v2 perplexed

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2026-05-03 17:46:52 -07:00
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src/FWL/Parser.hs Normal file
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module FWL.Parser
( parseProgram
, parseFile
) where
import Control.Monad (void)
import Data.Bits ((.&.), (.|.), shiftL)
import Data.List (foldl')
import Data.Word (Word8)
import Numeric (readHex)
import Text.Parsec
import Text.Parsec.String (Parser)
import Data.Functor.Identity (Identity)
import qualified Text.Parsec.Expr as Ex
import FWL.AST
import FWL.Lexer
-- ─── Entry points ────────────────────────────────────────────────────────────
parseProgram :: String -> String -> Either ParseError Program
parseProgram src input = parse program src input
parseFile :: FilePath -> IO (Either ParseError Program)
parseFile fp = parseProgram fp <$> readFile fp
-- ─── Top-level ───────────────────────────────────────────────────────────────
program :: Parser Program
program = do
whiteSpace
cfg <- option defaultConfig configBlock
ds <- many decl
eof
return (Program cfg ds)
configBlock :: Parser Config
configBlock = do
reserved "config"
props <- braces (semiSep configProp)
optional semi
return $ foldr applyProp defaultConfig props
where
applyProp ("table", v) c = c { configTable = v }
applyProp _ c = c
configProp :: Parser (String, String)
configProp = do
reserved "table"
reservedOp "="
v <- stringLit
return ("table", v)
-- ─── Declarations ────────────────────────────────────────────────────────────
decl :: Parser Decl
decl = interfaceDecl
<|> zoneDecl
<|> importDecl
<|> letDecl
<|> patternDecl
<|> flowDecl
<|> ruleDecl
<|> policyDecl
interfaceDecl :: Parser Decl
interfaceDecl = do
reserved "interface"
n <- identifier
reservedOp ":"
k <- ifaceKind
ps <- braces (endBy ifaceProp semi)
_ <- semi
return (DInterface n k ps)
ifaceKind :: Parser IfaceKind
ifaceKind = (reserved "WAN" >> return IWan)
<|> (reserved "LAN" >> return ILan)
<|> (reserved "WireGuard" >> return IWireGuard)
<|> (IUser <$> identifier)
ifaceProp :: Parser IfaceProp
ifaceProp = (reserved "dynamic" >> return IPDynamic)
<|> (reserved "cidr4" >> reservedOp "=" >> IPCidr4 <$> cidrSet)
<|> (reserved "cidr6" >> reservedOp "=" >> IPCidr6 <$> cidrSet)
cidrSet :: Parser [CIDR]
cidrSet = braces (commaSep1 cidrLit)
zoneDecl :: Parser Decl
zoneDecl = do
reserved "zone"
n <- identifier
reservedOp "="
ns <- braces (commaSep1 identifier)
_ <- semi
return (DZone n ns)
importDecl :: Parser Decl
importDecl = do
reserved "import"
n <- identifier
reservedOp ":"
t <- typeP
reserved "from"
s <- stringLit
_ <- semi
return (DImport n t s)
letDecl :: Parser Decl
letDecl = do
reserved "let"
n <- identifier
reservedOp ":"
t <- typeP
reservedOp "="
e <- expr
_ <- semi
return (DLet n t e)
patternDecl :: Parser Decl
patternDecl = do
reserved "pattern"
n <- identifier
reservedOp ":"
t <- typeP
reservedOp "="
p <- pat
_ <- semi
return (DPattern n t p)
flowDecl :: Parser Decl
flowDecl = do
reserved "flow"
n <- identifier
reservedOp ":"
reserved "FlowPattern"
reservedOp "="
f <- flowExpr
_ <- semi
return (DFlow n f)
ruleDecl :: Parser Decl
ruleDecl = do
reserved "rule"
n <- identifier
reservedOp ":"
t <- typeP
reservedOp "="
e <- expr
_ <- semi
return (DRule n t e)
policyDecl :: Parser Decl
policyDecl = do
reserved "policy"
n <- identifier
reservedOp ":"
t <- typeP
reserved "on"
pm <- braces policyMeta
reservedOp "="
ab <- armBlock
_ <- semi
return (DPolicy n t pm ab)
policyMeta :: Parser PolicyMeta
policyMeta = do
props <- commaSep1 metaProp
let h = foldr (\p a -> case p of Left v -> v; _ -> a) HInput props
tb = foldr (\p a -> case p of Right (Left v) -> v; _ -> a) TFilter props
pr = foldr (\p a -> case p of Right (Right v) -> v; _ -> a) pFilter props
return (PolicyMeta h tb pr)
metaProp :: Parser (Either Hook (Either TableName Priority))
metaProp
= (reserved "hook" >> reservedOp "=" >> fmap (Left) hookP)
<|> (reserved "table" >> reservedOp "=" >> fmap (Right . Left) tableNameP)
<|> (reserved "priority" >> reservedOp "=" >> fmap (Right . Right) priorityP)
hookP :: Parser Hook
hookP = (reserved "Input" >> return HInput)
<|> (reserved "Forward" >> return HForward)
<|> (reserved "Output" >> return HOutput)
<|> (reserved "Prerouting" >> return HPrerouting)
<|> (reserved "Postrouting" >> return HPostrouting)
tableNameP :: Parser TableName
tableNameP = (reserved "Filter" >> return TFilter)
<|> (reserved "NAT" >> return TNAT)
priorityP :: Parser Priority
priorityP
= (reserved "Filter" >> return pFilter)
<|> (reserved "DstNat" >> return pDstNat)
<|> (reserved "SrcNat" >> return pSrcNat)
<|> (reserved "Mangle" >> return pMangle)
<|> (reserved "Raw" >> return pRaw)
<|> (reserved "ConnTrack" >> return pConnTrack)
<|> (Priority . fromIntegral <$> integerP)
where
-- Accept optional leading minus for negative priorities
integerP = do
neg <- option 1 (char '-' >> return (-1))
n <- natural
whiteSpace
return (neg * fromIntegral n)
-- ─── Arm blocks ──────────────────────────────────────────────────────────────
armBlock :: Parser ArmBlock
armBlock = braces (many arm)
arm :: Parser Arm
arm = do
_ <- symbol "|"
p <- pat
g <- optionMaybe (reserved "if" >> expr)
reservedOp "->"
e <- expr
_ <- semi
return (Arm p g e)
-- ─── Patterns ────────────────────────────────────────────────────────────────
pat :: Parser Pat
pat = wildcardPat
<|> try framePat
<|> try tuplePat
<|> bytesPat
<|> try recordPat
<|> try namedOrCtorPat
wildcardPat :: Parser Pat
wildcardPat = symbol "_" >> return PWild
-- Frame(...) — optional path then inner pattern
-- Layer stripping: if the inner pattern is not Ether/IPv4/IPv6/etc the
-- type-checker will peel outer layers automatically. Parser just stores
-- whatever the user wrote.
framePat :: Parser Pat
framePat = do
reserved "Frame"
(mp, inner) <- parens frameArgs
return (PFrame mp inner)
frameArgs :: Parser (Maybe PathPat, Pat)
frameArgs = try withPath <|> withoutPath
where
withPath = do
pp <- pathPat
_ <- comma
inner <- pat
return (Just pp, inner)
withoutPath = do
inner <- pat
return (Nothing, inner)
pathPat :: Parser PathPat
pathPat = do
src <- optionMaybe (try endpointPat)
dst <- optionMaybe (try (reservedOp "->" >> endpointPat))
case (src, dst) of
(Nothing, Nothing) -> fail "empty path pattern"
_ -> return (PathPat src dst)
endpointPat :: Parser EndpointPat
endpointPat
= (symbol "_" >> return EPWild)
<|> try (do n <- identifier
memberOp
z <- identifier
return (EPMember n z))
<|> (EPName <$> identifier)
memberOp :: Parser ()
memberOp = (reservedOp "" <|> reserved "in") >> return ()
tuplePat :: Parser Pat
tuplePat = do
ps <- parens (commaSep2 pat)
return (PTuple ps)
commaSep2 :: Parser a -> Parser [a]
commaSep2 p = do
x <- p
_ <- comma
xs <- commaSep1 p
return (x:xs)
bytesPat :: Parser Pat
bytesPat = brackets (PBytes <$> many byteElem)
byteElem :: Parser ByteElem
byteElem
= try (symbol "_*" >> return BEWildStar)
<|> try (symbol "_" >> return BEWild)
<|> (BEHex <$> hexByte)
hexByte :: Parser Word8
hexByte = do
void (string "0x")
h1 <- hexDigit
h2 <- hexDigit
whiteSpace
case (readHex [h1,h2] :: [(Integer, String)]) of
[(v,"")] -> return (fromIntegral v)
_ -> fail "invalid hex byte"
-- Record pattern: ident { fields }
recordPat :: Parser Pat
recordPat = do
n <- identifier
fs <- braces (commaSep fieldPat)
return (PRecord n fs)
fieldPat :: Parser FieldPat
fieldPat = do
n <- identifier
try (reservedOp "=" >> FPEq n <$> fieldLiteral)
<|> try (reserved "as" >> FPAs n <$> identifier)
<|> return (FPBind n)
-- Port literals (:22) are valid in record field position as well as plain literals.
fieldLiteral :: Parser Literal
fieldLiteral = try portLit <|> literal
where
portLit = do
void (char ':')
n <- fromIntegral <$> natural
return (LPort n)
-- Named pattern reference OR constructor: starts with uppercase-ish ident
namedOrCtorPat :: Parser Pat
namedOrCtorPat = do
n <- identifier
args <- optionMaybe (try (parens (commaSep pat)))
case args of
Nothing -> return (PNamed n) -- bare name = named pattern ref
Just ps -> return (PCtor n ps)
-- ─── Flow expressions ────────────────────────────────────────────────────────
flowExpr :: Parser FlowExpr
flowExpr = do
first <- FAtom <$> identifier
rest <- many (reservedOp "." >> identifier)
mw <- optionMaybe (reserved "within" >> durationLit)
return $ buildSeq (first : map FAtom rest) mw
where
buildSeq [x] mw = case mw of
Nothing -> x
Just w -> FSeq x x (Just w) -- degenerate
buildSeq (x:xs) mw = FSeq x (buildSeq xs mw) mw
buildSeq [] _ = error "impossible"
durationLit :: Parser Duration
durationLit = do
n <- fromIntegral <$> natural
u <- (char 's' >> return Seconds)
<|> (string "ms" >> return Millis)
<|> (char 'm' >> return Minutes)
<|> (char 'h' >> return Hours)
whiteSpace
return (n, u)
-- ─── Types ───────────────────────────────────────────────────────────────────
typeP :: Parser Type
typeP = do
t <- baseType
option t (reservedOp "->" >> TFun t <$> typeP)
baseType :: Parser Type
baseType
= effectType
<|> try tupleTy
<|> simpleTy
effectType :: Parser Type
effectType = do
effs <- angles (commaSep identifier)
t <- simpleTy
return (TEffect effs t)
tupleTy :: Parser Type
tupleTy = TTuple <$> parens (commaSep2 typeP)
simpleTy :: Parser Type
simpleTy = do
n <- identifier
args <- option [] (angles (commaSep typeP))
return (TName n args)
-- ─── Expressions ─────────────────────────────────────────────────────────────
expr :: Parser Expr
expr = lamExpr
<|> ifExpr
<|> doExpr
<|> caseExpr
<|> letExpr
<|> infixExpr
lamExpr :: Parser Expr
lamExpr = do
reservedOp "\\"
n <- identifier
reservedOp "->"
e <- expr
return (ELam n e)
ifExpr :: Parser Expr
ifExpr = do
reserved "if"
c <- expr
reserved "then"
t <- expr
reserved "else"
f <- expr
return (EIf c t f)
doExpr :: Parser Expr
doExpr = reserved "do" >> braces (EDo <$> semiSep doStmt)
doStmt :: Parser DoStmt
doStmt = try bindStmt <|> (DSExpr <$> expr)
bindStmt :: Parser DoStmt
bindStmt = do
n <- identifier
reservedOp "<-"
e <- expr
return (DSBind n e)
caseExpr :: Parser Expr
caseExpr = do
reserved "case"
e <- expr
reserved "of"
ab <- armBlock
return (ECase e ab)
letExpr :: Parser Expr
letExpr = do
reserved "let"
n <- identifier
reservedOp "="
e1 <- expr
reserved "in"
e2 <- expr
return (ELet n e1 e2)
-- Operator table for infix expressions
infixExpr :: Parser Expr
infixExpr = Ex.buildExpressionParser opTable appExpr
opTable :: Ex.OperatorTable String () Identity Expr
opTable =
[ [ prefix "!" ENot ]
, [ infixL "==" OpEq, infixL "!=" OpNeq
, infixL "<" OpLt, infixL "<=" OpLte
, infixL ">" OpGt, infixL ">=" OpGte
, infixIn ]
, [ infixR "&&" OpAnd ]
, [ infixR "||" OpOr ]
, [ infixR "++" OpConcat ]
, [ infixL ">>=" OpBind ]
, [ infixL ">>" OpThen ]
]
where
prefix op f = Ex.Prefix (reservedOp op >> return f)
infixL op c = Ex.Infix (reservedOp op >> return (EInfix c)) Ex.AssocLeft
infixR op c = Ex.Infix (reservedOp op >> return (EInfix c)) Ex.AssocRight
infixIn = Ex.Infix
((memberOp <|> reserved "in") >> return (EInfix OpIn))
Ex.AssocNone
appExpr :: Parser Expr
appExpr = do
f <- atom
args <- many atom
return (foldl EApp f args)
atom :: Parser Expr
atom
= try performExpr
<|> try mapLit
<|> try setLit
<|> try tupleLit
<|> try (parens expr)
<|> try litExpr
<|> try portExpr
<|> qualNameExpr
performExpr :: Parser Expr
performExpr = do
reserved "perform"
parts <- sepBy1 identifier dot
args <- parens (commaSep expr)
return (EPerform parts args)
qualNameExpr :: Parser Expr
qualNameExpr = do
parts <- sepBy1 identifier (try (dot <* notFollowedBy digit))
case parts of
[n] -> return (EVar n)
ns -> return (EQual ns)
litExpr :: Parser Expr
litExpr = ELit <$> literal
portExpr :: Parser Expr
portExpr = do
void (char ':')
n <- fromIntegral <$> natural
return (ELit (LPort n))
tupleLit :: Parser Expr
tupleLit = ETuple <$> parens (commaSep2 expr)
setLit :: Parser Expr
setLit = braces $ do
items <- commaSep expr
return (ESet items)
-- map literal: { expr -> expr, ... }
mapLit :: Parser Expr
mapLit = braces $ do
entries <- commaSep1 mapEntry
return (EMap entries)
mapEntry :: Parser (Expr, Expr)
mapEntry = do
k <- expr
reservedOp "->"
v <- expr
return (k, v)
-- ─── Literals ────────────────────────────────────────────────────────────────
literal :: Parser Literal
literal
= try ipOrCidrLit
<|> try hexLit
<|> try (LBool True <$ reserved "true")
<|> try (LBool False <$ reserved "false")
<|> try (LString <$> stringLit)
<|> try (LInt . fromIntegral <$> natural)
hexLit :: Parser Literal
hexLit = LHex <$> hexByte
-- ─── IP / CIDR parsing ───────────────────────────────────────────────────────
-- | Parse an IPv4 or IPv6 address, optionally followed by /prefix.
-- Tries IPv6 first (it can start with hex digits too), then IPv4.
ipOrCidrLit :: Parser Literal
ipOrCidrLit = do
ip <- try ipv6Lit <|> ipv4Lit_
mPrefix <- optionMaybe (char '/' >> fromIntegral <$> natural)
whiteSpace
return $ case mPrefix of
Nothing -> ip
Just p -> LCIDR ip p
-- | IPv4: four decimal octets separated by dots → LIP IPv4 (32-bit Integer)
ipv4Lit_ :: Parser Literal
ipv4Lit_ = do
a <- octet
void (char '.')
b <- octet
void (char '.')
c <- octet
void (char '.')
d <- octet
return $ LIP IPv4
( fromIntegral a `shiftL` 24
.|. fromIntegral b `shiftL` 16
.|. fromIntegral c `shiftL` 8
.|. fromIntegral d)
where
octet = do
n <- fromIntegral <$> natural
if n > 255 then fail "octet out of range" else return n
-- | IPv6: full notation, :: abbreviation, and optional embedded IPv4.
-- Stores as LIP IPv6 (128-bit Integer).
ipv6Lit :: Parser Literal
ipv6Lit = do
(left, right) <- ipv6Groups
let missing = 8 - length left - length right
when (missing < 0) $ fail "too many groups in IPv6 address"
let groups = left ++ replicate missing 0 ++ right
when (length groups /= 8) $ fail "invalid IPv6 address"
let val = foldl' (\acc g -> (acc `shiftL` 16) .|. fromIntegral g) (0::Integer) groups
return (LIP IPv6 val)
-- Returns (left-of-::, right-of-::).
-- If no :: present, left has all 8 groups and right is empty.
ipv6Groups :: Parser ([Int], [Int])
ipv6Groups = do
-- must start with a hex digit or ':' (for ::)
ahead <- lookAhead (hexDigit <|> char ':')
case ahead of
':' -> do
void (string "::")
right <- ipv6RightGroups
return ([], right)
_ -> do
left <- ipv6LeftGroups
mDbl <- optionMaybe (try (string "::"))
case mDbl of
Nothing -> return (left, [])
Just _ -> do
right <- ipv6RightGroups
return (left, right)
-- Parse a run of hex16:hex16:... stopping before :: or end
ipv6LeftGroups :: Parser [Int]
ipv6LeftGroups = do
first <- hex16
rest <- many (try (char ':' >> notFollowedBy (char ':') >> hex16))
return (first : rest)
-- Parse groups to the right of ::, including optional embedded IPv4
ipv6RightGroups :: Parser [Int]
ipv6RightGroups = option [] $
try ipv4EmbeddedGroups <|> ipv6LeftGroups
-- IPv4-mapped groups: e.g. ffff:192.168.1.1 -> [0xffff, 0xc0a8, 0x0101]
ipv4EmbeddedGroups :: Parser [Int]
ipv4EmbeddedGroups = do
prefix <- many (try (hex16 <* char ':' <* lookAhead digit))
a <- octet_; void (char '.')
b <- octet_; void (char '.')
c <- octet_; void (char '.')
d <- octet_
let hi = (a `shiftL` 8) .|. b
lo = (c `shiftL` 8) .|. d
return (prefix ++ [hi, lo])
where
octet_ = do
n <- fromIntegral <$> natural
if n > 255 then fail "IPv4 octet out of range" else return n
hex16 :: Parser Int
hex16 = do
digits <- many1 hexDigit
case (reads ("0x" ++ digits)) :: [(Int,String)] of
[(v,"")] -> if v > 0xffff then fail "hex16 out of range" else return v
_ -> fail "invalid hex group"
cidrLit :: Parser CIDR
cidrLit = do
l <- ipOrCidrLit
case l of
LCIDR ip p -> return (ip, p)
_ -> fail "expected CIDR notation (address/prefix)"