Add JSON coder helper files

elm.json

@@ -8,6 +8,8 @@
         "Matrix",
         "Internal.Config.Default",
         "Internal.Config.Text",
+        "Internal.Tools.Decode",
+        "Internal.Tools.Encode",
         "Internal.Tools.Hashdict",
         "Internal.Tools.Iddict",
         "Internal.Tools.Timestamp",

src/Internal/Tools/Decode.elm

@@ -0,0 +1,155 @@
+module Internal.Tools.Decode exposing
+    ( opField, opFieldWithDefault
+    , map9, map10, map11
+    )
+
+{-|
+
+
+# Decode module
+
+This module contains helper functions that help decode JSON.
+
+
+## Optional field decoders
+
+@docs opField, opFieldWithDefault
+
+
+## Extended map functions
+
+@docs map9, map10, map11
+
+-}
+
+import Json.Decode as D
+
+
+{-| Add an optional field decoder. If the field exists, the decoder will fail
+if the field doesn't decode properly.
+
+This decoder standard out from `D.maybe <| D.field fieldName decoder` because
+that will decode into a `Nothing` if the `decoder` fails. This function will
+only decode into a `Nothing` if the field doesn't exist, and will fail if
+`decoder` fails.
+
+The function also returns Nothing if the field exists but it is null.
+
+-}
+opField : String -> D.Decoder a -> D.Decoder (Maybe a)
+opField fieldName decoder =
+    D.value
+        |> D.field fieldName
+        |> D.maybe
+        |> D.andThen
+            (\v ->
+                case v of
+                    Just _ ->
+                        D.oneOf
+                            [ D.null Nothing
+                            , D.map Just decoder
+                            ]
+                            |> D.field fieldName
+
+                    Nothing ->
+                        D.succeed Nothing
+            )
+
+
+{-| Add an optional field decoder. If the field is not given, the decoder will
+return a default value. If the field exists, the decoder will fail if the field
+doesn't decode properly.
+-}
+opFieldWithDefault : String -> a -> D.Decoder a -> D.Decoder a
+opFieldWithDefault fieldName default decoder =
+    opField fieldName decoder |> D.map (Maybe.withDefault default)
+
+
+{-| Try 9 decoders and combine the result.
+-}
+map9 :
+    (a -> b -> c -> d -> e -> f -> g -> h -> i -> value)
+    -> D.Decoder a
+    -> D.Decoder b
+    -> D.Decoder c
+    -> D.Decoder d
+    -> D.Decoder e
+    -> D.Decoder f
+    -> D.Decoder g
+    -> D.Decoder h
+    -> D.Decoder i
+    -> D.Decoder value
+map9 func da db dc dd de df dg dh di =
+    D.map8
+        (\a b c d e f g ( h, i ) ->
+            func a b c d e f g h i
+        )
+        da
+        db
+        dc
+        dd
+        de
+        df
+        dg
+        (D.map2 Tuple.pair dh di)
+
+
+{-| Try 10 decoders and combine the result.
+-}
+map10 :
+    (a -> b -> c -> d -> e -> f -> g -> h -> i -> j -> value)
+    -> D.Decoder a
+    -> D.Decoder b
+    -> D.Decoder c
+    -> D.Decoder d
+    -> D.Decoder e
+    -> D.Decoder f
+    -> D.Decoder g
+    -> D.Decoder h
+    -> D.Decoder i
+    -> D.Decoder j
+    -> D.Decoder value
+map10 func da db dc dd de df dg dh di dj =
+    D.map8
+        (\a b c d e f ( g, h ) ( i, j ) ->
+            func a b c d e f g h i j
+        )
+        da
+        db
+        dc
+        dd
+        de
+        df
+        (D.map2 Tuple.pair dg dh)
+        (D.map2 Tuple.pair di dj)
+
+
+{-| Try 11 decoders and combine the result.
+-}
+map11 :
+    (a -> b -> c -> d -> e -> f -> g -> h -> i -> j -> k -> value)
+    -> D.Decoder a
+    -> D.Decoder b
+    -> D.Decoder c
+    -> D.Decoder d
+    -> D.Decoder e
+    -> D.Decoder f
+    -> D.Decoder g
+    -> D.Decoder h
+    -> D.Decoder i
+    -> D.Decoder j
+    -> D.Decoder k
+    -> D.Decoder value
+map11 func da db dc dd de df dg dh di dj dk =
+    D.map8
+        (\a b c d e ( f, g ) ( h, i ) ( j, k ) ->
+            func a b c d e f g h i j k
+        )
+        da
+        db
+        dc
+        dd
+        de
+        (D.map2 Tuple.pair df dg)
+        (D.map2 Tuple.pair dh di)
+        (D.map2 Tuple.pair dj dk)

src/Internal/Tools/Encode.elm

@@ -0,0 +1,52 @@
+module Internal.Tools.Encode exposing (maybeObject)
+
+{-|
+
+
+# Encode module
+
+This module contains helper functions that help decode JSON.
+
+
+# Optional body object
+
+@docs maybeObject
+
+-}
+
+import Json.Encode as E
+
+
+{-| Create a body object based on optionally provided values.
+
+In other words, the following two variables create the same JSON value:
+
+    value1 : Json.Encode.Value
+    value1 =
+        maybeObject
+            [ ( "name", Just (Json.Encode.string "Alice") )
+            , ( "age", Nothing )
+            , ( "height", Just (Json.Encode.float 1.61) )
+            , ( "weight", Nothing )
+            ]
+
+    value2 : Json.Encode.Value
+    value2 =
+        Json.Encode.object
+            [ ( "name", Json.Encode.string "Alice" )
+            , ( "height", Json.Encode.float 1.61 )
+            ]
+
+-}
+maybeObject : List ( String, Maybe E.Value ) -> E.Value
+maybeObject =
+    List.filterMap
+        (\( name, value ) ->
+            case value of
+                Just v ->
+                    Just ( name, v )
+
+                _ ->
+                    Nothing
+        )
+        >> E.object