xmerl_sax_demo.ex

defrecord Person, id: nil, name: nil
defrecord ParserState, persons: [], current_person: nil

defmodule TestXmerlSax do
  def xml do
    %b(
      <doc>
        <person id="1">Joe Armstrong</person>
        <person id="2">José Valim</person>
      </doc>
    )
  end

  def run do
    IO.inspect :xmerl_sax_parser.stream("",
      continuation_state: xml,
      continuation_fun: function(:get_rest, 1),
      event_fun: function(:event_fun, 3),
      event_state: ParserState.new
    )
  end

  defp get_rest("") do
    {"", :undefined}
  end

  defp get_rest(buffer) do
    String.next_grapheme(buffer)
  end

  defp event_fun({:startElement, _, 'person', _, attributes}, _, state) do
    Person.new(id: id(attributes))
    |> state.current_person
  end

  defp event_fun({:characters, chars}, _, ParserState[current_person: person] = state) when person != nil do
    person.name(:unicode.characters_to_binary(chars))
    |> state.current_person
  end

  defp event_fun({:endElement, _, 'person', _}, _, ParserState[current_person: person] = state) do
    state.
      update_persons([person | &1]).
      current_person(nil)
  end

  defp event_fun(_event, _location, state) do
    state
  end

  defp id(attributes) do
    Enum.find_value(attributes, function do
      ({_, _, 'id', id}) -> list_to_integer(id)
      _ -> nil
    end)
  end
end

TestXmerlSax.run