[DOCKER] Pandoc: add wordcount custom filter (#159)

docker/pandoc/Dockerfile

@@ -13,6 +13,10 @@ COPY docker/pandoc/requirements.txt /requirements.txt
 RUN pip3 install --no-cache-dir -r /requirements.txt    \
     && rm -f /requirements.txt
 
+# Install custom filters
+COPY docker/pandoc/filters/* /root/.pandoc/filters/
+
+# Set working directory
 WORKDIR /data
 
 # Command

docker/pandoc/filters/wordcount.lua

@@ -0,0 +1,29 @@
+-- counts words in a document
+
+words = 0
+
+wordcount = {
+  Str = function(el)
+    -- we don't count a word if it's entirely punctuation:
+    if el.text:match("%P") then
+        words = words + 1
+    end
+  end,
+
+  Code = function(el)
+    _,n = el.text:gsub("%S+","")
+    words = words + n
+  end,
+
+  CodeBlock = function(el)
+    _,n = el.text:gsub("%S+","")
+    words = words + n
+  end
+}
+
+function Pandoc(el)
+    -- skip metadata, just count body:
+    el.blocks:walk(wordcount)
+    print(words .. " words in body")
+    os.exit(0)
+end