-----------------------------------------------------------------------------
-- |
-- Module      :  Network.XmlRpc.THDeriveXmlRpcType
-- Copyright   :  (c) Bjorn Bringert 2003-2005
-- License     :  BSD-style
--
-- Maintainer  :  bjorn@bringert.net
-- Stability   :  experimental
-- Portability :  non-portable (requires extensions and non-portable libraries)
--
-- Uses Template Haskell to automagically derive instances of 'XmlRpcType'
--
------------------------------------------------------------------------------

{-# LANGUAGE CPP             #-}
{-# LANGUAGE TemplateHaskell #-}

module Network.XmlRpc.THDeriveXmlRpcType (asXmlRpcStruct) where

import           Control.Monad            (liftM, replicateM)
import           Data.List                (genericLength)
import           Data.Maybe               (maybeToList)
import           Language.Haskell.TH
import           Network.XmlRpc.Internals hiding (Type)

-- | Creates an 'XmlRpcType' instance which handles a Haskell record
--   as an XmlRpc struct. Example:
-- @
-- data Person = Person { name :: String, age :: Int }
-- $(asXmlRpcStruct \'\'Person)
-- @
asXmlRpcStruct :: Name -> Q [Dec]
asXmlRpcStruct :: Name -> Q [Dec]
asXmlRpcStruct Name
name =
    do
    Info
info <- Name -> Q Info
reify Name
name
    Dec
dec <- case Info
info of
                     TyConI Dec
d -> forall (m :: * -> *) a. Monad m => a -> m a
return Dec
d
                     Info
_ -> forall (m :: * -> *) a. MonadFail m => String -> m a
fail forall a b. (a -> b) -> a -> b
$ forall a. Show a => a -> String
show Name
name forall a. [a] -> [a] -> [a]
++ String
" is not a type constructor"
    Dec -> Q [Dec]
mkInstance Dec
dec

mkInstance :: Dec -> Q [Dec]
#if MIN_VERSION_template_haskell(2,11,0)
mkInstance :: Dec -> Q [Dec]
mkInstance  (DataD Cxt
_ Name
n [TyVarBndr ()]
_ Maybe Kind
_ [RecC Name
c [VarBangType]
fs] [DerivClause]
_) =
#else
mkInstance  (DataD _ n _ [RecC c fs] _) =
#endif
    do
    let ns :: [(Name, Bool)]
ns = (forall a b. (a -> b) -> [a] -> [b]
map (\ (Name
f,Bang
_,Kind
t) -> (Name -> Name
unqual Name
f, Kind -> Bool
isMaybe Kind
t)) [VarBangType]
fs)
    [Dec]
tv <- [(Name, Bool)] -> Q [Dec]
mkToValue [(Name, Bool)]
ns
    [Dec]
fv <- Name -> [(Name, Bool)] -> Q [Dec]
mkFromValue Name
c [(Name, Bool)]
ns
    [Dec]
gt <- Q [Dec]
mkGetType
    forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
liftM (forall a. a -> [a] -> [a]
:[]) forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *).
Quote m =>
m Cxt -> m Kind -> [m Dec] -> m Dec
instanceD (forall (m :: * -> *). Quote m => [m Kind] -> m Cxt
cxt []) (forall (m :: * -> *). Quote m => m Kind -> m Kind -> m Kind
appT (forall (m :: * -> *). Quote m => Name -> m Kind
conT ''XmlRpcType)
                                    (forall (m :: * -> *). Quote m => Name -> m Kind
conT Name
n))
              (forall a b. (a -> b) -> [a] -> [b]
map forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[Dec]
tv, [Dec]
fv, [Dec]
gt])

mkInstance Dec
_ = forall a. HasCallStack => String -> a
error String
"Can only derive XML-RPC type for simple record types"


isMaybe :: Type -> Bool
isMaybe :: Kind -> Bool
isMaybe (AppT (ConT Name
n) Kind
_) | Name
n forall a. Eq a => a -> a -> Bool
== ''Maybe = Bool
True
isMaybe Kind
_ = Bool
False


unqual :: Name -> Name
unqual :: Name -> Name
unqual = String -> Name
mkName forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. (a -> Bool) -> [a] -> [a]
takeWhile (forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`notElem` [Char
':',Char
'.']) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. [a] -> [a]
reverse forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. Show a => a -> String
show

mkToValue :: [(Name,Bool)] -> Q [Dec]
mkToValue :: [(Name, Bool)] -> Q [Dec]
mkToValue [(Name, Bool)]
fs =
    do
    Name
p <- forall (m :: * -> *). Quote m => String -> m Name
newName String
"p"
    Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun 'toValue [forall (m :: * -> *). Quote m => Name -> m Pat
varP Name
p]
                (forall (m :: * -> *). Quote m => m Exp -> m Exp -> m Exp
appE (forall (m :: * -> *). Quote m => Name -> m Exp
varE 'toValue)
                          (forall (m :: * -> *). Quote m => m Exp -> m Exp -> m Exp
appE [| concat |] forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *). Quote m => [m Exp] -> m Exp
listE forall a b. (a -> b) -> a -> b
$ forall a b. (a -> b) -> [a] -> [b]
map (Name -> (Name, Bool) -> ExpQ
fieldToTuple Name
p) [(Name, Bool)]
fs))


simpleFun :: Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun :: Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun Name
n [PatQ]
ps ExpQ
b = forall (t :: * -> *) (m :: * -> *) a.
(Traversable t, Monad m) =>
t (m a) -> m (t a)
sequence [forall (m :: * -> *). Quote m => Name -> [m Clause] -> m Dec
funD Name
n [forall (m :: * -> *).
Quote m =>
[m Pat] -> m Body -> [m Dec] -> m Clause
clause [PatQ]
ps (forall (m :: * -> *). Quote m => m Exp -> m Body
normalB ExpQ
b) []]]

fieldToTuple :: Name -> (Name,Bool) -> ExpQ
fieldToTuple :: Name -> (Name, Bool) -> ExpQ
fieldToTuple Name
p (Name
n,Bool
False) = forall (m :: * -> *). Quote m => [m Exp] -> m Exp
listE [forall (m :: * -> *). Quote m => [m Exp] -> m Exp
tupE [forall (m :: * -> *). Quote m => String -> m Exp
stringE (forall a. Show a => a -> String
show Name
n),
                                         forall (m :: * -> *). Quote m => m Exp -> m Exp -> m Exp
appE (forall (m :: * -> *). Quote m => Name -> m Exp
varE 'toValue)
                                         (forall (m :: * -> *). Quote m => m Exp -> m Exp -> m Exp
appE (forall (m :: * -> *). Quote m => Name -> m Exp
varE Name
n) (forall (m :: * -> *). Quote m => Name -> m Exp
varE Name
p))
                                        ]
                                 ]
fieldToTuple Name
p (Name
n,Bool
True) =
    [| map (\v -> ($(stringE (show n)), toValue v)) $ maybeToList $(appE (varE n) (varE p)) |]

mkFromValue :: Name -> [(Name,Bool)] -> Q [Dec]
mkFromValue :: Name -> [(Name, Bool)] -> Q [Dec]
mkFromValue Name
c [(Name, Bool)]
fs =
    do
    [Name]
names <- forall (m :: * -> *) a. Applicative m => Int -> m a -> m [a]
replicateM (forall (t :: * -> *) a. Foldable t => t a -> Int
length [(Name, Bool)]
fs) (forall (m :: * -> *). Quote m => String -> m Name
newName String
"x")
    Name
v <- forall (m :: * -> *). Quote m => String -> m Name
newName String
"v"
    Name
t <- forall (m :: * -> *). Quote m => String -> m Name
newName String
"t"
    Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun 'fromValue [forall (m :: * -> *). Quote m => Name -> m Pat
varP Name
v] forall a b. (a -> b) -> a -> b
$
               forall (m :: * -> *). Quote m => [m Stmt] -> m Exp
doE forall a b. (a -> b) -> a -> b
$ [forall (m :: * -> *). Quote m => m Pat -> m Exp -> m Stmt
bindS (forall (m :: * -> *). Quote m => Name -> m Pat
varP Name
t) (forall (m :: * -> *). Quote m => m Exp -> m Exp -> m Exp
appE (forall (m :: * -> *). Quote m => Name -> m Exp
varE 'fromValue) (forall (m :: * -> *). Quote m => Name -> m Exp
varE Name
v))] forall a. [a] -> [a] -> [a]
++
                      forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
zipWith (forall {m :: * -> *} {a}.
(Quote m, Show a) =>
Name -> m Pat -> (a, Bool) -> m Stmt
mkGetField Name
t) (forall a b. (a -> b) -> [a] -> [b]
map forall (m :: * -> *). Quote m => Name -> m Pat
varP [Name]
names) [(Name, Bool)]
fs forall a. [a] -> [a] -> [a]
++
                      [forall (m :: * -> *). Quote m => m Exp -> m Stmt
noBindS forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *). Quote m => m Exp -> m Exp -> m Exp
appE [| return |] forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *). Quote m => [m Exp] -> m Exp
appsE (forall (m :: * -> *). Quote m => Name -> m Exp
conE Name
cforall a. a -> [a] -> [a]
:forall a b. (a -> b) -> [a] -> [b]
map forall (m :: * -> *). Quote m => Name -> m Exp
varE [Name]
names)]

mkGetField :: Name -> m Pat -> (a, Bool) -> m Stmt
mkGetField Name
t m Pat
p (a
f,Bool
False) = forall (m :: * -> *). Quote m => m Pat -> m Exp -> m Stmt
bindS m Pat
p (forall (m :: * -> *). Quote m => [m Exp] -> m Exp
appsE [forall (m :: * -> *). Quote m => Name -> m Exp
varE 'getField,
                                           forall (m :: * -> *). Quote m => String -> m Exp
stringE (forall a. Show a => a -> String
show a
f), forall (m :: * -> *). Quote m => Name -> m Exp
varE Name
t])
mkGetField Name
t m Pat
p (a
f,Bool
True) = forall (m :: * -> *). Quote m => m Pat -> m Exp -> m Stmt
bindS m Pat
p (forall (m :: * -> *). Quote m => [m Exp] -> m Exp
appsE [forall (m :: * -> *). Quote m => Name -> m Exp
varE 'getFieldMaybe,
                                          forall (m :: * -> *). Quote m => String -> m Exp
stringE (forall a. Show a => a -> String
show a
f), forall (m :: * -> *). Quote m => Name -> m Exp
varE Name
t])

mkGetType :: Q [Dec]
mkGetType :: Q [Dec]
mkGetType = Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun 'getType [forall (m :: * -> *). Quote m => m Pat
wildP]
             (forall (m :: * -> *). Quote m => Name -> m Exp
conE 'TStruct)