Re: XML

[Roberto Ierusalimschy <roberto@...>]

> Anyone written an XML parser for Lua?

I have this basic skeleton that parses the "main" part of an XML string (it
does not handle meta-data like "<?" and "<!"...).

-- Roberto

function parseargs (s)
  local arg = {}
  gsub(s, "(%w+)=([\"'])(.-)%2", function (w, _, a)
    %arg[w] = a
  end)
  return arg
end

function collect (s)
  local stack = {n=0}
  local top = {n=0}
  tinsert(stack, top)
  local ni,c,label,args, empty
  local i, j = 1, 1
  while 1 do
    ni,j,c,label,args, empty = strfind(s, "<(%/?)(%w+)(.-)(%/?)>", j)
    if not ni then break end
    local text = strsub(s, i, ni-1)
    if not strfind(text, "^%s*$") then
      tinsert(top, text)
    end
    if empty == "/" then  -- empty element tag
      tinsert(top, {n=0, label=label, args=parseargs(args), empty=1})
    elseif c == "" then   -- start tag
      top = {n=0, label=label, args=parseargs(args)}
      tinsert(stack, top)   -- new level
    else  -- end tag
      local toclose = tremove(stack)  -- remove top
      top = stack[stack.n]
      if stack.n < 1 then
        error("nothing to close with "..label)
      end
      if toclose.label ~= label then
        error("trying to close "..toclose.label.." with "..label)
      end
      tinsert(top, toclose)
    end 
    i = j+1
  end
  local text = strsub(s, i)
  if not strfind(text, "^%s*$") then
    tinsert(stack[stack.n], text)
  end
  if stack.n > 1 then
    error("unclosed "..stack[stack.n].label)
  end
  return stack[1]
end


-- example

x = collect[[
     <methodCall kind="xuxu">
      <methodName>examples.<em>getStateName</em></methodName>
      <params>
         <param>
            <value><i4>41</i4></value>
            </param>
         </params>
      </methodCall>
]]