Add quotes properly in markdown YAML metadata fields.

This fixes a bug, which caused the writer to look at the LAST
rather than the FIRST character in determining whether quotes
were needed.  So we got spurious quotes in some cases and
didn't get necessary quotes in others.

Closes #7245.  Updated a number of test cases accordingly.

9 files changed, 16 insertions, 17 deletions

diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index daf45ed53..3295d9e6c 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -26,7 +26,7 @@ import Data.Default
 import Data.List (intersperse, sortOn, transpose)
 import Data.List.NonEmpty (nonEmpty, NonEmpty(..))
 import qualified Data.Map as M
-import Data.Maybe (fromMaybe, mapMaybe)
+import Data.Maybe (fromMaybe, mapMaybe, isNothing)
 import qualified Data.Set as Set
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -142,18 +142,17 @@ valToYaml (SimpleVal x)
   | otherwise =
       if hasNewlines x
          then hang 0 ("|" <> cr) x
-         else if fst $ foldr needsDoubleQuotes (False, True) x
+         else if isNothing $ foldM needsDoubleQuotes True x
            then "\"" <> fmap escapeInDoubleQuotes x <> "\""
            else x
     where
-      needsDoubleQuotes t (positive, isFirst)
+      needsDoubleQuotes isFirst t
         = if T.any isBadAnywhere t ||
              (isFirst && T.any isYamlPunct (T.take 1 t))
-              then (True, False)
-              else (positive, False)
+              then Nothing
+              else Just False
       isBadAnywhere '#' = True
       isBadAnywhere ':' = True
-      isBadAnywhere '`' = False
       isBadAnywhere _   = False
       hasNewlines NewLine = True
       hasNewlines BlankLines{} = True
diff --git a/test/command/1279.md b/test/command/1279.md
index acad6859e..d3572f245 100644
--- a/test/command/1279.md
+++ b/test/command/1279.md
@@ -9,7 +9,7 @@ title: My Article
 [^1]: Dept. of This and That
 ^D
 ---
-author: "John Doe[^1]"
+author: John Doe[^1]
 date: 2014
 title: My Article
 ---
diff --git a/test/command/biblatex-inproceedings.md b/test/command/biblatex-inproceedings.md
index 29a1e0298..76b584800 100644
--- a/test/command/biblatex-inproceedings.md
+++ b/test/command/biblatex-inproceedings.md
@@ -63,7 +63,7 @@ references:
   publisher-place: Cambridge
   title: "Le *De Anima* dans la tradition grècque: Quelques aspects de
     l'interpretation du traité, de Theophraste à Themistius"
-  title-short: *De Anima* dans la tradition grècque
+  title-short: "*De Anima* dans la tradition grècque"
   type: paper-conference
 - author:
   - family: Salam
diff --git a/test/command/biblatex-jaffe.md b/test/command/biblatex-jaffe.md
index f172c6ae7..e0381772b 100644
--- a/test/command/biblatex-jaffe.md
+++ b/test/command/biblatex-jaffe.md
@@ -72,8 +72,8 @@ references:
   language: la
   number-of-volumes: 2
   publisher-place: Leipzig
-  title: "Regesta Pontificum Romanorum ab condita ecclesia ad annum post
-    Christum natum [mcxcviii]{.smallcaps}"
+  title: Regesta Pontificum Romanorum ab condita ecclesia ad annum post
+    Christum natum [mcxcviii]{.smallcaps}
   title-short: Regesta Pontificum Romanorum
   type: book
 ---
diff --git a/test/command/biblatex-moraux.md b/test/command/biblatex-moraux.md
index 8a1b084f8..1624ad960 100644
--- a/test/command/biblatex-moraux.md
+++ b/test/command/biblatex-moraux.md
@@ -86,7 +86,7 @@ references:
   publisher-place: Cambridge
   title: "Le *De Anima* dans la tradition grècque: Quelques aspects de
     l'interpretation du traité, de Theophraste à Themistius"
-  title-short: *De Anima* dans la tradition grècque
+  title-short: "*De Anima* dans la tradition grècque"
   type: paper-conference
 ---
 
diff --git a/test/command/biblatex-quotes.md b/test/command/biblatex-quotes.md
index 9d868cb76..50055316f 100644
--- a/test/command/biblatex-quotes.md
+++ b/test/command/biblatex-quotes.md
@@ -36,7 +36,7 @@ references:
   language: en-US
   publisher: Princeton University Press
   publisher-place: Princeton
-  title: "Aristotle's \"De Motu Animalium\""
+  title: Aristotle's "De Motu Animalium"
   type: book
 ---
 
diff --git a/test/command/biblatex-spiegelberg.md b/test/command/biblatex-spiegelberg.md
index 59d651958..59338ae88 100644
--- a/test/command/biblatex-spiegelberg.md
+++ b/test/command/biblatex-spiegelberg.md
@@ -63,8 +63,8 @@ references:
   issued: 1969
   language: de-DE
   page: 189-216
-  title: "Intention" und "Intentionalität" in der Scholastik, bei
-    Brentano und Husserl
+  title: "\"Intention\" und \"Intentionalität\" in der Scholastik, bei
+    Brentano und Husserl"
   title-short: Intention und Intentionalität
   type: article-journal
   volume: 29
diff --git a/test/command/biblatex-test-case-conversion.md b/test/command/biblatex-test-case-conversion.md
index aa30767ec..e69cb9336 100644
--- a/test/command/biblatex-test-case-conversion.md
+++ b/test/command/biblatex-test-case-conversion.md
@@ -63,9 +63,9 @@ references:
   id: item1
   issued: 2013
   language: en-US
-  title: "A title, in English, with a Proper Name and an ACRONYM and a
+  title: A title, in English, with a Proper Name and an ACRONYM and a
     [camelCase]{.nocase} word and some units, 400 [nm]{.nocase},
-    3 [cm]{.nocase}, and a quote, *Alea [iacta est]{.nocase}*"
+    3 [cm]{.nocase}, and a quote, *Alea [iacta est]{.nocase}*
   type: article-journal
 ---
 
diff --git a/test/command/biblatex-textnormal.md b/test/command/biblatex-textnormal.md
index 0aa5550c3..a4e6107ec 100644
--- a/test/command/biblatex-textnormal.md
+++ b/test/command/biblatex-textnormal.md
@@ -9,7 +9,7 @@
 nocite: "[@*]"
 references:
 - id: item1
-  title: "The title [of this book]{.nodecor}"
+  title: The title [of this book]{.nodecor}
   type: book
 ---