Mail::IMAPClient::MessageSet - ranges of message sequence numbers


 my @msgs = $imap->search("SUBJECT","Virus"); # returns 1,3,4,5,6,9,10
 my $msgset = Mail::IMAPClient::MessageSet->new(@msgs);
 print $msgset;  # prints "1,3:6,9:10"

 # add message 14 to the set:
 $msgset += 14;
 print $msgset;  # prints "1,3:6,9:10,14"

 # add messages 16,17,18,19, and 20 to the set:
 $msgset .= "16,17,18:20";
 print $msgset;  # prints "1,3:6,9:10,14,16:20"

 # Hey, I didn't really want message 17 in there; let's take it out:
 $msgset -= 17;
 print $msgset;  # prints "1,3:6,9:10,14,16,18:20"

 # Now let's iterate over each message:
 for my $msg (@$msgset)
 {  print "$msg\n";  # Prints: "1\n3\n4\n5\n6..16\n18\n19\n20\n"
 print join("\n", @$msgset)."\n";     # same simpler
 local $" = "\n"; print "@$msgset\n"; # even more simple


The Mail::IMAPClient::MessageSet module is designed to make life easier for programmers who need to manipulate potentially large sets of IMAP message UID's or sequence numbers.

This module presents an object-oriented interface into handling your message sets. The object reference returned by the new method is an overloaded reference to a scalar variable that contains the message set's compact RFC2060 representation. The object is overloaded so that using it like a string returns this compact message set representation. You can also add messages to the set (using either a '.=' operator or a '+=' operator) or remove messages (with the '-=' operator). And if you use it as an array reference, it will humor you and act like one by calling unfold for you.

RFC2060 specifies that multiple messages can be provided to certain IMAP commands by separating them with commas. For example, "1,2,3,4,5" would specify messages 1, 2, 3, 4, and (you guessed it!) 5. However, if you are performing an operation on lots of messages, this string can get quite long. So long that it may slow down your transaction, and perhaps even cause the server to reject it. So RFC2060 also permits you to specify a range of messages, so that messages 1, 2, 3, 4 and 5 can also be specified as "1:5".

This is where Mail::IMAPClient::MessageSet comes in. It will convert your message set into the shortest correct syntax. This could potentially save you tons of network I/O, as in the case where you want to fetch the flags for all messages in a 10000 message folder, where the messages are all numbered sequentially. Delimited as commas, and making the best-case assumption that the first message is message "1", it would take 48893 bytes to specify the whole message set using the comma-delimited method. To specify it as a range, it takes just seven bytes (1:10000).

Note that the Mail::IMAPClient Range method can be used as a short-cut to specifying Mail::IMAPClient::MessageSet->new(@etc).)


The only class method you need to worry about is new. And if you create your Mail::IMAPClient::MessageSet objects via Mail::IMAPClient's Range method then you don't even need to worry about new.



 my $msgset = Mail::IMAPClient::MessageSet->new(@msgs);

The new method requires at least one argument. That argument can be either a message, a comma-separated list of messages, a colon-separated range of messages, or a combination of comma-separated messages and colon-separated ranges. It can also be a reference to an array of messages, comma-separated message lists, and colon separated ranges.

If more then one argument is supplied to new, then those arguments should be more message numbers, lists, and ranges (or references to arrays of them) just as in the first argument.

The message numbers passed to new can really be any kind of number at all but to be useful in a Mail::IMAPClient session they should be either message UID's (if your Uid parameter is true) or message sequence numbers.

The new method will return a reference to a Mail::IMAPClient::MessageSet object. That object, when double quoted, will act just like a string whose value is the message set expressed in the shortest possible way, with the message numbers sorted in ascending order and with duplicates removed.


The only object method currently available to a Mail::IMAPClient::MessageSet object is the unfold method.



    my $msgset = $imap->Range( $imap->messages ) ;
    my @all_messages = $msgset->unfold;

The unfold method returns an array of messages that belong to the message set. If called in a scalar context it returns a reference to the array instead.


Mail::IMAPClient::MessageSet overrides a number of operators in order to make manipulating your message sets easier. The overridden operations are:


Attempts to stringify a Mail::IMAPClient::MessageSet object will result in the compact message specification being returned, which is almost certainly what you will want.


Attempts to autoincrement a Mail::IMAPClient::MessageSet object will result in a message (or messages) being added to the object's message set.


    $msgset += 34;
    # Message #34 is now in the message set


Attempts to concatenate to a Mail::IMAPClient::MessageSet object will result in a message (or messages) being added to the object's message set.


    $msgset .= "34,35,36,40:45";
    # Messages 34,35,36,40,41,42,43,44,and 45 are now in the message set

The .= operator and the += operator can be used interchangeably, but as you can see by looking at the examples there are times when use of one has an aesthetic advantage over use of the other.


Attempts to autodecrement a Mail::IMAPClient::MessageSet object will result in a message being removed from the object's message set.


    $msgset -= 34;
    # Message #34 is no longer in the message set
    $msgset -= "1:10";
    # Messages 1 through 10 are no longer in the message set

If you attempt to remove a message that was not in the original message set then your resulting message set will be the same as the original, only more expensive. However, if you attempt to remove several messages from the message set and some of those messages were in the message set and some were not, the additional overhead of checking for the messages that were not there is negligible. In either case you get back the message set you want regardless of whether it was already like that or not.


 David J. Kernen
 The Kernen Consulting Group, Inc


 Copyright 1999, 2000, 2001, 2002 The Kernen Group, Inc.
 All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of either:

a) the "Artistic License" which comes with this Kit, or
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