Lua: split strings into words when treating them as Inline list (#7712)

Using a Lua string where a list of inlines is expected will cause the
string to be split into words, replacing spaces and tabs into
`pandoc.Space()` elements and newlines into `pandoc.SoftBreak()`.

The previous behavior was to treat the string `s` as `{pandoc.Str(s)}`.
The old behavior can be recovered by wrapping the string into a table
`{s}`.

src/Text/Pandoc/Lua/Marshaling/AST.hs

@@ -67,6 +67,7 @@ import Text.Pandoc.Lua.Marshaling.ListAttributes
   (peekListAttributes, pushListAttributes)
 
 import qualified HsLua as Lua
+import qualified Text.Pandoc.Builder as B
 import qualified Text.Pandoc.Lua.Util as LuaUtil
 
 instance Pushable Pandoc where
@@ -796,10 +797,12 @@ peekInlineFuzzy = retrieving "Inline" . choice
 -- | Try extra-hard to return the value at the given index as a list of
 -- inlines.
 peekInlinesFuzzy :: LuaError e => Peeker e [Inline]
-peekInlinesFuzzy = choice
-  [ peekList peekInlineFuzzy
-  , fmap pure . peekInlineFuzzy
-  ]
+peekInlinesFuzzy idx = liftLua (ltype idx) >>= \case
+  TypeString -> B.toList . B.text <$> peekText idx
+  _ -> choice
+       [ peekList peekInlineFuzzy
+       , fmap pure . peekInlineFuzzy
+       ] idx
 
 -- | Try extra hard to retrieve a Block value from the stack. Treats bar
 -- Inline elements as if they were wrapped in 'Plain'.

test/lua/module/pandoc.lua

@@ -480,7 +480,10 @@ return {
         assert.are_same(deflist.content[1][2][2],
                          {pandoc.Plain{pandoc.Str 'company'}})
         assert.are_same(deflist.content[2][2],
-                         {{pandoc.Plain{pandoc.Str 'Best when hot.'}}})
+                        {{pandoc.Plain{
+                            pandoc.Str 'Best', pandoc.Space(),
+                            pandoc.Str 'when', pandoc.Space(),
+                            pandoc.Str 'hot.'}}})
       end),
       test('modify items via property `content`', function ()
         local deflist = pandoc.DefinitionList{
@@ -532,7 +535,7 @@ return {
         assert.are_same(header.content, {pandoc.Str 'test'})
 
         header.content = {'new text'}
-        assert.are_equal(header, pandoc.Header(1, 'new text'))
+        assert.are_equal(header, pandoc.Header(1, {'new text'}))
       end),
       test('access Attr via property `attr`', function ()
         local header = pandoc.Header(1, 'test', {'my-test'})
@@ -968,5 +971,26 @@ return {
       )
       assert.are_equal('1234', table.concat(acc))
     end)
+  },
+
+  group 'Marshal' {
+    group 'Inlines' {
+      test('Strings are broken into words', function ()
+        assert.are_equal(
+          pandoc.Emph 'Nice, init?',
+          pandoc.Emph{pandoc.Str 'Nice,', pandoc.Space(), pandoc.Str 'init?'}
+        )
+      end)
+    },
+    group 'Blocks' {
+      test('Strings are broken into words and wrapped in Plain', function ()
+        assert.are_equal(
+          pandoc.Div{
+            pandoc.Plain{pandoc.Str 'Nice,', pandoc.Space(), pandoc.Str 'init?'}
+          },
+          pandoc.Div{'Nice, init?'}
+        )
+      end)
+    }
   }
 }