DBus/Types/Containers/Array.lhs

% Copyright (C) 2009 John Millikin % % This program is free software: you can redistribute it and/or modify % it under the terms of the GNU General Public License as published by % the Free Software Foundation, either version 3 of the License, or % any later version. % % This program is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the % GNU General Public License for more details. % % You should have received a copy of the GNU General Public License % along with this program. If not, see . \ignore{ \begin{code}

{-# LANGUAGE DeriveDataTypeable #-}
module DBus.Types.Containers.Array
	( Array
	, toArray
	, fromArray
	, arrayItems
	, arrayFromItems
	, arraySignature
	) where

import Data.Typeable (Typeable, cast)
import qualified DBus.Types.Signature as S
import qualified DBus.Types.Containers.Variant as V

\end{code} } \subsubsection{Arrays} Arrays are homogeneous sequences of any valid type. They may be converted to and from standard Haskell lists, where the list contains elements with a valid type. \begin{code}

data Array = Array S.Signature [V.Variant]
	deriving (Show, Eq, Typeable)

\end{code} \begin{code}

instance V.Variable Array where
	defaultSignature _ = S.mkSignature' "ay"
	toVariant x = V.Variant (arraySignature x) x
	fromVariant (V.Variant _ x) = cast x

\end{code} \begin{code}

toArray :: V.Variable a => [a] -> Maybe Array
toArray vs = arrayFromItems sig variants where
	variants = map V.toVariant vs
	sig = case vs of
		[] -> V.defaultSignature . head $ undefined : vs
		_  -> V.variantSignature . head $ variants

\end{code} \begin{code}

arrayFromItems :: S.Signature -> [V.Variant] -> Maybe Array
arrayFromItems itemSig vs = array where
	array = if sameSignature
		then Just (Array sig vs)
		else Nothing
	sig = S.mkSignature' $ 'a' : S.strSignature itemSig
	sameSignature = all (== itemSig) . map V.variantSignature $ vs

\end{code} \begin{code}

fromArray :: V.Variable a => Array -> Maybe [a]
fromArray (Array _ vs) = mapM V.fromVariant vs

\end{code} \begin{code}

arrayItems :: Array -> [V.Variant]
arrayItems (Array _ vs) = vs

\end{code} \begin{code}

arraySignature :: Array -> S.Signature
arraySignature (Array s _) = s

\end{code}