module Id where

import Char

-- identifiers, fixed for all logics

type Pos = (Int, Int) -- line, column

nullPos :: Pos = (0,0)

type Region = (Pos,Pos)

-- tokens as supplied by the scanner

data Token = Token String Pos -- deriving (Show, Eq, Ord)

showTok (Token t _) = t

instance Eq Token where

Token s1 _ == Token s2 _ = s1 == s2

instance Ord Token where

Token s1 _ <= Token s2 _ = s1 <= s2

showSepList :: ShowS -> (a -> ShowS) -> [a] -> ShowS

showSepList _ _ [] = showString ""

showSepList _ f [x] = f x

showSepList s f (x:r) = f x . s . showSepList s f r

showPlainList :: Show a => [a] -> ShowS

showPlainList = showSepList (showString "") shows

instance Show Token where

showsPrec _ = showString . showTok

showList = showPlainList

-- spezial tokens

type Keyword = Token

type TokenOrPlace = Token

place = "__"

isPlace(Token t _) = t == place

-- an identifier may be mixfix (though not for a sort) and compound

-- TokenOrPlace list must be non-empty!

data Id = Id [TokenOrPlace] [Id] deriving (Eq, Ord)

splitMixToken l = let (pls, toks) = span isPlace (reverse l) in

(reverse toks, reverse pls)

showId (Id ts is) =

let (toks, places) = splitMixToken ts

comps = if null is then showString "" else shows is

in

showList toks . comps . showList places

instance Show Id where

showsPrec _ = showId

-- Simple Ids

data SIMPLE_ID = SimpleId String Pos deriving (Eq, Show)