root / htools / Ganeti / Qlang.hs @ 8a9ee1e9
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{-# LANGUAGE TemplateHaskell #-} |
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{-| Implementation of the Ganeti Query2 language. |
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-} |
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{- |
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Copyright (C) 2012 Google Inc. |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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02110-1301, USA. |
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-} |
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module Ganeti.Qlang |
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( Filter(..) |
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, FilterValue(..) |
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, Query(..) |
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, QueryResult(..) |
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, QueryFields(..) |
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, QueryFieldsResult(..) |
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, FieldDefinition(..) |
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, ResultEntry(..) |
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, ItemType(..) |
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) where |
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|
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import Control.Applicative |
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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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import Text.JSON |
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import qualified Ganeti.Constants as C |
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import Ganeti.THH |
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|
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-- * THH declarations, that require ordering. |
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-- | Status of a query field. |
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$(declareIADT "ResultStatus" |
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[ ("RSNormal", 'C.rsNormal ) |
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, ("RSUnknown", 'C.rsUnknown ) |
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, ("RSNoData", 'C.rsNodata ) |
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, ("RSUnavail", 'C.rsUnavail ) |
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, ("RSOffline", 'C.rsOffline ) |
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]) |
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$(makeJSONInstance ''ResultStatus) |
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-- | Type of a query field. |
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$(declareSADT "FieldType" |
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[ ("QFTUnknown", 'C.qftUnknown ) |
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, ("QFTText", 'C.qftText ) |
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, ("QFTBool", 'C.qftBool ) |
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, ("QFTNumber", 'C.qftNumber ) |
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, ("QFTUnit", 'C.qftUnit ) |
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, ("QFTTimestamp", 'C.qftTimestamp ) |
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, ("QFTOther", 'C.qftOther ) |
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]) |
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$(makeJSONInstance ''FieldType) |
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-- | Supported items on which Qlang works. |
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$(declareSADT "ItemType" |
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[ ("QRCluster", 'C.qrCluster ) |
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, ("QRInstance", 'C.qrInstance ) |
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, ("QRNode", 'C.qrNode ) |
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, ("QRLock", 'C.qrLock ) |
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, ("QRGroup", 'C.qrGroup ) |
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, ("QROs", 'C.qrOs ) |
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, ("QRJob", 'C.qrJob ) |
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, ("QRExport", 'C.qrExport ) |
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]) |
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$(makeJSONInstance ''ItemType) |
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-- * Main Qlang queries and responses. |
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-- | Query2 query. |
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data Query = Query ItemType Fields (Maybe Filter) |
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-- | Query2 result. |
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data QueryResult = QueryResult [ FieldDefinition ] [ ResultEntry ] |
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-- | Query2 Fields query. |
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-- (to get supported fields names, descriptions, and types) |
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data QueryFields = QueryFields ItemType Fields |
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-- | Query2 Fields result. |
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data QueryFieldsResult = QueryFieldsResult [ FieldDefinition ] |
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-- * Sub data types for query2 queries and responses. |
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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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deriving (Show, Read, Eq) |
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|
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-- | Serialiser for the 'Filter' data type. |
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showFilter :: Filter -> 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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showFilter (OrFilter exprs) = |
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JSArray $ (showJSON C.qlangOpOr):(map showJSON exprs) |
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showFilter (NotFilter flt) = |
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JSArray [showJSON C.qlangOpNot, showJSON flt] |
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showFilter (TrueFilter field) = |
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JSArray [showJSON C.qlangOpTrue, showJSON field] |
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showFilter (EQFilter field value) = |
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JSArray [showJSON C.qlangOpEqual, showJSON field, showJSON value] |
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showFilter (LTFilter field value) = |
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JSArray [showJSON C.qlangOpLt, showJSON field, showJSON value] |
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showFilter (GTFilter field value) = |
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JSArray [showJSON C.qlangOpGt, showJSON field, showJSON value] |
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showFilter (LEFilter field value) = |
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JSArray [showJSON C.qlangOpLe, showJSON field, showJSON value] |
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showFilter (GEFilter field value) = |
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JSArray [showJSON C.qlangOpGe, showJSON field, showJSON value] |
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showFilter (RegexpFilter field regexp) = |
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JSArray [showJSON C.qlangOpRegexp, showJSON field, showJSON regexp] |
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showFilter (ContainsFilter field value) = |
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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 JSNull = Ok EmptyFilter |
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readFilter (JSArray (JSString op:args)) = |
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readFilterArray (fromJSString op) args |
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readFilter v = |
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Error $ "Cannot deserialise filter: expected array [string, args], got " ++ |
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show (pp_value v) |
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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 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 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 constr [field, value] = |
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constr <$> readJSON field <*> readJSON value |
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readFilterFieldValue _ v = |
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Error $ "Cannot deserialise field/value pair, expected [fieldname, value]\ |
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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 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.qlangOpNot = readFilterArg NotFilter args |
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| op == C.qlangOpTrue = readFilterField TrueFilter args |
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| op == C.qlangOpEqual = readFilterFieldValue EQFilter args |
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| op == C.qlangOpLt = readFilterFieldValue LTFilter args |
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| op == C.qlangOpGt = readFilterFieldValue GTFilter args |
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| op == C.qlangOpLe = readFilterFieldValue LEFilter args |
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| op == C.qlangOpGe = readFilterFieldValue GEFilter args |
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| op == C.qlangOpRegexp = readFilterFieldValue RegexpFilter 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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showJSON = showFilter |
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readJSON = readFilter |
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-- | Field name to filter on. |
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type FilterField = String |
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-- | Value to compare the field value to, for filtering purposes. |
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data FilterValue = QuotedString String |
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| NumericValue Integer |
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deriving (Read, Show, Eq) |
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-- | Serialiser for 'FilterValue'. The Python code just sends this to |
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-- JSON as-is, so we'll do the same. |
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showFilterValue :: FilterValue -> JSValue |
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showFilterValue (QuotedString str) = showJSON str |
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showFilterValue (NumericValue val) = showJSON val |
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-- | Decoder for 'FilterValue'. We have to see what it contains, since |
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-- the context doesn't give us hints on what to expect. |
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readFilterValue :: JSValue -> Result FilterValue |
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readFilterValue (JSString a) = Ok . QuotedString $ fromJSString a |
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readFilterValue (JSRational _ x) = |
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if denominator x /= 1 |
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then Error $ "Cannot deserialise numeric filter value,\ |
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\ expecting integral but\ |
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\ got a fractional value: " ++ show x |
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else Ok . NumericValue $ numerator x |
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readFilterValue v = Error $ "Cannot deserialise filter value, expecting\ |
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\ string or integer, got " ++ show (pp_value v) |
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instance JSON FilterValue where |
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showJSON = showFilterValue |
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readJSON = readFilterValue |
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-- | Regexp to apply to the filter value, for filteriong purposes. |
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type FilterRegexp = String |
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-- | Definition of a field. |
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data FieldDefinition = FieldDefinition FieldName FieldTitle FieldType FieldDoc |
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-- | Name of a field. |
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type FieldName = String |
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-- | Title of a field, when represented in tabular format. |
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type FieldTitle = String |
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-- | Human redable description of a field. |
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type FieldDoc = String |
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--- | Single field entry result. |
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data ResultEntry = ResultEntry ResultStatus (Maybe ResultValue) |
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-- | Value of a field, in json encoding. |
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-- (its type will be depending on ResultStatus and FieldType) |
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type ResultValue = JSValue |