feed format behaviour

lib/feed_reader/format.ex

@@ -0,0 +1,22 @@
+defmodule FeedReader.Format do
+  @moduledoc """
+  Behaviour implemented by built-in and explicitly supplied feed formats.
+
+  Detection examines only the bounded, replayable prefix provided by the caller.
+  XML formats provide their dedicated Saxy handler and create parser state with
+  an event sink; normalization returns the standalone feed and item value types.
+  """
+
+  @callback id() :: atom()
+  @callback detect(prefix :: binary()) :: :match | :no_match
+  @callback handler() :: module()
+  @callback new_parser_state(event_sink :: function(), opts :: keyword()) :: term()
+
+  @callback normalize_feed(state :: term(), opts :: keyword()) :: FeedReader.Feed.t()
+
+  @callback normalize_item(
+              raw_item :: map(),
+              feed :: FeedReader.Feed.t(),
+              opts :: keyword()
+            ) :: {:ok, FeedReader.Item.t()} | :skip | {:error, term()}
+end