1 files changed, 12 insertions(+), 1 deletions(-)

M src/Data/Text/ParagraphLayout/Internal/TextContainer.hs

@@ 11,13 11,17 @@ where
 import Data.List.NonEmpty (NonEmpty((:|)))
 import Data.Text (Text)
 import qualified Data.Text as Text
-import Data.Text.Foreign (lengthWord8)
+import Data.Text.Foreign (dropWord8, lengthWord8, takeWord8)
 
 -- | Class of data types containing `Text` that can be accessed.
 class TextContainer a where
     -- | Extract a `Text` from its container.
     getText :: a -> Text
 
+-- | As a trivial instance, each `Text` contains itself.
+instance TextContainer Text where
+    getText = id
+
 -- | Class of data types containing `Text` that can be split at a given number
 -- of `Data.Word.Word8` units from the start of the text.
 class TextContainer a => SeparableTextContainer a where


@@ 26,6 30,13 @@ class TextContainer a => SeparableTextContainer a where
     -- constraints the instance requires.
     splitTextAt8 :: Int -> a -> (a, a)
 
+-- | As a trivial instance, each `Text` can be split directly.
+instance SeparableTextContainer Text where
+    splitTextAt8 n t = (t1, t2)
+        where
+            t1 = takeWord8 (fromIntegral n) t
+            t2 = dropWord8 (fromIntegral n) t
+
 -- | Treat a list of text containers as a contiguous sequence,
 -- and make a split at the given number of `Data.Word.Word8` from the beginning
 -- of this sequence.