1 files changed, 82 insertions, 0 deletions
diff --git a/paper/lua-filters/bibexport/bibexport.lua b/paper/lua-filters/bibexport/bibexport.lua
new file mode 100644
index 0000000..9174e69
--- /dev/null
+++ b/paper/lua-filters/bibexport/bibexport.lua
@@ -0,0 +1,82 @@
+local utils = require 'pandoc.utils'
+local List = require 'pandoc.List'
+
+local citation_id_set = {}
+
+-- Collect all citation IDs.
+function Cite (c)
+  local cs = c.citations
+  for i = 1, #cs do
+    citation_id_set[cs[i].id or cs[i].citationId] = true
+  end
+end
+
+--- Return a list of citation IDs
+function citation_ids ()
+  local citations = {};
+  for cid, _ in pairs(citation_id_set) do
+    citations[#citations + 1] = cid
+  end
+  return citations
+end
+
+function bibdata (bibliography)
+  function bibname (bibitem)
+    if type(bibitem) == 'string' then
+      return bibitem:gsub('%.bib$', '')
+    else
+      -- bibitem is assumed to be a list of inlines
+      return utils.stringify(pandoc.Span(bibitem)):gsub('%.bib$', '')
+    end
+  end
+
+  local bibs = bibliography.t == 'MetaList'
+    and List.map(bibliography, bibname)
+    or {bibname(bibliography)}
+  return table.concat(bibs, ',')
+end
+
+function aux_content(bibliography)
+  local cites = citation_ids()
+  table.sort(cites)
+  local citations = table.concat(cites, ',')
+  return table.concat(
+    {
+      '\\bibstyle{alpha}',
+      '\\bibdata{' .. bibdata(bibliography) .. '}',
+      '\\citation{' .. citations .. '}',
+      '',
+    },
+    '\n'
+  )
+end
+
+function write_dummy_aux (bibliography, auxfile)
+  local filename
+  if type(auxfile) == 'string' then
+    filename = auxfile
+  elseif type(auxfile) == 'table' then
+    -- assume list of inlines
+    filename = utils.stringify(pandoc.Span(auxfile))
+  else
+    filename = 'bibexport.aux'
+  end
+  local fh = io.open(filename, 'w')
+  fh:write(aux_content(bibliography))
+  fh:close()
+  io.stdout:write('Aux written to ' .. filename .. '\n')
+  return filename
+end
+
+function Pandoc (doc)
+  local meta = doc.meta
+  if not meta.bibliography then
+    return nil
+  else
+    -- create a dummy .aux file
+    local auxfile_name = write_dummy_aux(meta.bibliography, meta.auxfile)
+    os.execute('bibexport ' .. auxfile_name)
+    io.stdout:write('Output written to bibexport.bib\n')
+    return nil
+  end
+end