Files
gf-core/src/compiler/GF/Command/TreeOperations.hs
2025-02-19 12:59:43 +01:00

70 lines
2.6 KiB
Haskell

module GF.Command.TreeOperations (
treeOp,
allTreeOps,
treeChunks
) where
import PGF(Expr,PGF,CId,compute,mkApp,unApp,unapply,unMeta,exprSize,exprFunctions)
import PGF.Data(Expr(EApp,EFun))
import PGF.TypeCheck(inferExpr)
import Data.List
type TreeOp = [Expr] -> [Expr]
treeOp :: PGF -> String -> Maybe (Either TreeOp (CId -> TreeOp))
treeOp pgf f = fmap snd $ lookup f $ allTreeOps pgf
allTreeOps :: PGF -> [(String,(String,Either TreeOp (CId -> TreeOp)))]
allTreeOps pgf = [
("compute",("compute by using semantic definitions (def)",
Left $ map (compute pgf))),
("transfer",("apply this transfer function to all maximal subtrees of suitable type",
Right $ \f -> map (transfer pgf f))), -- HL 12/24, modified from gf-3.3
("largest",("sort trees from largest to smallest, in number of nodes",
Left $ largest)),
("nub\t",("remove duplicate trees",
Left $ nub)),
("smallest",("sort trees from smallest to largest, in number of nodes",
Left $ smallest)),
("subtrees",("return all fully applied subtrees (stopping at abstractions), by default sorted from the largest",
Left $ concatMap subtrees)),
("funs\t",("return all fun functions appearing in the tree, with duplications",
Left $ \es -> [mkApp f [] | e <- es, f <- exprFunctions e]))
]
largest :: [Expr] -> [Expr]
largest = reverse . smallest
smallest :: [Expr] -> [Expr]
smallest = sortBy (\t u -> compare (exprSize t) (exprSize u))
treeChunks :: Expr -> [Expr]
treeChunks = snd . cks where
cks t =
case unapply t of
(t, ts) -> case unMeta t of
Just _ -> (False,concatMap (snd . cks) ts)
Nothing -> case unzip (map cks ts) of
(bs,_) | and bs -> (True, [t])
(_,cts) -> (False,concat cts)
subtrees :: Expr -> [Expr]
subtrees t = t : case unApp t of
Just (f,ts) -> concatMap subtrees ts
_ -> [] -- don't go under abstractions
-- Apply transfer function f:C -> D to all maximal subtrees s:C of tree e and replace
-- these s by the values of f(s). This modifies the 'simple-minded transfer' of gf-3.3.
-- If applied to strict subtrees s of e, better use with f:C -> C only. HL 12/2024
transfer :: PGF -> CId -> Expr -> Expr
transfer pgf f e = case inferExpr pgf (appf e) of
Left _err -> case e of
EApp g a -> EApp (transfer pgf f g) (transfer pgf f a)
_ -> e
Right _ty -> case (compute pgf (appf e)) of
v | v /= (appf e) -> v
_ -> e -- default case of f, or f has no computation rule
where
appf = EApp (EFun f)