Saxy v0.6.0 Saxy.Handler behaviour View Source
This module provides callbacks to implement SAX events handler.
Link to this section Summary
Callbacks
Callback for event handling
Link to this section Callbacks
Callback for event handling.
This callback takes an event type, an event data and user_state
as the input.
The initial user_state
is the third argument in Saxy.parse_string/3
and Saxy.parse_stream/3
.
It can be accumulated and 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 feature is usually handy when we want to get the desired return without parsing the whole file.
SAX Events
There are a couple of events that need to be handled in the handler.
:start_document
The event data will be the XML prolog, which is a keyword list of :version
, :encoding
and :standalone
respectively.
:start_element
The event data is the element, which is a two-element tuple, respectively tag name, attributes.
:characters
The event data is the binary that matches CharData*
and Reference.
Note that it is not trimmed and includes all the whitespace characters that match CharData
.
:end_document
The event data is an empty tuple.
:end_element
The event data is the tag name of the closing element.
Examples
defmodule MyEventHandler do
@behaviour Saxy.Handler
def handle_event(:start_document, prolog, state) do
{:ok, [{:start_document, prolog} | state]}
end
def handle_event(:end_document, _data, state) do
{:ok, [{:end_document} | state]}
end
def handle_event(:start_element, {name, attributes}, state) do
{:ok, [{:start_element, name, attributes} | state]}
end
def handle_event(:end_element, name, state) do
{:ok, [{:end_element, name} | state]}
end
def handle_event(:characters, chars, state) do
{:ok, [{:chacters, chars} | state]}
end
end