mirror of
https://github.com/GrammaticalFramework/gf-core.git
synced 2026-04-30 06:52:49 -06:00
243 lines
8.1 KiB
Haskell
243 lines
8.1 KiB
Haskell
{-# LANGUAGE ExistentialQuantification #-}
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#include <pgf/pgf.h>
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module PGF2.Expr where
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import System.IO.Unsafe(unsafePerformIO)
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import Foreign hiding (unsafePerformIO)
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import Foreign.C
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import qualified Text.PrettyPrint as PP
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import PGF2.FFI
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import Data.List(mapAccumL)
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-- | An data type that represents
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-- identifiers for functions and categories in PGF.
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type CId = String
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ppCId = PP.text
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wildCId = "_" :: CId
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type Cat = CId -- ^ Name of syntactic category
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type Fun = CId -- ^ Name of function
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-----------------------------------------------------------------------------
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-- Expressions
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-- The C structure for the expression may point to other structures
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-- which are allocated from other pools. In order to ensure that
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-- they are not released prematurely we use the exprMaster to
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-- store references to other Haskell objects
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data Expr = forall a . Expr {expr :: PgfExpr, exprMaster :: a}
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instance Show Expr where
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show = showExpr []
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-- | Constructs an expression by lambda abstraction
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mkAbs :: BindType -> CId -> Expr -> Expr
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mkAbs bind_type var (Expr body master) =
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unsafePerformIO $ do
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exprPl <- gu_new_pool
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cvar <- newUtf8CString var exprPl
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c_expr <- pgf_expr_abs cbind_type cvar body exprPl
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exprFPl <- newForeignPtr gu_pool_finalizer exprPl
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return (Expr c_expr (exprFPl,body))
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where
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cbind_type =
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case bind_type of
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Explicit -> (#const PGF_BIND_TYPE_EXPLICIT)
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Implicit -> (#const PGF_BIND_TYPE_IMPLICIT)
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-- | Decomposes an expression into an abstraction and a body
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unAbs :: Expr -> Maybe (BindType, CId, Expr)
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unAbs (Expr expr master) =
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unsafePerformIO $ do
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c_abs <- pgf_expr_unabs expr
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if c_abs == nullPtr
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then return Nothing
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else do bt <- fmap toBindType ((#peek PgfExprAbs, bind_type) c_abs)
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var <- (#peek PgfExprAbs, id) c_abs >>= peekUtf8CString
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c_body <- (#peek PgfExprAbs, body) c_abs
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return (Just (bt, var, Expr c_body master))
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where
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toBindType :: CInt -> BindType
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toBindType (#const PGF_BIND_TYPE_EXPLICIT) = Explicit
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toBindType (#const PGF_BIND_TYPE_IMPLICIT) = Implicit
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-- | Constructs an expression by applying a function to a list of expressions
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mkApp :: Fun -> [Expr] -> Expr
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mkApp fun args =
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unsafePerformIO $
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withCString fun $ \cfun ->
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allocaBytes ((#size PgfApplication) + len * sizeOf (undefined :: PgfExpr)) $ \papp -> do
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(#poke PgfApplication, fun) papp cfun
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(#poke PgfApplication, n_args) papp len
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pokeArray (papp `plusPtr` (#offset PgfApplication, args)) (map expr args)
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exprPl <- gu_new_pool
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c_expr <- pgf_expr_apply papp exprPl
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exprFPl <- newForeignPtr gu_pool_finalizer exprPl
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return (Expr c_expr (exprFPl,args))
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where
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len = length args
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-- | Decomposes an expression into an application of a function
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unApp :: Expr -> Maybe (Fun,[Expr])
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unApp (Expr expr master) =
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unsafePerformIO $
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withGuPool $ \pl -> do
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appl <- pgf_expr_unapply expr pl
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if appl == nullPtr
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then return Nothing
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else do
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fun <- peekCString =<< (#peek PgfApplication, fun) appl
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arity <- (#peek PgfApplication, n_args) appl :: IO CInt
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c_args <- peekArray (fromIntegral arity) (appl `plusPtr` (#offset PgfApplication, args))
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return $ Just (fun, [Expr c_arg master | c_arg <- c_args])
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-- | Constructs an expression from a string literal
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mkStr :: String -> Expr
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mkStr str =
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unsafePerformIO $
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withCString str $ \cstr -> do
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exprPl <- gu_new_pool
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c_expr <- pgf_expr_string cstr exprPl
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exprFPl <- newForeignPtr gu_pool_finalizer exprPl
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return (Expr c_expr exprFPl)
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-- | Decomposes an expression into a string literal
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unStr :: Expr -> Maybe String
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unStr (Expr expr master) =
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unsafePerformIO $ do
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plit <- pgf_expr_unlit expr (#const PGF_LITERAL_STR)
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if plit == nullPtr
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then return Nothing
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else do s <- peekUtf8CString (plit `plusPtr` (#offset PgfLiteralStr, val))
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return (Just s)
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-- | Constructs an expression from an integer literal
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mkInt :: Int -> Expr
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mkInt val =
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unsafePerformIO $ do
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exprPl <- gu_new_pool
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c_expr <- pgf_expr_int (fromIntegral val) exprPl
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exprFPl <- newForeignPtr gu_pool_finalizer exprPl
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return (Expr c_expr exprFPl)
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-- | Decomposes an expression into an integer literal
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unInt :: Expr -> Maybe Int
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unInt (Expr expr master) =
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unsafePerformIO $ do
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plit <- pgf_expr_unlit expr (#const PGF_LITERAL_INT)
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if plit == nullPtr
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then return Nothing
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else do n <- peek (plit `plusPtr` (#offset PgfLiteralInt, val))
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return (Just (fromIntegral (n :: CInt)))
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-- | Constructs an expression from a real number
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mkFloat :: Double -> Expr
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mkFloat val =
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unsafePerformIO $ do
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exprPl <- gu_new_pool
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c_expr <- pgf_expr_float (realToFrac val) exprPl
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exprFPl <- newForeignPtr gu_pool_finalizer exprPl
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return (Expr c_expr exprFPl)
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-- | Decomposes an expression into a real number literal
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unFloat :: Expr -> Maybe Double
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unFloat (Expr expr master) =
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unsafePerformIO $ do
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plit <- pgf_expr_unlit expr (#const PGF_LITERAL_FLT)
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if plit == nullPtr
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then return Nothing
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else do n <- peek (plit `plusPtr` (#offset PgfLiteralFlt, val))
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return (Just (realToFrac (n :: CDouble)))
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-- | parses a 'String' as an expression
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readExpr :: String -> Maybe Expr
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readExpr str =
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unsafePerformIO $
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do exprPl <- gu_new_pool
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withGuPool $ \tmpPl ->
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withCString str $ \c_str ->
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do guin <- gu_string_in c_str tmpPl
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exn <- gu_new_exn tmpPl
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c_expr <- pgf_read_expr guin exprPl exn
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status <- gu_exn_is_raised exn
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if (not status && c_expr /= nullPtr)
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then do exprFPl <- newForeignPtr gu_pool_finalizer exprPl
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return $ Just (Expr c_expr exprFPl)
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else do gu_pool_free exprPl
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return Nothing
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ppExpr :: Int -> [CId] -> Expr -> PP.Doc
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ppExpr d xs e = ppParens (d>0) (PP.text (showExpr xs e)) -- just a quick hack !!!
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-- | renders an expression as a 'String'. The list
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-- of identifiers is the list of all free variables
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-- in the expression in order reverse to the order
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-- of binding.
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showExpr :: [CId] -> Expr -> String
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showExpr scope e =
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unsafePerformIO $
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withGuPool $ \tmpPl ->
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do (sb,out) <- newOut tmpPl
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let printCtxt = nullPtr
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exn <- gu_new_exn tmpPl
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pgf_print_expr (expr e) printCtxt 1 out exn
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s <- gu_string_buf_freeze sb tmpPl
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peekCString s
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-----------------------------------------------------------------------------
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-- Types
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data Type =
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DTyp [Hypo] CId [Expr]
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deriving Show
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data BindType =
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Explicit
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| Implicit
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deriving Show
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-- | 'Hypo' represents a hypothesis in a type i.e. in the type A -> B, A is the hypothesis
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type Hypo = (BindType,CId,Type)
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-- | renders type as 'String'.
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showType :: Type -> String
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showType = PP.render . ppType 0 []
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ppType :: Int -> [CId] -> Type -> PP.Doc
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ppType d scope (DTyp hyps cat args)
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| null hyps = ppRes scope cat args
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| otherwise = let (scope',hdocs) = mapAccumL (ppHypo 1) scope hyps
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in ppParens (d > 0) (foldr (\hdoc doc -> hdoc PP.<+> PP.text "->" PP.<+> doc) (ppRes scope cat args) hdocs)
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where
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ppRes scope cat es
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| null es = ppCId cat
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| otherwise = ppParens (d > 3) (ppCId cat PP.<+> PP.hsep (map (ppExpr 4 scope) es))
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ppHypo :: Int -> [CId]-> (BindType,CId,Type) -> ([CId],PP.Doc)
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ppHypo d scope (Explicit,x,typ) =
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if x == wildCId
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then (scope, ppType d scope typ)
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else let y = freshName x scope
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in (y:scope, PP.parens (ppCId x PP.<+> PP.char ':' PP.<+> ppType 0 scope typ))
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ppHypo d scope (Implicit,x,typ) =
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if x == wildCId
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then (scope,PP.parens (PP.braces (ppCId x) PP.<+> PP.char ':' PP.<+> ppType 0 scope typ))
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else let y = freshName x scope
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in (y:scope,PP.parens (PP.braces (ppCId x) PP.<+> PP.char ':' PP.<+> ppType 0 scope typ))
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freshName :: CId -> [CId] -> CId
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freshName x xs0 = loop 1 x
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where
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xs = wildCId : xs0
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loop i y
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| elem y xs = loop (i+1) (x++show i)
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| otherwise = y
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ppParens True = PP.parens
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ppParens False = id
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