Org reader: support LATEX_HEADER_EXTRA and HTML_HEAD_EXTRA settings

These export settings are treated like their non-extra counterparts,
i.e., the values are added to the `header-includes` metadata list.

3 files changed, 65 insertions, 40 deletions

diff --git a/doc/org.md b/doc/org.md
index d117d09dc..17b994f19 100644
--- a/doc/org.md
+++ b/doc/org.md
@@ -53,9 +53,10 @@ occur.
   the description. In contrast, the Org-mode HTML exporter treats
   the description as plain text.
 
-- LATEX_HEADER: arbitrary lines to add to the document's preamble.
-  Contrary to Org-mode, these lines are not inserted before the
-  hyperref settings, but close to the end of the preamble.
+- LATEX\_HEADER and LATEX_HEADER_EXTRA: arbitrary lines to add to
+  the document's preamble. Contrary to Org-mode, these lines are
+  not inserted before the hyperref settings, but close to the end
+  of the preamble.
 
   The contents of this option are stored as a list of raw LaTeX
   lines in the `header-includes` metadata field.
@@ -77,10 +78,10 @@ occur.
   The content of this option is stored as inlines in the
   `subtitle` metadata field.
 
-- HTML_HEAD: arbitrary lines to add to the HTML document's head;
-  fully supported.
+- HTML\_HEAD and HTML\_HEAD\_EXTRA: arbitrary lines to add to the
+  HTML document's head; fully supported.
 
-  The contents of this option are stored as a list of raw HTML
+  The contents of these options are stored as a list of raw HTML
   lines in the `header-includes` metadata field.
 
 Pandoc-specific options
diff --git a/src/Text/Pandoc/Readers/Org/Meta.hs b/src/Text/Pandoc/Readers/Org/Meta.hs
index c922403df..ae323f189 100644
--- a/src/Text/Pandoc/Readers/Org/Meta.hs
+++ b/src/Text/Pandoc/Readers/Org/Meta.hs
@@ -82,14 +82,18 @@ exportSettingHandlers = Map.fromList
   , ("subtitle"   , lineOfInlines `parseThen` collectLines "subtitle")
   , ("title"      , lineOfInlines `parseThen` collectLines "title")
     -- LaTeX
-  , ("latex_class", fmap pure anyLine `parseThen` setField "documentclass")
+  , ("latex_class"    , fmap pure anyLine `parseThen` setField "documentclass")
   , ("latex_class_options", (pure . T.filter (`notElem` ("[]" :: String)) <$> anyLine)
                             `parseThen` setField "classoption")
-  , ("latex_header", metaExportSnippet "latex" `parseThen`
-                     collectAsList "header-includes")
+  , ("latex_header"   , metaExportSnippet "latex" `parseThen`
+                        collectAsList "header-includes")
+  , ("latex_header_extra", metaExportSnippet "latex" `parseThen`
+                        collectAsList "header-includes")
     -- HTML
-  , ("html_head"  , metaExportSnippet "html" `parseThen`
-                    collectAsList "header-includes")
+  , ("html_head"      , metaExportSnippet "html" `parseThen`
+                        collectAsList "header-includes")
+  , ("html_head_extra", metaExportSnippet "html" `parseThen`
+                        collectAsList "header-includes")
     -- pandoc-specific
   , ("nocite"         , lineOfInlines `parseThen` collectLines "nocite")
   , ("header-includes", lineOfInlines `parseThen` collectLines "header-includes")
diff --git a/test/Tests/Readers/Org/Meta.hs b/test/Tests/Readers/Org/Meta.hs
index 89cd35b26..dd51cbd48 100644
--- a/test/Tests/Readers/Org/Meta.hs
+++ b/test/Tests/Readers/Org/Meta.hs
@@ -108,42 +108,62 @@ tests =
           meta = setMeta "keywords" (MetaInlines keywords) nullMeta
       in Pandoc meta mempty
 
-    , "LaTeX_headers options are translated to header-includes" =:
-      "#+LaTeX_header: \\usepackage{tikz}" =?>
-      let latexInlines = rawInline "latex" "\\usepackage{tikz}"
-          inclList = MetaList [MetaInlines (toList latexInlines)]
-          meta = setMeta "header-includes" inclList nullMeta
-      in Pandoc meta mempty
+    , "Institute" =:
+      "#+INSTITUTE: ACME Inc." =?>
+      Pandoc (setMeta "institute" ("ACME Inc." :: Inlines) nullMeta) mempty
 
-    , testGroup "LaTeX_CLASS"
-      [ "LaTeX_class option is translated to documentclass" =:
-        "#+LATEX_CLASS: article" =?>
-        let meta = setMeta "documentclass" (MetaString "article") nullMeta
+    , testGroup "LaTeX"
+      [ "LaTeX_headers options are translated to header-includes" =:
+        "#+LaTeX_header: \\usepackage{tikz}" =?>
+        let latexInlines = rawInline "latex" "\\usepackage{tikz}"
+            inclList = MetaList [MetaInlines (toList latexInlines)]
+            meta = setMeta "header-includes" inclList nullMeta
         in Pandoc meta mempty
 
-      , "last definition takes precedence" =:
-        T.unlines [ "#+LATEX_CLASS: this will not be used"
-                  , "#+LATEX_CLASS: report"
-                  ] =?>
-        let meta = setMeta "documentclass" (MetaString "report") nullMeta
+      , "LATEX_HEADER_EXTRA values are translated to header-includes" =:
+        "#+LATEX_HEADER_EXTRA: \\usepackage{calc}" =?>
+        let latexInlines = rawInline "latex" "\\usepackage{calc}"
+            inclList = toMetaValue [latexInlines]
+        in Pandoc (setMeta "header-includes" inclList nullMeta) mempty
+
+      , testGroup "LaTeX_CLASS"
+        [ "LaTeX_class option is translated to documentclass" =:
+          "#+LATEX_CLASS: article" =?>
+          let meta = setMeta "documentclass" (MetaString "article") nullMeta
+          in Pandoc meta mempty
+
+        , "last definition takes precedence" =:
+          T.unlines [ "#+LATEX_CLASS: this will not be used"
+                    , "#+LATEX_CLASS: report"
+                    ] =?>
+          let meta = setMeta "documentclass" (MetaString "report") nullMeta
+          in Pandoc meta mempty
+        ]
+
+      , "LaTeX_class_options is translated to classoption" =:
+        "#+LATEX_CLASS_OPTIONS: [a4paper]" =?>
+        let meta = setMeta "classoption" (MetaString "a4paper") nullMeta
         in Pandoc meta mempty
       ]
 
-    , "LaTeX_class_options is translated to classoption" =:
-      "#+LATEX_CLASS_OPTIONS: [a4paper]" =?>
-      let meta = setMeta "classoption" (MetaString "a4paper") nullMeta
-      in Pandoc meta mempty
-
-    , "LaTeX_class_options is translated to classoption" =:
-      "#+html_head: <meta/>" =?>
-      let html = rawInline "html" "<meta/>"
-          inclList = MetaList [MetaInlines (toList html)]
-          meta = setMeta "header-includes" inclList nullMeta
-      in Pandoc meta mempty
+    , testGroup "HTML"
+      [ "HTML_HEAD values are added to header-includes" =:
+        "#+html_head: <meta/>" =?>
+        let html = rawInline "html" "<meta/>"
+            inclList = MetaList [MetaInlines (toList html)]
+            meta = setMeta "header-includes" inclList nullMeta
+        in Pandoc meta mempty
 
-    , "Institute" =:
-      "#+INSTITUTE: ACME Inc." =?>
-      Pandoc (setMeta "institute" ("ACME Inc." :: Inlines) nullMeta) mempty
+      , "HTML_HEAD_EXTRA behaves like HTML_HEAD" =:
+        T.unlines [ "#+HTML_HEAD: <meta name=\"generator\" content=\"pandoc\">"
+                  , "#+HTML_HEAD_EXTRA: <meta charset=\"utf-8\">"
+                  ] =?>
+        let generator = rawInline "html"
+                                  "<meta name=\"generator\" content=\"pandoc\">"
+            charset = rawInline "html" "<meta charset=\"utf-8\">"
+            inclList = toMetaValue [generator, charset]
+        in Pandoc (setMeta "header-includes" inclList nullMeta) mempty
+      ]
     ]
 
   , "Properties drawer" =: