Revision a4f35477 src/Ganeti/JSON.hs

b/src/Ganeti/JSON.hs
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  , asJSObject
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  , asObjectList
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  , tryFromObj
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  , tryArrayMaybeFromObj
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  , toArray
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  , optionalJSField
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  , optFieldsToObj
......
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               -> m [J.JSObject J.JSValue]
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loadJSArray s = fromJResult s . J.decodeStrict
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-- | Helper function for missing-key errors


  		





  
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buildNoKeyError :: JSRecord -> String -> String


  		





  
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buildNoKeyError o k =


  		





  
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  printf "key '%s' not found, object contains only %s" k (show (map fst o))


  		





  
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-- | Reads the value of a key in a JSON object.


  		





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fromObj :: (J.JSON a, Monad m) => JSRecord -> String -> m a


  		





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fromObj o k =


  		





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  case lookup k o of


  		





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    Nothing -> fail $ printf "key '%s' not found, object contains only %s"


  		





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               k (show (map fst o))


  		





  
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    Nothing -> fail $ buildNoKeyError o k


  		





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    Just val -> fromKeyValue k val


  		





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-- | Reads the value of an optional key in a JSON object. Missing


  		





  ......




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                      JSRecord -> String -> a -> m a


  		





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fromObjWithDefault o k d = liftM (fromMaybe d) $ maybeFromObj o k


  		





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-- | Reads an array of optional items


  		





  
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arrayMaybeFromObj :: (J.JSON a, Monad m) =>


  		





  
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                     JSRecord -> String -> m [Maybe a]


  		





  
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arrayMaybeFromObj o k =


  		





  
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  case lookup k o of


  		





  
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    Just (J.JSArray xs) -> mapM parse xs


  		





  
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      where


  		





  
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        parse J.JSNull = return Nothing


  		





  
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        parse x = liftM Just $ fromJVal x


  		





  
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    _ -> fail $ buildNoKeyError o k


  		





  
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-- | Wrapper for arrayMaybeFromObj with better diagnostic


  		





  
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tryArrayMaybeFromObj :: (J.JSON a)


  		





  
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                     => String     -- ^ Textual "owner" in error messages


  		





  
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                     -> JSRecord   -- ^ The object array


  		





  
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                     -> String     -- ^ The desired key from the object


  		





  
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                     -> Result [Maybe a]


  		





  
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tryArrayMaybeFromObj t o = annotateResult t . arrayMaybeFromObj o


  		





  
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-- | Reads a JValue, that originated from an object key.


  		





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fromKeyValue :: (J.JSON a, Monad m)


  		





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              => String     -- ^ The key name


  		












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