BNFC-2.4.1.1: CF.hs
{-# OPTIONS -fglasgow-exts #-}
{-
BNF Converter: Abstract syntax
Copyright (C) 2004 Author: Markus Forberg, Michael Pellauer, Aarne Ranta
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-}
module CF (
-- Types.
CF,
Rule,
Pragma(..),
Exp(..),
Literal,
Symbol,
KeyWord,
Cat,
Fun,
Tree(..),
prTree, -- print an abstract syntax tree
Data, -- describes the abstract syntax of a grammar
cf2data, -- translates a grammar to a Data object.
cf2dataLists, -- translates to a Data with List categories included.
-- Literal categories, constants,
firstCat, -- the first value category in the grammar.
firstEntry, -- the first entry or the first value category
specialCats, -- ident
specialCatsP, -- all literals
specialData, -- special data
isCoercion, -- wildcards in grammar (avoid syntactic clutter)
isDefinedRule, -- defined rules (allows syntactic sugar)
isProperLabel, -- not coercion or defined rule
allCats, -- all categories of a grammar
allCatsIdNorm,
allEntryPoints, -- those categories that are entry points to the parser
reservedWords, -- get the keywords of a grammar.
symbols, -- get all symbols
literals, -- get all literals of a grammar. (e.g. String, Double)
reversibleCats, -- categories that is left-recursive transformable.
findAllReversibleCats, -- find all reversible categories
identCat, -- transforms '[C]' to ListC (others, unchanged).
valCat, -- The value category of a rule.
isParsable, -- Checks if the rule is parsable.
rulesOfCF, -- All rules of a grammar.
rulesForCat, -- rules for a given category
ruleGroups, -- Categories are grouped with their rules.
ruleGroupsInternals, --As above, but includes internal cats.
funRule, -- The function name of a rule.
notUniqueFuns, -- Returns a list of function labels that are not unique.
badInheritence, -- Returns a list of all function labels that can cause problems in languages with inheritence.
isList, -- Checks if a category is a list category.
-- Information functions for list functions.
isNilFun, -- empty list function? ([])
isOneFun, -- one element list function? (:[])
isConsFun, -- constructor function? (:)
isNilCons, -- either three of above?
isEmptyListCat, -- checks if the list permits []
revSepListRule, -- reverse a rule, if it is of form C t [C].
rhsRule, -- The list of Terminals/NonTerminals of a rule.
normCat, -- Removes precendence information. C1 => C, [C2] => [C]
normCatOfList, -- Removes precendence information and enclosed List. C1 => C, C2 => C
catOfList, -- Removes enclosed list: [C1] => C1
comments, -- translates the pragmas into two list containing the s./m. comments
tokenPragmas, -- user-defined regular expression tokens
tokenNames, -- The names of all user-defined tokens
precCat, -- get the precendence level of a Cat C1 => 1, C => 0
precLevels, -- get all precendence levels in the grammar, sorted in increasing order.
precRule, -- get the precendence level of the value category of a rule.
precCF, -- Check if the CF consists of precendence levels.
isUsedCat,
internalCat, -- the symbol #
isPositionCat, -- category that has a position in AST
hasIdent,
hasLayout,
layoutPragmas,
checkRule,
CFP, -- CF with profiles
RuleP,
FunP,
Prof,
cf2cfpRule,
cf2cfp,
cfp2cf,
trivialProf,
rulesOfCFP,
funRuleP, ruleGroupsP, allCatsP, allEntryPointsP
) where
import Utils (prParenth,(+++))
import List (nub, intersperse, partition, sort,sort,group)
import Char
import AbsBNF (Reg())
-- A context free grammar consists of a set of rules and some extended
-- information (e.g. pragmas, literals, symbols, keywords)
type CF = (Exts,[Rule])
-- A rule consists of a function name, a main category and a sequence of
-- terminals and non-terminals.
-- function_name . Main_Cat ::= sequence
type Rule = (Fun, (Cat, [Either Cat String]))
-- polymorphic types for common type signatures for CF and CFP
type Rul f = (f, (Cat, [Either Cat String]))
type CFG f = (Exts,[Rul f])
type Exts = ([Pragma],Info)
-- Info is information extracted from the CF, for easy access.
-- Literals - Char, String, Ident, Integer, Double
-- Strings are quoted strings, and Ident are unquoted.
-- Symbols - symbols in the grammar, e.g. ´*´, '->'.
-- KeyWord - reserved words, e.g. 'if' 'while'
type Info = ([Literal],[Symbol],[KeyWord],[Cat])
-- Expressions for function definitions
data Exp = App String [Exp]
| LitInt Integer
| LitDouble Double
| LitChar Char
| LitString String
instance Show Exp where
showsPrec p e =
case listView e of
Right es ->
showString "["
. foldr (.) id (intersperse (showString ", ") $ map shows es)
. showString "]"
Left (App x []) -> showString x
Left (App "(:)" [e1,e2]) ->
showParen (p>0)
$ showsPrec 1 e1
. showString " : "
. shows e2
Left (App x es) ->
showParen (p>1)
$ foldr (.) id
$ intersperse (showString " ")
$ showString x : map (showsPrec 2) es
Left (LitInt n) -> shows n
Left (LitDouble x) -> shows x
Left (LitChar c) -> shows c
Left (LitString s) -> shows s
where
listView (App "[]" []) = Right []
listView (App "(:)" [e1,e2])
| Right es <- listView e2 = Right $ e1:es
listView e = Left e
-- pragmas for single line comments and for multiple-line comments.
data Pragma = CommentS String
| CommentM (String,String)
| TokenReg String Bool Reg
| EntryPoints [Cat]
| Layout [String]
| LayoutStop [String]
| LayoutTop
| FunDef String [String] Exp
-- ...
deriving (Show)
tokenPragmas :: CFG f -> [(String,Reg)]
tokenPragmas cf = [(name,exp) | TokenReg name _ exp <- pragmasOfCF cf]
tokenNames :: CF -> [String]
tokenNames cf = fst (unzip (tokenPragmas cf))
layoutPragmas :: CF -> (Bool,[String],[String])
layoutPragmas cf = let ps = pragmasOfCF cf in (
not (null [() | LayoutTop <- ps]), -- if there's layout betw top-level
concat [ss | Layout ss <- ps], -- layout-block starting words
concat [ss | LayoutStop ss <- ps] -- layout-block ending words
)
hasLayout :: CF -> Bool
hasLayout cf = case layoutPragmas cf of
(t,ws,_) -> t || not (null ws) -- (True,[],_) means: top-level layout only
-- Literal: Char, String, Ident, Integer, Double
type Literal = Cat
type Symbol = String
type KeyWord = String
-- Cat is the Non-terminals of the grammar.
type Cat = String
-- Fun is the function name of a rule.
type Fun = String
internalCat :: Cat
internalCat = "#"
-- Abstract syntax tree.
newtype Tree = Tree (Fun,[Tree])
-- The abstract syntax of a grammar.
type Data = (Cat, [(Fun,[Cat])])
-- firstCat returns the first Category appearing in the grammar.
firstCat :: CF -> Cat
firstCat = valCat . head . rulesOfCF
firstEntry :: CF -> Cat
firstEntry cf = case allEntryPoints cf of
(x:_) -> x
_ -> firstCat cf
rulesOfCF :: CF -> [Rule]
rulesOfCF = snd
notUniqueFuns :: CF -> [Fun]
notUniqueFuns cf = let xss = group $ sort [ f | (f,_) <- rulesOfCF cf,
not (isNilCons f || isCoercion f)]
in [ head xs | xs <- xss, length xs > 1]
badInheritence :: CF -> [Cat]
badInheritence cf = concatMap checkGroup (ruleGroups cf)
where
checkGroup (cat, rs) = if (length rs <= 1)
then []
else case lookup cat rs of
Nothing -> []
Just x -> [cat]
infoOfCF :: CFG f -> Info
infoOfCF = snd . fst
pragmasOfCF :: CFG f -> [Pragma]
pragmasOfCF = fst . fst
-- extract the comment pragmas.
commentPragmas :: [Pragma] -> [Pragma]
commentPragmas = filter isComment
where isComment (CommentS _) = True
isComment (CommentM _) = True
isComment _ = False
-- returns all normal rules that constructs the given Cat.
rulesForCat :: CF -> Cat -> [Rule]
rulesForCat cf cat = [normRuleFun r | r <- rulesOfCF cf, isParsable r, valCat r == cat]
--This version doesn't exclude internal rules.
rulesForCat' :: CF -> Cat -> [Rule]
rulesForCat' cf cat = [normRuleFun r | r <- rulesOfCF cf, valCat r == cat]
valCat :: Rul f -> Cat
valCat = fst . snd
-- Get all categories of a grammar.
allCats :: CF -> [Cat]
allCats = nub . map valCat . rulesOfCF -- no cats w/o production
-- Gets all normalized identified Categories
allCatsIdNorm :: CF -> [Cat]
allCatsIdNorm = nub . map identCat . map normCat . allCats
-- category is used on an rhs
isUsedCat :: CF -> Cat -> Bool
isUsedCat cf cat = elem cat [c | r <- (rulesOfCF cf), Left c <- rhsRule r]
-- entry points to parser ----
allEntryPoints :: CF -> [Cat]
allEntryPoints cf = case concat [cats | EntryPoints cats <- pragmasOfCF cf] of
[] -> allCats cf
cs -> cs
-- group all categories with their rules.
ruleGroups :: CF -> [(Cat,[Rule])]
ruleGroups cf = [(c, rulesForCat cf c) | c <- allCats cf]
-- group all categories with their rules including internal rules.
ruleGroupsInternals :: CF -> [(Cat,[Rule])]
ruleGroupsInternals cf = [(c, rulesForCat' cf c) | c <- allCats cf]
literals :: CFG f -> [Cat]
literals cf = lits ++ owns
where
(lits,_,_,_) = infoOfCF cf
owns = map fst $ tokenPragmas cf
symbols :: CFG f -> [String]
symbols cf = syms
where (_,syms,_,_) = infoOfCF cf
reservedWords :: CFG f -> [String]
reservedWords cf = sort keywords
where (_,_,keywords,_) = infoOfCF cf
reversibleCats :: CFG f -> [Cat]
reversibleCats cf = cats
where (_,_,_,cats) = infoOfCF cf
-- Comments can be defined by the 'comment' pragma
comments :: CF -> ([(String,String)],[String])
comments cf = case commentPragmas (pragmasOfCF cf) of
xs -> ([p | CommentM p <- xs],
[s | CommentS s <- xs])
funRule :: Rule -> Fun
funRule = fst
rhsRule :: Rul f -> [Either Cat String]
rhsRule = snd . snd
-- built-in categories (corresponds to lexer)
-- if the gramamr uses the predefined Ident type
hasIdent :: CF -> Bool
hasIdent cf = isUsedCat cf "Ident"
-- these need new datatypes
specialCats :: CF -> [Cat]
specialCats cf = (if hasIdent cf then ("Ident":) else id) (map fst (tokenPragmas cf))
-- the parser needs these
specialCatsP :: [Cat]
specialCatsP = words "Ident Integer String Char Double"
-- to print parse trees
prTree :: Tree -> String
prTree (Tree (fun,[])) = fun
prTree (Tree (fun,trees)) = fun +++ unwords (map pr2 trees) where
pr2 t@(Tree (_,ts)) = (if (null ts) then id else prParenth) (prTree t)
-- abstract syntax trees: data type definitions
cf2data :: CF -> [Data]
cf2data cf =
[(cat, nub (map mkData [r | r@(f,_) <- rulesOfCF cf,
not (isDefinedRule f),
not (isCoercion f), eqCat cat (valCat r)]))
| cat <- allNormalCats cf]
where
mkData (f,(_,its)) = (normFun f,[normCat c | Left c <- its, c /= internalCat])
--This version includes lists in the returned data.
--Michael 4/03
cf2dataLists :: CF -> [Data]
cf2dataLists cf =
[(cat, nub (map mkData [r | r@(f,_) <- rulesOfCF cf,
not (isDefinedRule f),
not (isCoercion f), eqCat cat (valCat r)]))
| cat <- (filter (\x -> not $ isDigit $ last x) (allCats cf))]
where
mkData (f,(_,its)) = (normFun f,[normCat c | Left c <- its, c /= internalCat])
specialData :: CF -> [Data]
specialData cf = [(c,[(c,[arg c])]) | c <- specialCats cf] where
arg c = case c of
_ -> "String"
allNormalCats :: CF -> [Cat]
allNormalCats = filter isNormal . allCats
-- to deal with coercions
-- the Haskell convention: the wildcard _ is not a constructor
isCoercion :: Fun -> Bool
isCoercion = (== "_")
isDefinedRule :: Fun -> Bool
isDefinedRule (x:_) = isLower x
isProperLabel :: Fun -> Bool
isProperLabel f = not (isCoercion f || isDefinedRule f)
-- categories C1, C2,... (one digit in end) are variants of C
eqCat :: Cat -> Cat -> Bool
eqCat c c1 = catCat c == catCat c1
normCat :: Cat -> Cat
normCat c = case c of
'[':cs -> "[" ++ norm (init cs) ++ "]"
_ -> unList $ norm c -- to be deprecated
where
norm = reverse . dropWhile isDigit . reverse
normCatOfList :: Cat -> Cat
normCatOfList = normCat . catOfList
-- for Happy and Latex
-- When given a list Cat, i.e. '[C]', it removes the square brackets,
-- and adds the prefix List, i.e. 'ListC'.
identCat :: Cat -> Cat
identCat c = case c of
'[':cs -> "List" ++ identCat (init cs)
_ -> c
normFun :: Fun -> Fun
normFun = id -- takeWhile (not . isDigit)
normRuleFun :: Rule -> Rule
normRuleFun (f,p) = (normFun f, p)
isNormal :: Cat -> Bool
isNormal c = not (isList c || isDigit (last c))
isParsable :: Rul f -> Bool
isParsable (_,(_, Left "#":_)) = False
isParsable _ = True
isList :: Cat -> Bool
isList c = head c == '['
unList :: Cat -> Cat
unList c = c
catOfList :: Cat -> Cat
catOfList c = case c of
'[':_:_ -> init (tail c)
_ -> c
isNilFun, isOneFun, isConsFun, isNilCons :: Fun -> Bool
isNilCons f = isNilFun f || isOneFun f || isConsFun f
isNilFun f = f == "[]"
isOneFun f = f == "(:[])"
isConsFun f = f == "(:)"
isEmptyListCat :: CF -> Cat -> Bool
isEmptyListCat cf c = elem "[]" $ map fst $ rulesForCat' cf c
isNonterm = either (const True) (const False)
-- used in Happy to parse lists of form 'C t [C]' in reverse order
-- applies only if the [] rule has no terminals
revSepListRule :: Rul f -> Rul f
revSepListRule r@(f,(c, ts)) = (f, (c, xs : x : sep)) where
(x,sep,xs) = (head ts, init (tail ts), last ts)
-- invariant: test in findAllReversibleCats have been performed
findAllReversibleCats :: CF -> [Cat]
findAllReversibleCats cf = [c | (c,r) <- ruleGroups cf, isRev c r] where
isRev c rs = case rs of
[r1,r2] | isList c -> if isConsFun (funRule r2)
then tryRev r2 r1
else if isConsFun (funRule r1)
then tryRev r1 r2
else False
_ -> False
tryRev (f,(_,ts@(x:_:xs))) r = isEmptyNilRule r &&
isConsFun f && isNonterm x && isNonterm (last ts)
tryRev _ _ = False
isEmptyNilRule (f,(_,ts)) = isNilFun f && null ts
precCat :: Cat -> Int
precCat = snd . analyseCat
precRule :: Rule -> Int
precRule = precCat . valCat
precLevels :: CF -> [Int]
precLevels cf = sort $ nub $ [ precCat c | c <- allCats cf]
precCF :: CF -> Bool
precCF cf = length (precLevels cf) > 1
catCat :: Cat -> Cat
catCat = fst . analyseCat
analyseCat :: Cat -> (Cat,Int)
analyseCat c = if (isList c) then list c else noList c
where
list cat = let (rc,n) = noList (init (tail cat)) in ("[" ++ rc ++ "]",n)
noList cat = case span isDigit (reverse cat) of
([],c') -> (reverse c', 0)
(d,c') -> (reverse c', read (reverse d))
-- we should actually check that
-- (1) coercions are always between variants
-- (2) no other digits are used
checkRule :: CF -> RuleP -> Either RuleP String
checkRule cf r@((f,_),(cat,rhs))
| badCoercion = Right $ "Bad coercion in rule" +++ s
| badNil = Right $ "Bad empty list rule" +++ s
| badOne = Right $ "Bad one-element list rule" +++ s
| badCons = Right $ "Bad list construction rule" +++ s
| badList = Right $ "Bad list formation rule" +++ s
| badSpecial = Right $ "Bad special category rule" +++ s
| badTypeName = Right $ "Bad type name" +++ unwords badtypes +++ "in" +++ s
| badFunName = Right $ "Bad constructor name" +++ f +++ "in" +++ s
| badMissing = Right $ "No production for" +++ unwords missing ++
", appearing in rule" +++ s
| otherwise = Left r
where
s = f ++ "." +++ cat +++ "::=" +++ unwords (map (either id show) rhs) ---
c = normCat cat
cs = [normCat c | Left c <- rhs]
badCoercion = isCoercion f && not ([c] == cs)
badNil = isNilFun f && not (isList c && null cs)
badOne = isOneFun f && not (isList c && cs == [catOfList c])
badCons = isConsFun f && not (isList c && cs == [catOfList c, c])
badList = isList c &&
not (isCoercion f || isNilFun f || isOneFun f || isConsFun f)
badSpecial = elem c specialCatsP && not (isCoercion f)
badMissing = not (null missing)
missing = filter nodef [c | Left c <- rhs]
nodef t = notElem t defineds
defineds =
"#" : map fst (tokenPragmas cf) ++ specialCatsP ++ map valCat (rulesOfCF cf)
badTypeName = not (null badtypes)
badtypes = filter isBadType $ cat : [c | Left c <- rhs]
isBadType c = not (isUpper (head c) || isList c || c == "#")
badFunName = not (all (\c -> isAlphaNum c || c == '_') f {-isUpper (head f)-}
|| isCoercion f || isNilFun f || isOneFun f || isConsFun f)
isPositionCat :: CFG f -> Cat -> Bool
isPositionCat cf cat = or [b | TokenReg name b _ <- pragmasOfCF cf, name == cat]
-- grammar with permutation profile à la GF. AR 22/9/2004
type CFP = (Exts,[RuleP])
type FunP = (Fun,Prof)
type RuleP = (FunP, (Cat, [Either Cat String]))
type Prof = (Fun, [([[Int]],[Int])]) -- the original function name, profile
cf2cfp :: CF -> CFP
cf2cfp (es,rs) = (es, map cf2cfpRule rs)
cf2cfpRule :: Rule -> RuleP
cf2cfpRule (f,(c,its)) = ((f, (f, trivialProf its)),(c,its))
cfp2cf :: CFP -> CF
cfp2cf (es,rs) = (es,[(f,(c,its)) | ((f,_),(c,its)) <- rs])
trivialProf :: [Either Cat String] -> [([[Int]],[Int])]
trivialProf its = [([],[i]) | (i,_) <- zip [0..] [c | Left c <- its]]
rulesOfCFP :: CFP -> [RuleP]
rulesOfCFP = snd
funRuleP :: RuleP -> Fun
funRuleP = fst . snd . fst
ruleGroupsP :: CFP -> [(Cat,[RuleP])]
ruleGroupsP cf = [(c, rulesForCatP cf c) | c <- allCatsP cf]
rulesForCatP :: CFP -> Cat -> [RuleP]
rulesForCatP cf cat = [r | r <- rulesOfCFP cf, isParsable r, valCat r == cat]
allCatsP :: CFP -> [Cat]
allCatsP = nub . map valCat . rulesOfCFP -- no cats w/o production
allEntryPointsP :: CFP -> [Cat]
allEntryPointsP cf = case concat [cats | EntryPoints cats <- pragmasOfCF cf] of
[] -> allCatsP cf
cs -> cs