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authorGravatar Adam Chlipala <adam@chlipala.net>2019-10-11 15:06:18 -0400
committerGravatar Adam Chlipala <adam@chlipala.net>2019-10-11 15:06:18 -0400
commitf7b684dbdae9229a69258a7e575395af120d2654 (patch)
tree77fa2f81ea0456347baf757a8eabd65b6ac287ae /lib
parent56bb940f305fb3d32cc218a6dbc8fa1b1fd7ef89 (diff)
JSON records with optional fields
Diffstat (limited to 'lib')
-rw-r--r--lib/ur/json.ur85
-rw-r--r--lib/ur/json.urs4
2 files changed, 89 insertions, 0 deletions
diff --git a/lib/ur/json.ur b/lib/ur/json.ur
index e2bdd4df..0865ab33 100644
--- a/lib/ur/json.ur
+++ b/lib/ur/json.ur
@@ -287,6 +287,91 @@ fun skipOne s =
skipOne s False False 0 0
end
+fun json_record_withOptional [ts ::: {Type}] [ots ::: {Type}] [ts ~ ots]
+ (fl : folder ts) (jss : $(map json ts)) (names : $(map (fn _ => string) ts))
+ (ofl : folder ots) (ojss : $(map json ots)) (onames : $(map (fn _ => string) ots)): json $(ts ++ map option ots) =
+ {ToJson = fn r =>
+ let
+ val withRequired =
+ @foldR3 [json] [fn _ => string] [ident] [fn _ => string]
+ (fn [nm ::_] [t ::_] [r ::_] [[nm] ~ r] (j : json t) name v acc =>
+ escape name ^ ":" ^ j.ToJson v ^ (case acc of
+ "" => ""
+ | acc => "," ^ acc))
+ "" fl jss names (r --- _)
+
+ val withOptional =
+ @foldR3 [json] [fn _ => string] [option] [fn _ => string]
+ (fn [nm ::_] [t ::_] [r ::_] [[nm] ~ r] (j : json t) name v acc =>
+ case v of
+ None => acc
+ | Some v =>
+ escape name ^ ":" ^ j.ToJson v ^ (case acc of
+ "" => ""
+ | acc => "," ^ acc))
+ "" ofl ojss onames (r --- _)
+ in
+ "{" ^ withOptional ^ "}"
+ end,
+ FromJson = fn s =>
+ let
+ fun fromJ s (r : $(map option (ts ++ ots))) : $(map option (ts ++ ots)) * string =
+ if String.length s = 0 then
+ error <xml>JSON object doesn't end in brace</xml>
+ else if String.sub s 0 = #"}" then
+ (r, String.substring s {Start = 1, Len = String.length s - 1})
+ else let
+ val (name, s') = unescape s
+ val s' = skipSpaces s'
+ val s' = if String.length s' = 0 || String.sub s' 0 <> #":" then
+ error <xml>No colon after JSON object field name</xml>
+ else
+ skipSpaces (String.substring s' {Start = 1, Len = String.length s' - 1})
+
+ val (r, s') = @foldR2 [json] [fn _ => string] [fn ts => $(map option ts) -> $(map option ts) * string]
+ (fn [nm ::_] [t ::_] [r ::_] [[nm] ~ r] (j : json t) name' acc r =>
+ if name = name' then
+ let
+ val (v, s') = j.FromJson s'
+ in
+ (r -- nm ++ {nm = Some v}, s')
+ end
+ else
+ let
+ val (r', s') = acc (r -- nm)
+ in
+ (r' ++ {nm = r.nm}, s')
+ end)
+ (fn r => (r, skipOne s'))
+ (@Folder.concat ! fl ofl) (jss ++ ojss) (names ++ onames) r
+
+ val s' = skipSpaces s'
+ val s' = if String.length s' <> 0 && String.sub s' 0 = #"," then
+ skipSpaces (String.substring s' {Start = 1, Len = String.length s' - 1})
+ else
+ s'
+ in
+ fromJ s' r
+ end
+ in
+ if String.length s = 0 || String.sub s 0 <> #"{" then
+ error <xml>JSON record doesn't begin with brace</xml>
+ else
+ let
+ val (r, s') = fromJ (skipSpaces (String.substring s {Start = 1, Len = String.length s - 1}))
+ (@map0 [option] (fn [t ::_] => None) (@Folder.concat ! fl ofl))
+ in
+ (@map2 [option] [fn _ => string] [ident] (fn [t] (v : option t) name =>
+ case v of
+ None => error <xml>Missing JSON object field {[name]}</xml>
+ | Some v => v) fl (r --- _) names
+ ++ (r --- _), s')
+ end
+end}
+
+(* At the moment, the below code is largely copied and pasted from the last
+ * definition, because otherwise the compiler fails to inline enough for
+ * compilation to succeed. *)
fun json_record [ts ::: {Type}] (fl : folder ts) (jss : $(map json ts)) (names : $(map (fn _ => string) ts)) : json $ts =
{ToJson = fn r => "{" ^ @foldR3 [json] [fn _ => string] [ident] [fn _ => string]
(fn [nm ::_] [t ::_] [r ::_] [[nm] ~ r] (j : json t) name v acc =>
diff --git a/lib/ur/json.urs b/lib/ur/json.urs
index b4bd6350..56f5a897 100644
--- a/lib/ur/json.urs
+++ b/lib/ur/json.urs
@@ -17,6 +17,10 @@ val json_option : a ::: Type -> json a -> json (option a)
val json_list : a ::: Type -> json a -> json (list a)
val json_record : ts ::: {Type} -> folder ts -> $(map json ts) -> $(map (fn _ => string) ts) -> json $ts
+val json_record_withOptional : ts ::: {Type} -> ots ::: {Type} -> [ts ~ ots]
+ => folder ts -> $(map json ts) -> $(map (fn _ => string) ts)
+ -> folder ots -> $(map json ots) -> $(map (fn _ => string) ots)
+ -> json $(ts ++ map option ots)
val json_variant : ts ::: {Type} -> folder ts -> $(map json ts) -> $(map (fn _ => string) ts) -> json (variant ts)
val json_unit : json unit