix,"gmconfig"}.
 {author,"Ulf Wiger"}.
 {desc,"Configuration management support"}.
-{package_id,{"uwiger","gmconfig",{0,1,2}}}.
+{package_id,{"uwiger","gmconfig",{0,2,0}}}.
 {deps,[{"uwiger","setup",{2,2,4}}]}.
 {key_name,none}.
 {a_email,"ulf@wiger.net"}.