Add wiki pandoc files (Makefile+filters)

.wiki/Makefile

@@ -0,0 +1,38 @@
+entries := $(wildcard *.md)
+
+target=wiki
+exports= \
+  $(entries:.md=.html) \
+	# $(target).pdf  \
+
+VIMWIKI_DIR=/home/h/.wiki
+
+all: $(exports)
+
+%.html:%.md
+	pandoc																										 \
+	 -f markdown																							 \
+	 -t html5																									 \
+	 -c pandoc.css																						 \
+	 --pdf-engine=xelatex																			 \
+	 --bibliography $(VIMWIKI_DIR)/references.bib							 \
+	 --citeproc																								 \
+	 --lua-filter=$(VIMWIKI_DIR)/filters/html-links.lua        \
+	 --lua-filter=$(VIMWIKI_DIR)/filters/diagram-generator.lua \
+	 --lua-filter=$(VIMWIKI_DIR)/filters/lilypond.lua          \
+	 --mathjax																								 \
+	 --extract-media=diagrams																	 \
+	 -s -o $@ $<
+
+$(target).pdf:$(entries)
+	pandoc \
+		-f markdown $(entries)                       \
+		--pdf-engine=xelatex                         \
+		--bibliography $(VIMWIKI_DIR)/references.bib \
+		--citeproc                                   \
+		--table-of-contents                          \
+		-o $@
+
+# clean:
+# 	rm -f *.html
+# 	rm wiki.pdf

.wiki/filters/diagram-generator.lua

@@ -0,0 +1,396 @@
+--[[
+diagram-generator – create images and figures from code blocks.
+
+This Lua filter is used to create images with or without captions
+from code blocks. Currently PlantUML, GraphViz, Tikz, and Python
+can be processed. For further details, see README.md.
+
+Copyright: © 2018-2020 John MacFarlane <jgm@berkeley.edu>,
+             2018 Florian Schätzig <florian@schaetzig.de>,
+             2019 Thorsten Sommer <contact@sommer-engineering.com>,
+             2019-2020 Albert Krewinkel <albert+pandoc@zeitkraut.de>
+License:   MIT – see LICENSE file for details
+]]
+-- Module pandoc.system is required and was added in version 2.7.3
+PANDOC_VERSION:must_be_at_least '2.7.3'
+
+local system = require 'pandoc.system'
+local utils = require 'pandoc.utils'
+local stringify = utils.stringify
+local with_temporary_directory = system.with_temporary_directory
+local with_working_directory = system.with_working_directory
+
+-- The PlantUML path. If set, uses the environment variable PLANTUML or the
+-- value "plantuml.jar" (local PlantUML version). In order to define a
+-- PlantUML version per pandoc document, use the meta data to define the key
+-- "plantuml_path".
+local plantuml_path = os.getenv("PLANTUML") or "plantuml.jar"
+
+-- The Inkscape path. In order to define an Inkscape version per pandoc
+-- document, use the meta data to define the key "inkscape_path".
+local inkscape_path = os.getenv("INKSCAPE") or "inkscape"
+
+-- The Python path. In order to define a Python version per pandoc document,
+-- use the meta data to define the key "python_path".
+local python_path = os.getenv("PYTHON") or "python"
+
+-- The Python environment's activate script. Can be set on a per document
+-- basis by using the meta data key "activatePythonPath".
+local python_activate_path = os.getenv("PYTHON_ACTIVATE")
+
+-- The Java path. In order to define a Java version per pandoc document,
+-- use the meta data to define the key "java_path".
+local java_path = os.getenv("JAVA_HOME")
+if java_path then
+    java_path = java_path .. package.config:sub(1,1) .. "bin"
+        .. package.config:sub(1,1) .. "java"
+else
+    java_path = "java"
+end
+
+-- The dot (Graphviz) path. In order to define a dot version per pandoc
+-- document, use the meta data to define the key "dot_path".
+local dot_path = os.getenv("DOT") or "dot"
+
+-- The pdflatex path. In order to define a pdflatex version per pandoc
+-- document, use the meta data to define the key "pdflatex_path".
+local pdflatex_path = os.getenv("PDFLATEX") or "pdflatex"
+
+-- The asymptote path. There is also the metadata variable
+-- "asymptote_path".
+local asymptote_path = os.getenv ("ASYMPTOTE") or "asy"
+
+-- The default format is SVG i.e. vector graphics:
+local filetype = "svg"
+local mimetype = "image/svg+xml"
+
+-- Check for output formats that potentially cannot use SVG
+-- vector graphics. In these cases, we use a different format
+-- such as PNG:
+if FORMAT == "docx" then
+    filetype = "png"
+    mimetype = "image/png"
+elseif FORMAT == "pptx" then
+    filetype = "png"
+    mimetype = "image/png"
+elseif FORMAT == "rtf" then
+    filetype = "png"
+    mimetype = "image/png"
+end
+
+-- Execute the meta data table to determine the paths. This function
+-- must be called first to get the desired path. If one of these
+-- meta options was set, it gets used instead of the corresponding
+-- environment variable:
+function Meta(meta)
+  plantuml_path = stringify(
+    meta.plantuml_path or meta.plantumlPath or plantuml_path
+  )
+  inkscape_path = stringify(
+    meta.inkscape_path or meta.inkscapePath or inkscape_path
+  )
+  python_path = stringify(
+    meta.python_path or meta.pythonPath or python_path
+  )
+  python_activate_path =
+    meta.activate_python_path or meta.activatePythonPath or python_activate_path
+  python_activate_path = python_activate_path and stringify(python_activate_path)
+  java_path = stringify(
+    meta.java_path or meta.javaPath or java_path
+  )
+  dot_path = stringify(
+    meta.path_dot or meta.dotPath or dot_path
+  )
+  pdflatex_path = stringify(
+    meta.pdflatex_path or meta.pdflatexPath or pdflatex_path
+  )
+  asymptote_path = stringify(
+     meta.asymptote_path or meta.asymptotePath or asymptote_path
+  )
+end
+
+-- Call plantuml.jar with some parameters (cf. PlantUML help):
+local function plantuml(puml, filetype)
+  return pandoc.pipe(
+    java_path,
+    {"-jar", plantuml_path, "-t" .. filetype, "-pipe", "-charset", "UTF8"},
+    puml
+  )
+end
+
+-- Call dot (GraphViz) in order to generate the image
+-- (thanks @muxueqz for this code):
+local function graphviz(code, filetype)
+  return pandoc.pipe(dot_path, {"-T" .. filetype}, code)
+end
+
+--
+-- TikZ
+--
+
+--- LaTeX template used to compile TikZ images. Takes additional
+--- packages as the first, and the actual TikZ code as the second
+--- argument.
+local tikz_template = [[
+\documentclass{standalone}
+\usepackage{tikz}
+%% begin: additional packages
+%s
+%% end: additional packages
+\begin{document}
+%s
+\end{document}
+]]
+
+-- Returns a function which takes the filename of a PDF or SVG file
+-- and a target filename, and writes the input as the given format.
+-- Returns `nil` if conversion into the target format is not possible.
+local function convert_with_inkscape(filetype)
+  -- Build the basic Inkscape command for the conversion
+  local inkscape_output_args
+  if filetype == 'png' then
+    inkscape_output_args = '--export-png="%s" --export-dpi=300'
+  elseif filetype == 'svg' then
+    inkscape_output_args = '--export-plain-svg="%s"'
+  else
+    return nil
+  end
+  return function (pdf_file, outfile)
+    local inkscape_command = string.format(
+      '"%s" --without-gui --file="%s" ' .. inkscape_output_args,
+      inkscape_path,
+      pdf_file,
+      outfile
+    )
+    io.stderr:write(inkscape_command .. '\n')
+    local command_output = io.popen(inkscape_command)
+    -- TODO: print output when debugging.
+    command_output:close()
+  end
+end
+
+--- Compile LaTeX with Tikz code to an image
+local function tikz2image(src, filetype, additional_packages)
+  local convert = convert_with_inkscape(filetype)
+  -- Bail if there is now known way from PDF to the target format.
+  if not convert then
+    error(string.format("Don't know how to convert pdf to %s.", filetype))
+  end
+  return with_temporary_directory("tikz2image", function (tmpdir)
+    return with_working_directory(tmpdir, function ()
+      -- Define file names:
+      local file_template = "%s/tikz-image.%s"
+      local tikz_file = file_template:format(tmpdir, "tex")
+      local pdf_file = file_template:format(tmpdir, "pdf")
+      local outfile = file_template:format(tmpdir, filetype)
+
+      -- Build and write the LaTeX document:
+      local f = io.open(tikz_file, 'w')
+      f:write(tikz_template:format(additional_packages or '', src))
+      f:close()
+
+      -- Execute the LaTeX compiler:
+      pandoc.pipe(pdflatex_path, {'-output-directory', tmpdir, tikz_file}, '')
+
+      convert(pdf_file, outfile)
+
+      -- Try to open and read the image:
+      local img_data
+      local r = io.open(outfile, 'rb')
+      if r then
+        img_data = r:read("*all")
+        r:close()
+      else
+        -- TODO: print warning
+      end
+
+      return img_data
+    end)
+  end)
+end
+
+-- Run Python to generate an image:
+local function py2image(code, filetype)
+
+    -- Define the temp files:
+    local outfile = string.format('%s.%s', os.tmpname(), filetype)
+    local pyfile = os.tmpname()
+
+    -- Replace the desired destination's file type in the Python code:
+    local extendedCode = string.gsub(code, "%$FORMAT%$", filetype)
+
+    -- Replace the desired destination's path in the Python code:
+    extendedCode = string.gsub(extendedCode, "%$DESTINATION%$", outfile)
+
+    -- Write the Python code:
+    local f = io.open(pyfile, 'w')
+    f:write(extendedCode)
+    f:close()
+
+    -- Execute Python in the desired environment:
+    local pycmd = python_path .. ' ' .. pyfile
+    local command = python_activate_path
+      and python_activate_path .. ' && ' .. pycmd
+      or pycmd
+    os.execute(command)
+
+    -- Try to open the written image:
+    local r = io.open(outfile, 'rb')
+    local imgData = nil
+
+    -- When the image exist, read it:
+    if r then
+        imgData = r:read("*all")
+        r:close()
+    else
+        io.stderr:write(string.format("File '%s' could not be opened", outfile))
+        error 'Could not create image from python code.'
+    end
+
+    -- Delete the tmp files:
+    os.remove(pyfile)
+    os.remove(outfile)
+
+    return imgData
+end
+
+--
+-- Asymptote
+--
+
+local function asymptote(code, filetype)
+  local convert
+  if filetype ~= 'svg' and filetype ~= 'png' then
+    error(string.format("Conversion to %s not implemented", filetype))
+  end
+  return with_temporary_directory(
+    "asymptote",
+    function(tmpdir)
+      return with_working_directory(
+        tmpdir,
+        function ()
+          local asy_file = "pandoc_diagram.asy"
+          local svg_file = "pandoc_diagram.svg"
+          local f = io.open(asy_file, 'w')
+          f:write(code)
+          f:close()
+
+          pandoc.pipe(asymptote_path, {"-f", "svg", "-o", "pandoc_diagram", asy_file}, "")
+
+          local r
+          if filetype == 'svg' then
+            r = io.open(svg_file, 'rb')
+          else
+            local png_file = "pandoc_diagram.png"
+            convert_with_inkscape("png")(svg_file, png_file)
+            r = io.open(png_file, 'rb')
+          end
+
+          local img_data
+          if r then
+            img_data = r:read("*all")
+            r:close()
+          else
+            error("could not read asymptote result file")
+          end
+          return img_data
+      end)
+  end)
+end
+
+-- Executes each document's code block to find matching code blocks:
+function CodeBlock(block)
+
+    -- Predefine a potential image:
+    local fname = nil
+
+    -- Using a table with all known generators i.e. converters:
+    local converters = {
+        plantuml = plantuml,
+        graphviz = graphviz,
+        tikz = tikz2image,
+        py2image = py2image,
+        asymptote = asymptote,
+    }
+
+    -- Check if a converter exists for this block. If not, return the block
+    -- unchanged.
+    local img_converter = converters[block.classes[1]]
+    if not img_converter then
+      return nil
+    end
+
+    -- Call the correct converter which belongs to the used class:
+    local success, img = pcall(img_converter, block.text,
+        filetype, block.attributes["additionalPackages"] or nil)
+
+    -- Was ok?
+    if success and img then
+        -- Hash the figure name and content:
+        fname = pandoc.sha1(img) .. "." .. filetype
+
+        -- Store the data in the media bag:
+        pandoc.mediabag.insert(fname, mimetype, img)
+
+    else
+
+        -- an error occured; img contains the error message
+        io.stderr:write(tostring(img))
+        io.stderr:write('\n')
+        error 'Image conversion failed. Aborting.'
+
+    end
+
+    -- Case: This code block was an image e.g. PlantUML or dot/Graphviz, etc.:
+    if fname then
+
+        -- Define the default caption:
+        local caption = {}
+        local enableCaption = nil
+
+        -- If the user defines a caption, use it:
+        if block.attributes["caption"] then
+            caption = pandoc.read(block.attributes.caption).blocks[1].content
+
+            -- This is pandoc's current hack to enforce a caption:
+            enableCaption = "fig:"
+        end
+
+        -- Create a new image for the document's structure. Attach the user's
+        -- caption. Also use a hack (fig:) to enforce pandoc to create a
+        -- figure i.e. attach a caption to the image.
+        local imgObj = pandoc.Image(caption, fname, enableCaption)
+
+        -- Now, transfer the attribute "name" from the code block to the new
+        -- image block. It might gets used by the figure numbering lua filter.
+        -- If the figure numbering gets not used, this additional attribute
+        -- gets ignored as well.
+        if block.attributes["name"] then
+            imgObj.attributes["name"] = block.attributes["name"]
+        end
+    
+        -- Transfer the identifier from the code block to the new image block
+        -- to enable downstream filters like pandoc-crossref. This allows a figure
+        -- block starting with:
+        --
+        --     ```{#fig:pumlExample .plantuml caption="This is an image, created by **PlantUML**."}
+        --
+        -- to be referenced as @fig:pumlExample outside of the figure.
+        if block.identifier then
+            imgObj.identifier = block.identifier
+        end
+
+        -- Finally, put the image inside an empty paragraph. By returning the
+        -- resulting paragraph object, the source code block gets replaced by
+        -- the image:
+        return pandoc.Para{ imgObj }
+    end
+end
+
+-- Normally, pandoc will run the function in the built-in order Inlines ->
+-- Blocks -> Meta -> Pandoc. We instead want Meta -> Blocks. Thus, we must
+-- define our custom order:
+return {
+    {Meta = Meta},
+    {CodeBlock = CodeBlock},
+}

.wiki/filters/html-links.lua

@@ -0,0 +1,5 @@
+-- https://stackoverflow.com/questions/40993488/convert-markdown-links-to-html-with-pandoc
+function Link(el)
+  el.target = string.gsub(el.target, "%.md", ".html")
+  return el
+end

.wiki/filters/lilypond.html

@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml" lang="" xml:lang="">
+<head>
+  <meta charset="utf-8" />
+  <meta name="generator" content="pandoc" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes" />
+  <title>lilypond</title>
+  <style>
+    code{white-space: pre-wrap;}
+    span.smallcaps{font-variant: small-caps;}
+    span.underline{text-decoration: underline;}
+    div.column{display: inline-block; vertical-align: top; width: 50%;}
+    div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
+    ul.task-list{list-style: none;}
+  </style>
+  <link rel="stylesheet" href="pandoc.css" />
+  <!--[if lt IE 9]>
+    <script src="//cdnjs.cloudflare.com/ajax/libs/html5shiv/3.7.3/html5shiv-printshiv.min.js"></script>
+  <![endif]-->
+</head>
+<body>
+<p>if PANDOC_VERSION and PANDOC_VERSION.must_be_at_least then – Actually, this check is redundant since `Version’ objects were – introduced in pandoc v2.7.3, but I’ve left it in for clarity. PANDOC_VERSION:must_be_at_least(“2.7.3”) else error(“pandoc version &gt;=2.7.3 is required”) end</p>
+<p>local OPTIONS = { image_directory = “.” }</p>
+<p>local SPECIAL_CLASSES = { [“lilypond”] = true, [“ly-fragment”] = true, [“ly-norender”] = true }</p>
+<p>local SPECIAL_ATTRIBUTES = { [“ly-caption”] = true, [“ly-name”] = true, [“ly-resolution”] = true, [“ly-title”] = true }</p>
+<p>– pandoc.system.with_temporary_directory had a different (undocumented) – name in the 2.7.3 release. local with_temporary_directory = tostring(PANDOC_VERSION) == “2.7.3” and pandoc.system.with_temp_directory or pandoc.system.with_temporary_directory</p>
+– This is the extra boilerplate that’s added to code snippets when the – <code>ly-fragment' class is present. It's adapted from what</code>lilypond-book’ – does. (The file `lilypond-book-preamble.ly’ is placed on the include – path as part of the default LilyPond installation.) local function wrap_fragment(src) return table.concat( { [[
+<p>“lilypond-book-preamble.ly”]], [[]], src, }, “” ) end</p>
+<p>local function generate_image(name, input, dpi) local fullname = name .. “.png” return fullname, with_temporary_directory( “lilypond-lua-XXXXX,” function (tmp_dir) return pandoc.system.with_working_directory( tmp_dir, function () pandoc.pipe( “lilypond,” { “–silent,” “–png,” dpi and “-dresolution=” .. dpi or "“,”–output=" .. name, “-” }, input ) local fh = io.open(fullname, ‘rb’) local data = fh:read(’*all’) fh:close() return data end ) end ) end</p>
+<p>local function process_lilypond(elem, inline) local code = elem.text local fragment = elem.classes:includes(“ly-fragment”) or inline local input = fragment and wrap_fragment(code) or code local dpi = elem.attributes[“ly-resolution”] local name = elem.attributes[“ly-name”] or pandoc.sha1(code)</p>
+<p>local image_filename, image_data = generate_image(name, input, dpi) local src = OPTIONS.image_directory .. ‘/’ .. image_filename pandoc.mediabag.insert(src, “image/png,” image_data)</p>
+<p>local caption = elem.attributes[“ly-caption”] or “Musical notation” – The “fig:” prefix causes this image to be rendered as a proper figure – in HTML ouput (this is a rather ugly pandoc feature and may be replaced – by something more elegant in the future). local fudge = inline and "" or “fig:” – Strip newlines, indendation, etc. from the code for a more readable title. local title = fudge .. (elem.attributes[“ly-title”] or code:gsub(“%s+,” " "))</p>
+<p>– Strip most of the LilyPond-related attributes from this code element, for – tidiness. local classes = elem.classes:filter( function (cls) return not SPECIAL_CLASSES[cls] end ) table.insert( classes, – Add one special class for styling/manipulation purposes. inline and “lilypond-image-inline” or “lilypond-image-standalone” ) local attributes = elem.attributes for a, t in pairs(SPECIAL_ATTRIBUTES) do attributes[a] = nil end local attrs = pandoc.Attr(elem.identifier, classes, attributes)</p>
+<p>return pandoc.Image(caption, src, title, attrs) end</p>
+<p>– Update `OPTIONS’ based on the document metadata. local function meta_transformer(md) local ly_block = md.lilypond or {} local dir_conf = ly_block.image_directory OPTIONS.image_directory = dir_conf and pandoc.utils.stringify(dir_conf) or OPTIONS.image_directory md.lilypond = nil return md end</p>
+<p>local function code_transformer(elem) if elem.classes:includes(“lilypond”) and not elem.classes:includes(“ly-norender”) then return process_lilypond(elem, true) else return elem end end</p>
+<p>local function code_block_transformer(elem) if elem.classes:includes(“lilypond”) and not elem.classes:includes(“ly-norender”) then – When replacing a block element we must wrap the generated image – in a <code>Para' since</code>Image’ is an inline element. return pandoc.Para({process_lilypond(elem, false)}) else return elem end end</p>
+<p>– Make sure the metadata transformation runs first so that the code – transformations operate with the correct options. return { {Meta = meta_transformer}, {Code = code_transformer, CodeBlock = code_block_transformer}, }</p>
+</body>
+</html>

.wiki/filters/lilypond.lua

@@ -0,0 +1,154 @@
+if PANDOC_VERSION and PANDOC_VERSION.must_be_at_least then
+  -- Actually, this check is redundant since `Version' objects were
+  -- introduced in pandoc v2.7.3, but I've left it in for clarity.
+  PANDOC_VERSION:must_be_at_least("2.7.3")
+else
+  error("pandoc version >=2.7.3 is required")
+end
+
+local OPTIONS = {
+  image_directory = ".",
+}
+
+local SPECIAL_CLASSES = {
+        ["lilypond"] = true,
+        ["ly-fragment"] = true,
+        ["ly-norender"] = true
+      }
+
+local SPECIAL_ATTRIBUTES = {
+        ["ly-caption"] = true,
+        ["ly-name"] = true,
+        ["ly-resolution"] = true,
+        ["ly-title"] = true
+      }
+
+-- pandoc.system.with_temporary_directory had a different (undocumented)
+-- name in the 2.7.3 release.
+local with_temporary_directory = tostring(PANDOC_VERSION) == "2.7.3"
+                                   and pandoc.system.with_temp_directory
+                                    or pandoc.system.with_temporary_directory
+
+-- This is the extra boilerplate that's added to code snippets when the
+-- `ly-fragment' class is present. It's adapted from what `lilypond-book'
+-- does. (The file `lilypond-book-preamble.ly' is placed on the include
+-- path as part of the default LilyPond installation.)
+local function wrap_fragment(src)
+  return table.concat(
+           {
+             [[\include "lilypond-book-preamble.ly"]],
+             [[\paper { indent = 0\mm }]],
+             src,
+           },
+           "\n"
+         )
+end
+
+local function generate_image(name, input, dpi)
+  local fullname = name .. ".png"
+  return fullname, with_temporary_directory(
+    "lilypond-lua-XXXXX",
+    function (tmp_dir)
+      return pandoc.system.with_working_directory(
+        tmp_dir,
+        function ()
+          pandoc.pipe(
+            "lilypond",
+            {
+              "--silent",
+              "--png", dpi and "-dresolution=" .. dpi or "",
+              "--output=" .. name, "-"
+            },
+            input
+          )
+          local fh = io.open(fullname, 'rb')
+          local data = fh:read('*all')
+          fh:close()
+          return data
+        end
+      )
+    end
+  )
+end
+
+local function process_lilypond(elem, inline)
+  local code = elem.text
+  local fragment = elem.classes:includes("ly-fragment") or inline
+  local input = fragment
+                  and wrap_fragment(code)
+                   or code
+  local dpi = elem.attributes["ly-resolution"]
+  local name = elem.attributes["ly-name"] or pandoc.sha1(code)
+
+  local image_filename, image_data = generate_image(name, input, dpi)
+  local src = OPTIONS.image_directory .. '/' .. image_filename
+  pandoc.mediabag.insert(src, "image/png", image_data)
+
+  local caption = elem.attributes["ly-caption"] or "Musical notation"
+  -- The "fig:" prefix causes this image to be rendered as a proper figure
+  -- in HTML ouput (this is a rather ugly pandoc feature and may be replaced
+  -- by something more elegant in the future).
+  local fudge = inline and "" or "fig:"
+  -- Strip newlines, indendation, etc. from the code for a more readable title.
+  local title = fudge .. (elem.attributes["ly-title"]
+                            or code:gsub("%s+", " "))
+
+  -- Strip most of the LilyPond-related attributes from this code element, for
+  -- tidiness.
+  local classes = elem.classes:filter(
+    function (cls)
+      return not SPECIAL_CLASSES[cls]
+    end
+  )
+  table.insert(
+    classes,
+    -- Add one special class for styling/manipulation purposes.
+    inline and "lilypond-image-inline"
+            or "lilypond-image-standalone"
+  )
+  local attributes = elem.attributes
+  for a, t in pairs(SPECIAL_ATTRIBUTES) do
+    attributes[a] = nil
+  end
+  local attrs = pandoc.Attr(elem.identifier, classes, attributes)
+
+  return pandoc.Image(caption, src, title, attrs)
+end
+
+-- Update `OPTIONS' based on the document metadata.
+local function meta_transformer(md)
+  local ly_block = md.lilypond or {}
+  local dir_conf = ly_block.image_directory
+  OPTIONS.image_directory = dir_conf
+                              and pandoc.utils.stringify(dir_conf)
+                               or OPTIONS.image_directory
+  md.lilypond = nil
+  return md
+end
+
+local function code_transformer(elem)
+  if elem.classes:includes("lilypond")
+       and not elem.classes:includes("ly-norender") then
+    return process_lilypond(elem, true)
+  else
+    return elem
+  end
+end
+
+local function code_block_transformer(elem)
+  if elem.classes:includes("lilypond")
+       and not elem.classes:includes("ly-norender") then
+    -- When replacing a block element we must wrap the generated image
+    -- in a `Para' since `Image' is an inline element.
+    return pandoc.Para({process_lilypond(elem, false)})
+  else
+    return elem
+  end
+end
+
+-- Make sure the metadata transformation runs first so that the code
+-- transformations operate with the correct options.
+return {
+         {Meta = meta_transformer},
+         {Code = code_transformer, CodeBlock = code_block_transformer},
+       }

.wiki/filters/tikz.lua

@@ -0,0 +1,63 @@
+local system = require 'pandoc.system'
+
+local tikz_doc_template = [[
+\documentclass{standalone}
+\usepackage{xcolor}
+\usepackage{tikz}
+\begin{document}
+\nopagecolor
+%s
+\end{document}
+]]
+
+local function tikz2image(src, filetype, outfile)
+  system.with_temporary_directory('tikz2image', function (tmpdir)
+    system.with_working_directory(tmpdir, function()
+      local f = io.open('tikz.tex', 'w')
+      f:write(tikz_doc_template:format(src))
+      f:close()
+      os.execute('pdflatex tikz.tex')
+      if filetype == 'pdf' then
+        os.rename('tikz.pdf', outfile)
+      else
+        os.execute('pdf2svg tikz.pdf ' .. outfile)
+      end
+    end)
+  end)
+end
+
+extension_for = {
+  html = 'svg',
+  html4 = 'svg',
+  html5 = 'svg',
+  latex = 'pdf',
+  beamer = 'pdf' }
+
+  local function file_exists(name)
+    local f = io.open(name, 'r')
+    if f ~= nil then
+      io.close(f)
+      return true
+    else
+      return false
+    end
+  end
+
+  local function starts_with(start, str)
+    return str:sub(1, #start) == start
+  end
+
+
+  function RawBlock(el)
+    if starts_with('\\begin{tikzpicture}', el.text) then
+      local filetype = extension_for[FORMAT] or 'svg'
+      local fname = system.get_working_directory() .. '/' ..
+      pandoc.sha1(el.text) .. '.' .. filetype
+      if not file_exists(fname) then
+        tikz2image(el.text, filetype, fname)
+      end
+      return pandoc.Para({pandoc.Image({}, fname)})
+    else
+      return el
+    end
+  end