3 files changed, 26 insertions(+), 15 deletions(-)

M balkon.cabal
M lib/Data/Text/ParagraphLayout.hs
R src/Data/Text/ParagraphLayout/Internal/{ParagraphPagination.hs => Paginable.hs}

@@ 128,11 128,11 @@ library balkon-internal
         Data.Text.ParagraphLayout.Internal.Fragment,
         Data.Text.ParagraphLayout.Internal.LineHeight,
         Data.Text.ParagraphLayout.Internal.LinePagination,
+        Data.Text.ParagraphLayout.Internal.Paginable,
         Data.Text.ParagraphLayout.Internal.Paragraph,
         Data.Text.ParagraphLayout.Internal.ParagraphConstruction,
         Data.Text.ParagraphLayout.Internal.ParagraphLayout,
         Data.Text.ParagraphLayout.Internal.ParagraphLine,
-        Data.Text.ParagraphLayout.Internal.ParagraphPagination,
         Data.Text.ParagraphLayout.Internal.Plain,
         Data.Text.ParagraphLayout.Internal.Rect,
         Data.Text.ParagraphLayout.Internal.ResolvedSpan,

@@ 42,8 42,8 @@ where
 import Data.Text.ParagraphLayout.Internal.Fragment
 import Data.Text.ParagraphLayout.Internal.LineHeight
 import Data.Text.ParagraphLayout.Internal.LinePagination
+import Data.Text.ParagraphLayout.Internal.Paginable
 import Data.Text.ParagraphLayout.Internal.Paragraph
 import Data.Text.ParagraphLayout.Internal.ParagraphLayout
-import Data.Text.ParagraphLayout.Internal.ParagraphPagination
 import Data.Text.ParagraphLayout.Internal.Plain
 import Data.Text.ParagraphLayout.Internal.Span

@@ 1,4 1,8 @@
-module Data.Text.ParagraphLayout.Internal.ParagraphPagination
+module Data.Text.ParagraphLayout.Internal.Paginable
+    (PageOptions(..)
+    ,Paginable
+    ,paginate
+    )
 where
 
 import Data.Int (Int32)


@@ 30,7 34,7 @@ data PageOptions = PageOptions
 
     }
 
--- | Break a paragraph in order to fit the given pagination constraints.
+-- | Typeclass for layouts that can be broken into pages.
 --
 -- The first component of the output determines whether a page break should
 -- be inserted before the paragraph.


@@ 42,14 46,21 @@ data PageOptions = PageOptions
 -- The third component of the output will be `Just` the remainder of the
 -- paragraph that can be passed to this function again, or `Nothing` if there
 -- is nothing left to put on further pages.
-paginate :: PageOptions -> ParagraphLayout ->
-    (PageContinuity, ParagraphLayout, Maybe ParagraphLayout)
-paginate opts pl = case paginateLines o w h1 h2 ls of
-    (c, ls1, []) -> (c, mergeLines ls1, Nothing)
-    (c, ls1, ls2) -> (c, mergeLines ls1, Just (mergeLines ls2))
-    where
-        o = pageOrphans opts
-        w = pageWidows opts
-        h1 = pageCurrentHeight opts
-        h2 = pageNextHeight opts
-        ls = cutLines pl
+class Paginable pl where
+    paginate :: PageOptions -> pl -> (PageContinuity, pl, Maybe pl)
+
+instance Line a => Paginable [a] where
+    paginate opts ls = case paginateLines o w h1 h2 ls of
+        (c, p, []) -> (c, p, Nothing)
+        (c, p, rest) -> (c, p, Just rest)
+        where
+            o = pageOrphans opts
+            w = pageWidows opts
+            h1 = pageCurrentHeight opts
+            h2 = pageNextHeight opts
+
+-- | Break a paragraph in order to fit the given pagination constraints.
+instance Paginable ParagraphLayout where
+    paginate opts pl = case paginate opts (cutLines pl) of
+        (c, p, Nothing) -> (c, mergeLines p, Nothing)
+        (c, p, Just rest) -> (c, mergeLines p, Just (mergeLines rest))