1 files changed, 83 insertions, 0 deletions
diff --git a/src/Buffer/Motion.hs b/src/Buffer/Motion.hs
new file mode 100644
index 0000000..fa9e059
--- /dev/null
+++ b/src/Buffer/Motion.hs
@@ -0,0 +1,83 @@
+module Buffer.Motion where
+
+import Data.List (dropWhileEnd)
+import Buffer.Class
+
+--data Motion = Motion Int LeftRightMotion
+
+
+-- TODO factor Count
+-- TODO various Vim gX
+data LeftRightMotion
+  = GotoLeft Int
+  | GotoRight Int
+  | GotoFirstChar
+  -- | GotoFirstNonBlankChar
+  | GotoEndOfLine             -- XXX in Vi this can go downwards
+  | GotoColumn Int
+  -- | GotoFindLeft Int (Char -> Bool)   -- TODO don't use functions here
+  -- | GotoFindRight Int (Char -> Bool)  -- TODO ^ dto.
+  -- | GotillFindLeft Int Char
+  -- | GotillFindRight Int Char
+  -- | RepeatLastFind Int
+  -- | RepeatLastFindReverse Int
+  | WordsForward Int
+  | WordsBackward Int
+  deriving (Show)
+
+
+-- TODO fail if cannot splitAt properly OR if we didn't modify the buffer
+gotoLeft :: Int -> Buffer -> Buffer
+gotoLeft i (ls, rs) =
+  let (lls, rls) = splitAt (length ls - i) ls in (lls, rls ++ rs)
+
+
+-- TODO fail if cannot splitAt properly OR if we didn't modify the buffer
+gotoRight :: Int -> Buffer -> Buffer
+gotoRight i (ls, rs) =
+  let (lrs, rrs) = splitAt i rs in (ls ++ lrs, rrs)
+
+
+gotoFirstChar :: Buffer -> Buffer
+gotoFirstChar (ls, rs) = ("", ls ++ rs)
+
+
+gotoEndOfLine :: Buffer -> Buffer
+gotoEndOfLine (ls, rs) = (ls ++ rs, "")
+
+
+-- TODO fail if i <= 0 or i > length
+gotoColumn :: Int -> Buffer -> Buffer
+gotoColumn i (ls, rs) = splitAt (i - 1) $ ls ++ rs
+
+
+wordsForward :: Int -> Buffer -> Buffer
+wordsForward i (ls, rs) =
+  let rs' = dropWhile (==' ') $ dropWhile (/=' ') rs
+      ls' = ls ++ take (length rs - length rs') rs
+      b' = (ls', rs')
+  in
+    if i > 1
+      then wordsForward (i - 1) b'
+      else b'
+
+
+wordsBackward :: Int -> Buffer -> Buffer
+wordsBackward i (ls, rs) =
+  let ls' = dropWhileEnd (/=' ') $ dropWhileEnd (==' ') ls
+      rs' = drop (length ls') ls ++ rs
+      b' = (ls', rs')
+  in
+    if i > 1
+      then wordsBackward (i - 1) b'
+      else b'
+
+
+move :: LeftRightMotion -> Buffer -> Buffer
+move (GotoLeft i) = gotoLeft i
+move (GotoRight i) = gotoRight i
+move GotoFirstChar = gotoFirstChar
+move GotoEndOfLine = gotoEndOfLine
+move (GotoColumn i) = gotoColumn i
+move (WordsForward i) = wordsForward i
+move (WordsBackward i) = wordsBackward i