From 3ae359721d174205582cd5bd3b13525493e10619 Mon Sep 17 00:00:00 2001
From: Alexander Krotov <ilabdsf@gmail.com>
Date: Wed, 6 Dec 2017 19:04:35 +0300
Subject: Muse reader: don't allow emphasis to be preceded by letter

---
 src/Text/Pandoc/Readers/Muse.hs | 14 ++++++++++++--
 test/Tests/Readers/Muse.hs      |  4 ++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/Text/Pandoc/Readers/Muse.hs b/src/Text/Pandoc/Readers/Muse.hs
index 39aa67f82..72344bfe0 100644
--- a/src/Text/Pandoc/Readers/Muse.hs
+++ b/src/Text/Pandoc/Readers/Muse.hs
@@ -136,6 +136,13 @@ commonPrefix (x:xs) (y:ys)
   | x == y    = x : commonPrefix xs ys
   | otherwise = []
 
+atStart :: PandocMonad m => MuseParser m a -> MuseParser m a
+atStart p = do
+  pos <- getPosition
+  st <- getState
+  guard $ stateLastStrPos st /= Just pos
+  p
+
 --
 -- directive parsers
 --
@@ -668,7 +675,7 @@ enclosedInlines :: (PandocMonad m, Show a, Show b)
                 -> MuseParser m b
                 -> MuseParser m (F Inlines)
 enclosedInlines start end = try $
-  trimInlinesF . mconcat <$> (enclosed start end inline <* notFollowedBy (satisfy isLetter))
+  trimInlinesF . mconcat <$> (enclosed (atStart start) end inline <* notFollowedBy (satisfy isLetter))
 
 inlineTag :: PandocMonad m
           => (Inlines -> Inlines)
@@ -745,7 +752,10 @@ inlineLiteralTag = do
     rawInline (attrs, content) = B.rawInline (format attrs) content
 
 str :: PandocMonad m => MuseParser m (F Inlines)
-str = return . B.str <$> many1 alphaNum
+str = do
+  result <- many1 alphaNum
+  updateLastStrPos
+  return $ return $ B.str result
 
 symbol :: PandocMonad m => MuseParser m (F Inlines)
 symbol = return . B.str <$> count 1 nonspaceChar
diff --git a/test/Tests/Readers/Muse.hs b/test/Tests/Readers/Muse.hs
index 3a3d7d864..51e249fb4 100644
--- a/test/Tests/Readers/Muse.hs
+++ b/test/Tests/Readers/Muse.hs
@@ -70,6 +70,10 @@ tests =
         "Foo *bar*x baz" =?>
         para "Foo *bar*x baz"
 
+      , "Letter before opening *" =:
+        "Foo x*bar* baz" =?>
+        para "Foo x*bar* baz"
+
       , "Emphasis tag" =:
         "<em>Foo bar</em>" =?>
         para (emph . spcSep $ ["Foo", "bar"])
-- 
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