Decoding.hs

-- | Decoding functions for JSON data

module Hydra.Ext.Org.Json.Decoding where

import qualified Hydra.Compute as Compute
import qualified Hydra.Json as Json
import qualified Hydra.Lib.Flows as Flows
import qualified Hydra.Lib.Maps as Maps
import qualified Hydra.Lib.Strings as Strings
import Data.Int
import Data.List as L
import Data.Map as M
import Data.Set as S

decodeString :: (Json.Value -> Compute.Flow s String)
decodeString x = case x of
  Json.ValueString v320 -> (Flows.pure v320)
  _ -> (Flows.fail "expected a string")

decodeNumber :: (Json.Value -> Compute.Flow s Double)
decodeNumber x = case x of
  Json.ValueNumber v321 -> (Flows.pure v321)
  _ -> (Flows.fail "expected a number")

decodeBoolean :: (Json.Value -> Compute.Flow s Bool)
decodeBoolean x = case x of
  Json.ValueBoolean v322 -> (Flows.pure v322)
  _ -> (Flows.fail "expected a boolean")

decodeArray :: ((Json.Value -> Compute.Flow s a) -> Json.Value -> Compute.Flow s [a])
decodeArray decodeElem x = case x of
  Json.ValueArray v323 -> (Flows.mapList decodeElem v323)
  _ -> (Flows.fail "expected an array")

decodeObject :: (Json.Value -> Compute.Flow s (Map String Json.Value))
decodeObject x = case x of
  Json.ValueObject v324 -> (Flows.pure v324)
  _ -> (Flows.fail "expected an object")

decodeField :: ((Json.Value -> Compute.Flow s a) -> String -> Map String Json.Value -> Compute.Flow s a)
decodeField decodeValue name m = (Flows.bind (decodeOptionalField decodeValue name m) (\x -> case x of
  Nothing -> (Flows.fail (Strings.cat [
    "missing field: ",
    name]))
  Just v325 -> (Flows.pure v325)))

decodeOptionalField :: ((Json.Value -> Compute.Flow s a) -> String -> Map String Json.Value -> Compute.Flow s (Maybe a))
decodeOptionalField decodeValue name m = ((\x -> case x of
  Nothing -> (Flows.pure Nothing)
  Just v326 -> (Flows.map (\x -> Just x) (decodeValue v326))) (Maps.lookup name m))