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Pure Lua XML Parser

/ Published in: Lua
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From: Roberto Ierusalimschy

Parses the "main" part of an XML string. It does not handle meta-data. Outputs to a table.

Example:
myVar = collect( myXml )
-- myVar would be a table/array of myXml

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  1. function parseargs(s)
  2.       local arg = {}
  3.       string.gsub(s, "(%w+)=([\"'])(.-)%2", function (w, _, a)
  4.         arg[w] = a
  5.       end)
  6.       return arg
  7.     end
  8.  
  9.     function collect(s)
  10.       local stack = {}
  11.       local top = {}
  12.       table.insert(stack, top)
  13.       local ni,c,label,xarg, empty
  14.       local i, j = 1, 1
  15.       while true do
  16.         ni,j,c,label,xarg, empty = string.find(s, "<(%/?)(%w+)(.-)(%/?)>", i)
  17.         if not ni then break end
  18.         local text = string.sub(s, i, ni-1)
  19.         if not string.find(text, "^%s*$") then
  20.           table.insert(top, text)
  21.         end
  22.         if empty == "/" then  -- empty element tag
  23.           table.insert(top, {label=label, xarg=parseargs(xarg), empty=1})
  24.         elseif c == "" then   -- start tag
  25.           top = {label=label, xarg=parseargs(xarg)}
  26.           table.insert(stack, top)   -- new level
  27.         else  -- end tag
  28.           local toclose = table.remove(stack)  -- remove top
  29.           top = stack[#stack]
  30.           if #stack < 1 then
  31.             error("nothing to close with "..label)
  32.           end
  33.           if toclose.label ~= label then
  34.             error("trying to close "..toclose.label.." with "..label)
  35.           end
  36.           table.insert(top, toclose)
  37.         end
  38.         i = j+1
  39.       end
  40.       local text = string.sub(s, i)
  41.       if not string.find(text, "^%s*$") then
  42.         table.insert(stack[#stack], text)
  43.       end
  44.       if #stack > 1 then
  45.         error("unclosed "..stack[stack.n].label)
  46.       end
  47.       return stack[1]
  48.     end

URL: http://lua-users.org/wiki/LuaXml

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