1 files changed, 41 insertions, 8 deletions

diff --git a/AufgabeFFP7.hs b/AufgabeFFP7.hs
index 13f1448..fc9d594 100644
--- a/AufgabeFFP7.hs
+++ b/AufgabeFFP7.hs
@@ -2,7 +2,7 @@ module AufgabeFFP7
 where
 
 import Data.Char
-import Data.List hiding ((\\))
+import Data.List hiding ((\\), insert)
 import Test.QuickCheck
 
 type Buffer = (Int, String)
@@ -47,33 +47,66 @@ atRight (cur, buf) = cur >= length buf
 type BufferI = (String, String)
 
 -- the empty buffer
---TODO emptyI :: BufferI
+emptyI :: BufferI
+emptyI = ("", "")
 
 -- insert character before cursor
---TODO insertI :: Char -> BufferI -> BufferI
+insertI :: Char -> BufferI -> BufferI
+insertI c (beforeC, afterC) = ([c] ++ beforeC, afterC)
 
 -- delete character before cursor
 --TODO deleteI :: BufferI -> BufferI
 
 -- move cursor left one character
---TODO leftI :: BufferI -> BufferI
+leftI :: BufferI -> BufferI
+leftI ([], afterC) = ([], afterC)
+leftI (last:beforeC, afterC) = (beforeC, [last] ++ afterC)
 
 -- move cursor right one character
 --TODO rightI :: BufferI -> BufferI
 
 -- is cursor at left end?
---TODO atLeftI :: BufferI -> Bool
+atLeftI :: BufferI -> Bool
+atLeftI ([], _) = True
+atLeftI (_, _) = False
 
 -- is cursor at right end?
---TODO atRightI :: BufferI -> Bool
+atRightI :: BufferI -> Bool
+atRightI (_, []) = True
+atRightI (_, _) = False
+
 
 --------------------------------------------------------------------------------
 
---TODO retrieve :: BufferI -> Buffer
+retrieve :: BufferI -> Buffer
+retrieve (beforeC, afterC) = (length beforeC, (reverse beforeC) ++ afterC)
 
 --------------------------------------------------------------------------------
 
---TODO: quicheck stuff
+-- quickcheck Buffer == BufferI
+
+bufEqual :: BufferI -> Buffer -> Bool
+bufEqual bi b = (retrieve bi) == b
+
+-- generator for equal data
+genEqualBuf :: Gen(Buffer, BufferI)
+genEqualBuf = do s <- arbitrary ; c <- choose (0, length s) ; return ( (c, s), revFst (splitAt c s) )
+                where 
+                revFst = \(a, b) -> (reverse a, b)
+
+instance Arbitrary Char where
+        arbitrary = elements $ ['a'..'z'] ++ ['A'..'Z']
+
+-- naive insert test, will exhaust
+prop_insert :: BufferI -> Buffer -> Char -> Property
+prop_insert bi b c = bufEqual bi b
+        ==> bufEqual (insertI c bi) (insert c b)
+
+-- use equal data generator
+prop_insert2 :: Char -> Property
+prop_insert2 c =
+        forAll (genEqualBuf) $ \(b, bi) -> bufEqual (insertI c bi) (insert c b)
+
 
 --------------------------------------------------------------------------------