DocBook reader: handle "book" for xref references

This also adds a test xref to book and part. See also 4ea0508e6 / #8712.

src/Text/Pandoc/Readers/DocBook.hs

@@ -1354,6 +1354,7 @@ parseInline (Elem e) =
          xrefTitleByElem el
              | not (T.null xrefLabel) = xrefLabel
              | otherwise              = case qName (elName el) of
+                  "book"         -> descendantContent "title" el
                   "part"         -> descendantContent "title" el
                   "chapter"      -> descendantContent "title" el
                   "section"      -> descendantContent "title" el

test/docbook-xref.docbook

@@ -1,6 +1,6 @@
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
           "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
-<book><title>An Example Book</title>
+<book id='book01'><title>An Example Book</title>
 <chapter id="ch01"><title>XRef Samples</title>
 <para>
 This paragraph demonstrates several features of
@@ -30,6 +30,12 @@ cross-reference text: <xref linkend="ch02"/>.
 <listitem><para>A link to a
 <sgmltag>table</sgmltag> element: <xref linkend="table01"/>.
 </para></listitem>
+<listitem><para>A link to a
+<sgmltag>part</sgmltag> element: <xref linkend="part01"/>.
+</para></listitem>
+<listitem><para>A link to a
+<sgmltag>book</sgmltag> element: <xref linkend="book01"/>.
+</para></listitem>
 </itemizedlist>
 </chapter>
 
@@ -38,6 +44,9 @@ cross-reference text: <xref linkend="ch02"/>.
   <para>Some content here</para>
 </chapter>
 
+<part id="part01">
+  <title>Later Part</title>
+
 <chapter id="ch03" xreflabel="Chapter the Third">
   <title>The Third Chapter</title>
   <para>Some content here</para>
@@ -101,4 +110,5 @@ cross-reference text: <xref linkend="ch02"/>.
 </table>
 
 </chapter>
+</part>
 </book>

test/docbook-xref.native

@@ -14,7 +14,7 @@ Pandoc
           ]
     }
   [ Header
-      1
+      2
       ( "ch01" , [] , [] )
       [ Str "XRef" , Space , Str "Samples" ]
   , Para
@@ -195,21 +195,70 @@ Pandoc
             , Str "."
             ]
         ]
+      , [ Para
+            [ Str "A"
+            , Space
+            , Str "link"
+            , Space
+            , Str "to"
+            , Space
+            , Str "a"
+            , SoftBreak
+            , Str "part"
+            , Space
+            , Str "element:"
+            , Space
+            , Link
+                ( "" , [] , [] )
+                [ Str "Later" , Space , Str "Part" ]
+                ( "#part01" , "" )
+            , Str "."
+            ]
+        ]
+      , [ Para
+            [ Str "A"
+            , Space
+            , Str "link"
+            , Space
+            , Str "to"
+            , Space
+            , Str "a"
+            , SoftBreak
+            , Str "book"
+            , Space
+            , Str "element:"
+            , Space
+            , Link
+                ( "" , [] , [] )
+                [ Str "An"
+                , Space
+                , Str "Example"
+                , Space
+                , Str "Book"
+                ]
+                ( "#book01" , "" )
+            , Str "."
+            ]
+        ]
       ]
   , Header
-      1
+      2
       ( "ch02" , [] , [] )
       [ Str "The" , Space , Str "Second" , Space , Str "Chapter" ]
   , Para
       [ Str "Some" , Space , Str "content" , Space , Str "here" ]
   , Header
       1
+      ( "part01" , [] , [] )
+      [ Str "Later" , Space , Str "Part" ]
+  , Header
+      2
       ( "ch03" , [] , [] )
       [ Str "The" , Space , Str "Third" , Space , Str "Chapter" ]
   , Para
       [ Str "Some" , Space , Str "content" , Space , Str "here" ]
   , Header
-      1
+      2
       ( "ch04" , [] , [ ( "titleabbrev" , "Chapter 4" ) ] )
       [ Str "The" , Space , Str "Fourth" , Space , Str "Chapter" ]
   , Para