LIB/GTK: use ByteString instead of String for

src/HSFM/GUI/Glib/GlibString.hs

@@ -0,0 +1,84 @@
+{--
+HSFM, a filemanager written in Haskell.
+Copyright (C) 2016 Julian Ospald
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+version 2 as published by the Free Software Foundation.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+--}
+
+{-# LANGUAGE OverloadedStrings #-}
+{-# OPTIONS_HADDOCK ignore-exports #-}
+
+
+module HSFM.GUI.Glib.GlibString where
+
+
+import qualified Data.ByteString as BS
+import Data.Encoding
+  (
+    decodeStrictByteString
+  )
+import Data.Encoding.UTF8
+  (
+    UTF8(..)
+  )
+import Data.Word8
+  (
+    _percent
+  )
+import Foreign.C.String
+  (
+    CStringLen
+  , CString
+  )
+import Foreign.C.Types
+  (
+    CSize(..)
+  )
+import Foreign.Marshal.Utils
+  (
+    maybePeek
+  )
+import Foreign.Ptr
+  (
+    nullPtr
+  , plusPtr
+  )
+import System.Glib.UTFString
+
+
+
+-- TODO: move this to its own module
+instance GlibString BS.ByteString where
+    withUTFString = BS.useAsCString
+    withUTFStringLen s f = BS.useAsCStringLen  s (f . noNullPtrs)
+    peekUTFString s = do
+        len <- c_strlen s
+        BS.packCStringLen (s, fromIntegral len)
+    maybePeekUTFString = maybePeek peekUTFString
+    peekUTFStringLen = BS.packCStringLen
+    newUTFString = newUTFString . decodeStrictByteString UTF8
+    newUTFStringLen = newUTFStringLen . decodeStrictByteString UTF8
+    genUTFOfs = genUTFOfs . decodeStrictByteString UTF8
+    stringLength = BS.length
+    unPrintf s = BS.intercalate "%%" (BS.split _percent s)
+
+
+foreign import ccall unsafe "string.h strlen" c_strlen
+    :: CString -> IO CSize
+
+
+noNullPtrs :: CStringLen -> CStringLen
+noNullPtrs (p, 0) | p == nullPtr = (plusPtr p 1, 0)
+noNullPtrs s = s
+