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{-# LANGUAGE TemplateHaskell #-} |
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|
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{-| TemplateHaskell helper for HTools. |
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|
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As TemplateHaskell require that splices be defined in a separate |
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module, we combine all the TemplateHaskell functionality that HTools |
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needs in this module (except the one for unittests). |
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|
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-} |
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|
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{- |
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|
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Copyright (C) 2011, 2012 Google Inc. |
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|
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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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|
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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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-} |
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|
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module Ganeti.THH ( declareSADT |
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, declareIADT |
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, makeJSONInstance |
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, genOpID |
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, genAllOpIDs |
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, genOpCode |
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, genStrOfOp |
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, genStrOfKey |
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, genLuxiOp |
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, Field |
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, simpleField |
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, defaultField |
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, optionalField |
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, renameField |
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, customField |
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, timeStampFields |
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, uuidFields |
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, serialFields |
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, tagsFields |
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, buildObject |
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, buildObjectSerialisation |
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, buildParam |
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, DictObject(..) |
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) where |
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|
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import Control.Monad (liftM) |
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import Data.Char |
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import Data.List |
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import Data.Maybe (fromMaybe) |
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import qualified Data.Set as Set |
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import Language.Haskell.TH |
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|
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import qualified Text.JSON as JSON |
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|
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-- * Exported types |
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|
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-- | Class of objects that can be converted to 'JSObject' |
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-- lists-format. |
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class DictObject a where |
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toDict :: a -> [(String, JSON.JSValue)] |
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|
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-- | Serialised field data type. |
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data Field = Field { fieldName :: String |
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, fieldType :: Q Type |
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, fieldRead :: Maybe (Q Exp) |
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, fieldShow :: Maybe (Q Exp) |
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, fieldDefault :: Maybe (Q Exp) |
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, fieldConstr :: Maybe String |
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, fieldIsOptional :: Bool |
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} |
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|
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-- | Generates a simple field. |
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simpleField :: String -> Q Type -> Field |
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simpleField fname ftype = |
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Field { fieldName = fname |
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, fieldType = ftype |
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, fieldRead = Nothing |
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, fieldShow = Nothing |
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, fieldDefault = Nothing |
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, fieldConstr = Nothing |
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, fieldIsOptional = False |
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} |
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|
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-- | Sets the renamed constructor field. |
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renameField :: String -> Field -> Field |
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renameField constrName field = field { fieldConstr = Just constrName } |
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|
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-- | Sets the default value on a field (makes it optional with a |
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-- default value). |
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defaultField :: Q Exp -> Field -> Field |
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defaultField defval field = field { fieldDefault = Just defval } |
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|
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-- | Marks a field optional (turning its base type into a Maybe). |
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optionalField :: Field -> Field |
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optionalField field = field { fieldIsOptional = True } |
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|
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-- | Sets custom functions on a field. |
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customField :: Name -- ^ The name of the read function |
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-> Name -- ^ The name of the show function |
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-> Field -- ^ The original field |
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-> Field -- ^ Updated field |
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customField readfn showfn field = |
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field { fieldRead = Just (varE readfn), fieldShow = Just (varE showfn) } |
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|
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-- | Computes the record name for a given field, based on either the |
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-- string value in the JSON serialisation or the custom named if any |
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-- exists. |
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fieldRecordName :: Field -> String |
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fieldRecordName (Field { fieldName = name, fieldConstr = alias }) = |
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fromMaybe (camelCase name) alias |
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|
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-- | Computes the preferred variable name to use for the value of this |
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-- field. If the field has a specific constructor name, then we use a |
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-- first-letter-lowercased version of that; otherwise, we simply use |
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-- the field name. See also 'fieldRecordName'. |
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fieldVariable :: Field -> String |
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fieldVariable f = |
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case (fieldConstr f) of |
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Just name -> ensureLower name |
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_ -> map (\c -> if c == '-' then '_' else c) $ fieldName f |
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|
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actualFieldType :: Field -> Q Type |
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actualFieldType f | fieldIsOptional f = [t| Maybe $t |] |
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| otherwise = t |
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where t = fieldType f |
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|
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checkNonOptDef :: (Monad m) => Field -> m () |
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checkNonOptDef (Field { fieldIsOptional = True, fieldName = name }) = |
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fail $ "Optional field " ++ name ++ " used in parameter declaration" |
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checkNonOptDef (Field { fieldDefault = (Just _), fieldName = name }) = |
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fail $ "Default field " ++ name ++ " used in parameter declaration" |
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checkNonOptDef _ = return () |
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|
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-- | Produces the expression that will de-serialise a given |
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-- field. Since some custom parsing functions might need to use the |
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-- entire object, we do take and pass the object to any custom read |
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-- functions. |
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loadFn :: Field -- ^ The field definition |
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-> Q Exp -- ^ The value of the field as existing in the JSON message |
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-> Q Exp -- ^ The entire object in JSON object format |
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-> Q Exp -- ^ Resulting expression |
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loadFn (Field { fieldRead = Just readfn }) expr o = [| $expr >>= $readfn $o |] |
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loadFn _ expr _ = expr |
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|
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-- * Common field declarations |
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|
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-- | Timestamp fields description. |
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timeStampFields :: [Field] |
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timeStampFields = |
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[ defaultField [| 0::Double |] $ simpleField "ctime" [t| Double |] |
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, defaultField [| 0::Double |] $ simpleField "mtime" [t| Double |] |
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] |
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|
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-- | Serial number fields description. |
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serialFields :: [Field] |
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serialFields = |
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[ renameField "Serial" $ simpleField "serial_no" [t| Int |] ] |
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|
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-- | UUID fields description. |
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uuidFields :: [Field] |
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uuidFields = [ simpleField "uuid" [t| String |] ] |
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|
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-- | Tag field description. |
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tagsFields :: [Field] |
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tagsFields = [ defaultField [| Set.empty |] $ |
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simpleField "tags" [t| Set.Set String |] ] |
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|
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-- * Helper functions |
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|
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-- | Ensure first letter is lowercase. |
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-- |
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-- Used to convert type name to function prefix, e.g. in @data Aa -> |
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-- aaToRaw@. |
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ensureLower :: String -> String |
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ensureLower [] = [] |
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ensureLower (x:xs) = toLower x:xs |
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|
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-- | Ensure first letter is uppercase. |
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-- |
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-- Used to convert constructor name to component |
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ensureUpper :: String -> String |
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ensureUpper [] = [] |
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ensureUpper (x:xs) = toUpper x:xs |
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|
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-- | Helper for quoted expressions. |
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varNameE :: String -> Q Exp |
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varNameE = varE . mkName |
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|
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-- | showJSON as an expression, for reuse. |
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showJSONE :: Q Exp |
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showJSONE = varNameE "showJSON" |
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|
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-- | ToRaw function name. |
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toRawName :: String -> Name |
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toRawName = mkName . (++ "ToRaw") . ensureLower |
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|
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-- | FromRaw function name. |
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fromRawName :: String -> Name |
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fromRawName = mkName . (++ "FromRaw") . ensureLower |
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|
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-- | Converts a name to it's varE\/litE representations. |
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reprE :: Either String Name -> Q Exp |
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reprE = either stringE varE |
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|
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-- | Smarter function application. |
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-- |
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-- This does simply f x, except that if is 'id', it will skip it, in |
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-- order to generate more readable code when using -ddump-splices. |
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appFn :: Exp -> Exp -> Exp |
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appFn f x | f == VarE 'id = x |
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| otherwise = AppE f x |
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|
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-- * Template code for simple raw type-equivalent ADTs |
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|
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-- | Generates a data type declaration. |
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-- |
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-- The type will have a fixed list of instances. |
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strADTDecl :: Name -> [String] -> Dec |
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strADTDecl name constructors = |
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DataD [] name [] |
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(map (flip NormalC [] . mkName) constructors) |
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[''Show, ''Read, ''Eq, ''Enum, ''Bounded, ''Ord] |
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|
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-- | Generates a toRaw function. |
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-- |
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-- This generates a simple function of the form: |
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-- |
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-- @ |
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-- nameToRaw :: Name -> /traw/ |
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-- nameToRaw Cons1 = var1 |
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-- nameToRaw Cons2 = \"value2\" |
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-- @ |
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genToRaw :: Name -> Name -> Name -> [(String, Either String Name)] -> Q [Dec] |
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genToRaw traw fname tname constructors = do |
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let sigt = AppT (AppT ArrowT (ConT tname)) (ConT traw) |
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-- the body clauses, matching on the constructor and returning the |
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-- raw value |
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clauses <- mapM (\(c, v) -> clause [recP (mkName c) []] |
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(normalB (reprE v)) []) constructors |
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return [SigD fname sigt, FunD fname clauses] |
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|
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-- | Generates a fromRaw function. |
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-- |
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-- The function generated is monadic and can fail parsing the |
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-- raw value. It is of the form: |
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-- |
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-- @ |
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-- nameFromRaw :: (Monad m) => /traw/ -> m Name |
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-- nameFromRaw s | s == var1 = Cons1 |
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-- | s == \"value2\" = Cons2 |
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-- | otherwise = fail /.../ |
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-- @ |
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genFromRaw :: Name -> Name -> Name -> [(String, Name)] -> Q [Dec] |
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genFromRaw traw fname tname constructors = do |
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-- signature of form (Monad m) => String -> m $name |
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sigt <- [t| (Monad m) => $(conT traw) -> m $(conT tname) |] |
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-- clauses for a guarded pattern |
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let varp = mkName "s" |
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varpe = varE varp |
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clauses <- mapM (\(c, v) -> do |
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-- the clause match condition |
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g <- normalG [| $varpe == $(varE v) |] |
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-- the clause result |
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r <- [| return $(conE (mkName c)) |] |
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return (g, r)) constructors |
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-- the otherwise clause (fallback) |
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oth_clause <- do |
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g <- normalG [| otherwise |] |
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r <- [|fail ("Invalid string value for type " ++ |
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$(litE (stringL (nameBase tname))) ++ ": " ++ show $varpe) |] |
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return (g, r) |
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let fun = FunD fname [Clause [VarP varp] |
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(GuardedB (clauses++[oth_clause])) []] |
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return [SigD fname sigt, fun] |
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|
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-- | Generates a data type from a given raw format. |
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-- |
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-- The format is expected to multiline. The first line contains the |
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-- type name, and the rest of the lines must contain two words: the |
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-- constructor name and then the string representation of the |
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-- respective constructor. |
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-- |
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-- The function will generate the data type declaration, and then two |
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-- functions: |
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-- |
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-- * /name/ToRaw, which converts the type to a raw type |
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-- |
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-- * /name/FromRaw, which (monadically) converts from a raw type to the type |
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-- |
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-- Note that this is basically just a custom show\/read instance, |
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-- nothing else. |
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declareADT :: Name -> String -> [(String, Name)] -> Q [Dec] |
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declareADT traw sname cons = do |
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let name = mkName sname |
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ddecl = strADTDecl name (map fst cons) |
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-- process cons in the format expected by genToRaw |
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cons' = map (\(a, b) -> (a, Right b)) cons |
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toraw <- genToRaw traw (toRawName sname) name cons' |
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fromraw <- genFromRaw traw (fromRawName sname) name cons |
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return $ ddecl:toraw ++ fromraw |
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|
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declareIADT :: String -> [(String, Name)] -> Q [Dec] |
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declareIADT = declareADT ''Int |
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|
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declareSADT :: String -> [(String, Name)] -> Q [Dec] |
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declareSADT = declareADT ''String |
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|
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-- | Creates the showJSON member of a JSON instance declaration. |
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-- |
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-- This will create what is the equivalent of: |
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-- |
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-- @ |
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-- showJSON = showJSON . /name/ToRaw |
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-- @ |
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-- |
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-- in an instance JSON /name/ declaration |
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genShowJSON :: String -> Q Dec |
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genShowJSON name = do |
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body <- [| JSON.showJSON . $(varE (toRawName name)) |] |
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return $ FunD (mkName "showJSON") [Clause [] (NormalB body) []] |
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|
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-- | Creates the readJSON member of a JSON instance declaration. |
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-- |
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-- This will create what is the equivalent of: |
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-- |
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-- @ |
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-- readJSON s = case readJSON s of |
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-- Ok s' -> /name/FromRaw s' |
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-- Error e -> Error /description/ |
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-- @ |
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-- |
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-- in an instance JSON /name/ declaration |
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genReadJSON :: String -> Q Dec |
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genReadJSON name = do |
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let s = mkName "s" |
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body <- [| case JSON.readJSON $(varE s) of |
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JSON.Ok s' -> $(varE (fromRawName name)) s' |
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JSON.Error e -> |
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JSON.Error $ "Can't parse raw value for type " ++ |
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$(stringE name) ++ ": " ++ e ++ " from " ++ |
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show $(varE s) |
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|] |
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return $ FunD (mkName "readJSON") [Clause [VarP s] (NormalB body) []] |
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|
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-- | Generates a JSON instance for a given type. |
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-- |
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-- This assumes that the /name/ToRaw and /name/FromRaw functions |
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-- have been defined as by the 'declareSADT' function. |
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makeJSONInstance :: Name -> Q [Dec] |
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makeJSONInstance name = do |
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let base = nameBase name |
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showJ <- genShowJSON base |
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readJ <- genReadJSON base |
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return [InstanceD [] (AppT (ConT ''JSON.JSON) (ConT name)) [readJ,showJ]] |
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|
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-- * Template code for opcodes |
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|
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-- | Transforms a CamelCase string into an_underscore_based_one. |
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deCamelCase :: String -> String |
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deCamelCase = |
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intercalate "_" . map (map toUpper) . groupBy (\_ b -> not $ isUpper b) |
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|
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-- | Transform an underscore_name into a CamelCase one. |
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camelCase :: String -> String |
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camelCase = concatMap (ensureUpper . drop 1) . |
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groupBy (\_ b -> b /= '_' && b /= '-') . ('_':) |
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|
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-- | Computes the name of a given constructor. |
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constructorName :: Con -> Q Name |
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constructorName (NormalC name _) = return name |
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constructorName (RecC name _) = return name |
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constructorName x = fail $ "Unhandled constructor " ++ show x |
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|
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-- | Extract all constructor names from a given type. |
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reifyConsNames :: Name -> Q [String] |
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reifyConsNames name = do |
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reify_result <- reify name |
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case reify_result of |
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TyConI (DataD _ _ _ cons _) -> mapM (liftM nameBase . constructorName) cons |
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o -> fail $ "Unhandled name passed to reifyConsNames, expected\ |
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\ type constructor but got '" ++ show o ++ "'" |
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|
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-- | Builds the generic constructor-to-string function. |
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-- |
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-- This generates a simple function of the following form: |
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-- |
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-- @ |
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-- fname (ConStructorOne {}) = trans_fun("ConStructorOne") |
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-- fname (ConStructorTwo {}) = trans_fun("ConStructorTwo") |
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-- @ |
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-- |
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-- This builds a custom list of name\/string pairs and then uses |
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-- 'genToRaw' to actually generate the function. |
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genConstrToStr :: (String -> String) -> Name -> String -> Q [Dec] |
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genConstrToStr trans_fun name fname = do |
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cnames <- reifyConsNames name |
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let svalues = map (Left . trans_fun) cnames |
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genToRaw ''String (mkName fname) name $ zip cnames svalues |
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|
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-- | Constructor-to-string for OpCode. |
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genOpID :: Name -> String -> Q [Dec] |
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genOpID = genConstrToStr deCamelCase |
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|
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-- | Builds a list with all defined constructor names for a type. |
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-- |
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-- @ |
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-- vstr :: String |
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-- vstr = [...] |
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-- @ |
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-- |
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-- Where the actual values of the string are the constructor names |
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-- mapped via @trans_fun@. |
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genAllConstr :: (String -> String) -> Name -> String -> Q [Dec] |
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genAllConstr trans_fun name vstr = do |
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cnames <- reifyConsNames name |
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let svalues = sort $ map trans_fun cnames |
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vname = mkName vstr |
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sig = SigD vname (AppT ListT (ConT ''String)) |
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body = NormalB (ListE (map (LitE . StringL) svalues)) |
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return $ [sig, ValD (VarP vname) body []] |
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|
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-- | Generates a list of all defined opcode IDs. |
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genAllOpIDs :: Name -> String -> Q [Dec] |
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genAllOpIDs = genAllConstr deCamelCase |
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|
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-- | OpCode parameter (field) type. |
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type OpParam = (String, Q Type, Q Exp) |
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|
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-- | Generates the OpCode data type. |
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-- |
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-- This takes an opcode logical definition, and builds both the |
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-- datatype and the JSON serialisation out of it. We can't use a |
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-- generic serialisation since we need to be compatible with Ganeti's |
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-- own, so we have a few quirks to work around. |
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genOpCode :: String -- ^ Type name to use |
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-> [(String, [Field])] -- ^ Constructor name and parameters |
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-> Q [Dec] |
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genOpCode name cons = do |
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decl_d <- mapM (\(cname, fields) -> do |
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-- we only need the type of the field, without Q |
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fields' <- mapM actualFieldType fields |
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let fields'' = zip (repeat NotStrict) fields' |
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return $ NormalC (mkName cname) fields'') |
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cons |
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let declD = DataD [] (mkName name) [] decl_d [''Show, ''Read, ''Eq] |
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|
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(savesig, savefn) <- genSaveOpCode cons |
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(loadsig, loadfn) <- genLoadOpCode cons |
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return [declD, loadsig, loadfn, savesig, savefn] |
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|
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-- | Checks whether a given parameter is options. |
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-- |
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-- This requires that it's a 'Maybe'. |
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isOptional :: Type -> Bool |
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isOptional (AppT (ConT dt) _) | dt == ''Maybe = True |
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isOptional _ = False |
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|
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-- | Generates the \"save\" clause for an entire opcode constructor. |
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-- |
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-- This matches the opcode with variables named the same as the |
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-- constructor fields (just so that the spliced in code looks nicer), |
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-- and passes those name plus the parameter definition to 'saveObjectField'. |
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saveConstructor :: String -- ^ The constructor name |
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-> [Field] -- ^ The parameter definitions for this |
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-- constructor |
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-> Q Clause -- ^ Resulting clause |
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saveConstructor sname fields = do |
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let cname = mkName sname |
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fnames <- mapM (newName . fieldVariable) fields |
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let pat = conP cname (map varP fnames) |
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let felems = map (uncurry saveObjectField) (zip fnames fields) |
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-- now build the OP_ID serialisation |
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opid = [| [( $(stringE "OP_ID"), |
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JSON.showJSON $(stringE . deCamelCase $ sname) )] |] |
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flist = listE (opid:felems) |
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-- and finally convert all this to a json object |
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flist' = [| $(varNameE "makeObj") (concat $flist) |] |
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clause [pat] (normalB flist') [] |
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|
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-- | Generates the main save opcode function. |
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-- |
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-- This builds a per-constructor match clause that contains the |
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-- respective constructor-serialisation code. |
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genSaveOpCode :: [(String, [Field])] -> Q (Dec, Dec) |
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genSaveOpCode opdefs = do |
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cclauses <- mapM (uncurry saveConstructor) opdefs |
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let fname = mkName "saveOpCode" |
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sigt <- [t| $(conT (mkName "OpCode")) -> JSON.JSValue |] |
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return $ (SigD fname sigt, FunD fname cclauses) |
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|
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-- | Generates load code for a single constructor of the opcode data type. |
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loadConstructor :: String -> [Field] -> Q Exp |
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loadConstructor sname fields = do |
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let name = mkName sname |
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fbinds <- mapM loadObjectField fields |
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let (fnames, fstmts) = unzip fbinds |
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let cval = foldl (\accu fn -> AppE accu (VarE fn)) (ConE name) fnames |
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fstmts' = fstmts ++ [NoBindS (AppE (VarE 'return) cval)] |
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return $ DoE fstmts' |
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|
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-- | Generates the loadOpCode function. |
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genLoadOpCode :: [(String, [Field])] -> Q (Dec, Dec) |
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genLoadOpCode opdefs = do |
515 |
let fname = mkName "loadOpCode" |
516 |
arg1 = mkName "v" |
517 |
objname = mkName "o" |
518 |
opid = mkName "op_id" |
519 |
st1 <- bindS (varP objname) [| liftM JSON.fromJSObject |
520 |
(JSON.readJSON $(varE arg1)) |] |
521 |
st2 <- bindS (varP opid) [| $(varNameE "fromObj") |
522 |
$(varE objname) $(stringE "OP_ID") |] |
523 |
-- the match results (per-constructor blocks) |
524 |
mexps <- mapM (uncurry loadConstructor) opdefs |
525 |
fails <- [| fail $ "Unknown opcode " ++ $(varE opid) |] |
526 |
let mpats = map (\(me, c) -> |
527 |
let mp = LitP . StringL . deCamelCase . fst $ c |
528 |
in Match mp (NormalB me) [] |
529 |
) $ zip mexps opdefs |
530 |
defmatch = Match WildP (NormalB fails) [] |
531 |
cst = NoBindS $ CaseE (VarE opid) $ mpats++[defmatch] |
532 |
body = DoE [st1, st2, cst] |
533 |
sigt <- [t| JSON.JSValue -> JSON.Result $(conT (mkName "OpCode")) |] |
534 |
return $ (SigD fname sigt, FunD fname [Clause [VarP arg1] (NormalB body) []]) |
535 |
|
536 |
-- * Template code for luxi |
537 |
|
538 |
-- | Constructor-to-string for LuxiOp. |
539 |
genStrOfOp :: Name -> String -> Q [Dec] |
540 |
genStrOfOp = genConstrToStr id |
541 |
|
542 |
-- | Constructor-to-string for MsgKeys. |
543 |
genStrOfKey :: Name -> String -> Q [Dec] |
544 |
genStrOfKey = genConstrToStr ensureLower |
545 |
|
546 |
-- | LuxiOp parameter type. |
547 |
type LuxiParam = (String, Q Type) |
548 |
|
549 |
-- | Generates the LuxiOp data type. |
550 |
-- |
551 |
-- This takes a Luxi operation definition and builds both the |
552 |
-- datatype and the function trnasforming the arguments to JSON. |
553 |
-- We can't use anything less generic, because the way different |
554 |
-- operations are serialized differs on both parameter- and top-level. |
555 |
-- |
556 |
-- There are two things to be defined for each parameter: |
557 |
-- |
558 |
-- * name |
559 |
-- |
560 |
-- * type |
561 |
-- |
562 |
genLuxiOp :: String -> [(String, [LuxiParam])] -> Q [Dec] |
563 |
genLuxiOp name cons = do |
564 |
decl_d <- mapM (\(cname, fields) -> do |
565 |
fields' <- mapM (\(_, qt) -> |
566 |
qt >>= \t -> return (NotStrict, t)) |
567 |
fields |
568 |
return $ NormalC (mkName cname) fields') |
569 |
cons |
570 |
let declD = DataD [] (mkName name) [] decl_d [''Show, ''Read, ''Eq] |
571 |
(savesig, savefn) <- genSaveLuxiOp cons |
572 |
req_defs <- declareSADT "LuxiReq" . |
573 |
map (\(str, _) -> ("Req" ++ str, mkName ("luxiReq" ++ str))) $ |
574 |
cons |
575 |
return $ [declD, savesig, savefn] ++ req_defs |
576 |
|
577 |
-- | Generates the \"save\" expression for a single luxi parameter. |
578 |
saveLuxiField :: Name -> LuxiParam -> Q Exp |
579 |
saveLuxiField fvar (_, qt) = |
580 |
[| JSON.showJSON $(varE fvar) |] |
581 |
|
582 |
-- | Generates the \"save\" clause for entire LuxiOp constructor. |
583 |
saveLuxiConstructor :: (String, [LuxiParam]) -> Q Clause |
584 |
saveLuxiConstructor (sname, fields) = do |
585 |
let cname = mkName sname |
586 |
fnames = map (mkName . fst) fields |
587 |
pat = conP cname (map varP fnames) |
588 |
flist = map (uncurry saveLuxiField) (zip fnames fields) |
589 |
finval = if null flist |
590 |
then [| JSON.showJSON () |] |
591 |
else [| JSON.showJSON $(listE flist) |] |
592 |
clause [pat] (normalB finval) [] |
593 |
|
594 |
-- | Generates the main save LuxiOp function. |
595 |
genSaveLuxiOp :: [(String, [LuxiParam])]-> Q (Dec, Dec) |
596 |
genSaveLuxiOp opdefs = do |
597 |
sigt <- [t| $(conT (mkName "LuxiOp")) -> JSON.JSValue |] |
598 |
let fname = mkName "opToArgs" |
599 |
cclauses <- mapM saveLuxiConstructor opdefs |
600 |
return $ (SigD fname sigt, FunD fname cclauses) |
601 |
|
602 |
-- * "Objects" functionality |
603 |
|
604 |
-- | Extract the field's declaration from a Field structure. |
605 |
fieldTypeInfo :: String -> Field -> Q (Name, Strict, Type) |
606 |
fieldTypeInfo field_pfx fd = do |
607 |
t <- actualFieldType fd |
608 |
let n = mkName . (field_pfx ++) . fieldRecordName $ fd |
609 |
return (n, NotStrict, t) |
610 |
|
611 |
-- | Build an object declaration. |
612 |
buildObject :: String -> String -> [Field] -> Q [Dec] |
613 |
buildObject sname field_pfx fields = do |
614 |
let name = mkName sname |
615 |
fields_d <- mapM (fieldTypeInfo field_pfx) fields |
616 |
let decl_d = RecC name fields_d |
617 |
let declD = DataD [] name [] [decl_d] [''Show, ''Read, ''Eq] |
618 |
ser_decls <- buildObjectSerialisation sname fields |
619 |
return $ declD:ser_decls |
620 |
|
621 |
-- | Generates an object definition: data type and its JSON instance. |
622 |
buildObjectSerialisation :: String -> [Field] -> Q [Dec] |
623 |
buildObjectSerialisation sname fields = do |
624 |
let name = mkName sname |
625 |
savedecls <- genSaveObject saveObjectField sname fields |
626 |
(loadsig, loadfn) <- genLoadObject loadObjectField sname fields |
627 |
shjson <- objectShowJSON sname |
628 |
rdjson <- objectReadJSON sname |
629 |
let instdecl = InstanceD [] (AppT (ConT ''JSON.JSON) (ConT name)) |
630 |
[rdjson, shjson] |
631 |
return $ savedecls ++ [loadsig, loadfn, instdecl] |
632 |
|
633 |
-- | The toDict function name for a given type. |
634 |
toDictName :: String -> Name |
635 |
toDictName sname = mkName ("toDict" ++ sname) |
636 |
|
637 |
-- | Generates the save object functionality. |
638 |
genSaveObject :: (Name -> Field -> Q Exp) |
639 |
-> String -> [Field] -> Q [Dec] |
640 |
genSaveObject save_fn sname fields = do |
641 |
let name = mkName sname |
642 |
fnames <- mapM (newName . fieldVariable) fields |
643 |
let pat = conP name (map varP fnames) |
644 |
let tdname = toDictName sname |
645 |
tdsigt <- [t| $(conT name) -> [(String, JSON.JSValue)] |] |
646 |
|
647 |
let felems = map (uncurry save_fn) (zip fnames fields) |
648 |
flist = listE felems |
649 |
-- and finally convert all this to a json object |
650 |
tdlist = [| concat $flist |] |
651 |
iname = mkName "i" |
652 |
tclause <- clause [pat] (normalB tdlist) [] |
653 |
cclause <- [| $(varNameE "makeObj") . $(varE tdname) |] |
654 |
let fname = mkName ("save" ++ sname) |
655 |
sigt <- [t| $(conT name) -> JSON.JSValue |] |
656 |
return [SigD tdname tdsigt, FunD tdname [tclause], |
657 |
SigD fname sigt, ValD (VarP fname) (NormalB cclause) []] |
658 |
|
659 |
-- | Generates the code for saving an object's field, handling the |
660 |
-- various types of fields that we have. |
661 |
saveObjectField :: Name -> Field -> Q Exp |
662 |
saveObjectField fvar field |
663 |
| fisOptional = [| case $(varE fvar) of |
664 |
Nothing -> [] |
665 |
Just v -> [( $nameE, JSON.showJSON v)] |
666 |
|] |
667 |
| otherwise = case fieldShow field of |
668 |
Nothing -> [| [( $nameE, JSON.showJSON $fvarE)] |] |
669 |
Just fn -> [| let (actual, extra) = $fn $fvarE |
670 |
in extra ++ [( $nameE, JSON.showJSON actual)] |
671 |
|] |
672 |
where fisOptional = fieldIsOptional field |
673 |
nameE = stringE (fieldName field) |
674 |
fvarE = varE fvar |
675 |
|
676 |
-- | Generates the showJSON clause for a given object name. |
677 |
objectShowJSON :: String -> Q Dec |
678 |
objectShowJSON name = do |
679 |
body <- [| JSON.showJSON . $(varE . mkName $ "save" ++ name) |] |
680 |
return $ FunD (mkName "showJSON") [Clause [] (NormalB body) []] |
681 |
|
682 |
-- | Generates the load object functionality. |
683 |
genLoadObject :: (Field -> Q (Name, Stmt)) |
684 |
-> String -> [Field] -> Q (Dec, Dec) |
685 |
genLoadObject load_fn sname fields = do |
686 |
let name = mkName sname |
687 |
funname = mkName $ "load" ++ sname |
688 |
arg1 = mkName "v" |
689 |
objname = mkName "o" |
690 |
opid = mkName "op_id" |
691 |
st1 <- bindS (varP objname) [| liftM JSON.fromJSObject |
692 |
(JSON.readJSON $(varE arg1)) |] |
693 |
fbinds <- mapM load_fn fields |
694 |
let (fnames, fstmts) = unzip fbinds |
695 |
let cval = foldl (\accu fn -> AppE accu (VarE fn)) (ConE name) fnames |
696 |
fstmts' = st1:fstmts ++ [NoBindS (AppE (VarE 'return) cval)] |
697 |
sigt <- [t| JSON.JSValue -> JSON.Result $(conT name) |] |
698 |
return $ (SigD funname sigt, |
699 |
FunD funname [Clause [VarP arg1] (NormalB (DoE fstmts')) []]) |
700 |
|
701 |
-- | Generates code for loading an object's field. |
702 |
loadObjectField :: Field -> Q (Name, Stmt) |
703 |
loadObjectField field = do |
704 |
let name = fieldVariable field |
705 |
fvar <- newName name |
706 |
-- these are used in all patterns below |
707 |
let objvar = varNameE "o" |
708 |
objfield = stringE (fieldName field) |
709 |
loadexp = |
710 |
if fieldIsOptional field |
711 |
then [| $(varNameE "maybeFromObj") $objvar $objfield |] |
712 |
else case fieldDefault field of |
713 |
Just defv -> |
714 |
[| $(varNameE "fromObjWithDefault") $objvar |
715 |
$objfield $defv |] |
716 |
Nothing -> [| $(varNameE "fromObj") $objvar $objfield |] |
717 |
bexp <- loadFn field loadexp objvar |
718 |
|
719 |
return (fvar, BindS (VarP fvar) bexp) |
720 |
|
721 |
-- | Builds the readJSON instance for a given object name. |
722 |
objectReadJSON :: String -> Q Dec |
723 |
objectReadJSON name = do |
724 |
let s = mkName "s" |
725 |
body <- [| case JSON.readJSON $(varE s) of |
726 |
JSON.Ok s' -> $(varE .mkName $ "load" ++ name) s' |
727 |
JSON.Error e -> |
728 |
JSON.Error $ "Can't parse value for type " ++ |
729 |
$(stringE name) ++ ": " ++ e |
730 |
|] |
731 |
return $ FunD (mkName "readJSON") [Clause [VarP s] (NormalB body) []] |
732 |
|
733 |
-- * Inheritable parameter tables implementation |
734 |
|
735 |
-- | Compute parameter type names. |
736 |
paramTypeNames :: String -> (String, String) |
737 |
paramTypeNames root = ("Filled" ++ root ++ "Params", |
738 |
"Partial" ++ root ++ "Params") |
739 |
|
740 |
-- | Compute information about the type of a parameter field. |
741 |
paramFieldTypeInfo :: String -> Field -> Q (Name, Strict, Type) |
742 |
paramFieldTypeInfo field_pfx fd = do |
743 |
t <- actualFieldType fd |
744 |
let n = mkName . (++ "P") . (field_pfx ++) . |
745 |
fieldRecordName $ fd |
746 |
return (n, NotStrict, AppT (ConT ''Maybe) t) |
747 |
|
748 |
-- | Build a parameter declaration. |
749 |
-- |
750 |
-- This function builds two different data structures: a /filled/ one, |
751 |
-- in which all fields are required, and a /partial/ one, in which all |
752 |
-- fields are optional. Due to the current record syntax issues, the |
753 |
-- fields need to be named differrently for the two structures, so the |
754 |
-- partial ones get a /P/ suffix. |
755 |
buildParam :: String -> String -> [Field] -> Q [Dec] |
756 |
buildParam sname field_pfx fields = do |
757 |
let (sname_f, sname_p) = paramTypeNames sname |
758 |
name_f = mkName sname_f |
759 |
name_p = mkName sname_p |
760 |
fields_f <- mapM (fieldTypeInfo field_pfx) fields |
761 |
fields_p <- mapM (paramFieldTypeInfo field_pfx) fields |
762 |
let decl_f = RecC name_f fields_f |
763 |
decl_p = RecC name_p fields_p |
764 |
let declF = DataD [] name_f [] [decl_f] [''Show, ''Read, ''Eq] |
765 |
declP = DataD [] name_p [] [decl_p] [''Show, ''Read, ''Eq] |
766 |
ser_decls_f <- buildObjectSerialisation sname_f fields |
767 |
ser_decls_p <- buildPParamSerialisation sname_p fields |
768 |
fill_decls <- fillParam sname field_pfx fields |
769 |
return $ [declF, declP] ++ ser_decls_f ++ ser_decls_p ++ fill_decls ++ |
770 |
buildParamAllFields sname fields ++ |
771 |
buildDictObjectInst name_f sname_f |
772 |
|
773 |
-- | Builds a list of all fields of a parameter. |
774 |
buildParamAllFields :: String -> [Field] -> [Dec] |
775 |
buildParamAllFields sname fields = |
776 |
let vname = mkName ("all" ++ sname ++ "ParamFields") |
777 |
sig = SigD vname (AppT ListT (ConT ''String)) |
778 |
val = ListE $ map (LitE . StringL . fieldName) fields |
779 |
in [sig, ValD (VarP vname) (NormalB val) []] |
780 |
|
781 |
-- | Builds the 'DictObject' instance for a filled parameter. |
782 |
buildDictObjectInst :: Name -> String -> [Dec] |
783 |
buildDictObjectInst name sname = |
784 |
[InstanceD [] (AppT (ConT ''DictObject) (ConT name)) |
785 |
[ValD (VarP 'toDict) (NormalB (VarE (toDictName sname))) []]] |
786 |
|
787 |
-- | Generates the serialisation for a partial parameter. |
788 |
buildPParamSerialisation :: String -> [Field] -> Q [Dec] |
789 |
buildPParamSerialisation sname fields = do |
790 |
let name = mkName sname |
791 |
savedecls <- genSaveObject savePParamField sname fields |
792 |
(loadsig, loadfn) <- genLoadObject loadPParamField sname fields |
793 |
shjson <- objectShowJSON sname |
794 |
rdjson <- objectReadJSON sname |
795 |
let instdecl = InstanceD [] (AppT (ConT ''JSON.JSON) (ConT name)) |
796 |
[rdjson, shjson] |
797 |
return $ savedecls ++ [loadsig, loadfn, instdecl] |
798 |
|
799 |
-- | Generates code to save an optional parameter field. |
800 |
savePParamField :: Name -> Field -> Q Exp |
801 |
savePParamField fvar field = do |
802 |
checkNonOptDef field |
803 |
let actualVal = mkName "v" |
804 |
normalexpr <- saveObjectField actualVal field |
805 |
-- we have to construct the block here manually, because we can't |
806 |
-- splice-in-splice |
807 |
return $ CaseE (VarE fvar) [ Match (ConP 'Nothing []) |
808 |
(NormalB (ConE '[])) [] |
809 |
, Match (ConP 'Just [VarP actualVal]) |
810 |
(NormalB normalexpr) [] |
811 |
] |
812 |
|
813 |
-- | Generates code to load an optional parameter field. |
814 |
loadPParamField :: Field -> Q (Name, Stmt) |
815 |
loadPParamField field = do |
816 |
checkNonOptDef field |
817 |
let name = fieldName field |
818 |
fvar <- newName name |
819 |
-- these are used in all patterns below |
820 |
let objvar = varNameE "o" |
821 |
objfield = stringE name |
822 |
loadexp = [| $(varNameE "maybeFromObj") $objvar $objfield |] |
823 |
bexp <- loadFn field loadexp objvar |
824 |
return (fvar, BindS (VarP fvar) bexp) |
825 |
|
826 |
-- | Builds a simple declaration of type @n_x = fromMaybe f_x p_x@. |
827 |
buildFromMaybe :: String -> Q Dec |
828 |
buildFromMaybe fname = |
829 |
valD (varP (mkName $ "n_" ++ fname)) |
830 |
(normalB [| $(varNameE "fromMaybe") |
831 |
$(varNameE $ "f_" ++ fname) |
832 |
$(varNameE $ "p_" ++ fname) |]) [] |
833 |
|
834 |
-- | Builds a function that executes the filling of partial parameter |
835 |
-- from a full copy (similar to Python's fillDict). |
836 |
fillParam :: String -> String -> [Field] -> Q [Dec] |
837 |
fillParam sname field_pfx fields = do |
838 |
let fnames = map (\fd -> field_pfx ++ fieldRecordName fd) fields |
839 |
(sname_f, sname_p) = paramTypeNames sname |
840 |
oname_f = "fobj" |
841 |
oname_p = "pobj" |
842 |
name_f = mkName sname_f |
843 |
name_p = mkName sname_p |
844 |
fun_name = mkName $ "fill" ++ sname ++ "Params" |
845 |
le_full = ValD (ConP name_f (map (VarP . mkName . ("f_" ++)) fnames)) |
846 |
(NormalB . VarE . mkName $ oname_f) [] |
847 |
le_part = ValD (ConP name_p (map (VarP . mkName . ("p_" ++)) fnames)) |
848 |
(NormalB . VarE . mkName $ oname_p) [] |
849 |
obj_new = foldl (\accu vname -> AppE accu (VarE vname)) (ConE name_f) |
850 |
$ map (mkName . ("n_" ++)) fnames |
851 |
le_new <- mapM buildFromMaybe fnames |
852 |
funt <- [t| $(conT name_f) -> $(conT name_p) -> $(conT name_f) |] |
853 |
let sig = SigD fun_name funt |
854 |
fclause = Clause [VarP (mkName oname_f), VarP (mkName oname_p)] |
855 |
(NormalB $ LetE (le_full:le_part:le_new) obj_new) [] |
856 |
fun = FunD fun_name [fclause] |
857 |
return [sig, fun] |