From 4617f229ea051fea50bce6307fe8221b246a23fe Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Mon, 22 Feb 2021 13:28:47 -0800
Subject: Text.Pandoc.MIME: add exported function getCharset.

[API change]
---
 src/Text/Pandoc/MIME.hs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/Text/Pandoc/MIME.hs b/src/Text/Pandoc/MIME.hs
index 53c5cd018..3d06e1579 100644
--- a/src/Text/Pandoc/MIME.hs
+++ b/src/Text/Pandoc/MIME.hs
@@ -10,8 +10,13 @@
 
 Mime type lookup.
 -}
-module Text.Pandoc.MIME ( MimeType, getMimeType, getMimeTypeDef,
-                          extensionFromMimeType, mediaCategory ) where
+module Text.Pandoc.MIME (
+  MimeType,
+  getMimeType,
+  getMimeTypeDef,
+  getCharset,
+  extensionFromMimeType,
+  mediaCategory ) where
 import Data.List (isPrefixOf, isSuffixOf)
 import qualified Data.Map as M
 import qualified Data.Text as T
@@ -54,6 +59,14 @@ reverseMimeTypes = M.fromList $ map swap mimeTypesList
 mimeTypes :: M.Map T.Text MimeType
 mimeTypes = M.fromList mimeTypesList
 
+-- | Get the charset from a mime type, if one is present.
+getCharset :: MimeType -> Maybe T.Text
+getCharset mt =
+  let (_,y) = T.breakOn "charset=" mt
+   in if T.null y
+         then Nothing
+         else Just $ T.toUpper $ T.takeWhile (/= ';') $ T.drop 8 y
+
 -- | Collection of common mime types.
 -- Except for first entry, list borrowed from
 -- <https://github.com/Happstack/happstack-server/blob/master/src/Happstack/Server/FileServe/BuildingBlocks.hs happstack-server>
-- 
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