Refactor getLine to return TextLines / Rope

src/Data/Text/Lines/Internal.hs

@@ -245,20 +245,20 @@ splitAtLine :: HasCallStack => Word -> TextLines -> (TextLines, TextLines)
 splitAtLine k = splitAtPosition (Position k 0)
 
 -- | Get line with given 0-based index, O(1).
--- The resulting Text does not contain @\\n@ characters..
--- Returns "" if the line index is out of bounds.
+-- The result does not contain @\\n@ characters..
+-- Returns 'mempty' if the line index is out of bounds.
 --
 -- >>> :set -XOverloadedStrings
 -- >>> map (\l -> getLine l "fя𐀀\n☺bar\n\n") [0..3]
 -- ["fя𐀀","☺bar","",""]
 --
 -- @since 0.3
-getLine :: Word -> TextLines -> Text
+getLine :: Word -> TextLines -> TextLines
 getLine line (TextLines t@(Text arr off len) nls)
   | intToWord (U.length nls) < line = mempty
   | otherwise =
     let lineIdx = wordToInt line
-    in case (nls U.!? (lineIdx - 1), nls U.!? lineIdx) of
+    in (`TextLines` mempty) $ case (nls U.!? (lineIdx - 1), nls U.!? lineIdx) of
       (Nothing, Nothing) -> t
       (Nothing, Just endNl) -> Text arr off (endNl - off) -- branch triggered by `getLine 0 "a\n"`
       (Just startNl, Nothing) -> Text arr (startNl + 1) (len + off - startNl - 1)

src/Data/Text/Mixed/Rope.hs

@@ -567,20 +567,23 @@ utf16SplitAtPosition (Utf16.Position l c) rp = do
   Just (beforeLine <> beforeColumn, afterColumn)
 
 -- | Get a line by its 0-based index.
--- Returns @""@ if the index is out of bounds.
+-- Returns 'mempty' if the index is out of bounds.
 -- The result doesn't contain @\\n@ characters.
 --
 -- >>> :set -XOverloadedStrings
 -- >>> map (\l -> getLine l "foo\nbar\n😊😊\n\n") [0..3]
 -- ["foo","bar","😊😊",""]
 --
 -- @since 0.3
-getLine :: Word -> Rope -> Text
+getLine :: Word -> Rope -> Rope
 getLine lineIdx rp =
-  case T.unsnoc firstLine of
-    Just (firstLineInit, '\n') -> firstLineInit
+  case charSplitAt (charLength firstLine - 1) firstLine of
+    (firstLineInit, firstLineLast)
+      | isNewline firstLineLast -> firstLineInit
     _ -> firstLine
   where
     (_, afterIndex) = splitAtLine lineIdx rp
-    (firstLineRope, _ ) = splitAtLine 1 afterIndex
-    firstLine = toText firstLineRope
+    (firstLine, _ ) = splitAtLine 1 afterIndex
+
+isNewline :: Rope -> Bool
+isNewline = (== T.singleton '\n') . toText

src/Data/Text/Rope.hs

@@ -391,20 +391,23 @@ splitAtPosition (Position l c) rp = (beforeLine <> beforeColumn, afterColumn)
     (beforeColumn, afterColumn) = splitAt c afterLine
 
 -- | Get a line by its 0-based index.
--- Returns @""@ if the index is out of bounds.
+-- Returns 'mempty' if the index is out of bounds.
 -- The result doesn't contain @\\n@ characters.
 --
 -- >>> :set -XOverloadedStrings
 -- >>> map (\l -> getLine l "foo\nbar\n😊😊\n\n") [0..3]
 -- ["foo","bar","😊😊",""]
 --
 -- @since 0.3
-getLine :: Word -> Rope -> Text
+getLine :: Word -> Rope -> Rope
 getLine lineIdx rp =
-  case T.unsnoc firstLine of
-    Just (firstLineInit, '\n') -> firstLineInit
+  case splitAt (length firstLine - 1) firstLine of
+    (firstLineInit, firstLineLast)
+      | isNewline firstLineLast -> firstLineInit
     _ -> firstLine
   where
     (_, afterIndex) = splitAtLine lineIdx rp
-    (firstLineRope, _ ) = splitAtLine 1 afterIndex
-    firstLine = toText firstLineRope
+    (firstLine, _ ) = splitAtLine 1 afterIndex
+
+isNewline :: Rope -> Bool
+isNewline = (== T.singleton '\n') . toText

src/Data/Text/Utf16/Rope.hs

@@ -394,20 +394,23 @@ splitAtPosition (Position l c) rp = do
   Just (beforeLine <> beforeColumn, afterColumn)
 
 -- | Get a line by its 0-based index.
--- Returns @""@ if the index is out of bounds.
+-- Returns 'mempty' if the index is out of bounds.
 -- The result doesn't contain @\\n@ characters.
 --
 -- >>> :set -XOverloadedStrings
 -- >>> map (\l -> getLine l "foo\nbar\n😊😊\n\n") [0..3]
 -- ["foo","bar","😊😊",""]
 --
 -- @since 0.3
-getLine :: Word -> Rope -> Text
+getLine :: Word -> Rope -> Rope
 getLine lineIdx rp =
-  case T.unsnoc firstLine of
-    Just (firstLineInit, '\n') -> firstLineInit
+  case splitAt (length firstLine - 1) firstLine of
+    Just (firstLineInit, firstLineLast)
+      | isNewline firstLineLast -> firstLineInit
     _ -> firstLine
   where
     (_, afterIndex) = splitAtLine lineIdx rp
-    (firstLineRope, _ ) = splitAtLine 1 afterIndex
-    firstLine = toText firstLineRope
+    (firstLine, _ ) = splitAtLine 1 afterIndex
+
+isNewline :: Rope -> Bool
+isNewline = (== T.singleton '\n') . toText

src/Data/Text/Utf8/Rope.hs

@@ -395,20 +395,23 @@ splitAtPosition (Position l c) rp = do
   Just (beforeLine <> beforeColumn, afterColumn)
 
 -- | Get a line by its 0-based index.
--- Returns @""@ if the index is out of bounds.
+-- Returns 'mempty' if the index is out of bounds.
 -- The result doesn't contain @\\n@ characters.
 --
 -- >>> :set -XOverloadedStrings
 -- >>> map (\l -> getLine l "foo\nbar\n😊😊\n\n") [0..3]
 -- ["foo","bar","😊😊",""]
 --
 -- @since 0.3
-getLine :: Word -> Rope -> Text
+getLine :: Word -> Rope -> Rope
 getLine lineIdx rp =
-  case T.unsnoc firstLine of
-    Just (firstLineInit, '\n') -> firstLineInit
+  case splitAt (length firstLine - 1) firstLine of
+    Just (firstLineInit, firstLineLast)
+      | isNewline firstLineLast -> firstLineInit
     _ -> firstLine
   where
     (_, afterIndex) = splitAtLine lineIdx rp
-    (firstLineRope, _ ) = splitAtLine 1 afterIndex
-    firstLine = toText firstLineRope
+    (firstLine, _ ) = splitAtLine 1 afterIndex
+
+isNewline :: Rope -> Bool
+isNewline = (== T.singleton '\n') . toText

test/CharLines.hs

@@ -105,7 +105,7 @@ testSuite = testGroup "Char Lines"
 
   , testProperty "forall i in bounds: getLine i x == lines x !! i" $
     \x -> let lns = lines x in
-      conjoin $ zipWith (\idx ln -> getLine idx x === ln) [0..] lns
+      conjoin $ zipWith (\idx ln -> getLine idx x === fromText ln) [0..] lns
   , testProperty "forall i out of bounds: getLine i x == mempty" $
     \x (Positive offset) ->
       let maxIdx = L.genericLength (lines x) - 1

test/CharRope.hs

@@ -53,7 +53,7 @@ testSuite = testGroup "Char Rope"
 
   , testProperty "forall i in bounds: getLine i x == lines x !! i" $
     \x -> let lns = Rope.lines x in
-      conjoin $ L.zipWith (\idx ln -> Rope.getLine idx x === ln) [0..] lns
+      conjoin $ L.zipWith (\idx ln -> Rope.getLine idx x === Rope.fromText ln) [0..] lns
   , testProperty "forall i out of bounds: getLine i x == mempty" $
     \x (Positive offset) ->
       let maxIdx = L.genericLength (Rope.lines x) - 1

test/MixedRope.hs

@@ -111,7 +111,7 @@ testSuite = testGroup "Utf16 Mixed"
 
   , testProperty "forall i in bounds: getLine i x == lines x !! i" $
     \x -> let lns = Mixed.lines x in
-      conjoin $ L.zipWith (\idx ln -> Mixed.getLine idx x === ln) [0..] lns
+      conjoin $ L.zipWith (\idx ln -> Mixed.getLine idx x === Mixed.fromText ln) [0..] lns
   , testProperty "forall i out of bounds: getLine i x == mempty" $
     \x (Positive offset) ->
       let maxIdx = L.genericLength (Mixed.lines x) - 1

test/Utf16Rope.hs

@@ -71,7 +71,7 @@ testSuite = testGroup "Utf16 Rope"
 
   , testProperty "forall i in bounds: getLine i x == lines x !! i" $
     \x -> let lns = Rope.lines x in
-      conjoin $ L.zipWith (\idx ln -> Rope.getLine idx x === ln) [0..] lns
+      conjoin $ L.zipWith (\idx ln -> Rope.getLine idx x === Rope.fromText ln) [0..] lns
   , testProperty "forall i out of bounds: getLine i x == mempty" $
     \x (Positive offset) ->
       let maxIdx = L.genericLength (Rope.lines x) - 1

test/Utf8Rope.hs

@@ -58,7 +58,7 @@ testSuite = testGroup "Utf8 Rope"
 
   , testProperty "forall i in bounds: getLine i x == lines x !! i" $
     \x -> let lns = Rope.lines x in
-      conjoin $ L.zipWith (\idx ln -> Rope.getLine idx x === ln) [0..] lns
+      conjoin $ L.zipWith (\idx ln -> Rope.getLine idx x === Rope.fromText ln) [0..] lns
   , testProperty "forall i out of bounds: getLine i x == mempty" $
     \x (Positive offset) ->
       let maxIdx = L.genericLength (Rope.lines x) - 1