NAME

       struct::set - Procedures for manipulating sets

SYNOPSIS

       package require Tcl  8.0

       package require struct::set  ?2.2.3?

       ::struct::set empty set

       ::struct::set size set

       ::struct::set contains set item

       ::struct::set union ?set1...?

       ::struct::set intersect ?set1...?

       ::struct::set difference set1 set2

       ::struct::set symdiff set1 set2

       ::struct::set intersect3 set1 set2

       ::struct::set equal set1 set2

       ::struct::set include svar item

       ::struct::set exclude svar item

       ::struct::set add svar set

       ::struct::set subtract svar set

       ::struct::set subsetof A B

_________________________________________________________________________________________________

DESCRIPTION

       The ::struct::set namespace contains several useful commands for processing finite sets.

       It  exports  only  a  single  command, struct::set. All functionality provided here can be
       reached through a subcommand of this command.

       Note: As of version 2.2 of this package a critcl based C implementation is available. This
       implementation however requires Tcl 8.4 to run.

COMMANDS

       ::struct::set empty set
              Returns a boolean value indicating if the set is empty (true), or not (false).

       ::struct::set size set
              Returns  an  integer  number  greater  than or equal to zero. This is the number of
              elements in the set. In other words, its cardinality.

       ::struct::set contains set item
              Returns a boolean value indicating if the set contains the element item (true),  or
              not (false).

       ::struct::set union ?set1...?
              Computes  the  set  containing  the  union of set1, set2, etc., i.e. "set1 + set2 +
              ...", and returns this set as the result of the command.

       ::struct::set intersect ?set1...?
              Computes the set containing the intersection of set1, set2, etc., i.e. "set1 * set2
              * ...", and returns this set as the result of the command.

       ::struct::set difference set1 set2
              Computes  the  set containing the difference of set1 and set2, i.e. ("set1 - set2")
              and returns this set as the result of the command.

       ::struct::set symdiff set1 set2
              Computes the set containing the symmetric difference of set1 and set2, i.e. ("(set1
              - set2) + (set2 - set1)") and returns this set as the result of the command.

       ::struct::set intersect3 set1 set2
              This  command is a combination of the methods intersect and difference.  It returns
              a three-element list containing "set1*set2", "set1-set2", and "set2-set1", in  this
              order.  In  other  words,  the  intersection  of  the two parameter sets, and their
              differences.

       ::struct::set equal set1 set2
              Returns a boolean value indicating if the two sets are equal (true) or not (false).

       ::struct::set include svar item
              The element item is added to the set specified by the variable name  in  svar.  The
              return  value  of the command is empty. This is the equivalent of lappend for sets.
              If the variable named by svar does not exist it will be created.

       ::struct::set exclude svar item
              The element item is removed from the set specified by the variable  name  in  svar.
              The return value of the command is empty. This is a near-equivalent of lreplace for
              sets.

       ::struct::set add svar set
              All the element of set are added to the set specified by the variable name in svar.
              The  return value of the command is empty. This is like the method include, but for
              the addition of a whole set. If the variable named by svar does not exist  it  will
              be created.

       ::struct::set subtract svar set
              All  the  element of set are removed from the set specified by the variable name in
              svar. The return value of the command is empty. This is like  the  method  exclude,
              but for the removal of a whole set.

       ::struct::set subsetof A B
              Returns a boolean value indicating if the set A is a true subset of or equal to the
              set B (true), or not (false).

REFERENCES

BUGS, IDEAS, FEEDBACK

       This document, and the package it describes,  will  undoubtedly  contain  bugs  and  other
       problems.   Please  report  such  in  the  category  struct  :: set of the Tcllib Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you
       may have for either package and/or documentation.

       When proposing code changes, please provide unified diffs, i.e the output of diff -u.

       Note further that attachments are strongly preferred over inlined patches. Attachments can
       be made by going to the Edit form of the ticket immediately after its creation,  and  then
       using the left-most button in the secondary navigation bar.

KEYWORDS

       cardinality,  difference,  emptiness, exclusion, inclusion, intersection, membership, set,
       symmetric difference, union

CATEGORY

       Data structures

COPYRIGHT

       Copyright (c) 2004-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>