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module PGF.Generate
( generateAll, generateAllDepth
, generateFrom, generateFromDepth
, generateRandom, generateRandomDepth
, generateRandomFrom, generateRandomFromDepth
) where
import PGF.CId
import PGF.Data
import PGF.Expr
import PGF.Macros
import PGF.TypeCheck
import PGF.Probabilistic
import qualified Data.Map as Map
import qualified Data.IntMap as IntMap
import Control.Monad
import Control.Monad.Identity
import System.Random
-- | 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 = generateForMetas () pgf e dp
-- | 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 -> generateForMetas (Identity g) pgf e dp)
------------------------------------------------------------------------------
-- The main generation algorithm
generate :: Selector sel => sel -> PGF -> Type -> Maybe Int -> [Expr]
generate sel pgf ty dp =
[value2expr (funs (abstract pgf),lookupMeta ms) 0 v |
(ms,v) <- runGenM (abstract pgf) (prove emptyScope (TTyp [] ty) dp) sel emptyMetaStore]
generateForMetas :: Selector sel => sel -> PGF -> Expr -> Maybe Int -> [Expr]
generateForMetas sel pgf e dp =
case unTcM (infExpr emptyScope e) abs sel emptyMetaStore of
Ok sel ms (e,_) -> let gen = do fillinVariables $ \scope tty -> do
v <- prove scope tty dp
return (value2expr (funs abs,lookupMeta ms) 0 v)
refineExpr e
in [e | (ms,e) <- runGenM abs gen sel ms]
Fail _ -> []
where
abs = abstract pgf
prove :: Selector sel => Scope -> TType -> Maybe Int -> TcM sel Value
prove scope (TTyp env1 (DTyp [] cat es1)) dp = do
(fn,DTyp hypos _ es2) <- clauses cat
case dp of
Just 0 | not (null hypos) -> mzero
_ -> return ()
(env2,args) <- mkEnv [] hypos
vs1 <- mapM (PGF.TypeCheck.eval env1) es1
vs2 <- mapM (PGF.TypeCheck.eval env2) es2
sequence_ [eqValue mzero suspend (scopeSize scope) v1 v2 | (v1,v2) <- zip vs1 vs2]
vs <- mapM descend args
return (VApp fn vs)
where
suspend i c = do
mv <- getMeta i
case mv of
MBound e -> c e
MUnbound scope tty cs -> do v <- prove scope tty dp
e <- TcM (\abs sel ms -> Ok sel ms (value2expr (funs abs,lookupMeta ms) 0 v))
setMeta i (MBound e)
sequence_ [c e | c <- (c:cs)]
clauses cat = do
fn <- select cat
if fn == mkCId "plus" then mzero else return ()
ty <- lookupFunType fn
return (fn,ty)
mkEnv env [] = return (env,[])
mkEnv env ((bt,x,ty):hypos) = do
(env,arg) <- if x /= wildCId
then do i <- newMeta scope (TTyp env ty)
let v = VMeta i env []
return (v : env,Right v)
else return (env,Left (TTyp env ty))
(env,args) <- mkEnv env hypos
return (env,(bt,arg):args)
descend (bt,arg) = do let dp' = fmap (flip (-) 1) dp
v <- case arg of
Right v -> return v
Left tty -> prove scope tty dp'
v <- case bt of
Implicit -> return (VImplArg v)
Explicit -> return v
return v
------------------------------------------------------------------------------
-- Generation Monad
runGenM :: Abstr -> TcM s a -> s -> MetaStore s -> [(MetaStore s,a)]
runGenM abs f s ms = toList (unTcM f abs s ms) []
where
toList (Ok s ms x) xs = (ms,x) : xs
toList (Fail _) xs = xs
toList (Zero) xs = xs
toList (Plus b1 b2) xs = toList b1 (toList b2 xs)
-- 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
[] -> restart g2 f
(x:xs) -> x : restart g2 f
|
