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|
module PGF.Generate
( generateAll, generateAllDepth
, generateFrom, generateFromDepth
, generateRandom, generateRandomDepth
, generateRandomFrom, generateRandomFromDepth
, generateOntology, generateOntologyDepth
, prove
) where
import PGF.CId
import PGF.Data
import PGF.TypeCheck
import Control.Monad
import Control.Monad.State
import Control.Monad.Identity
import System.Random
import Data.Maybe(isNothing)
------------------------------------------------------------------------------
-- The API
-- | Generates an exhaustive possibly infinite list of
-- abstract syntax expressions.
generateAll :: PGF -> Type -> [Expr]
generateAll pgf ty = generateAllDepth pgf ty Nothing
-- | A variant of 'generateAll' which also takes as argument
-- the upper limit of the depth of the generated expression.
generateAllDepth :: PGF -> Type -> Maybe Int -> [Expr]
generateAllDepth pgf ty dp = generate () pgf ty dp
-- | Generates a list of abstract syntax expressions
-- in a way similar to 'generateAll' but instead of
-- generating all instances of a given type, this
-- function uses a template.
generateFrom :: PGF -> Expr -> [Expr]
generateFrom pgf ex = generateFromDepth pgf ex Nothing
-- | A variant of 'generateFrom' which also takes as argument
-- the upper limit of the depth of the generated subexpressions.
generateFromDepth :: PGF -> Expr -> Maybe Int -> [Expr]
generateFromDepth pgf e dp =
[e | (_,_,e) <- snd $ runTcM (abstract pgf)
(generateForMetas (prove dp) e)
emptyMetaStore ()]
-- | Generates an infinite list of random abstract syntax expressions.
-- This is usefull for tree bank generation which after that can be used
-- for grammar testing.
generateRandom :: RandomGen g => g -> PGF -> Type -> [Expr]
generateRandom g pgf ty = generateRandomDepth g pgf ty Nothing
-- | A variant of 'generateRandom' which also takes as argument
-- the upper limit of the depth of the generated expression.
generateRandomDepth :: RandomGen g => g -> PGF -> Type -> Maybe Int -> [Expr]
generateRandomDepth g pgf ty dp = restart g (\g -> generate (Identity g) pgf ty dp)
-- | Random generation based on template
generateRandomFrom :: RandomGen g => g -> PGF -> Expr -> [Expr]
generateRandomFrom g pgf e = generateRandomFromDepth g pgf e Nothing
-- | Random generation based on template with a limitation in the depth.
generateRandomFromDepth :: RandomGen g => g -> PGF -> Expr -> Maybe Int -> [Expr]
generateRandomFromDepth g pgf e dp =
restart g (\g -> [e | (_,ms,e) <- snd $ runTcM (abstract pgf)
(generateForMetas (prove dp) e)
emptyMetaStore (Identity g)])
generateOntology :: RandomGen g => g -> PGF -> Type -> [(Maybe Expr, Type)] -> [Expr]
generateOntology g pgf ty args = generateOntologyDepth g pgf ty args Nothing
generateOntologyDepth :: RandomGen g => g -> PGF -> Type -> [(Maybe Expr, Type)] -> Maybe Int -> [Expr]
generateOntologyDepth g pgf ty args dp =
restart g (\g -> [e | (_,(Ontology args' _),e) <- snd $ runTcM (abstract pgf)
(prove dp emptyScope (TTyp [] ty) >>= checkResolvedMetaStore emptyScope)
emptyMetaStore
(Ontology args g),
all (isNothing . fst) args'])
------------------------------------------------------------------------------
-- The main generation algorithm
generate :: Selector sel => sel -> PGF -> Type -> Maybe Int -> [Expr]
generate sel pgf ty dp =
[e | (_,ms,e) <- snd $ runTcM (abstract pgf)
(prove dp emptyScope (TTyp [] ty) >>= checkResolvedMetaStore emptyScope)
emptyMetaStore sel]
prove :: Selector sel => Maybe Int -> Scope -> TType -> TcM sel Expr
prove dp scope (TTyp env1 (DTyp hypos1 cat es1)) = do
vs1 <- mapM (PGF.TypeCheck.eval env1) es1
let scope' = exScope scope env1 hypos1
(fe,TTyp env2 (DTyp hypos2 _ es2)) <- select cat scope' dp
case dp of
Just 0 | not (null hypos2) -> mzero
_ -> return ()
(env2,args) <- mkEnv scope' env2 hypos2
vs2 <- mapM (PGF.TypeCheck.eval env2) es2
sequence_ [eqValue mzero suspend (scopeSize scope') v1 v2 | (v1,v2) <- zip vs1 vs2]
es <- mapM (descend scope') args
return (abs hypos1 (foldl EApp fe es))
where
suspend i c = do
mv <- getMeta i
case mv of
MBound e -> c e
MUnbound x scope tty cs -> setMeta i (MUnbound x scope tty (c:cs))
abs [] e = e
abs ((bt,x,ty):hypos) e = EAbs bt x (abs hypos e)
exScope scope env [] = scope
exScope scope env ((bt,x,ty):hypos) =
let env' | x /= wildCId = VGen (scopeSize scope) [] : env
| otherwise = env
in exScope (addScopedVar x (TTyp env ty) scope) env' hypos
mkEnv scope env [] = return (env,[])
mkEnv scope env ((bt,x,ty):hypos) = do
(env,arg) <- if x /= wildCId
then do i <- newMeta scope (TTyp env ty)
return (VMeta i (scopeEnv scope) [] : env,Right (EMeta i))
else return (env,Left (TTyp env ty))
(env,args) <- mkEnv scope env hypos
return (env,(bt,arg):args)
descend scope (bt,arg) = do
let dp' = fmap (flip (-) 1) dp
e <- case arg of
Right e -> return e
Left tty -> prove dp' scope tty
e <- case bt of
Implicit -> return (EImplArg e)
Explicit -> return e
return e
-- Helper function for random generation. After every
-- success we must restart the search to find sufficiently different solution.
restart :: RandomGen g => g -> (g -> [a]) -> [a]
restart g f =
let (g1,g2) = split g
in case f g1 of
[] -> []
(x:xs) -> x : restart g2 f
------------------------------------------------------------------------------
-- Selectors
instance Selector () where
splitSelector s = (s,s)
select cat scope dp = do
gens <- typeGenerators scope cat
TcM (\abstr k h -> iter k gens)
where
iter k [] ms s = id
iter k ((_,e,tty):fns) ms s = k (e,tty) ms s . iter k fns ms s
instance RandomGen g => Selector (Identity g) where
splitSelector (Identity g) = let (g1,g2) = split g
in (Identity g1, Identity g2)
select cat scope dp = do
gens <- typeGenerators scope cat
TcM (\abstr k h -> iter k 1.0 gens)
where
iter k p [] ms (Identity g) = id
iter k p gens ms (Identity g) = let (d,g') = randomR (0.0,p) g
(g1,g2) = split g'
(p',e_ty,gens') = hit d gens
in k e_ty ms (Identity g1) . iter k (p-p') gens' ms (Identity g2)
hit :: Double -> [(Double,Expr,TType)] -> (Double,(Expr,TType),[(Double,Expr,TType)])
hit d (gen@(p,e,ty):gens)
| d < p || null gens = (p,(e,ty),gens)
| otherwise = let (p',e_ty',gens') = hit (d-p) gens
in (p',e_ty',gen:gens')
data Ontology a = Ontology [(Maybe Expr, Type)] a
instance RandomGen g => Selector (Ontology g) where
splitSelector (Ontology args g) = let (g1,g2) = split g
in (Ontology args g1, Ontology args g2)
select cat scope dp = do
Ontology args g <- get
case pickArg [] cat args of
[] -> do gens <- typeGenerators scope cat
TcM (\abstr k h -> iter k 1.0 gens)
alts -> msum [ case mb_e of
Just e -> do put (Ontology args g)
return (e, TTyp [] ty)
Nothing -> mzero
| (mb_e,ty,args) <- alts]
where
iter k p [] ms (Ontology ce g) = id
iter k p gens ms (Ontology ce g) =
let (d,g') = randomR (0.0,p) g
(g1,g2) = split g'
(p',e_ty,gens') = hit d gens
in k e_ty ms (Ontology ce g1) . iter k (p-p') gens' ms (Ontology ce g2)
hit :: Double -> [(Double,Expr,TType)] -> (Double,(Expr,TType),[(Double,Expr,TType)])
hit d (gen@(p,e,ty):gens) | d < p || null gens = (p,(e,ty),gens)
| otherwise = let (p',e_ty',gens') = hit (d-p) gens
in (p',e_ty',gen:gens')
pickArg args' cat' [] = []
pickArg args' cat' (arg@(mb_e,ty@(DTyp _ cat _)):args)
| cat' == cat = (mb_e, ty, foldl (flip (:)) args args') :
pickArg (arg:args') cat' args
| otherwise = pickArg (arg:args') cat' args
|
