Mail::Mbox::MessageParser - A fast and simple mbox folder
reader
#!/usr/bin/perl
use Mail::Mbox::MessageParser;
# Compression support
my $file_name = 'mail/saved-mail.xz';
my $file_handle = new FileHandle($file_name);
# Set up cache. (Not necessary if enable_cache is false.)
Mail::Mbox::MessageParser::SETUP_CACHE(
{ 'file_name' => '/tmp/cache' } );
my $folder_reader =
new Mail::Mbox::MessageParser( {
'file_name' => $file_name,
'file_handle' => $file_handle,
'enable_cache' => 1,
'enable_grep' => 1,
} );
die $folder_reader unless ref $folder_reader;
# Any newlines or such before the start of the first email
my $prologue = $folder_reader->prologue;
print $prologue;
# This is the main loop. It's executed once for each email
while(!$folder_reader->end_of_file())
{
my $email = $folder_reader->read_next_email();
print $$email;
}
This module implements a fast but simple mbox folder reader. One
of three implementations (Cache, Grep, Perl) will be used depending on the
wishes of the user and the system configuration. The first implementation is
a cached-based one which stores email information about mailboxes on the
file system. Subsequent accesses will be faster because no analysis of the
mailbox will be needed. The second implementation is one based on GNU grep,
and is significantly faster than the Perl version for mailboxes which
contain very large (10MB) emails. The final implementation is a fast
Perl-based one which should always be applicable.
The Cache implementation is about 6 times faster than the standard
Perl implementation. The Grep implementation is about 4 times faster than
the standard Perl implementation. If you have GNU grep, it's best to enable
both the Cache and Grep implementations. If the cache information is
available, you'll get very fast speeds. Otherwise, you'll take about a 1/3
performance hit when the Grep version is used instead.
The overriding requirement for this module is speed. If you wish
more sophisticated parsing, use Mail::MboxParser (which is based on this
module) or Mail::Box.
- SETUP_CACHE(...)
-
SETUP_CACHE( { 'file_name' => <cache file name> } );
<cache file name> - the file name of the cache
Call this function once to set up the cache before creating
any parsers. You must provide the location to the cache file. There is
no default value.
- new(...)
-
new( { 'file_name' => <mailbox file name>,
'file_handle' => <mailbox file handle>,
'enable_cache' => <1 or 0>,
'enable_grep' => <1 or 0>,
'force_processing' => <1 or 0>,
'debug' => <1 or 0>,
} );
<mailbox file name> - the file name of the mailbox
<mailbox file handle> - the already opened file handle for the mailbox
<enable_cache> - true to attempt to use the cache implementation
<enable_grep> - true to attempt to use the grep implementation
<force_processing> - true to force processing of files that look invalid
<debug> - true to print some debugging information to STDERR
The constructor takes either a file name or a file handle, or
both. If the file handle is not defined, Mail::Mbox::MessageParser will
attempt to open the file using the file name. You should always pass the
file name if you have it, so that the parser can cache the mailbox
information.
This module will automatically decompress the mailbox as
necessary. If a filename is available but the file handle is undef, the
module will call bzip, bzip2, gzip, lzip, xz to decompress the file in
memory if the filename ends with the appropriate suffix. If the file
handle is defined, it will detect the type of compression and apply the
correct decompression program.
The Cache, Grep, or Perl implementation of the parser will be
loaded, whichever is most appropriate. For example, the first time you
use caching, there will be no cache. In this case, the grep
implementation can be used instead. The cache will be updated in memory
as the grep implementation parses the mailbox, and the cache will be
written after the program exits. The file name is optional, in which
case enable_cache and enable_grep must both be false.
force_processing will cause the module to process
folders that look to be binary, or whose text data doesn't look like a
mailbox.
Returns a reference to a Mail::Mbox::MessageParser object on
success, and a scalar desribing an error on failure. ("Not a
mailbox", "Can't open <filename>: <system
error>", "Can't execute <uncompress command> for file
<filename>"
- reset()
- Reset the filehandle and all internal state. Note that this will not work
with filehandles which are streams. If there is enough demand, I may add
the ability to store the previously read stream data internally so that
reset() will work correctly.
- endline()
- Returns "\n" or "\r\n", depending on the file
format.
- prologue()
- Returns any newlines or other content at the start of the mailbox prior to
the first email.
- end_of_file()
- Returns true if the end of the file has been encountered.
- line_number()
- Returns the line number for the start of the last email read.
- number()
- Returns the number of the last email read. (i.e. The first email will have
a number of 1.)
- length()
- Returns the length of the last email read.
- offset()
- Returns the byte offset of the last email read.
- read_next_email()
- Returns a reference to a scalar holding the text of the next email in the
mailbox, or undef at the end of the file.
No known bugs.
Contact david@coppit.org for bug reports and suggestions.
David Coppit <david@coppit.org>.
This code is distributed under the GNU General Public License
(GPL) Version 2. See the file LICENSE in the distribution for details.
This code was originally part of the grepmail distribution. See
http://grepmail.sf.net/ for previous versions of grepmail which included
early versions of this code.
Mail::MboxParser, Mail::Box