xmlparser.lua

-- from https://github.com/jonathanpoelen/lua-xmlparser

local io, string, pairs = io, string, pairs

local slashchar = string.byte('/', 1)
local E = string.byte('E', 1)

--! Return the default entity table.
--! @return table
local function defaultEntityTable()
  return { quot='"', apos='\'', lt='<', gt='>', amp='&', tab='\t', nbsp=' ', }
end

--! @param[in] s string
--! @param[in] entities table : with entity name as key and value as replacement
--! @return string
local function replaceEntities(s, entities)
  return s:gsub('&([^;]+);', entities)
end

--! Add entities to resultEntities then return it.
--! Create new table when resultEntities is nul.
--! Create an entity table from the document entity table.
--! @param[in] docEntities table
--! @param[in,out] resultEntities table|nil
--! @return table
local function createEntityTable(docEntities, resultEntities)
  local entities = resultEntities or defaultEntityTable()
  for _,e in pairs(docEntities) do
    e.value = replaceEntities(e.value, entities)
    entities[e.name] = e.value
  end
  return entities
end

--! Return a document `table`.
--! @code
--!   document = {
--!     children = {
--!       { text=string } or
--!       { tag=string,
--!         attrs={ [name]=value ... },
--!         orderedattrs={ { name=string, value=string }, ... },
--!         children={ ... }
--!       },
--!       ...
--!     },
--!     entities = { { name=string, value=string }, ... },
--!     tentities = { name=value, ... } -- only if evalEntities = true
--!   }
--! @endcode
--! If `evalEntities` is `true`, the entities are replaced and
--! a `tentity` member is added to the document `table`.
--! @param[in] s string : xml data
--! @param[in] evalEntities boolean
--! @return table
local function parse(s, evalEntities)
  -- remove comments
  s = s:gsub('<!%-%-(.-)%-%->', '')

  local entities, tentities = {}

  if evalEntities then
    local pos = s:find('<[_%w]')
    if pos then
      s:sub(1, pos):gsub('<!ENTITY%s+([_%w]+)%s+(.)(.-)%2', function(name, _, entity)
        entities[#entities+1] = {name=name, value=entity}
      end)
      tentities = createEntityTable(entities)
      s = replaceEntities(s:sub(pos), tentities)
    end
  end

  local t, l = {}, {}

  local addtext = function(txt)
    txt = txt:match'^%s*(.*%S)' or ''
    if #txt ~= 0 then
      t[#t+1] = {text=txt}
    end
  end

  s:gsub('<([?!/]?)([-:_%w]+)%s*(/?>?)([^<]*)', function(type, name, closed, txt)
    -- open
    if #type == 0 then
      local attrs, orderedattrs = {}, {}
      if #closed == 0 then
        local len = 0
        for all,aname,_,value,starttxt in string.gmatch(txt, "(.-([-_%w]+)%s*=%s*(.)(.-)%3%s*(/?>?))") do
          len = len + #all
          attrs[aname] = value
          orderedattrs[#orderedattrs+1] = {name=aname, value=value}
          if #starttxt ~= 0 then
            txt = txt:sub(len+1)
            closed = starttxt
            break
          end
        end
      end
      t[#t+1] = {tag=name, attrs=attrs, children={}, orderedattrs=orderedattrs}

      if closed:byte(1) ~= slashchar then
        l[#l+1] = t
        t = t[#t].children
      end

      addtext(txt)
    -- close
    elseif '/' == type then
      t = l[#l]
      l[#l] = nil

      addtext(txt)
    -- ENTITY
    elseif '!' == type then
      if E == name:byte(1) then
        txt:gsub('([_%w]+)%s+(.)(.-)%2', function(name, _, entity)
          entities[#entities+1] = {name=name, value=entity}
        end, 1)
      end
    -- elseif '?' == type then
    --   print('?  ' .. name .. ' // ' .. attrs .. '$$')
    -- elseif '-' == type then
    --   print('comment  ' .. name .. ' // ' .. attrs .. '$$')
    -- else
    --   print('o  ' .. #p .. ' // ' .. name .. ' // ' .. attrs .. '$$')
    end
  end)

  return {children=t, entities=entities, tentities=tentities}
end

-- Return a tuple `document table, error file`.
-- @param filename[in] string
-- @param evalEntities[in] boolean : see \c parse()
-- @return table : see parse
local function parseFile(filename, evalEntities)
  local f, err = io.open(filename)
  if f then
    local content = f:read'*a'
    f:close()
    return parse(content, evalEntities), nil
  end
  return f, err
end

return {
  parse = parse,
  parseFile = parseFile,
  defaultEntityTable = defaultEntityTable,
  replaceEntities = replaceEntities,
  createEntityTable = createEntityTable,
}