summaryrefslogtreecommitdiff
path: root/progs/prelude/PreludeText.hs
diff options
context:
space:
mode:
Diffstat (limited to 'progs/prelude/PreludeText.hs')
-rw-r--r--progs/prelude/PreludeText.hs260
1 files changed, 260 insertions, 0 deletions
diff --git a/progs/prelude/PreludeText.hs b/progs/prelude/PreludeText.hs
new file mode 100644
index 0000000..9e4e353
--- /dev/null
+++ b/progs/prelude/PreludeText.hs
@@ -0,0 +1,260 @@
+module PreludeText (
+ reads, shows, show, read, lex,
+ showChar, showString, readParen, showParen, readLitChar, showLitChar,
+ readSigned, showSigned, readDec, showInt, readFloat, showFloat ) where
+
+{-#Prelude#-} -- Indicates definitions of compiler prelude symbols
+
+reads :: (Text a) => ReadS a
+reads = readsPrec 0
+
+shows :: (Text a) => a -> ShowS
+shows = showsPrec 0
+
+read :: (Text a) => String -> a
+read s = case [x | (x,t) <- reads s, ("","") <- lex t] of
+ [x] -> x
+ [] -> error "read{PreludeText}: no parse"
+ _ -> error "read{PreludeText}: ambiguous parse"
+
+show :: (Text a) => a -> String
+show x = shows x ""
+
+showChar :: Char -> ShowS
+showChar = (:)
+
+showString :: String -> ShowS
+showString = (++)
+
+showParen :: Bool -> ShowS -> ShowS
+showParen b p = if b then showChar '(' . p . showChar ')' else p
+
+readParen :: Bool -> ReadS a -> ReadS a
+readParen b g = if b then mandatory else optional
+ where optional r = g r ++ mandatory r
+ mandatory r = [(x,u) | ("(",s) <- lex r,
+ (x,t) <- optional s,
+ (")",u) <- lex t ]
+
+lex :: ReadS String
+lex "" = [("","")]
+lex (c:s) | isSpace c = lex (dropWhile isSpace s)
+lex ('-':'-':s) = case dropWhile (/= '\n') s of
+ '\n':t -> lex t
+ _ -> [] -- unterminated end-of-line
+ -- comment
+
+lex ('{':'-':s) = lexNest lex s
+ where
+ lexNest f ('-':'}':s) = f s
+ lexNest f ('{':'-':s) = lexNest (lexNest f) s
+ lexNest f (c:s) = lexNest f s
+ lexNest _ "" = [] -- unterminated
+ -- nested comment
+
+lex ('<':'-':s) = [("<-",s)]
+lex ('\'':s) = [('\'':ch++"'", t) | (ch,'\'':t) <- lexLitChar s,
+ ch /= "'" ]
+lex ('"':s) = [('"':str, t) | (str,t) <- lexString s]
+ where
+ lexString ('"':s) = [("\"",s)]
+ lexString s = [(ch++str, u)
+ | (ch,t) <- lexStrItem s,
+ (str,u) <- lexString t ]
+
+ lexStrItem ('\\':'&':s) = [("\\&",s)]
+ lexStrItem ('\\':c:s) | isSpace c
+ = [("\\&",t) | '\\':t <- [dropWhile isSpace s]]
+ lexStrItem s = lexLitChar s
+
+lex (c:s) | isSingle c = [([c],s)]
+ | isSym1 c = [(c:sym,t) | (sym,t) <- [span isSym s]]
+ | isAlpha c = [(c:nam,t) | (nam,t) <- [span isIdChar s]]
+ | isDigit c = [(c:ds++fe,t) | (ds,s) <- [span isDigit s],
+ (fe,t) <- lexFracExp s ]
+ | otherwise = [] -- bad character
+ where
+ isSingle c = c `elem` ",;()[]{}_"
+ isSym1 c = c `elem` "-~" || isSym c
+ isSym c = c `elem` "!@#$%&*+./<=>?\\^|:"
+ isIdChar c = isAlphanum c || c `elem` "_'"
+
+ lexFracExp ('.':s) = [('.':ds++e,u) | (ds,t) <- lexDigits s,
+ (e,u) <- lexExp t ]
+ lexFracExp s = [("",s)]
+
+ lexExp (e:s) | e `elem` "eE"
+ = [(e:c:ds,u) | (c:t) <- [s], c `elem` "+-",
+ (ds,u) <- lexDigits t] ++
+ [(e:ds,t) | (ds,t) <- lexDigits s]
+ lexExp s = [("",s)]
+
+lexDigits :: ReadS String
+lexDigits = nonnull isDigit
+
+nonnull :: (Char -> Bool) -> ReadS String
+nonnull p s = [(cs,t) | (cs@(_:_),t) <- [span p s]]
+
+lexLitChar :: ReadS String
+lexLitChar ('\\':s) = [('\\':esc, t) | (esc,t) <- lexEsc s]
+ where
+ lexEsc (c:s) | c `elem` "abfnrtv\\\"'" = [([c],s)]
+ lexEsc ('^':c:s) | c >= '@' && c <= '_' = [(['^',c],s)]
+ lexEsc s@(d:_) | isDigit d = lexDigits s
+ lexEsc ('o':s) = [('o':os, t) | (os,t) <- nonnull isOctDigit s]
+ lexEsc ('x':s) = [('x':xs, t) | (xs,t) <- nonnull isHexDigit s]
+ lexEsc s@(c:_) | isUpper c
+ = case [(mne,s') | mne <- "DEL" : elems asciiTab,
+ ([],s') <- [match mne s] ]
+ of (pr:_) -> [pr]
+ [] -> []
+ lexEsc _ = []
+lexLitChar (c:s) = [([c],s)]
+lexLitChar "" = []
+
+isOctDigit c = c >= '0' && c <= '7'
+isHexDigit c = isDigit c || c >= 'A' && c <= 'F'
+ || c >= 'a' && c <= 'f'
+
+match :: (Eq a) => [a] -> [a] -> ([a],[a])
+match (x:xs) (y:ys) | x == y = match xs ys
+match xs ys = (xs,ys)
+
+asciiTab = listArray ('\NUL', ' ')
+ ["NUL", "SOH", "STX", "ETX", "EOT", "ENQ", "ACK", "BEL",
+ "BS", "HT", "LF", "VT", "FF", "CR", "SO", "SI",
+ "DLE", "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB",
+ "CAN", "EM", "SUB", "ESC", "FS", "GS", "RS", "US",
+ "SP"]
+
+
+
+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") : assocs asciiTab
+ in case [(c,s') | (c := mne) <- table,
+ ([],s') <- [match mne s]]
+ of (pr:_) -> [pr]
+ [] -> []
+ readEsc _ = []
+readLitChar (c:s) = [(c,s)]
+
+showLitChar :: Char -> ShowS
+showLitChar c | c > '\DEL' = showChar '\\' . protectEsc isDigit (shows (ord c))
+showLitChar '\DEL' = showString "\\DEL"
+showLitChar '\\' = showString "\\\\"
+showLitChar c | c >= ' ' = showChar c
+showLitChar '\a' = showString "\\a"
+showLitChar '\b' = showString "\\b"
+showLitChar '\f' = showString "\\f"
+showLitChar '\n' = showString "\\n"
+showLitChar '\r' = showString "\\r"
+showLitChar '\t' = showString "\\t"
+showLitChar '\v' = showString "\\v"
+showLitChar '\SO' = protectEsc (== 'H') (showString "\\SO")
+showLitChar c = showString ('\\' : asciiTab!c)
+
+protectEsc p f = f . cont
+ where cont s@(c:_) | p c = "\\&" ++ s
+ cont s = s
+
+readDec, readOct, readHex :: (Integral a) => ReadS a
+readDec = readInt 10 isDigit (\d -> ord d - ord '0')
+readOct = readInt 8 isOctDigit (\d -> ord d - ord '0')
+readHex = readInt 16 isHexDigit hex
+ where hex d = ord d - (if isDigit d then ord '0'
+ else ord (if isUpper d then 'A' else 'a')
+ - 10)
+
+readInt :: (Integral a) => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
+readInt radix isDig digToInt s =
+ [(foldl1 (\n d -> n * radix + d) (map (fromIntegral . digToInt) ds), r)
+ | (ds,r) <- nonnull isDig s ]
+
+showInt :: (Integral a) => a -> ShowS
+showInt n r = let (n',d) = quotRem n 10
+ r' = chr (ord '0' + fromIntegral d) : r
+ in if n' == 0 then r' else showInt n' r'
+
+readSigned:: (Real a) => ReadS a -> ReadS a
+readSigned readPos = readParen False read'
+ where read' r = read'' r ++
+ [(-x,t) | ("-",s) <- lex r,
+ (x,t) <- read'' s]
+ read'' r = [(n,s) | (str,s) <- lex r,
+ (n,"") <- readPos str]
+
+showSigned:: (Real a) => (a -> ShowS) -> Int -> a -> ShowS
+showSigned showPos p x = if x < 0 then showParen (p > 6)
+ (showChar '-' . showPos (-x))
+ else showPos x
+
+
+-- The functions readFloat and showFloat below use rational arithmetic
+-- to insure correct conversion between the floating-point radix and
+-- decimal. It is often possible to use a higher-precision floating-
+-- point type to obtain the same results.
+
+readFloat:: (RealFloat a) => ReadS a
+readFloat r = [(fromRational ((n%1)*10^^(k-d)), t) | (n,d,s) <- readFix r,
+ (k,t) <- readExp s]
+ where readFix r = [(read (ds++ds'), length ds', t)
+ | (ds,'.':s) <- lexDigits r,
+ (ds',t) <- lexDigits s ]
+
+ readExp (e:s) | e `elem` "eE" = readExp' s
+ readExp s = [(0,s)]
+
+ readExp' ('-':s) = [(-k,t) | (k,t) <- readDec s]
+ readExp' ('+':s) = readDec s
+ readExp' s = readDec s
+
+-- The number of decimal digits m below is chosen to guarantee
+-- read (show x) == x. See
+-- Matula, D. W. A formalization of floating-point numeric base
+-- conversion. IEEE Transactions on Computers C-19, 8 (1970 August),
+-- 681-692.
+
+showFloat:: (RealFloat a) => a -> ShowS
+showFloat x =
+ if x == 0 then showString ("0." ++ take (m-1) (repeat '0'))
+ else if e >= m-1 || e < 0 then showSci else showFix
+ where
+ showFix = showString whole . showChar '.' . showString frac
+ where (whole,frac) = splitAt (e+1) (show sig)
+ showSci = showChar d . showChar '.' . showString frac
+ . showChar 'e' . shows e
+ where (d:frac) = show sig
+ (m, sig, e) = if b == 10 then (w, s, n+w-1)
+ else (m', sig', e' )
+ m' = ceiling
+ (fromIntegral w * log (fromInteger b) / log 10 :: Double)
+ + 1
+ (sig', e') = if sig1 >= 10^m' then (round (t/10), e1+1)
+ else if sig1 < 10^(m'-1) then (round (t*10), e1-1)
+ else (sig1, e1 )
+ sig1 :: Integer
+ sig1 = round t
+ t = s%1 * (b%1)^^n * 10^^(m'-e1-1)
+ e1 = floor (logBase 10 x)
+ (s, n) = decodeFloat x
+ b = floatRadix x
+ w = floatDigits x
generated by cgit v1.2.3 (git 2.46.0) at 2024-09-16 19:25:34 +0000