From cf8224045bf927420ce4cb67f6fe703a95645fe6 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Sun, 14 Oct 2018 13:02:36 -0700
Subject: Markdown reader: Fix awkward soft break movements before
 abbreviations.

Closes #4635.
---
 src/Text/Pandoc/Readers/Markdown.hs | 15 ++++++++++-----
 test/command/4635.md                | 31 +++++++++++++++++++++++++++++++
 test/markdown-citations.native      |  2 +-
 3 files changed, 42 insertions(+), 6 deletions(-)
 create mode 100644 test/command/4635.md

diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index 81c7cbaf9..5944ecf82 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -1717,19 +1717,24 @@ nonEndline = satisfy (/='\n')
 
 str :: PandocMonad m => MarkdownParser m (F Inlines)
 str = do
+  canRelocateSpace <- notAfterString
   result <- many1 (alphaNum <|> try (char '.' <* notFollowedBy (char '.')))
   updateLastStrPos
   (do guardEnabled Ext_smart
       abbrevs <- getOption readerAbbreviations
       if not (null result) && last result == '.' && result `Set.member` abbrevs
          then try (do ils <- whitespace <|> endline
-                      lookAhead alphaNum
+                      -- ?? lookAhead alphaNum
+                      -- replace space after with nonbreaking space
+                      -- if softbreak, move before abbrev if possible (#4635)
                       return $ do
                         ils' <- ils
-                        if ils' == B.space
-                           then return (B.str result <> B.str "\160")
-                           else -- linebreak or softbreak
-                                return (ils' <> B.str result <> B.str "\160"))
+                        case B.toList ils' of
+                             [Space] ->
+                                 return (B.str result <> B.str "\160")
+                             [SoftBreak] | canRelocateSpace ->
+                                 return (ils' <> B.str result <> B.str "\160")
+                             _ -> return (B.str result <> ils'))
                 <|> return (return (B.str result))
          else return (return (B.str result)))
      <|> return (return (B.str result))
diff --git a/test/command/4635.md b/test/command/4635.md
new file mode 100644
index 000000000..320b83956
--- /dev/null
+++ b/test/command/4635.md
@@ -0,0 +1,31 @@
+```
+% pandoc -f markdown -t native
+(cf.
+foo)
+^D
+[Para [Str "(cf.",SoftBreak,Str "foo)"]]
+```
+
+```
+% pandoc -f markdown -t native
+a (cf.
+foo)
+^D
+[Para [Str "a",Space,Str "(cf.",SoftBreak,Str "foo)"]]
+```
+
+```
+% pandoc -f markdown -t native
+cf.
+foo
+^D
+[Para [Str "cf.\160foo"]]
+```
+
+```
+% pandoc -f markdown -t native
+a cf.
+foo
+^D
+[Para [Str "a",SoftBreak,Str "cf.\160foo"]]
+```
diff --git a/test/markdown-citations.native b/test/markdown-citations.native
index c77ccbbfc..3d37dbae4 100644
--- a/test/markdown-citations.native
+++ b/test/markdown-citations.native
@@ -13,5 +13,5 @@
  ,[Para [Str "Citation",Space,Str "with",Space,Str "a",Space,Str "suffix",Space,Str "and",Space,Str "locator",Space,Cite [Citation {citationId = "item1", citationPrefix = [], citationSuffix = [Space,Str "pp.\160\&33,",Space,Str "35-37,",Space,Str "and",Space,Str "nowhere",Space,Str "else"], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0}] [Str "[@item1",Space,Str "pp.",Space,Str "33,",Space,Str "35-37,",Space,Str "and",Space,Str "nowhere",Space,Str "else]"],Str "."]]
  ,[Para [Str "Citation",Space,Str "with",Space,Str "suffix",Space,Str "only",Space,Cite [Citation {citationId = "item1", citationPrefix = [], citationSuffix = [Space,Str "and",Space,Str "nowhere",Space,Str "else"], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0}] [Str "[@item1",Space,Str "and",Space,Str "nowhere",Space,Str "else]"],Str "."]]
  ,[Para [Str "Now",Space,Str "some",Space,Str "modifiers.",Note [Para [Str "Like",Space,Str "a",Space,Str "citation",Space,Str "without",Space,Str "author:",Space,Cite [Citation {citationId = "item1", citationPrefix = [], citationSuffix = [], citationMode = SuppressAuthor, citationNoteNum = 0, citationHash = 0}] [Str "[-@item1]"],Str ",",Space,Str "and",Space,Str "now",Space,Str "Doe",Space,Str "with",Space,Str "a",Space,Str "locator",Space,Cite [Citation {citationId = "item2", citationPrefix = [], citationSuffix = [Space,Str "p.\160\&44"], citationMode = SuppressAuthor, citationNoteNum = 0, citationHash = 0}] [Str "[-@item2",Space,Str "p.",Space,Str "44]"],Str "."]]]]
- ,[Para [Str "With",Space,Str "some",Space,Str "markup",Space,Cite [Citation {citationId = "item1", citationPrefix = [Emph [Str "see"]], citationSuffix = [Space,Str "p.",Space,Strong [Str "32"]], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0}] [Str "[*see*",Space,Str "@item1",Space,Str "p.",Space,Str "**32**]"],Str "."]]]
+ ,[Para [Str "With",Space,Str "some",Space,Str "markup",Space,Cite [Citation {citationId = "item1", citationPrefix = [Emph [Str "see"]], citationSuffix = [Space,Str "p.\160",Strong [Str "32"]], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0}] [Str "[*see*",Space,Str "@item1",Space,Str "p.",Space,Str "**32**]"],Str "."]]]
 ,Header 1 ("references",[],[]) [Str "References"]]
-- 
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