Support multiple bibliographies per topic (etc.)

_extensions/multibib/multibib.lua

@@ -15,6 +15,8 @@ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 ]]
+
+-- --citeproc was added in 2.11, so we never use the old pandoc-citeproc
 PANDOC_VERSION:must_be_at_least '2.11'
 
 local pandoc = require 'pandoc'
@@ -32,21 +34,24 @@ local metatype = pandoc.utils.type or
 
 --- Collection of all cites in the document
 local all_cites = {}
+
 --- Document meta value
 local doc_meta = pandoc.Meta{}
 
 --- Div used by citeproc to insert the bibliography.
 local refs_div = pandoc.Div({}, pandoc.Attr('refs'))
 
+--- 'references' metadata for each topic
+local topic_refs = {}
+
 -- Div filled by citeproc with properties set according to
 -- the output format and the attributes of cs:bibliography
 local refs_div_with_properties
 
 --- Run citeproc on a pandoc document
 --
--- Falls back to the external `pandoc-citeproc` filter if the built-in
--- citeproc processor is not available. Tries to silence all citeproc
--- warnings, which isn't possible in some versions.
+-- Tries to silence all citeproc warnings, which isn't possible in some
+-- versions.
 local citeproc = utils.citeproc
 if pcall(require, 'pandoc.log') and citeproc then
   -- silence all warnings if possible
@@ -65,13 +70,28 @@ end
 --- Resolve citations in the document by combining all bibliographies
 -- before running citeproc on the full document.
 local function resolve_doc_citations (doc)
-  -- combine all bibliographies
+  -- combine all bibliographies and references
   local meta = doc.meta
   local bibconf = meta.bibliography
   meta.bibliography = pandoc.MetaList{}
   if metatype(bibconf) == 'table' then
     for _, value in pairs(bibconf) do
-      table.insert(meta.bibliography, stringify(value))
+      -- support list-valued items
+      if metatype(value) ~= 'List' then value = List{value} end
+      for _, val in ipairs(value) do
+        table.insert(meta.bibliography, stringify(val))
+      end
+    end
+  end
+  local refconf = meta.references
+  meta.references = pandoc.MetaList{}
+  if metatype(refconf) == 'table' then
+    for topic, refs in pairs(refconf) do
+      -- save topic references for meta_for_citeproc()
+      topic_refs[topic] = refs
+      for _, ref in ipairs(refs) do
+        table.insert(meta.references, ref)
+      end
     end
   end
   -- add refs div to catch the created bibliography
@@ -80,30 +100,53 @@ local function resolve_doc_citations (doc)
   doc = citeproc(doc)
   -- remove catch-all bibliography and keep it for future use
   refs_div_with_properties = table.remove(doc.blocks)
-  -- restore bibliography to original value
-  doc.meta.bibliography = orig_bib
+  -- restore bibliography and references to original values
+  doc.meta.bibliography = bibconf
+  doc.meta.references = refconf
   return doc
 end
 
---- Explicitly create a new meta object with all fields relevant for
---- pandoc-citeproc.
-local function meta_for_pandoc_citeproc (bibliography)
+--- Explicitly create a new meta object with all fields relevant for citeproc.
+local function meta_for_citeproc (bibliography, topic)
   -- We could just indiscriminately copy all meta fields, but let's be
   -- explicit about what's important.
   local fields = {
     'bibliography', 'references', 'csl', 'citation-style',
     'link-citations', 'citation-abbreviations', 'lang',
     'suppress-bibliography', 'reference-section-title',
-    'notes-after-punctuation', 'nocite'
+    'notes-after-punctuation', 'nocite', 'link-bibliography'
   }
   local new_meta = pandoc.Meta{}
   for _, field in ipairs(fields) do
-    new_meta[field] = doc_meta[field]
+    local value = doc_meta[field]
+    -- replace 'references' with the topic references
+    if field == 'references' and metatype(value) == 'table' and topic then
+      value = topic_refs[topic]
+    end
+    new_meta[field] = value
   end
   new_meta.bibliography = bibliography
   return new_meta
 end
 
+-- list of ref-xxx identifiers that have already been output
+local identifiers = List()
+
+-- ignore duplicate references (the first definition will win)
+local function ignore_duplicates(blocks)
+  local new_blocks = pandoc.Blocks{}
+  for _, block in ipairs(blocks) do
+    local identifier = block.attr.identifier
+    if not identifiers:includes(identifier) then
+      local new_block = pandoc.walk_block(block, {Span=_span})
+      new_blocks:insert(new_block)
+      identifiers:insert(identifier)
+    end
+  end
+
+  return new_blocks
+end
+
 local function remove_duplicates(classes)
   local seen = {}
   return classes:filter(function(x)
@@ -126,12 +169,12 @@ local function create_topic_bibliography (div)
     return nil
   end
   local tmp_blocks = {pandoc.Para(all_cites), refs_div}
-  local tmp_meta = meta_for_pandoc_citeproc(bibfile)
+  local tmp_meta = meta_for_citeproc(bibfile, name)
   local tmp_doc = pandoc.Pandoc(tmp_blocks, tmp_meta)
-  local res = citeproc(tmp_doc)
+  local res = citeproc(tmp_doc, true)
   -- First block of the result contains the dummy paragraph, second is
   -- the refs Div filled by citeproc.
-  div.content = res.blocks[2].content
+  div.content = ignore_duplicates(res.blocks[2].content)
   -- Set the classes and attributes as citeproc did it on refs_div
   div.classes = remove_duplicates(refs_div_with_properties.classes)
   div.attributes = refs_div_with_properties.attributes