Saxy v0.3.0 Saxy.Handler behaviour View Source

This module provides callbacks for implementing SAX events handler.

Link to this section Summary

Link to this section Callbacks

Link to this callback handle_event(event_type, data, user_state) View Source
handle_event(event_type :: atom(), data :: tuple(), user_state :: term()) ::
  {:ok, user_state :: term()} | {:stop, returning :: term()}

Callback for event handling.

This callback takes an event type, an event data and user_state as the input.

user_state is the third argument in Saxy.parse_string/3 and Saxy.parse_stream/3. It and can be accumulated, passed around during the parsing time by returning it as the result of the callback implementation, which can be used to keep track of data when parsing is happening.

Returning {:ok, new_state} continues the parsing process with the new state.

Returning {:stop, anything} stops the prosing process immediately, and anything will be returned. This is useful when we want to get the desired return without parsing the whole file.

Examples

defmodule MyEventHandler do
  @behaviour Saxy.Handler

  def handle_event(:start_document, prolog, state) do
    IO.inspect "Start parsing document"
    {:ok, [{:start_document, prolog} | state]}
  end

  def handle_event(:end_document, _data, state) do
    IO.inspect "Finish parsing document"
    {:ok, [{:end_document} | state]}
  end

  def handle_event(:start_element, {name, attributes}, state) do
    IO.inspect "Start parsing element #{name} with attributes #{inspect(attributes)}"
    {:ok, [{:start_element, name, attributes} | state]}
  end

  def handle_event(:end_element, {name}, state) do
    IO.inspect "Finish parsing element #{name}"
    {:ok, [{:end_element, name} | state]}
  end

  def handle_event(:characters, chars, state) do
    IO.inspect "Receive characters #{chars}"
    {:ok, [{:chacters, chars} | state]}
  end
end