From 3446c3aa4d60c7d7e87e4b2c5fea1564181f82c1 Mon Sep 17 00:00:00 2001
From: Moises Macia <mmacia@gmail.com>
Date: Mon, 23 Feb 2026 21:51:31 +0000
Subject: [PATCH] feed format behaviour

---
 lib/feed_reader/format.ex | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 lib/feed_reader/format.ex

diff --git a/lib/feed_reader/format.ex b/lib/feed_reader/format.ex
new file mode 100644
index 0000000..ff52156
--- /dev/null
+++ b/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