diff options
| author | krasimir <krasimir@chalmers.se> | 2009-12-13 18:50:29 +0000 |
|---|---|---|
| committer | krasimir <krasimir@chalmers.se> | 2009-12-13 18:50:29 +0000 |
| commit | f85232947e74ee7ef8c7b0ad2338212e7e68f1be (patch) | |
| tree | 667b886a5e3a4b026a63d4e3597f32497d824761 /src/PGF/Tree.hs | |
| parent | d88a865faff59c98fc91556ff8700b10ee5f2df8 (diff) | |
reorganize the directories under src, and rescue the JavaScript interpreter from deprecated
Diffstat (limited to 'src/PGF/Tree.hs')
| -rw-r--r-- | src/PGF/Tree.hs | 71 |
1 files changed, 0 insertions, 71 deletions
diff --git a/src/PGF/Tree.hs b/src/PGF/Tree.hs deleted file mode 100644 index cb2052cd7..000000000 --- a/src/PGF/Tree.hs +++ /dev/null @@ -1,71 +0,0 @@ -module PGF.Tree - ( Tree(..), - tree2expr, expr2tree, - prTree - ) where - -import PGF.CId -import PGF.Expr hiding (Tree) - -import Data.Char -import Data.List as List -import Control.Monad -import qualified Text.PrettyPrint as PP -import qualified Text.ParserCombinators.ReadP as RP - --- | The tree is an evaluated expression in the abstract syntax --- of the grammar. The type is especially restricted to not --- allow unapplied lambda abstractions. The tree is used directly --- from the linearizer and is produced directly from the parser. -data Tree = - Abs [(BindType,CId)] Tree -- ^ lambda abstraction. The list of variables is non-empty - | Var CId -- ^ variable - | Fun CId [Tree] -- ^ function application - | Lit Literal -- ^ literal - | Meta {-# UNPACK #-} !MetaId -- ^ meta variable - deriving (Eq, Ord) - ------------------------------------------------------ --- Conversion Expr <-> Tree ------------------------------------------------------ - --- | Converts a tree to expression. The conversion --- is always total, every tree is a valid expression. -tree2expr :: Tree -> Expr -tree2expr = tree2expr [] - where - tree2expr ys (Fun x ts) = foldl EApp (EFun x) (List.map (tree2expr ys) ts) - tree2expr ys (Lit l) = ELit l - tree2expr ys (Meta n) = EMeta n - tree2expr ys (Abs xs t) = foldr (\(b,x) e -> EAbs b x e) (tree2expr (List.map snd (reverse xs)++ys) t) xs - tree2expr ys (Var x) = case List.lookup x (zip ys [0..]) of - Just i -> EVar i - Nothing -> error "unknown variable" - --- | Converts an expression to tree. The conversion is only partial. --- Variables and meta variables of function type and beta redexes are not allowed. -expr2tree :: Expr -> Tree -expr2tree e = abs [] [] e - where - abs ys xs (EAbs b x e) = abs ys ((b,x):xs) e - abs ys xs (ETyped e _) = abs ys xs e - abs ys xs e = case xs of - [] -> app ys [] e - xs -> Abs (reverse xs) (app (map snd xs++ys) [] e) - - app xs as (EApp e1 e2) = app xs ((abs xs [] e2) : as) e1 - app xs as (ELit l) - | List.null as = Lit l - | otherwise = error "literal of function type encountered" - app xs as (EMeta n) - | List.null as = Meta n - | otherwise = error "meta variables of function type are not allowed in trees" - app xs as (EAbs _ x e) = error "beta redexes are not allowed in trees" - app xs as (EVar i) = Var (xs !! i) - app xs as (EFun f) = Fun f as - app xs as (ETyped e _) = app xs as e - - -prTree :: Tree -> String -prTree = showExpr [] . tree2expr - |
