2 files changed, 70 insertions, 0 deletions

diff --git a/doc/build-aux/pandoc-filters/docbook-writer/labelless-link-is-xref.lua b/doc/build-aux/pandoc-filters/docbook-writer/labelless-link-is-xref.lua
new file mode 100644
index 00000000000..fa97729a28b
--- /dev/null
+++ b/doc/build-aux/pandoc-filters/docbook-writer/labelless-link-is-xref.lua
@@ -0,0 +1,34 @@
+--[[
+Converts Link AST nodes with empty label to DocBook xref elements.
+
+This is a temporary script to be able use cross-references conveniently
+using syntax taken from MyST, while we still use docbook-xsl
+for generating the documentation.
+
+Reference: https://myst-parser.readthedocs.io/en/latest/using/syntax.html#targets-and-cross-referencing
+]]
+
+local function starts_with(start, str)
+  return str:sub(1, #start) == start
+end
+
+local function escape_xml_arg(arg)
+  amps = arg:gsub('&', '&')
+  amps_quotes = amps:gsub('"', '"')
+  amps_quotes_lt = amps_quotes:gsub('<', '&lt;')
+
+  return amps_quotes_lt
+end
+
+function Link(elem)
+  has_no_content = #elem.content == 0
+  targets_anchor = starts_with('#', elem.target)
+  has_no_attributes = elem.title == '' and elem.identifier == '' and #elem.classes == 0 and #elem.attributes == 0
+
+  if has_no_content and targets_anchor and has_no_attributes then
+    -- xref expects idref without the pound-sign
+    target_without_hash = elem.target:sub(2, #elem.target)
+
+    return pandoc.RawInline('docbook', '<xref linkend="' .. escape_xml_arg(target_without_hash) .. '" />')
+  end
+end
diff --git a/doc/build-aux/pandoc-filters/docbook-writer/rst-roles.lua b/doc/build-aux/pandoc-filters/docbook-writer/rst-roles.lua
new file mode 100644
index 00000000000..92dc6895750
--- /dev/null
+++ b/doc/build-aux/pandoc-filters/docbook-writer/rst-roles.lua
@@ -0,0 +1,36 @@
+--[[
+Converts AST for reStructuredText roles into corresponding
+DocBook elements.
+
+Currently, only a subset of roles is supported.
+
+Reference:
+  List of roles:
+    https://www.sphinx-doc.org/en/master/usage/restructuredtext/roles.html
+  manpage:
+    https://tdg.docbook.org/tdg/5.1/citerefentry.html
+  file:
+    https://tdg.docbook.org/tdg/5.1/filename.html
+]]
+
+function Code(elem)
+  if elem.classes:includes('interpreted-text') then
+    local tag = nil
+    local content = elem.text
+    if elem.attributes['role'] == 'manpage' then
+      tag = 'citerefentry'
+      local title, volnum = content:match('^(.+)%((%w+)%)$')
+      if title == nil then
+        -- No volnum in parentheses.
+        title = content
+      end
+      content = '<refentrytitle>' .. title .. '</refentrytitle>' .. (volnum ~= nil and ('<manvolnum>' .. volnum .. '</manvolnum>') or '')
+    elseif elem.attributes['role'] == 'file' then
+      tag = 'filename'
+    end
+
+    if tag ~= nil then
+      return pandoc.RawInline('docbook', '<' .. tag .. '>' .. content .. '</' .. tag .. '>')
+    end
+  end
+end