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-----------------------------------------------------------------------------
-- |
-- Module : Data.Json.Builder
-- Copyright : (c) 2011 Leon P Smith
-- License : BSD3
--
-- Maintainer : Leon P Smith <leon@melding-monads.com>
--
-- Data structure agnostic JSON serialization
--
-----------------------------------------------------------------------------
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE IncoherentInstances #-}
module Data.Json.Builder
( Value(toJson)
, Json
, toBuilder
, toJsonByteString
, toJsonLazyByteString
, Array
, element
, Object
, row
, JsString(escape)
, Escaped
) where
import Prelude hiding ((++))
import Blaze.ByteString.Builder as Blaze
( Write
, Builder
, copyByteString
, fromByteString
, fromLazyByteString
, writeByteString
, fromWrite
, fromWriteList
, writeWord8
, toByteString
, toLazyByteString )
import Blaze.ByteString.Builder.Char.Utf8
( fromChar, writeChar, fromText, fromLazyText )
import Blaze.Text (float, double, integral)
import Data.Bits ( Bits((.&.), shiftR) )
import qualified Data.Map as Map
import Data.Monoid ( Monoid (mempty, mappend, mconcat) )
import Data.Int ( Int8, Int16, Int32, Int64)
import Data.Word ( Word, Word8, Word16, Word32, Word64 )
import qualified Data.Char as Char
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as BL
import qualified Data.ByteString.UTF8 as BU
import qualified Data.ByteString.Lazy.UTF8 as BLU
import Data.ByteString.Internal ( c2w )
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import qualified Data.HashMap.Lazy as HashMap
import Data.Json.Builder.Internal
(++) :: Monoid a => a -> a -> a
(++) = mappend
infixr 5 ++
toBuilder :: Value a => a -> Builder
toBuilder x = case toJson x of
Json y -> y
{-# SPECIALIZE toBuilder :: Json -> Builder #-}
{-# INLINE toBuilder #-}
toJsonByteString :: Value a => a -> BS.ByteString
toJsonByteString = toByteString . toBuilder
toJsonLazyByteString :: Value a => a -> BL.ByteString
toJsonLazyByteString = toLazyByteString . toBuilder
-- | The 'row' function constructs a json object consisting of exactly
-- one field. These objects can be concatinated using 'mappend'.
row :: (JsString k, Value a) => k -> a -> Object
row k a = Object (Comma (toBuilder k ++ fromChar ':' ++ toBuilder a))
-- | The 'element' function constructs a json array consisting of exactly
-- one value. These arrays can be concatinated using 'mappend'.
element :: Value a => a -> Array
element a = Array (Comma (toBuilder a))
-- Primitive instances for json-builder
-- | renders as @null@
instance Value () where
toJson _ = Json (copyByteString "null")
instance Value Int where
toJson = Json . integral
instance Value Int8 where
toJson = Json . integral
instance Value Int16 where
toJson = Json . integral
instance Value Int32 where
toJson = Json . integral
instance Value Int64 where
toJson = Json . integral
instance Value Integer where
toJson = Json . integral
instance Value Word where
toJson = Json . integral
instance Value Word8 where
toJson = Json . integral
instance Value Word16 where
toJson = Json . integral
instance Value Word32 where
toJson = Json . integral
instance Value Word64 where
toJson = Json . integral
instance Value Double where
toJson = Json . double
instance Value Float where
toJson = Json . float
-- | renders as @true@ or @false@
instance Value Bool where
toJson True = Json (copyByteString "true")
toJson False = Json (copyByteString "false")
-- | must be UTF-8 encoded
instance JsString BS.ByteString where
escape x = Escaped (loop x)
where
loop (BU.break quoteNeeded -> (a,b))
= fromByteString a ++
case BU.decode b of
Nothing -> mempty
Just (c,n) -> quoteChar c ++ loop (BS.drop n b)
instance Value BS.ByteString where
toJson = toJson . escape
-- | must be UTF-8 encoded
instance JsString BL.ByteString where
escape x = Escaped (loop x)
where
loop (BLU.break quoteNeeded -> (a,b))
= fromLazyByteString a ++
case BLU.decode b of
Nothing -> mempty
Just (c,n) -> quoteChar c ++ loop (BL.drop n b)
instance Value BL.ByteString where
toJson = toJson . escape
instance JsString T.Text where
escape x = Escaped (loop x)
where
loop (T.break quoteNeeded -> (a,b))
= fromText a ++
case T.uncons b of
Nothing -> mempty
Just (c,b') -> quoteChar c ++ loop b'
instance Value T.Text where
toJson = toJson . escape
instance JsString TL.Text where
escape x = Escaped (loop x)
where
loop (TL.break quoteNeeded -> (a,b))
= fromLazyText a ++
case TL.uncons b of
Nothing -> mempty
Just (c,b') -> quoteChar c ++ loop b'
instance Value TL.Text where
toJson = toJson . escape
instance JsString [Char] where
escape str = Escaped (fromWriteList writeEscapedChar str)
where
writeEscapedChar c | quoteNeeded c = quoteCharW c
| otherwise = writeChar c
instance Value [Char] where
toJson = toJson . escape
-- | renders as an 'Array'
instance Value a => Value [a] where
toJson = toJson . mconcat . map element
-- | renders as an 'Object'
instance (JsString k, Value a) => Value (Map.Map k a) where
toJson = toJson . Map.foldrWithKey (\k a b -> row k a ++ b) mempty
-- | renders as an 'Object'
instance (JsString k, Value a) => Value (HashMap.HashMap k a) where
toJson = toJson . HashMap.foldrWithKey (\k a b -> row k a ++ b) mempty
------------------------------------------------------------------------------
quoteNeeded :: Char -> Bool
quoteNeeded c = c == '\\' || c == '"' || Char.ord c < 0x20
{-# INLINE quoteNeeded #-}
quoteChar :: Char -> Builder
quoteChar c = case c of
'\\' -> copyByteString "\\\\"
'"' -> copyByteString "\\\""
'\b' -> copyByteString "\\b"
'\f' -> copyByteString "\\f"
'\n' -> copyByteString "\\n"
'\r' -> copyByteString "\\r"
'\t' -> copyByteString "\\t"
_ -> fromWrite (hexEscape c)
quoteCharW :: Char -> Write
quoteCharW c = case c of
'\\' -> writeByteString "\\\\"
'"' -> writeByteString "\\\""
'\b' -> writeByteString "\\b"
'\f' -> writeByteString "\\f"
'\n' -> writeByteString "\\n"
'\r' -> writeByteString "\\r"
'\t' -> writeByteString "\\t"
_ -> hexEscape c
hexEscape :: Char -> Write
hexEscape (c2w -> c)
= writeByteString "\\u00"
++ writeWord8 (char ((c `shiftR` 4) .&. 0xF))
++ writeWord8 (char ( c .&. 0xF))
char :: Word8 -> Word8
char i | i < 10 = i + 48
| otherwise = i + 87
{-# INLINE char #-}
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