From c80e26f888bcc5bd59192e40f5332da73767762f Mon Sep 17 00:00:00 2001
From: bucklereed <horridimpfoobarbaz@chammy.info>
Date: Thu, 24 Aug 2017 17:45:58 +0100
Subject: LaTeX reader: RN and Rn, from biblatex (#3854)

---
 src/Text/Pandoc/Readers/LaTeX.hs | 30 +++++++++++++++++++++++++++++-
 test/Tests/Readers/LaTeX.hs      | 23 +++++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/src/Text/Pandoc/Readers/LaTeX.hs b/src/Text/Pandoc/Readers/LaTeX.hs
index 3292550b2..ac471bdb1 100644
--- a/src/Text/Pandoc/Readers/LaTeX.hs
+++ b/src/Text/Pandoc/Readers/LaTeX.hs
@@ -44,7 +44,7 @@ import Control.Applicative (many, optional, (<|>))
 import Control.Monad
 import Control.Monad.Except (throwError)
 import Control.Monad.Trans (lift)
-import Data.Char (chr, isAlphaNum, isLetter, ord, isDigit)
+import Data.Char (chr, isAlphaNum, isLetter, ord, isDigit, toLower)
 import Data.Default
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -1445,8 +1445,36 @@ inlineCommands = M.fromList $
   , ("toggletrue", braced >>= setToggle True)
   , ("togglefalse", braced >>= setToggle False)
   , ("iftoggle", try $ ifToggle >> inline)
+  -- biblatex misc
+  , ("RN", romanNumeralUpper)
+  , ("Rn", romanNumeralLower)
   ]
 
+romanNumeralUpper :: (PandocMonad m) => LP m Inlines
+romanNumeralUpper =
+  str . toRomanNumeral <$> romanNumeralArg
+
+romanNumeralLower :: (PandocMonad m) => LP m Inlines
+romanNumeralLower =
+  str . map toLower . toRomanNumeral <$> romanNumeralArg
+
+romanNumeralArg :: (PandocMonad m) => LP m Int
+romanNumeralArg = spaces *> (parser <|> inBraces)
+  where
+    inBraces = do
+      symbol '{'
+      spaces
+      res <- parser
+      spaces
+      symbol '}'
+      return res
+    parser = do
+      Tok _ Word s <- satisfyTok isWordTok
+      let (digits, rest) = T.span isDigit s
+      unless (T.null rest) $
+        fail "Non-digits in argument to \\Rn or \\RN"
+      safeRead $ T.unpack digits
+
 newToggle :: (Monoid a, PandocMonad m) => [Tok] -> LP m a
 newToggle name = do
   updateState $ \st ->
diff --git a/test/Tests/Readers/LaTeX.hs b/test/Tests/Readers/LaTeX.hs
index b07eb875a..4effe26e8 100644
--- a/test/Tests/Readers/LaTeX.hs
+++ b/test/Tests/Readers/LaTeX.hs
@@ -143,6 +143,29 @@ tests = [ testGroup "basic"
             "hello\\pfbreak*{}goodbye" =?>
             para (str "hello") <> horizontalRule <> para (str "goodbye")
           ]
+        , testGroup "biblatex roman numerals"
+          [ "upper" =:
+            "number \\RN{12}" =?>
+            para (str "number" <> space <> str "XII")
+          , "lower" =:
+            "number \\Rn{29}" =?>
+            para (str "number" <> space <> str "xxix")
+          , "leading zero" =:
+            "\\Rn{014}" =?>
+            para (str "xiv")
+          , "surrounding spaces" =:
+            "number \\Rn{ 41 }" =?>
+            para (str "number" <> space <> str "xli")
+          , "zero" =:
+            "\\RN{0}" =?>
+            para (str "")
+          , "space then unbraced argument" =:
+            "\\RN 7 ok" =?>
+            para (str "VII" <> space <> str "ok")
+          , "space before braced argument" =:
+            "\\Rn {13}ok" =?>
+            para (str "xiiiok")
+          ]
         ]
 
 baseCitation :: Citation
-- 
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