Shared: new export `splitSentences` [API change].

This was duplicated in the Man and Ms writers, and really
belongs in Shared.

1 files changed, 26 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Shared.hs b/src/Text/Pandoc/Shared.hs
index 412de99a0..9f48080b8 100644
--- a/src/Text/Pandoc/Shared.hs
+++ b/src/Text/Pandoc/Shared.hs
@@ -79,6 +79,7 @@ module Text.Pandoc.Shared (
                      makeMeta,
                      eastAsianLineBreakFilter,
                      underlineSpan,
+                     splitSentences,
                      -- * TagSoup HTML handling
                      renderTags',
                      -- * File handling
@@ -582,6 +583,31 @@ eastAsianLineBreakFilter = bottomUp go
 underlineSpan :: Inlines -> Inlines
 underlineSpan = B.spanWith ("", ["underline"], [])
 
+-- | Returns the first sentence in a list of inlines, and the rest.
+breakSentence :: [Inline] -> ([Inline], [Inline])
+breakSentence [] = ([],[])
+breakSentence xs =
+  let isSentenceEndInline (Str ys@(_:_)) | last ys == '.' = True
+      isSentenceEndInline (Str ys@(_:_)) | last ys == '?' = True
+      isSentenceEndInline LineBreak      = True
+      isSentenceEndInline _              = False
+      (as, bs) = break isSentenceEndInline xs
+  in  case bs of
+           []             -> (as, [])
+           [c]            -> (as ++ [c], [])
+           (c:Space:cs)   -> (as ++ [c], cs)
+           (c:SoftBreak:cs) -> (as ++ [c], cs)
+           (Str ".":Str (')':ys):cs) -> (as ++ [Str ".", Str (')':ys)], cs)
+           (x@(Str ('.':')':_)):cs) -> (as ++ [x], cs)
+           (LineBreak:x@(Str ('.':_)):cs) -> (as ++[LineBreak], x:cs)
+           (c:cs)         -> (as ++ [c] ++ ds, es)
+              where (ds, es) = breakSentence cs
+
+-- | Split a list of inlines into sentences.
+splitSentences :: [Inline] -> [[Inline]]
+splitSentences xs =
+  let (sent, rest) = breakSentence xs
+  in  if null rest then [sent] else sent : splitSentences rest
 
 --
 -- TagSoup HTML handling