1 {-# LANGUAGE TemplateHaskell, QuasiQuotes #-}
3 {-| TemplateHaskell helper for HTools.
5 As TemplateHaskell require that splices be defined in a separate
6 module, we combine all the TemplateHaskell functionality that HTools
7 needs in this module (except the one for unittests).
13 Copyright (C) 2011 Google Inc.
15 This program is free software; you can redistribute it and/or modify
16 it under the terms of the GNU General Public License as published by
17 the Free Software Foundation; either version 2 of the License, or
18 (at your option) any later version.
20 This program is distributed in the hope that it will be useful, but
21 WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 General Public License for more details.
25 You should have received a copy of the GNU General Public License
26 along with this program; if not, write to the Free Software
27 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
32 module Ganeti.THH ( declareSADT
52 , buildObjectSerialisation
58 import Control.Monad (liftM, liftM2)
61 import qualified Data.Map as M
62 import Language.Haskell.TH
64 import qualified Text.JSON as JSON
66 import Ganeti.HTools.JSON
70 type Container = M.Map String
72 -- | Serialised field data type.
73 data Field = Field { fieldName :: String
75 , fieldRead :: Maybe (Q Exp)
76 , fieldShow :: Maybe (Q Exp)
77 , fieldDefault :: Maybe (Q Exp)
78 , fieldConstr :: Maybe String
79 , fieldIsContainer :: Bool
80 , fieldIsOptional :: Bool
83 -- | Generates a simple field.
84 simpleField :: String -> Q Type -> Field
85 simpleField fname ftype =
86 Field { fieldName = fname
90 , fieldDefault = Nothing
91 , fieldConstr = Nothing
92 , fieldIsContainer = False
93 , fieldIsOptional = False
96 -- | Sets the renamed constructor field.
97 renameField :: String -> Field -> Field
98 renameField constrName field = field { fieldConstr = Just constrName }
100 -- | Sets the default value on a field (makes it optional with a
102 defaultField :: Q Exp -> Field -> Field
103 defaultField defval field = field { fieldDefault = Just defval }
105 -- | Marks a field optional (turning its base type into a Maybe).
106 optionalField :: Field -> Field
107 optionalField field = field { fieldIsOptional = True }
109 -- | Marks a field as a container.
110 containerField :: Field -> Field
111 containerField field = field { fieldIsContainer = True }
113 -- | Sets custom functions on a field.
114 customField :: Q Exp -> Q Exp -> Field -> Field
115 customField readfn showfn field =
116 field { fieldRead = Just readfn, fieldShow = Just showfn }
118 fieldRecordName :: Field -> String
119 fieldRecordName (Field { fieldName = name, fieldConstr = alias }) =
120 maybe (camelCase name) id alias
122 fieldVariable :: Field -> String
123 fieldVariable = map toLower . fieldRecordName
125 actualFieldType :: Field -> Q Type
126 actualFieldType f | fieldIsContainer f = [t| Container $t |]
127 | fieldIsOptional f = [t| Maybe $t |]
129 where t = fieldType f
131 checkNonOptDef :: (Monad m) => Field -> m ()
132 checkNonOptDef (Field { fieldIsOptional = True, fieldName = name }) =
133 fail $ "Optional field " ++ name ++ " used in parameter declaration"
134 checkNonOptDef (Field { fieldDefault = (Just _), fieldName = name }) =
135 fail $ "Default field " ++ name ++ " used in parameter declaration"
136 checkNonOptDef _ = return ()
138 loadFn :: Field -> Q Exp -> Q Exp
139 loadFn (Field { fieldIsContainer = True }) expr = [| $expr >>= readContainer |]
140 loadFn (Field { fieldRead = Just readfn }) expr = [| $expr >>= $readfn |]
143 saveFn :: Field -> Q Exp -> Q Exp
144 saveFn (Field { fieldIsContainer = True }) expr = [| showContainer $expr |]
145 saveFn (Field { fieldRead = Just readfn }) expr = [| $readfn $expr |]
148 -- * Common field declarations
150 timeStampFields :: [Field]
152 [ defaultField [| 0::Double |] $ simpleField "ctime" [t| Double |]
153 , defaultField [| 0::Double |] $ simpleField "mtime" [t| Double |]
156 serialFields :: [Field]
158 [ renameField "Serial" $ simpleField "serial_no" [t| Int |] ]
160 uuidFields :: [Field]
161 uuidFields = [ simpleField "uuid" [t| String |] ]
163 -- * Helper functions
165 -- | Ensure first letter is lowercase.
167 -- Used to convert type name to function prefix, e.g. in @data Aa ->
169 ensureLower :: String -> String
171 ensureLower (x:xs) = toLower x:xs
173 -- | Ensure first letter is uppercase.
175 -- Used to convert constructor name to component
176 ensureUpper :: String -> String
178 ensureUpper (x:xs) = toUpper x:xs
180 -- | Helper for quoted expressions.
181 varNameE :: String -> Q Exp
182 varNameE = varE . mkName
184 -- | showJSON as an expression, for reuse.
186 showJSONE = varNameE "showJSON"
188 -- | ToRaw function name.
189 toRawName :: String -> Name
190 toRawName = mkName . (++ "ToRaw") . ensureLower
192 -- | FromRaw function name.
193 fromRawName :: String -> Name
194 fromRawName = mkName . (++ "FromRaw") . ensureLower
196 -- | Converts a name to it's varE/litE representations.
198 reprE :: Either String Name -> Q Exp
199 reprE = either stringE varE
201 -- | Smarter function application.
203 -- This does simply f x, except that if is 'id', it will skip it, in
204 -- order to generate more readable code when using -ddump-splices.
205 appFn :: Exp -> Exp -> Exp
206 appFn f x | f == VarE 'id = x
207 | otherwise = AppE f x
209 -- | Container loader
210 readContainer :: (Monad m, JSON.JSON a) =>
211 JSON.JSObject JSON.JSValue -> m (Container a)
212 readContainer obj = do
213 let kjvlist = JSON.fromJSObject obj
214 kalist <- mapM (\(k, v) -> fromKeyValue k v >>= \a -> return (k, a)) kjvlist
215 return $ M.fromList kalist
217 -- | Container dumper
218 showContainer :: (JSON.JSON a) => Container a -> JSON.JSValue
219 showContainer = JSON.makeObj . map (second JSON.showJSON) . M.toList
221 -- * Template code for simple raw type-equivalent ADTs
223 -- | Generates a data type declaration.
225 -- The type will have a fixed list of instances.
226 strADTDecl :: Name -> [String] -> Dec
227 strADTDecl name constructors =
229 (map (flip NormalC [] . mkName) constructors)
230 [''Show, ''Read, ''Eq, ''Enum, ''Bounded, ''Ord]
232 -- | Generates a toRaw function.
234 -- This generates a simple function of the form:
237 -- nameToRaw :: Name -> /traw/
238 -- nameToRaw Cons1 = var1
239 -- nameToRaw Cons2 = \"value2\"
241 genToRaw :: Name -> Name -> Name -> [(String, Either String Name)] -> Q [Dec]
242 genToRaw traw fname tname constructors = do
243 sigt <- [t| $(conT tname) -> $(conT traw) |]
244 -- the body clauses, matching on the constructor and returning the
246 clauses <- mapM (\(c, v) -> clause [recP (mkName c) []]
247 (normalB (reprE v)) []) constructors
248 return [SigD fname sigt, FunD fname clauses]
250 -- | Generates a fromRaw function.
252 -- The function generated is monadic and can fail parsing the
253 -- raw value. It is of the form:
256 -- nameFromRaw :: (Monad m) => /traw/ -> m Name
257 -- nameFromRaw s | s == var1 = Cons1
258 -- | s == \"value2\" = Cons2
259 -- | otherwise = fail /.../
261 genFromRaw :: Name -> Name -> Name -> [(String, Name)] -> Q [Dec]
262 genFromRaw traw fname tname constructors = do
263 -- signature of form (Monad m) => String -> m $name
264 sigt <- [t| (Monad m) => $(conT traw) -> m $(conT tname) |]
265 -- clauses for a guarded pattern
266 let varp = mkName "s"
268 clauses <- mapM (\(c, v) -> do
269 -- the clause match condition
270 g <- normalG [| $varpe == $(varE v) |]
272 r <- [| return $(conE (mkName c)) |]
273 return (g, r)) constructors
274 -- the otherwise clause (fallback)
276 g <- normalG [| otherwise |]
277 r <- [|fail ("Invalid string value for type " ++
278 $(litE (stringL (nameBase tname))) ++ ": " ++ show $varpe) |]
280 let fun = FunD fname [Clause [VarP varp]
281 (GuardedB (clauses++[oth_clause])) []]
282 return [SigD fname sigt, fun]
284 -- | Generates a data type from a given raw format.
286 -- The format is expected to multiline. The first line contains the
287 -- type name, and the rest of the lines must contain two words: the
288 -- constructor name and then the string representation of the
289 -- respective constructor.
291 -- The function will generate the data type declaration, and then two
294 -- * /name/ToRaw, which converts the type to a raw type
296 -- * /name/FromRaw, which (monadically) converts from a raw type to the type
298 -- Note that this is basically just a custom show/read instance,
300 declareADT :: Name -> String -> [(String, Name)] -> Q [Dec]
301 declareADT traw sname cons = do
302 let name = mkName sname
303 ddecl = strADTDecl name (map fst cons)
304 -- process cons in the format expected by genToRaw
305 cons' = map (\(a, b) -> (a, Right b)) cons
306 toraw <- genToRaw traw (toRawName sname) name cons'
307 fromraw <- genFromRaw traw (fromRawName sname) name cons
308 return $ ddecl:toraw ++ fromraw
310 declareIADT :: String -> [(String, Name)] -> Q [Dec]
311 declareIADT = declareADT ''Int
313 declareSADT :: String -> [(String, Name)] -> Q [Dec]
314 declareSADT = declareADT ''String
316 -- | Creates the showJSON member of a JSON instance declaration.
318 -- This will create what is the equivalent of:
321 -- showJSON = showJSON . /name/ToRaw
324 -- in an instance JSON /name/ declaration
325 genShowJSON :: String -> Q [Dec]
326 genShowJSON name = [d| showJSON = JSON.showJSON . $(varE (toRawName name)) |]
328 -- | Creates the readJSON member of a JSON instance declaration.
330 -- This will create what is the equivalent of:
333 -- readJSON s = case readJSON s of
334 -- Ok s' -> /name/FromRaw s'
335 -- Error e -> Error /description/
338 -- in an instance JSON /name/ declaration
339 genReadJSON :: String -> Q Dec
340 genReadJSON name = do
342 body <- [| case JSON.readJSON $(varE s) of
343 JSON.Ok s' -> $(varE (fromRawName name)) s'
345 JSON.Error $ "Can't parse raw value for type " ++
346 $(stringE name) ++ ": " ++ e ++ " from " ++
349 return $ FunD (mkName "readJSON") [Clause [VarP s] (NormalB body) []]
351 -- | Generates a JSON instance for a given type.
353 -- This assumes that the /name/ToRaw and /name/FromRaw functions
354 -- have been defined as by the 'declareSADT' function.
355 makeJSONInstance :: Name -> Q [Dec]
356 makeJSONInstance name = do
357 let base = nameBase name
358 showJ <- genShowJSON base
359 readJ <- genReadJSON base
360 return [InstanceD [] (AppT (ConT ''JSON.JSON) (ConT name)) (readJ:showJ)]
362 -- * Template code for opcodes
364 -- | Transforms a CamelCase string into an_underscore_based_one.
365 deCamelCase :: String -> String
367 intercalate "_" . map (map toUpper) . groupBy (\_ b -> not $ isUpper b)
369 -- | Transform an underscore_name into a CamelCase one.
370 camelCase :: String -> String
371 camelCase = concatMap (ensureUpper . drop 1) .
372 groupBy (\_ b -> b /= '_') . ('_':)
374 -- | Computes the name of a given constructor.
375 constructorName :: Con -> Q Name
376 constructorName (NormalC name _) = return name
377 constructorName (RecC name _) = return name
378 constructorName x = fail $ "Unhandled constructor " ++ show x
380 -- | Builds the generic constructor-to-string function.
382 -- This generates a simple function of the following form:
385 -- fname (ConStructorOne {}) = trans_fun("ConStructorOne")
386 -- fname (ConStructorTwo {}) = trans_fun("ConStructorTwo")
389 -- This builds a custom list of name/string pairs and then uses
390 -- 'genToRaw' to actually generate the function
391 genConstrToStr :: (String -> String) -> Name -> String -> Q [Dec]
392 genConstrToStr trans_fun name fname = do
393 TyConI (DataD _ _ _ cons _) <- reify name
394 cnames <- mapM (liftM nameBase . constructorName) cons
395 let svalues = map (Left . trans_fun) cnames
396 genToRaw ''String (mkName fname) name $ zip cnames svalues
398 -- | Constructor-to-string for OpCode.
399 genOpID :: Name -> String -> Q [Dec]
400 genOpID = genConstrToStr deCamelCase
402 -- | OpCode parameter (field) type.
403 type OpParam = (String, Q Type, Q Exp)
405 -- | Generates the OpCode data type.
407 -- This takes an opcode logical definition, and builds both the
408 -- datatype and the JSON serialisation out of it. We can't use a
409 -- generic serialisation since we need to be compatible with Ganeti's
410 -- own, so we have a few quirks to work around.
412 -- There are three things to be defined for each parameter:
416 -- * type; if this is 'Maybe', will only be serialised if it's a
419 -- * default; if missing, won't raise an exception, but will instead
422 genOpCode :: String -- ^ Type name to use
423 -> [(String, [OpParam])] -- ^ Constructor name and parameters
425 genOpCode name cons = do
426 decl_d <- mapM (\(cname, fields) -> do
427 -- we only need the type of the field, without Q
428 fields' <- mapM (\(_, qt, _) ->
429 qt >>= \t -> return (NotStrict, t))
431 return $ NormalC (mkName cname) fields')
433 let declD = DataD [] (mkName name) [] decl_d [''Show, ''Read, ''Eq]
435 (savesig, savefn) <- genSaveOpCode cons
436 (loadsig, loadfn) <- genLoadOpCode cons
437 return [declD, loadsig, loadfn, savesig, savefn]
439 -- | Checks whether a given parameter is options.
441 -- This requires that it's a 'Maybe'.
442 isOptional :: Type -> Bool
443 isOptional (AppT (ConT dt) _) | dt == ''Maybe = True
446 -- | Generates the \"save\" expression for a single opcode parameter.
448 -- There is only one special handling mode: if the parameter is of
449 -- 'Maybe' type, then we only save it if it's a 'Just' value,
450 -- otherwise we skip it.
451 saveField :: Name -- ^ The name of variable that contains the value
452 -> OpParam -- ^ Parameter definition
454 saveField fvar (fname, qt, _) = do
456 let fnexp = stringE fname
459 then [| case $fvare of
460 Just v' -> [( $fnexp, $showJSONE v')]
463 else [| [( $fnexp, $showJSONE $fvare )] |])
465 -- | Generates the \"save\" clause for an entire opcode constructor.
467 -- This matches the opcode with variables named the same as the
468 -- constructor fields (just so that the spliced in code looks nicer),
469 -- and passes those name plus the parameter definition to 'saveField'.
470 saveConstructor :: String -- ^ The constructor name
471 -> [OpParam] -- ^ The parameter definitions for this
473 -> Q Clause -- ^ Resulting clause
474 saveConstructor sname fields = do
475 let cname = mkName sname
476 let fnames = map (\(n, _, _) -> mkName n) fields
477 let pat = conP cname (map varP fnames)
478 let felems = map (uncurry saveField) (zip fnames fields)
479 -- now build the OP_ID serialisation
480 opid = [| [( $(stringE "OP_ID"),
481 $showJSONE $(stringE . deCamelCase $ sname) )] |]
482 flist = listE (opid:felems)
483 -- and finally convert all this to a json object
484 flist' = [| $(varNameE "makeObj") (concat $flist) |]
485 clause [pat] (normalB flist') []
487 -- | Generates the main save opcode function.
489 -- This builds a per-constructor match clause that contains the
490 -- respective constructor-serialisation code.
491 genSaveOpCode :: [(String, [OpParam])] -> Q (Dec, Dec)
492 genSaveOpCode opdefs = do
493 cclauses <- mapM (uncurry saveConstructor) opdefs
494 let fname = mkName "saveOpCode"
495 sigt <- [t| $(conT (mkName "OpCode")) -> JSON.JSValue |]
496 return $ (SigD fname sigt, FunD fname cclauses)
498 -- | Generates the \"load\" field for a single parameter.
500 -- There is custom handling, depending on how the parameter is
501 -- specified. For a 'Maybe' type parameter, we allow that it is not
502 -- present (via 'Utils.maybeFromObj'). Otherwise, if there is a
503 -- default value, we allow the parameter to be abset, and finally if
504 -- there is no default value, we require its presence.
505 loadField :: OpParam -> Q (Name, Stmt)
506 loadField (fname, qt, qdefa) = do
507 let fvar = mkName fname
510 -- these are used in all patterns below
511 let objvar = varNameE "o"
512 objfield = stringE fname
513 bexp <- if isOptional t
514 then [| $((varNameE "maybeFromObj")) $objvar $objfield |]
516 AppE (ConE dt) defval | dt == 'Just ->
517 -- but has a default value
518 [| $(varNameE "fromObjWithDefault")
519 $objvar $objfield $(return defval) |]
520 ConE dt | dt == 'Nothing ->
521 [| $(varNameE "fromObj") $objvar $objfield |]
522 s -> fail $ "Invalid default value " ++ show s ++
523 ", expecting either 'Nothing' or a 'Just defval'"
524 return (fvar, BindS (VarP fvar) bexp)
526 loadConstructor :: String -> [OpParam] -> Q Exp
527 loadConstructor sname fields = do
528 let name = mkName sname
529 fbinds <- mapM loadField fields
530 let (fnames, fstmts) = unzip fbinds
531 let cval = foldl (\accu fn -> AppE accu (VarE fn)) (ConE name) fnames
532 fstmts' = fstmts ++ [NoBindS (AppE (VarE 'return) cval)]
535 genLoadOpCode :: [(String, [OpParam])] -> Q (Dec, Dec)
536 genLoadOpCode opdefs = do
537 let fname = mkName "loadOpCode"
540 opid = mkName "op_id"
541 st1 <- bindS (varP objname) [| liftM JSON.fromJSObject
542 (JSON.readJSON $(varE arg1)) |]
543 st2 <- bindS (varP opid) [| $(varNameE "fromObj")
544 $(varE objname) $(stringE "OP_ID") |]
545 -- the match results (per-constructor blocks)
546 mexps <- mapM (uncurry loadConstructor) opdefs
547 fails <- [| fail $ "Unknown opcode " ++ $(varE opid) |]
548 let mpats = map (\(me, c) ->
549 let mp = LitP . StringL . deCamelCase . fst $ c
550 in Match mp (NormalB me) []
552 defmatch = Match WildP (NormalB fails) []
553 cst = NoBindS $ CaseE (VarE opid) $ mpats++[defmatch]
554 body = DoE [st1, st2, cst]
555 sigt <- [t| JSON.JSValue -> JSON.Result $(conT (mkName "OpCode")) |]
556 return $ (SigD fname sigt, FunD fname [Clause [VarP arg1] (NormalB body) []])
558 -- | No default type.
560 noDefault = conE 'Nothing
562 -- * Template code for luxi
564 -- | Constructor-to-string for LuxiOp.
565 genStrOfOp :: Name -> String -> Q [Dec]
566 genStrOfOp = genConstrToStr id
568 -- | Constructor-to-string for MsgKeys.
569 genStrOfKey :: Name -> String -> Q [Dec]
570 genStrOfKey = genConstrToStr ensureLower
572 -- | LuxiOp parameter type.
573 type LuxiParam = (String, Q Type, Q Exp)
575 -- | Generates the LuxiOp data type.
577 -- This takes a Luxi operation definition and builds both the
578 -- datatype and the function trnasforming the arguments to JSON.
579 -- We can't use anything less generic, because the way different
580 -- operations are serialized differs on both parameter- and top-level.
582 -- There are three things to be defined for each parameter:
588 -- * operation; this is the operation performed on the parameter before
591 genLuxiOp :: String -> [(String, [LuxiParam])] -> Q [Dec]
592 genLuxiOp name cons = do
593 decl_d <- mapM (\(cname, fields) -> do
594 fields' <- mapM (\(_, qt, _) ->
595 qt >>= \t -> return (NotStrict, t))
597 return $ NormalC (mkName cname) fields')
599 let declD = DataD [] (mkName name) [] decl_d [''Show, ''Read]
600 (savesig, savefn) <- genSaveLuxiOp cons
601 return [declD, savesig, savefn]
603 -- | Generates the \"save\" expression for a single luxi parameter.
604 saveLuxiField :: Name -> LuxiParam -> Q Exp
605 saveLuxiField fvar (_, qt, fn) =
606 [| JSON.showJSON ( $(liftM2 appFn fn $ varE fvar) ) |]
608 -- | Generates the \"save\" clause for entire LuxiOp constructor.
609 saveLuxiConstructor :: (String, [LuxiParam]) -> Q Clause
610 saveLuxiConstructor (sname, fields) = do
611 let cname = mkName sname
612 fnames = map (\(nm, _, _) -> mkName nm) fields
613 pat = conP cname (map varP fnames)
614 flist = map (uncurry saveLuxiField) (zip fnames fields)
615 finval = if null flist
616 then [| JSON.showJSON () |]
617 else [| JSON.showJSON $(listE flist) |]
618 clause [pat] (normalB finval) []
620 -- | Generates the main save LuxiOp function.
621 genSaveLuxiOp :: [(String, [LuxiParam])]-> Q (Dec, Dec)
622 genSaveLuxiOp opdefs = do
623 sigt <- [t| $(conT (mkName "LuxiOp")) -> JSON.JSValue |]
624 let fname = mkName "opToArgs"
625 cclauses <- mapM saveLuxiConstructor opdefs
626 return $ (SigD fname sigt, FunD fname cclauses)
628 -- * "Objects" functionality
630 -- | Extract the field's declaration from a Field structure.
631 fieldTypeInfo :: String -> Field -> Q (Name, Strict, Type)
632 fieldTypeInfo field_pfx fd = do
633 t <- actualFieldType fd
634 let n = mkName . (field_pfx ++) . fieldRecordName $ fd
635 return (n, NotStrict, t)
637 -- | Build an object declaration.
638 buildObject :: String -> String -> [Field] -> Q [Dec]
639 buildObject sname field_pfx fields = do
640 let name = mkName sname
641 fields_d <- mapM (fieldTypeInfo field_pfx) fields
642 let decl_d = RecC name fields_d
643 let declD = DataD [] name [] [decl_d] [''Show, ''Read]
644 ser_decls <- buildObjectSerialisation sname fields
645 return $ declD:ser_decls
647 buildObjectSerialisation :: String -> [Field] -> Q [Dec]
648 buildObjectSerialisation sname fields = do
649 let name = mkName sname
650 savedecls <- genSaveObject saveObjectField sname fields
651 (loadsig, loadfn) <- genLoadObject loadObjectField sname fields
652 shjson <- objectShowJSON sname
653 rdjson <- objectReadJSON sname
654 let instdecl = InstanceD [] (AppT (ConT ''JSON.JSON) (ConT name))
656 return $ savedecls ++ [loadsig, loadfn, instdecl]
658 genSaveObject :: (Name -> Field -> Q Exp)
659 -> String -> [Field] -> Q [Dec]
660 genSaveObject save_fn sname fields = do
661 let name = mkName sname
662 let fnames = map (mkName . fieldVariable) fields
663 let pat = conP name (map varP fnames)
664 let tdname = mkName ("toDict" ++ sname)
665 tdsigt <- [t| $(conT name) -> [(String, JSON.JSValue)] |]
667 let felems = map (uncurry save_fn) (zip fnames fields)
669 -- and finally convert all this to a json object
670 tdlist = [| concat $flist |]
672 tclause <- clause [pat] (normalB tdlist) []
673 cclause <- [| $(varNameE "makeObj") . $(varE tdname) |]
674 let fname = mkName ("save" ++ sname)
675 sigt <- [t| $(conT name) -> JSON.JSValue |]
676 return [SigD tdname tdsigt, FunD tdname [tclause],
677 SigD fname sigt, ValD (VarP fname) (NormalB cclause) []]
679 saveObjectField :: Name -> Field -> Q Exp
680 saveObjectField fvar field
681 | isContainer = [| [( $nameE , $showJSONE . showContainer $ $fvarE)] |]
682 | fisOptional = [| case $(varE fvar) of
684 Just v -> [( $nameE, $showJSONE v)]
686 | otherwise = case fieldShow field of
687 Nothing -> [| [( $nameE, $showJSONE $fvarE)] |]
688 Just fn -> [| [( $nameE, $showJSONE . $fn $ $fvarE)] |]
689 where isContainer = fieldIsContainer field
690 fisOptional = fieldIsOptional field
691 nameE = stringE (fieldName field)
694 objectShowJSON :: String -> Q [Dec]
695 objectShowJSON name =
696 [d| showJSON = JSON.showJSON . $(varE . mkName $ "save" ++ name) |]
698 genLoadObject :: (Field -> Q (Name, Stmt))
699 -> String -> [Field] -> Q (Dec, Dec)
700 genLoadObject load_fn sname fields = do
701 let name = mkName sname
702 funname = mkName $ "load" ++ sname
705 opid = mkName "op_id"
706 st1 <- bindS (varP objname) [| liftM JSON.fromJSObject
707 (JSON.readJSON $(varE arg1)) |]
708 fbinds <- mapM load_fn fields
709 let (fnames, fstmts) = unzip fbinds
710 let cval = foldl (\accu fn -> AppE accu (VarE fn)) (ConE name) fnames
711 fstmts' = st1:fstmts ++ [NoBindS (AppE (VarE 'return) cval)]
712 sigt <- [t| JSON.JSValue -> JSON.Result $(conT name) |]
713 return $ (SigD funname sigt,
714 FunD funname [Clause [VarP arg1] (NormalB (DoE fstmts')) []])
716 loadObjectField :: Field -> Q (Name, Stmt)
717 loadObjectField field = do
718 let name = fieldVariable field
720 -- these are used in all patterns below
721 let objvar = varNameE "o"
722 objfield = stringE (fieldName field)
724 if fieldIsOptional field
725 then [| $(varNameE "maybeFromObj") $objvar $objfield |]
726 else case fieldDefault field of
728 [| $(varNameE "fromObjWithDefault") $objvar
730 Nothing -> [| $(varNameE "fromObj") $objvar $objfield |]
731 bexp <- loadFn field loadexp
733 return (fvar, BindS (VarP fvar) bexp)
735 objectReadJSON :: String -> Q Dec
736 objectReadJSON name = do
738 body <- [| case JSON.readJSON $(varE s) of
739 JSON.Ok s' -> $(varE .mkName $ "load" ++ name) s'
741 JSON.Error $ "Can't parse value for type " ++
742 $(stringE name) ++ ": " ++ e
744 return $ FunD (mkName "readJSON") [Clause [VarP s] (NormalB body) []]
746 -- * Inheritable parameter tables implementation
748 -- | Compute parameter type names.
749 paramTypeNames :: String -> (String, String)
750 paramTypeNames root = ("Filled" ++ root ++ "Params",
751 "Partial" ++ root ++ "Params")
753 -- | Compute information about the type of a parameter field.
754 paramFieldTypeInfo :: String -> Field -> Q (Name, Strict, Type)
755 paramFieldTypeInfo field_pfx fd = do
756 t <- actualFieldType fd
757 let n = mkName . (++ "P") . (field_pfx ++) .
759 return (n, NotStrict, AppT (ConT ''Maybe) t)
761 -- | Build a parameter declaration.
763 -- This function builds two different data structures: a /filled/ one,
764 -- in which all fields are required, and a /partial/ one, in which all
765 -- fields are optional. Due to the current record syntax issues, the
766 -- fields need to be named differrently for the two structures, so the
767 -- partial ones get a /P/ suffix.
768 buildParam :: String -> String -> [Field] -> Q [Dec]
769 buildParam sname field_pfx fields = do
770 let (sname_f, sname_p) = paramTypeNames sname
771 name_f = mkName sname_f
772 name_p = mkName sname_p
773 fields_f <- mapM (fieldTypeInfo field_pfx) fields
774 fields_p <- mapM (paramFieldTypeInfo field_pfx) fields
775 let decl_f = RecC name_f fields_f
776 decl_p = RecC name_p fields_p
777 let declF = DataD [] name_f [] [decl_f] [''Show, ''Read]
778 declP = DataD [] name_p [] [decl_p] [''Show, ''Read]
779 ser_decls_f <- buildObjectSerialisation sname_f fields
780 ser_decls_p <- buildPParamSerialisation sname_p fields
781 fill_decls <- fillParam sname field_pfx fields
782 return $ [declF, declP] ++ ser_decls_f ++ ser_decls_p ++ fill_decls
784 buildPParamSerialisation :: String -> [Field] -> Q [Dec]
785 buildPParamSerialisation sname fields = do
786 let name = mkName sname
787 savedecls <- genSaveObject savePParamField sname fields
788 (loadsig, loadfn) <- genLoadObject loadPParamField sname fields
789 shjson <- objectShowJSON sname
790 rdjson <- objectReadJSON sname
791 let instdecl = InstanceD [] (AppT (ConT ''JSON.JSON) (ConT name))
793 return $ savedecls ++ [loadsig, loadfn, instdecl]
795 savePParamField :: Name -> Field -> Q Exp
796 savePParamField fvar field = do
798 let actualVal = mkName "v"
799 normalexpr <- saveObjectField actualVal field
800 -- we have to construct the block here manually, because we can't
802 return $ CaseE (VarE fvar) [ Match (ConP 'Nothing [])
803 (NormalB (ConE '[])) []
804 , Match (ConP 'Just [VarP actualVal])
805 (NormalB normalexpr) []
807 loadPParamField :: Field -> Q (Name, Stmt)
808 loadPParamField field = do
810 let name = fieldName field
812 -- these are used in all patterns below
813 let objvar = varNameE "o"
814 objfield = stringE name
815 loadexp = [| $(varNameE "maybeFromObj") $objvar $objfield |]
816 bexp <- loadFn field loadexp
817 return (fvar, BindS (VarP fvar) bexp)
819 -- | Builds a simple declaration of type @n_x = fromMaybe f_x p_x@.
820 buildFromMaybe :: String -> Q Dec
821 buildFromMaybe fname =
822 valD (varP (mkName $ "n_" ++ fname))
823 (normalB [| $(varNameE "fromMaybe")
824 $(varNameE $ "f_" ++ fname)
825 $(varNameE $ "p_" ++ fname) |]) []
827 fillParam :: String -> String -> [Field] -> Q [Dec]
828 fillParam sname field_pfx fields = do
829 let fnames = map (\fd -> field_pfx ++ fieldRecordName fd) fields
830 (sname_f, sname_p) = paramTypeNames sname
833 name_f = mkName sname_f
834 name_p = mkName sname_p
835 fun_name = mkName $ "fill" ++ sname ++ "Params"
836 le_full = ValD (ConP name_f (map (VarP . mkName . ("f_" ++)) fnames))
837 (NormalB . VarE . mkName $ oname_f) []
838 le_part = ValD (ConP name_p (map (VarP . mkName . ("p_" ++)) fnames))
839 (NormalB . VarE . mkName $ oname_p) []
840 obj_new = foldl (\accu vname -> AppE accu (VarE vname)) (ConE name_f)
841 $ map (mkName . ("n_" ++)) fnames
842 le_new <- mapM buildFromMaybe fnames
843 funt <- [t| $(conT name_f) -> $(conT name_p) -> $(conT name_f) |]
844 let sig = SigD fun_name funt
845 fclause = Clause [VarP (mkName oname_f), VarP (mkName oname_p)]
846 (NormalB $ LetE (le_full:le_part:le_new) obj_new) []
847 fun = FunD fun_name [fclause]