shithub: MicroHs

ref: dd6d15f672fd622dbca510bd562d66c629bca6a3
dir: /lib/Text/String.hs/

-- Copyright 2023 Lennart Augustsson
-- See LICENSE file for full license.
module Text.String(module Text.String) where
import Primitives
import Data.Bool
import Data.Char
import Data.Either
import Data.Function
import Data.Int
import Data.List
import Data.Maybe
import Data.Tuple

showChar :: Char -> String
showChar c = "'" ++ encodeChar c ++ "'"

encodeChar :: Char -> String
encodeChar c =
  let
    spec = [('\n', "\\n"), ('\r', "\\r"), ('\t', "\\t"), ('\b', "\\b"),
            ('\\', "\\\\"), ('\'', "\\'"), ('"', "\"")]
  in
    case lookupBy eqChar c spec of
      Nothing -> if isPrint c then [c] else "'\\" ++ showInt (ord c) ++ "'"
      Just s  -> s

showString :: String -> String
showString s = "\"" ++ concatMap encodeChar s ++ "\""

-- XXX wrong for minInt
showInt :: Int -> String
showInt n =
  if n < 0 then
    '-' : showUnsignedInt (negate n)
  else
    showUnsignedInt n

showUnsignedInt :: Int -> String
showUnsignedInt n =
  let
    c = chr (ord '0' + rem n 10)
  in  if n < 10 then
        [c]
      else
        showUnsignedInt (quot n 10) ++ [c]

readInt :: String -> Int
readInt cs =
  let
    rd = foldl (\ a c -> a * 10 + ord c - ord '0') 0
  in if eqChar (head cs) '-' then 0 - rd (tail cs) else rd cs

showBool :: Bool -> String
showBool arg =
  case arg of
    False -> "False"
    True  -> "True"

showUnit :: () -> String
showUnit arg =
  case arg of
    () -> "()"

showPair :: forall a b . (a -> String) -> (b -> String) -> (a, b) -> String
showPair sa sb ab =
  case ab of
    (a, b) -> "(" ++ sa a ++ "," ++ sb b ++ ")"

showList :: forall a . (a -> String) -> [a] -> String
showList sa as = "[" ++ intercalate "," (map sa as) ++ "]"

showMaybe :: forall a . (a -> String) -> Maybe a -> String
showMaybe _ Nothing = "Nothing"
showMaybe fa (Just a) = "(Just " ++ fa a ++ ")"

showEither :: forall a b . (a -> String) -> (b -> String) -> Either a b -> String
showEither fa _ (Left  a) = "(Left "  ++ fa a ++ ")"
showEither _ fb (Right b) = "(Right " ++ fb b ++ ")"

lines :: String -> [String]
lines "" = []
lines s =
  case span (not . eqChar '\n') s of
    (l, s') -> case s' of { [] -> [l]; _:s'' -> l : lines s'' }

unlines :: [String] -> String
unlines = concatMap (++ "\n")

unwords :: [String] -> String
unwords ss = intercalate " " ss

-- Using a primitive for string equality makes a huge speed difference.
eqString :: String -> String -> Bool
eqString = primEqString
{-
eqString axs ays =
  case axs of
    [] ->
      case ays of
        [] -> True
        _  -> False
    x:xs ->
      case ays of
        [] -> False
        y:ys -> eqChar x y && eqString xs ys
-}

leString :: String -> String -> Bool
leString axs ays =
  case axs of
    [] -> True
    x:xs ->
      case ays of
        [] -> False
        y:ys -> ltChar x y || eqChar x y && leString xs ys

padLeft :: Int -> String -> String
padLeft n s = replicate (n - length s) ' ' ++ s

forceString :: String -> ()
forceString [] = ()
forceString (c:cs) = c `primSeq` forceString cs