esqueleto-postgis-1.2.0: src/Database/Esqueleto/Postgis/Hex.hs

-- | friendly copied from github.com/zellige/wkt-geom.git
--   Copyright 2017-2018 wkt-geom Project
--   Apache license
module Database.Esqueleto.Postgis.Hex
  ( safeConvert
  , Hex(..)
  ) where

import qualified Data.ByteString        as ByteString
import qualified Data.ByteString.Base16 as ByteStringBase16
import qualified Data.ByteString.Char8  as ByteStringChar8
import qualified Data.ByteString.Lazy   as LazyByteString
import qualified Data.Geospatial        as Geospatial

newtype Hex = Hex ByteString.ByteString

safeConvert :: (LazyByteString.ByteString -> Either String Geospatial.GeospatialGeometry) -> Hex -> Either String Geospatial.GeospatialGeometry
safeConvert f (Hex byteString) =
    case ByteStringBase16.decodeBase16Untyped byteString of
         Left  _       -> Left $ "Invalid hex representation: " <> ByteStringChar8.unpack byteString
         Right decoded -> f    $ LazyByteString.fromStrict decoded