module Char(readLitChar) where

import ReadDec	-- Numeric
import ReadOct	-- Numeric
import ReadHex	-- Numeric
import AsciiTab
import IsUpper
import IsDigit
import Chr
import Ord

readLitChar 		:: ReadS Char

readLitChar ('\\':s)	=  readEsc s
	where
	readEsc ('a':s)	 = [('\a',s)]
	readEsc ('b':s)	 = [('\b',s)]
	readEsc ('f':s)	 = [('\f',s)]
	readEsc ('n':s)	 = [('\n',s)]
	readEsc ('r':s)	 = [('\r',s)]
	readEsc ('t':s)	 = [('\t',s)]
	readEsc ('v':s)	 = [('\v',s)]
	readEsc ('\\':s) = [('\\',s)]
	readEsc ('"':s)	 = [('"',s)]
	readEsc ('\'':s) = [('\'',s)]
	readEsc ('^':c:s) | c >= '@' && c <= '_'
			 = [(chr (ord c - ord '@'), s)]
	readEsc s@(d:_) | isDigit d
			 = [(chr n, t) | (n,t) <- readDec s]
	readEsc ('o':s)  = [(chr n, t) | (n,t) <- readOct s]
	readEsc ('x':s)	 = [(chr n, t) | (n,t) <- readHex s]
	readEsc s@(c:_) | isUpper c
			 = let table = ('\DEL', "DEL") : asciiTab
			   in case [(c,s') | (c, mne) <- table,
					     ([],s') <- [match mne s]]
			      of (pr:_) -> [pr]
				 []	-> []
	readEsc _	 = []

        match :: (Eq a) => [a] -> [a] -> ([a],[a])
        match (x:xs) (y:ys) | x == y  =  match xs ys
        match xs     ys		      =  (xs,ys)

readLitChar (c:s)	=  [(c,s)]