building digraph

filter.lua

@@ -1,16 +1,43 @@
-local label_map = {}               -- label has to be unique!
 
-local function collect_labels(div) -- only collect labels in div
-    if div.identifier and div.identifier ~= "" then
-        label_map[div.identifier] = div:clone()
+local label_map = {} -- label has to be unique!
+
+-- helper functions for debugging
+local function show(s)
+    io.stderr:write("[Debug] " .. s .. "\n")
+end
+
+local function collect_labels(blk)
+    if blk.identifier and blk.identifier ~= "" then
+        label_map[blk.identifier] = blk:clone()
     end
     return nil
 end
 
+local function dfs(blk, stack) -- depth first search on a top level blk
+    -- check for identifier and build label_map
+    if blk.identifier and blk.identifier ~= "" then
+        label_map[blk.identifier] = blk:clone()
+        table.insert(stack, blk.identifier)
+    end
+
+    -- recurse into child blocks
+    -- type matters. see https://hackage-content.haskell.org/package/pandoc-types-1.23.1/docs/Text-Pandoc-Definition.html#t:Block
+    -- fortunately, we only need to recurse on divs.
+    if blk.t == 'Div' then
+        for _, inner in ipairs(blk.content) do
+            dfs(inner, stack)
+        end
+    end
+    -- pop
+    if blk.identifier and blk.identifier ~= "" then
+        table.remove(stack) -- pop
+    end
+end
+
 local function words(s)
     local res = {}
-    for part in s:gmatch("[^,]+") do                -- split by commas
-        local trimmed = part:match("^%s*(.-)%s*$")  -- remove leading/trailing spaces
+    for part in s:gmatch("[^,]+") do               -- split by commas
+        local trimmed = part:match("^%s*(.-)%s*$") -- remove leading/trailing spaces
         if trimmed ~= "" then
             table.insert(res, trimmed)
         end
@@ -26,9 +53,9 @@ local function replace(e)
         for _, l in ipairs(words(include)) do
             if label_map[l] then
                 table.insert(blocks, label_map[l]:clone())
-                io.stderr:write("insert [" .. label_map[l].identifier .. ']\n')
+                show("insert [" .. label_map[l].identifier .. ']\n')
             else
-                io.stderr:write("Cannot find AST node with label " .. l)
+                io.stderr:write("Cannot find AST node with label " .. l .. "\n")
             end
         end
         return pandoc.Div(blocks, e.attr)
@@ -41,7 +68,7 @@ return {
     Pandoc = function(doc)
         -- collect labels
         for _, blk in ipairs(doc.blocks) do
-            collect_labels(blk)
+            dfs(blk,{})
         end
 
         -- replace