Produce "native" pandoc XML

native-xml.lua

local stringify = pandoc.utils.stringify
local List = pandoc.List

-- The global variable PANDOC_DOCUMENT contains the full AST of
-- the document which is going to be written. It can be used to
-- configure the writer.
local meta = PANDOC_DOCUMENT.meta

-- Character escaping
local function escape(s, in_attribute)
  return s:gsub("[<>&\"']",
    function(x)
      if x == '<' then
        return '&lt;'
      elseif x == '>' then
        return '&gt;'
      elseif x == '&' then
        return '&amp;'
      elseif in_attribute and x == '"' then
        return '&quot;'
      elseif in_attribute and x == "'" then
        return '&#39;'
      else
        return x
      end
    end)
end

-- Helper function to convert an attributes table into
-- a string that can be put into HTML tags.
local function attributes(attr)
  local attr_table = {}
  for x,y in pairs(attr) do
    if y and y ~= "" then
      table.insert(attr_table, ' ' .. x .. '="' .. escape(y,true) .. '"')
    end
  end
  return table.concat(attr_table)
end

-- Blocksep is used to separate block elements.
function Blocksep()
  return "\n"
end

-- This function is called once for the whole document. Parameters:
-- body is a string, metadata is a table, variables is a table.
-- This gives you a fragment.  You could use the metadata table to
-- fill variables in a custom lua template.  Or, pass `--template=...`
-- to pandoc, and pandoc will do the template processing as usual.
function Doc(body, metadata, variables)
  return '<pandoc>' .. body .. '</pandoc>'
end

-- The functions that follow render corresponding pandoc elements.
-- s is always a string, attr is always a table of attributes, and
-- items is always an array of strings (the items in a list).
-- Comments indicate the types of other variables.

function Str(s)
  return '<str>' .. escape(s) .. '</str>'
end

function Space()
  return '<space/>'
end

function SoftBreak()
  return "<softbreak/>"
end

function LineBreak()
  return "<linebreak/>"
end

function Emph(s)
  return "<emph>" .. s .. "</emph>"
end

function Strong(s)
  return "<strong>" .. s .. "</strong>"
end

function Subscript(s)
  return "<subscript>" .. s .. "</subscript>"
end

function Superscript(s)
  return "<superscript>" .. s .. "</superscript>"
end

function SmallCaps(s)
  return '<smallcaps>' .. s .. '</smallcaps>'
end

function Strikeout(s)
  return '<strikeout>' .. s .. '</strikeout>'
end

local link_template = '<link href="%s" title="%s" %s>%s</link>'
function Link(s, tgt, tit, attr)
  return link_template:format(
    escape(tgt, true),
    escape(tit,true),
    attributes(attr),
    s
  )
end

local image_template = '<image src="%s" title="%s" %s>%s</image>'
function Image(s, src, tit, attr)
  return image_template:format(
    escape(src, true),
    escape(tit,true),
    attributes(attr),
    s
  )
end

function Code(s, attr)
  return "<code" .. attributes(attr) .. ">" .. escape(s) .. "</code>"
end

function InlineMath(s)
  return '<math type="inline">'.. s .. '</math>'
end

function DisplayMath(s)
  return '<math type="display">'.. s .. '</math>'
end

function SingleQuoted(s)
  return '<quoted type="single">'.. s .. '</quoted>'
end

function DoubleQuoted(s)
  return '<quoted type="double">'.. s .. '</quoted>'
end

function Note(s)
  return '<note>' .. s .. '</note>'
end

function Span(s, attr)
  return "<span" .. attributes(attr) .. ">" .. s .. "</span>"
end

function RawInline(format, str)
  return ('<raw-inline format="%s">%s</raw-inline'):format(format, str)
end

function Cite(s, cs)
  error 'Cite has not been implemented yet'
end

function Plain(s)
  return '<plain>' .. s .. '</plain>'
end

function Para(s)
  return "<para>" .. s .. "</para>"
end

-- lev is an integer, the header level.
function Header(lev, s, attr)
  return ('<header level="%d" %s>%s</header>'):format(lev, attributes(attr), s)
end

function BlockQuote(s)
  return "<blockquote>" .. s .. "</blockquote>"
end

function HorizontalRule()
  return "<horizontal-rule/>"
end

function LineBlock(ls)
  error 'LineBlock has not been implemented yet'
end

function CodeBlock(s, attr)
  return ('<code-block %s>%s</code-block>'):format(attributes(attr), s)
end

function BulletList(items)
  return '<bullet-list>\n' ..
    table.concat(
      List.map(items, function (item) return '<item>' .. item .. '</item>' end)
    ) ..
    '</bullet-list>\n'
end

function OrderedList(items)
  return '<ordered-list>\n' ..
    table.concat(
      List.map(items, function (item) return '<item>' .. item .. '</item>' end)
    ) ..
    '</ordered-list>\n'
end

function DefinitionList(items)
  error 'DefinitionList has not been implemented yet'
end

function CaptionedImage(src, tit, caption, attr)
  return Para(Image(src, tit, caption, attr))
end

-- Caption is a string, aligns is an array of strings,
-- widths is an array of floats, headers is an array of
-- strings, rows is an array of arrays of strings.
function Table(caption, aligns, widths, headers, rows)
  error 'Table has not been implemented yet'
end

function RawBlock(format, str)
  return ('<raw-block format="%s">%s</raw-block>'):format(format, str)
end

function Div(s, attr)
  return "<div" .. attributes(attr) .. ">" .. s .. "</div>"
end

-- The following code will produce runtime warnings when you haven't defined
-- all of the functions you need for the custom writer, so it's useful
-- to include when you're working on a writer.
local meta = {}
meta.__index =
  function(_, key)
    io.stderr:write(string.format("WARNING: Undefined function '%s'\n",key))
    return function() return "" end
  end
setmetatable(_G, meta)