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lib/GHCup/Prelude/Ansi.hs

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+module GHCup.Prelude.Ansi where
+
+import           Control.Applicative
+import           Data.Char
+import           Data.Void
+
+import qualified Text.Megaparsec               as MP
+import qualified Text.Megaparsec.Char          as MPC
+
+
+-- | Calculate the render width of a string, considering
+-- wide characters (counted as double width), ANSI escape codes
+-- (not counted), and line breaks (in a multi-line string, the longest
+-- line determines the width).
+strWidth :: String -> Int
+strWidth =
+  maximum
+    . (0 :)
+    . map (foldr (\a b -> charWidth a + b) 0)
+    . lines
+    . stripAnsi
+
+-- | Strip ANSI escape sequences from a string.
+--
+-- >>> stripAnsi "\ESC[31m-1\ESC[m"
+-- "-1"
+stripAnsi :: String -> String
+stripAnsi s' =
+  case
+      MP.parseMaybe (many $ "" <$ MP.try ansi <|> pure <$> MP.anySingle) s'
+    of
+      Nothing -> error "Bad ansi escape"  -- PARTIAL: should not happen
+      Just xs -> concat xs
+ where
+    -- This parses lots of invalid ANSI escape codes, but that should be fine
+  ansi =
+    MPC.string "\ESC[" *> digitSemicolons *> suffix MP.<?> "ansi" :: MP.Parsec
+        Void
+        String
+        Char
+  digitSemicolons = MP.takeWhileP Nothing (\c -> isDigit c || c == ';')
+  suffix = MP.oneOf ['A', 'B', 'C', 'D', 'H', 'J', 'K', 'f', 'm', 's', 'u']
+
+-- | Get the designated render width of a character: 0 for a combining
+-- character, 1 for a regular character, 2 for a wide character.
+-- (Wide characters are rendered as exactly double width in apps and
+-- fonts that support it.) (From Pandoc.)
+charWidth :: Char -> Int
+charWidth c = case c of
+  _ | c < '\x0300'                     -> 1
+    | c >= '\x0300' && c <= '\x036F'   -> 0
+    |  -- combining
+      c >= '\x0370' && c <= '\x10FC'   -> 1
+    | c >= '\x1100' && c <= '\x115F'   -> 2
+    | c >= '\x1160' && c <= '\x11A2'   -> 1
+    | c >= '\x11A3' && c <= '\x11A7'   -> 2
+    | c >= '\x11A8' && c <= '\x11F9'   -> 1
+    | c >= '\x11FA' && c <= '\x11FF'   -> 2
+    | c >= '\x1200' && c <= '\x2328'   -> 1
+    | c >= '\x2329' && c <= '\x232A'   -> 2
+    | c >= '\x232B' && c <= '\x2E31'   -> 1
+    | c >= '\x2E80' && c <= '\x303E'   -> 2
+    | c == '\x303F'                    -> 1
+    | c >= '\x3041' && c <= '\x3247'   -> 2
+    | c >= '\x3248' && c <= '\x324F'   -> 1
+    | -- ambiguous
+      c >= '\x3250' && c <= '\x4DBF'   -> 2
+    | c >= '\x4DC0' && c <= '\x4DFF'   -> 1
+    | c >= '\x4E00' && c <= '\xA4C6'   -> 2
+    | c >= '\xA4D0' && c <= '\xA95F'   -> 1
+    | c >= '\xA960' && c <= '\xA97C'   -> 2
+    | c >= '\xA980' && c <= '\xABF9'   -> 1
+    | c >= '\xAC00' && c <= '\xD7FB'   -> 2
+    | c >= '\xD800' && c <= '\xDFFF'   -> 1
+    | c >= '\xE000' && c <= '\xF8FF'   -> 1
+    | -- ambiguous
+      c >= '\xF900' && c <= '\xFAFF'   -> 2
+    | c >= '\xFB00' && c <= '\xFDFD'   -> 1
+    | c >= '\xFE00' && c <= '\xFE0F'   -> 1
+    | -- ambiguous
+      c >= '\xFE10' && c <= '\xFE19'   -> 2
+    | c >= '\xFE20' && c <= '\xFE26'   -> 1
+    | c >= '\xFE30' && c <= '\xFE6B'   -> 2
+    | c >= '\xFE70' && c <= '\xFEFF'   -> 1
+    | c >= '\xFF01' && c <= '\xFF60'   -> 2
+    | c >= '\xFF61' && c <= '\x16A38'  -> 1
+    | c >= '\x1B000' && c <= '\x1B001' -> 2
+    | c >= '\x1D000' && c <= '\x1F1FF' -> 1
+    | c >= '\x1F200' && c <= '\x1F251' -> 2
+    | c >= '\x1F300' && c <= '\x1F773' -> 1
+    | c >= '\x20000' && c <= '\x3FFFD' -> 2
+    | otherwise                        -> 1