refactor(inputters): Move XML parser setup local to reader

inputters/xml.lua

@@ -1,6 +1,5 @@
 local base = require("inputters.base")
-
-local lom = require("lomwithpos")
+local lxp = require("lxp")
 
 local xml = pl.class(base)
 xml._name = "xml"
@@ -20,8 +19,58 @@ function xml.appropriate (round, filename, doc)
   end
 end
 
+local function startcommand (parser, command, options)
+  local stack = parser:getcallbacks().stack
+  local lno, col, pos = parser:pos()
+  local element = { command = command, options = options, lno = lno, col = col }
+  table.insert(stack, element)
+end
+
+local function endcommand (parser, command)
+  local stack = parser:getcallbacks().stack
+  local element = table.remove(stack)
+  assert(element.command == command)
+  local level = #stack
+  table.insert(stack[level], element)
+end
+
+local function text (parser, text)
+  local stack = parser:getcallbacks().stack
+  local element = stack[#stack]
+  local n = #element
+  if type(element[n]) == "string" then
+    element[n] = element[n] .. text
+  else
+    table.insert(element, text)
+  end
+end
+
+local function parse (doc)
+  local content = { StartElement = startcommand,
+              EndElement = endcommand,
+              CharacterData = text,
+              _nonstrict = true,
+              stack = {{}}
+            }
+  local parser = lxp.new(content)
+  local status, err
+  if type(doc) == "string" then
+    status, err = parser:parse(doc)
+    if not status then return nil, err end
+  else
+    for element in pairs(doc) do
+      status, err = parser:parse(element)
+      if not status then return nil, err end
+    end
+  end
+  status, err = parser:parse()
+  if not status then return nil, err end
+  parser:close()
+  return content.stack[1][1]
+end
+
 function xml.parse (_, doc)
-  local tree, err = lom.parse(doc)
+  local tree, err = parse(doc)
   if not tree then
     SU.error(err)
   end