Revision 05ac718f htools/Ganeti/Qlang.hs
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module Ganeti.Qlang |
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( Filter(..) |
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, FilterField |
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, FilterValue(..) |
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, Fields |
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, Query(..) |
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) where |
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import Control.Applicative |
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import Data.Foldable |
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import Data.Traversable (Traversable, traverse, fmapDefault, foldMapDefault) |
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import Data.Ratio (numerator, denominator) |
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import Text.JSON.Pretty (pp_value) |
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import Text.JSON.Types |
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-- | List of requested fields. |
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type Fields = [ String ] |
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-- | Query2 filter expression. |
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data Filter |
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= EmptyFilter -- ^ No filter at all |
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| AndFilter [ Filter ] -- ^ & [<expression>, ...] |
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| OrFilter [ Filter ] -- ^ | [<expression>, ...] |
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| NotFilter Filter -- ^ ! <expression> |
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| TrueFilter FilterField -- ^ ? <field> |
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| EQFilter FilterField FilterValue -- ^ (=|!=) <field> <value> |
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| LTFilter FilterField FilterValue -- ^ < <field> <value> |
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| GTFilter FilterField FilterValue -- ^ > <field> <value> |
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| LEFilter FilterField FilterValue -- ^ <= <field> <value> |
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| GEFilter FilterField FilterValue -- ^ >= <field> <value> |
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| RegexpFilter FilterField FilterRegexp -- ^ =~ <field> <regexp> |
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| ContainsFilter FilterField FilterValue -- ^ =[] <list-field> <value> |
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-- | Query2 filter expression. It's a parameteric type since we can |
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-- filter different \"things\"; e.g. field names, or actual field |
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-- getters, etc. |
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data Filter a |
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= EmptyFilter -- ^ No filter at all |
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| AndFilter [ Filter a ] -- ^ & [<expression>, ...] |
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| OrFilter [ Filter a ] -- ^ | [<expression>, ...] |
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| NotFilter (Filter a) -- ^ ! <expression> |
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| TrueFilter a -- ^ ? <field> |
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| EQFilter a FilterValue -- ^ (=|!=) <field> <value> |
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| LTFilter a FilterValue -- ^ < <field> <value> |
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| GTFilter a FilterValue -- ^ > <field> <value> |
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| LEFilter a FilterValue -- ^ <= <field> <value> |
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| GEFilter a FilterValue -- ^ >= <field> <value> |
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| RegexpFilter a FilterRegexp -- ^ =~ <field> <regexp> |
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| ContainsFilter a FilterValue -- ^ =[] <list-field> <value> |
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deriving (Show, Read, Eq) |
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-- | Serialiser for the 'Filter' data type. |
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showFilter :: Filter -> JSValue
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showFilter :: (JSON a) => Filter a -> JSValue
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showFilter (EmptyFilter) = JSNull |
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showFilter (AndFilter exprs) = |
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JSArray $ (showJSON C.qlangOpAnd):(map showJSON exprs) |
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JSArray [showJSON C.qlangOpContains, showJSON field, showJSON value] |
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-- | Deserializer for the 'Filter' data type. |
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readFilter :: JSValue -> Result Filter
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readFilter :: (JSON a) => JSValue -> Result (Filter a)
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readFilter JSNull = Ok EmptyFilter |
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readFilter (JSArray (JSString op:args)) = |
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readFilterArray (fromJSString op) args |
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-- | Helper to deserialise an array corresponding to a single filter |
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-- and return the built filter. Note this looks generic but is (at |
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-- least currently) only used for the NotFilter. |
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readFilterArg :: (Filter -> Filter) -- ^ Constructor |
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-> [JSValue] -- ^ Single argument |
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-> Result Filter |
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readFilterArg :: (JSON a) => |
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(Filter a -> Filter a) -- ^ Constructor |
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-> [JSValue] -- ^ Single argument |
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-> Result (Filter a) |
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readFilterArg constr [flt] = constr <$> readJSON flt |
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readFilterArg _ v = Error $ "Cannot deserialise field, expected [filter]\ |
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\ but got " ++ show (pp_value (showJSON v)) |
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-- | Helper to deserialise an array corresponding to a single field |
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-- and return the built filter. |
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readFilterField :: (FilterField -> Filter) -- ^ Constructor |
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-> [JSValue] -- ^ Single argument |
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-> Result Filter |
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readFilterField :: (JSON a) => |
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(a -> Filter a) -- ^ Constructor |
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-> [JSValue] -- ^ Single argument |
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-> Result (Filter a) |
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readFilterField constr [field] = constr <$> readJSON field |
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readFilterField _ v = Error $ "Cannot deserialise field, expected [fieldname]\ |
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\ but got " ++ show (pp_value (showJSON v)) |
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-- | Helper to deserialise an array corresponding to a field and |
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-- value, returning the built filter. |
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readFilterFieldValue :: (JSON a) => |
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(FilterField -> a -> Filter) -- ^ Constructor
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-> [JSValue] -- ^ Arguments array |
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-> Result Filter
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readFilterFieldValue :: (JSON a, JSON b) =>
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(a -> b -> Filter a) -- ^ Constructor
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-> [JSValue] -- ^ Arguments array
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-> Result (Filter a)
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readFilterFieldValue constr [field, value] = |
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constr <$> readJSON field <*> readJSON value |
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readFilterFieldValue _ v = |
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\ but got " ++ show (pp_value (showJSON v)) |
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-- | Inner deserialiser for 'Filter'. |
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readFilterArray :: String -> [JSValue] -> Result Filter
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readFilterArray :: (JSON a) => String -> [JSValue] -> Result (Filter a)
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readFilterArray op args |
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| op == C.qlangOpAnd = AndFilter <$> mapM readJSON args |
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| op == C.qlangOpOr = OrFilter <$> mapM readJSON args |
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| op == C.qlangOpContains = readFilterFieldValue ContainsFilter args |
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| otherwise = Error $ "Unknown filter operand '" ++ op ++ "'" |
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instance JSON Filter where
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instance (JSON a) => JSON (Filter a) where
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showJSON = showFilter |
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readJSON = readFilter |
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-- Traversable implementation for 'Filter'. |
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traverseFlt :: (Applicative f) => (a -> f b) -> Filter a -> f (Filter b) |
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traverseFlt _ EmptyFilter = pure EmptyFilter |
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traverseFlt f (AndFilter flts) = AndFilter <$> (traverse (traverseFlt f) flts) |
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traverseFlt f (OrFilter flts) = OrFilter <$> (traverse (traverseFlt f) flts) |
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traverseFlt f (NotFilter flt) = NotFilter <$> (traverseFlt f flt) |
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traverseFlt f (TrueFilter a) = TrueFilter <$> f a |
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traverseFlt f (EQFilter a fval) = EQFilter <$> f a <*> pure fval |
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traverseFlt f (LTFilter a fval) = LTFilter <$> f a <*> pure fval |
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traverseFlt f (GTFilter a fval) = GTFilter <$> f a <*> pure fval |
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traverseFlt f (LEFilter a fval) = LEFilter <$> f a <*> pure fval |
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traverseFlt f (GEFilter a fval) = GEFilter <$> f a <*> pure fval |
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traverseFlt f (RegexpFilter a re) = RegexpFilter <$> f a <*> pure re |
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traverseFlt f (ContainsFilter a fval) = ContainsFilter <$> f a <*> pure fval |
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instance Traversable Filter where |
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traverse = traverseFlt |
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instance Functor Filter where |
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fmap = fmapDefault |
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instance Foldable Filter where |
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foldMap = foldMapDefault |
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-- | Field name to filter on. |
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type FilterField = String |
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-- * Main Qlang queries and responses. |
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-- | Query2 query. |
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data Query = Query ItemType Fields Filter
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data Query = Query ItemType Fields (Filter FilterField)
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-- | Query2 result. |
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$(buildObject "QueryResult" "qres" |
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