### 12.2.2.1 FeedParser API

New in version 2.4.

The `FeedParser` provides an API that is conducive to incremental parsing of email messages, such as would be necessary when reading the text of an email message from a source that can block (e.g. a socket). The `FeedParser` can of course be used to parse an email message fully contained in a string or a file, but the classic `Parser` API may be more convenient for such use cases. The semantics and results of the two parser APIs are identical.

The `FeedParser`'s API is simple; you create an instance, feed it a bunch of text until there's no more to feed it, then close the parser to retrieve the root message object. The `FeedParser` is extremely accurate when parsing standards-compliant messages, and it does a very good job of parsing non-compliant messages, providing information about how a message was deemed broken. It will populate a message object's defects attribute with a list of any problems it found in a message. See the `email.Errors` module for the list of defects that it can find.

Here is the API for the `FeedParser`:

class `FeedParser`( | [_factory])

  Create a `FeedParser` instance. Optional _factory is a no-argument callable that will be called whenever a new message object is needed. It defaults to the `email.Message.Message` class.

`feed`( | data)

  Feed the `FeedParser` some more data. data should be a string containing one or more lines. The lines can be partial and the `FeedParser` will stitch such partial lines together properly. The lines in the string can have any of the common three line endings, carriage return, newline, or carriage return and newline (they can even be mixed).

`close`( | )

  Closing a `FeedParser` completes the parsing of all previously fed data, and returns the root message object. It is undefined what happens if you feed more data to a closed `FeedParser`.