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|
-----------------------------------------------------------------------------
-- |
-- Module : Language.Haskell.ParseUtils
-- Copyright : (c) The GHC Team, 1997-2000
-- License : BSD-3-Clause
--
-- Maintainer : Andreas Abel
-- Stability : stable
-- Portability : portable
--
-- Utilities for the Haskell parser.
--
-----------------------------------------------------------------------------
module Language.Haskell.ParseUtils (
splitTyConApp -- HsType -> P (HsName,[HsType])
, mkRecConstrOrUpdate -- HsExp -> [HsFieldUpdate] -> P HsExp
, checkPrec -- Integer -> P Int
, checkContext -- HsType -> P HsContext
, checkAssertion -- HsType -> P HsAsst
, checkDataHeader -- HsQualType -> P (HsContext,HsName,[HsName])
, checkClassHeader -- HsQualType -> P (HsContext,HsName,[HsName])
, checkInstHeader -- HsQualType -> P (HsContext,HsQName,[HsType])
, checkPattern -- HsExp -> P HsPat
, checkExpr -- HsExp -> P HsExp
, checkValDef -- SrcLoc -> HsExp -> HsRhs -> [HsDecl] -> P HsDecl
, checkClassBody -- [HsDecl] -> P [HsDecl]
, checkUnQual -- HsQName -> P HsName
, checkRevDecls -- [HsDecl] -> P [HsDecl]
) where
import Language.Haskell.ParseMonad
import Language.Haskell.Pretty
import Language.Haskell.Syntax
splitTyConApp :: HsType -> P (HsName,[HsType])
splitTyConApp t0 = split t0 []
where
split :: HsType -> [HsType] -> P (HsName,[HsType])
split (HsTyApp t u) ts = split t (u:ts)
split (HsTyCon (UnQual t)) ts = return (t,ts)
split _ _ = fail "Illegal data/newtype declaration"
-----------------------------------------------------------------------------
-- Various Syntactic Checks
checkContext :: HsType -> P HsContext
checkContext (HsTyTuple ts) =
mapM checkAssertion ts
checkContext t = do
c <- checkAssertion t
return [c]
-- Changed for multi-parameter type classes
checkAssertion :: HsType -> P HsAsst
checkAssertion = checkAssertion' []
where checkAssertion' ts (HsTyCon c) = return (c,ts)
checkAssertion' ts (HsTyApp a t) = checkAssertion' (t:ts) a
checkAssertion' _ _ = fail "Illegal class assertion"
checkDataHeader :: HsQualType -> P (HsContext,HsName,[HsName])
checkDataHeader (HsQualType cs t) = do
(c,ts) <- checkSimple "data/newtype" t []
return (cs,c,ts)
checkClassHeader :: HsQualType -> P (HsContext,HsName,[HsName])
checkClassHeader (HsQualType cs t) = do
(c,ts) <- checkSimple "class" t []
return (cs,c,ts)
checkSimple :: String -> HsType -> [HsName] -> P ((HsName,[HsName]))
checkSimple kw (HsTyApp l (HsTyVar a)) xs = checkSimple kw l (a:xs)
checkSimple _kw (HsTyCon (UnQual t)) xs = return (t,xs)
checkSimple kw _ _ = fail ("Illegal " ++ kw ++ " declaration")
checkInstHeader :: HsQualType -> P (HsContext,HsQName,[HsType])
checkInstHeader (HsQualType cs t) = do
(c,ts) <- checkInsts t []
return (cs,c,ts)
checkInsts :: HsType -> [HsType] -> P ((HsQName,[HsType]))
checkInsts (HsTyApp l t) ts = checkInsts l (t:ts)
checkInsts (HsTyCon c) ts = return (c,ts)
checkInsts _ _ = fail "Illegal instance declaration"
-----------------------------------------------------------------------------
-- Checking Patterns.
-- We parse patterns as expressions and check for valid patterns below,
-- converting the expression into a pattern at the same time.
checkPattern :: HsExp -> P HsPat
checkPattern e = checkPat e []
checkPat :: HsExp -> [HsPat] -> P HsPat
checkPat (HsCon c) args = return (HsPApp c args)
checkPat (HsApp f x) args = do
x' <- checkPat x []
checkPat f (x':args)
checkPat e [] = case e of
HsVar (UnQual x) -> return (HsPVar x)
HsLit l -> return (HsPLit l)
HsInfixApp l op r -> do
l' <- checkPat l []
r' <- checkPat r []
case op of
HsQConOp c -> return (HsPInfixApp l' c r')
_ -> patFail
HsTuple es -> do
ps <- mapM (\e' -> checkPat e' []) es
return (HsPTuple ps)
HsList es -> do
ps <- mapM (\e' -> checkPat e' []) es
return (HsPList ps)
HsParen e' -> do
p <- checkPat e' []
return (HsPParen p)
HsAsPat n e' -> do
p <- checkPat e' []
return (HsPAsPat n p)
HsWildCard -> return HsPWildCard
HsIrrPat e' -> do
p <- checkPat e' []
return (HsPIrrPat p)
HsRecConstr c fs -> do
fs' <- mapM checkPatField fs
return (HsPRec c fs')
HsNegApp (HsLit l) -> return (HsPNeg (HsPLit l))
_ -> patFail
checkPat _ _ = patFail
checkPatField :: HsFieldUpdate -> P HsPatField
checkPatField (HsFieldUpdate n e) = do
p <- checkPat e []
return (HsPFieldPat n p)
patFail :: P a
patFail = fail "Parse error in pattern"
-----------------------------------------------------------------------------
-- Check Expression Syntax
checkExpr :: HsExp -> P HsExp
checkExpr e = case e of
HsVar _ -> return e
HsCon _ -> return e
HsLit _ -> return e
HsInfixApp e1 op e2 -> check2Exprs e1 e2 (flip HsInfixApp op)
HsApp e1 e2 -> check2Exprs e1 e2 HsApp
HsNegApp e1 -> check1Expr e1 HsNegApp
HsLambda loc ps e1 -> check1Expr e1 (HsLambda loc ps)
HsLet bs e1 -> check1Expr e1 (HsLet bs)
HsIf e1 e2 e3 -> check3Exprs e1 e2 e3 HsIf
HsCase e1 alts -> do
alts' <- mapM checkAlt alts
e1' <- checkExpr e1
return (HsCase e1' alts')
HsDo stmts -> do
stmts' <- mapM checkStmt stmts
return (HsDo stmts')
HsTuple es -> checkManyExprs es HsTuple
HsList es -> checkManyExprs es HsList
HsParen e1 -> check1Expr e1 HsParen
HsLeftSection e1 op -> check1Expr e1 (flip HsLeftSection op)
HsRightSection op e1 -> check1Expr e1 (HsRightSection op)
HsRecConstr c fields -> do
fields' <- mapM checkField fields
return (HsRecConstr c fields')
HsRecUpdate e1 fields -> do
fields' <- mapM checkField fields
e1' <- checkExpr e1
return (HsRecUpdate e1' fields')
HsEnumFrom e1 -> check1Expr e1 HsEnumFrom
HsEnumFromTo e1 e2 -> check2Exprs e1 e2 HsEnumFromTo
HsEnumFromThen e1 e2 -> check2Exprs e1 e2 HsEnumFromThen
HsEnumFromThenTo e1 e2 e3 -> check3Exprs e1 e2 e3 HsEnumFromThenTo
HsListComp e1 stmts -> do
stmts' <- mapM checkStmt stmts
e1' <- checkExpr e1
return (HsListComp e1' stmts')
HsExpTypeSig loc e1 ty -> do
e1' <- checkExpr e1
return (HsExpTypeSig loc e1' ty)
_ -> fail "Parse error in expression"
-- type signature for polymorphic recursion!!
check1Expr :: HsExp -> (HsExp -> a) -> P a
check1Expr e1 f = do
e1' <- checkExpr e1
return (f e1')
check2Exprs :: HsExp -> HsExp -> (HsExp -> HsExp -> a) -> P a
check2Exprs e1 e2 f = do
e1' <- checkExpr e1
e2' <- checkExpr e2
return (f e1' e2')
check3Exprs :: HsExp -> HsExp -> HsExp -> (HsExp -> HsExp -> HsExp -> a) -> P a
check3Exprs e1 e2 e3 f = do
e1' <- checkExpr e1
e2' <- checkExpr e2
e3' <- checkExpr e3
return (f e1' e2' e3')
checkManyExprs :: [HsExp] -> ([HsExp] -> a) -> P a
checkManyExprs es f = do
es' <- mapM checkExpr es
return (f es')
checkAlt :: HsAlt -> P HsAlt
checkAlt (HsAlt loc p galts bs) = do
galts' <- checkGAlts galts
return (HsAlt loc p galts' bs)
checkGAlts :: HsGuardedAlts -> P HsGuardedAlts
checkGAlts (HsUnGuardedAlt e) = check1Expr e HsUnGuardedAlt
checkGAlts (HsGuardedAlts galts) = do
galts' <- mapM checkGAlt galts
return (HsGuardedAlts galts')
checkGAlt :: HsGuardedAlt -> P HsGuardedAlt
checkGAlt (HsGuardedAlt loc e1 e2) = check2Exprs e1 e2 (HsGuardedAlt loc)
checkStmt :: HsStmt -> P HsStmt
checkStmt (HsGenerator loc p e) = check1Expr e (HsGenerator loc p)
checkStmt (HsQualifier e) = check1Expr e HsQualifier
checkStmt s@(HsLetStmt _) = return s
checkField :: HsFieldUpdate -> P HsFieldUpdate
checkField (HsFieldUpdate n e) = check1Expr e (HsFieldUpdate n)
-----------------------------------------------------------------------------
-- Check Equation Syntax
checkValDef :: SrcLoc -> HsExp -> HsRhs -> [HsDecl] -> P HsDecl
checkValDef srcloc lhs rhs whereBinds =
case isFunLhs lhs [] of
Just (f,es) -> do
ps <- mapM checkPattern es
return (HsFunBind [HsMatch srcloc f ps rhs whereBinds])
Nothing -> do
lhs' <- checkPattern lhs
return (HsPatBind srcloc lhs' rhs whereBinds)
-- A variable binding is parsed as an HsPatBind.
isFunLhs :: HsExp -> [HsExp] -> Maybe (HsName, [HsExp])
isFunLhs (HsInfixApp l (HsQVarOp (UnQual op)) r) es = Just (op, l:r:es)
isFunLhs (HsApp (HsVar (UnQual f)) e) es = Just (f, e:es)
isFunLhs (HsApp (HsParen f) e) es = isFunLhs f (e:es)
isFunLhs (HsApp f e) es = isFunLhs f (e:es)
isFunLhs _ _ = Nothing
-----------------------------------------------------------------------------
-- In a class or instance body, a pattern binding must be of a variable.
checkClassBody :: [HsDecl] -> P [HsDecl]
checkClassBody decls = do
mapM_ checkMethodDef decls
return decls
checkMethodDef :: HsDecl -> P ()
checkMethodDef (HsPatBind _ (HsPVar _) _ _) = return ()
checkMethodDef (HsPatBind loc _ _ _) =
fail "illegal method definition" `atSrcLoc` loc
checkMethodDef _ = return ()
-----------------------------------------------------------------------------
-- Check that an identifier or symbol is unqualified.
-- For occasions when doing this in the grammar would cause conflicts.
checkUnQual :: HsQName -> P HsName
checkUnQual (Qual _ _) = fail "Illegal qualified name"
checkUnQual (UnQual n) = return n
checkUnQual (Special _) = fail "Illegal special name"
-----------------------------------------------------------------------------
-- Miscellaneous utilities
checkPrec :: Integer -> P Int
checkPrec i | 0 <= i && i <= 9 = return (fromInteger i)
checkPrec i | otherwise = fail ("Illegal precedence " ++ show i)
mkRecConstrOrUpdate :: HsExp -> [HsFieldUpdate] -> P HsExp
mkRecConstrOrUpdate (HsCon c) fs = return (HsRecConstr c fs)
mkRecConstrOrUpdate e fs@(_:_) = return (HsRecUpdate e fs)
mkRecConstrOrUpdate _ _ = fail "Empty record update"
-----------------------------------------------------------------------------
-- Reverse a list of declarations, merging adjacent HsFunBinds of the
-- same name and checking that their arities match.
checkRevDecls :: [HsDecl] -> P [HsDecl]
checkRevDecls = mergeFunBinds []
where
mergeFunBinds revDs [] = return revDs
mergeFunBinds revDs (HsFunBind ms1@(HsMatch _ name ps _ _:_):ds1) =
mergeMatches ms1 ds1
where
arity = length ps
mergeMatches ms' (HsFunBind ms@(HsMatch loc name' ps' _ _:_):ds)
| name' == name =
if length ps' /= arity
then fail ("arity mismatch for '" ++ prettyPrint name ++ "'")
`atSrcLoc` loc
else mergeMatches (ms++ms') ds
mergeMatches ms' ds = mergeFunBinds (HsFunBind ms':revDs) ds
mergeFunBinds revDs (d:ds) = mergeFunBinds (d:revDs) ds
|
