\declaremodule{standard}{email.parser}\modulesynopsis{Parse flat text email messages to produce a message	        object structure.} Message object structures can be created in one of two ways: they can becreated from whole cloth by instantiating \class{Message} objects andstringing them together via \method{attach()} and\method{set_payload()} calls, or they can be created by parsing a flat textrepresentation of the email message. The \module{email} package provides a standard parser that understandsmost email document structures, including MIME documents.  You canpass the parser a string or a file object, and the parser will returnto you the root \class{Message} instance of the object structure.  Forsimple, non-MIME messages the payload of this root object will likelybe a string containing the text of the message.  For MIMEmessages, the root object will return \code{True} from its\method{is_multipart()} method, and the subparts can be accessed viathe \method{get_payload()} and \method{walk()} methods. There are actually two parser interfaces available for use, the classic\class{Parser} API and the incremental \class{FeedParser} API.  The classic\class{Parser} API is fine if you have the entire text of the message inmemory as a string, or if the entire message lives in a file on the filesystem.  \class{FeedParser} is more appropriate for when you're reading themessage from a stream which might block waiting for more input (e.g. readingan email message from a socket).  The \class{FeedParser} can consume and parsethe message incrementally, and only returns the root object when you close theparser\footnote{As of email package version 3.0, introduced inPython 2.4, the classic \class{Parser} was re-implemented in terms of the\class{FeedParser}, so the semantics and results are identical between the twoparsers.}. Note that the parser can be extended in limited ways, and of courseyou can implement your own parser completely from scratch.  There isno magical connection between the \module{email} package's bundledparser and the \class{Message} class, so your custom parser can createmessage object trees any way it finds necessary. \subsubsection{FeedParser API} \versionadded{2.4} The \class{FeedParser}, imported from the \module{email.feedparser} module,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 asource that can block (e.g. a socket).  The\class{FeedParser} can of course be used to parse an email message fullycontained in a string or a file, but the classic \class{Parser} API may bemore convenient for such use cases.  The semantics and results of the twoparser APIs are identical. The \class{FeedParser}'s API is simple; you create an instance, feed it abunch of text until there's no more to feed it, then close the parser toretrieve the root message object.  The \class{FeedParser} is extremelyaccurate when parsing standards-compliant messages, and it does a very goodjob of parsing non-compliant messages, providing information about how amessage was deemed broken.  It will populate a message object's \var{defects}attribute with a list of any problems it found in a message.  See the\refmodule{email.errors} module for the list of defects that it can find. Here is the API for the \class{FeedParser}: \begin{classdesc}{FeedParser}{\optional{_factory}}Create a \class{FeedParser} instance.  Optional \var{_factory} is ano-argument callable that will be called whenever a new message object isneeded.  It defaults to the \class{email.message.Message} class.\end{classdesc} \begin{methoddesc}[FeedParser]{feed}{data}Feed the \class{FeedParser} some more data.  \var{data} should be astring containing one or more lines.  The lines can be partial and the\class{FeedParser} will stitch such partial lines together properly.  Thelines in the string can have any of the common three line endings, carriagereturn, newline, or carriage return and newline (they can even be mixed).\end{methoddesc} \begin{methoddesc}[FeedParser]{close}{}Closing a \class{FeedParser} completes the parsing of all previously fed data,and returns the root message object.  It is undefined what happens if you feedmore data to a closed \class{FeedParser}.\end{methoddesc} \subsubsection{Parser class API} The \class{Parser} class, imported from the \module{email.parser} module,provides an API that can be used to parse a message when the complete contentsof the message are available in a string or file.  The\module{email.parser} module also provides a second class, called\class{HeaderParser} which can be used if you're only interested inthe headers of the message. \class{HeaderParser} can be much faster inthese situations, since it does not attempt to parse the message body,instead setting the payload to the raw body as a string.\class{HeaderParser} has the same API as the \class{Parser} class. \begin{classdesc}{Parser}{\optional{_class}}The constructor for the \class{Parser} class takes an optionalargument \var{_class}.  This must be a callable factory (such as afunction or a class), and it is used whenever a sub-message objectneeds to be created.  It defaults to \class{Message} (see\refmodule{email.message}).  The factory will be called withoutarguments. The optional \var{strict} flag is ignored.  \deprecated{2.4}{Because the\class{Parser} class is a backward compatible API wrapper around thenew-in-Python 2.4 \class{FeedParser}, \emph{all} parsing is effectivelynon-strict.  You should simply stop passing a \var{strict} flag to the\class{Parser} constructor.} \versionchanged[The \var{strict} flag was added]{2.2.2}\versionchanged[The \var{strict} flag was deprecated]{2.4}\end{classdesc} The other public \class{Parser} methods are: \begin{methoddesc}[Parser]{parse}{fp\optional{, headersonly}}Read all the data from the file-like object \var{fp}, parse theresulting text, and return the root message object.  \var{fp} mustsupport both the \method{readline()} and the \method{read()} methodson file-like objects. The text contained in \var{fp} must be formatted as a block of \rfc{2822}style headers and header continuation lines, optionally preceded by aenvelope header.  The header block is terminated either by theend of the data or by a blank line.  Following the header block is thebody of the message (which may contain MIME-encoded subparts). Optional \var{headersonly} is as with the \method{parse()} method. \versionchanged[The \var{headersonly} flag was added]{2.2.2}\end{methoddesc} \begin{methoddesc}[Parser]{parsestr}{text\optional{, headersonly}}Similar to the \method{parse()} method, except it takes a stringobject instead of a file-like object.  Calling this method on a stringis exactly equivalent to wrapping \var{text} in a \class{StringIO}instance first and calling \method{parse()}. Optional \var{headersonly} is a flag specifying whether to stopparsing after reading the headers or not.  The default is \code{False},meaning it parses the entire contents of the file. \versionchanged[The \var{headersonly} flag was added]{2.2.2}\end{methoddesc} Since creating a message object structure from a string or a fileobject is such a common task, two functions are provided as aconvenience.  They are available in the top-level \module{email}package namespace. \begin{funcdesc}{message_from_string}{s\optional{, _class\optional{, strict}}}Return a message object structure from a string.  This is exactlyequivalent to \code{Parser().parsestr(s)}.  Optional \var{_class} and\var{strict} are interpreted as with the \class{Parser} class constructor. \versionchanged[The \var{strict} flag was added]{2.2.2}\end{funcdesc} \begin{funcdesc}{message_from_file}{fp\optional{, _class\optional{, strict}}}Return a message object structure tree from an open file object.  Thisis exactly equivalent to \code{Parser().parse(fp)}.  Optional\var{_class} and \var{strict} are interpreted as with the\class{Parser} class constructor. \versionchanged[The \var{strict} flag was added]{2.2.2}\end{funcdesc} Here's an example of how you might use this at an interactive Pythonprompt: \begin{verbatim}>>> import email>>> msg = email.message_from_string(myString)\end{verbatim} \subsubsection{Additional notes} Here are some notes on the parsing semantics: \begin{itemize}\item Most non-\mimetype{multipart} type messages are parsed as a single      message object with a string payload.  These objects will return      \code{False} for \method{is_multipart()}.  Their      \method{get_payload()} method will return a string object. \item All \mimetype{multipart} type messages will be parsed as a      container message object with a list of sub-message objects for      their payload.  The outer container message will return      \code{True} for \method{is_multipart()} and their      \method{get_payload()} method will return the list of      \class{Message} subparts. \item Most messages with a content type of \mimetype{message/*}      (e.g. \mimetype{message/delivery-status} and      \mimetype{message/rfc822}) will also be parsed as container      object containing a list payload of length 1.  Their      \method{is_multipart()} method will return \code{True}.  The      single element in the list payload will be a sub-message object. \item Some non-standards compliant messages may not be internally consistent      about their \mimetype{multipart}-edness.  Such messages may have a      \mailheader{Content-Type} header of type \mimetype{multipart}, but their      \method{is_multipart()} method may return \code{False}.  If such      messages were parsed with the \class{FeedParser}, they will have an      instance of the \class{MultipartInvariantViolationDefect} class in their      \var{defects} attribute list.  See \refmodule{email.errors} for      details.\end{itemize}