local assert, loadstring, string_find, string_format, string_gfind, string_sub, table_concat, table_insert
    = assert, loadstring, string.find, string.format, string.gfind, string.sub, table.concat, table.insert

module(arg and arg[1] or "slslpp")

-- Source: http://lua-users.org/wiki/SlightlyLessSimpleLuaPreprocessor
local function parseDollarParen(pieces, chunk, s, e)
  local s = 1
  for term, executed, e in string_gfind(chunk, "()$(%b())()") do
      table_insert(pieces, string_format("%q..(%s or '')..",
        string_sub(chunk, s, term - 1), executed))
      s = e
  end
  table_insert(pieces, string_format("%q", string_sub(chunk, s)))
end
-------------------------------------------------------------------------------
local function parseHashLines(chunk)
  local pieces, s = {"return function(_put)", n=1}, 1
  while true do
    local ss, e, lua = string_find(chunk, "^#+([^\n]*\n?)", s)
    if not e then
      ss, e, lua = string_find(chunk, "\n#+([^\n]*\n?)", s)
      table_insert(pieces, "_put(")
      parseDollarParen(pieces, string_sub(chunk, s, ss))
      table_insert(pieces, ")")
      if not e then break end
    end
    table_insert(pieces, lua)
    s = e + 1
  end
  table_insert(pieces, " end")
  return table_concat(pieces)
end
-------------------------------------------------------------------------------
function preprocess(chunk, name)
  return assert(loadstring(parseHashLines(chunk), name))()
end