Set-Formula

   Set::Formula - Formula calculation for sets.

SYNOPSIS
   use Set::Formula;
   formula_checker (string_containing_formula);    # syntax check without debug
   formula_checker (string_containing_formula, 1); # syntax check with    debug

   formula_calcul  (string_containing_formula, \%result, \%HoH_sets);    # without 
   formula_calcul  (string_containing_formula, \%result, \%HoH_sets, 1); # with    

   equality_checker (\%set1, \%set2);              # without debug
   equality_checker (\%set1, \%set2, 1);           # with    debug

DESCRIPTION
   formula_checker  - checks syntax of formula without its calculation.
   formula_calcul   - calculates formula without its syntax check.
   equality_checker - checks, if 2 sets are equal.

   Formula should be written in common arithmetic notation (infix notation)
   and can contain unrestricted amount of nested parentheses ().

   Supported set operators are
   "+"    - union,
   "-"    - complement,
   "^"    - intersection.

   All these operators are binary operators, i.e. they require 2 operands.

   Formula without parentheses is evaluated from left to right
   with equal priority for all operators.
   Parentheses increase priority of partial formula expressions.

   White characters including new line in formula are accepted and ignored.
   Thus formula might be placed into both a single line and multiple lines.

   Return Values
   formula_checker and formula_calcul return nonzero on success,
   the undefined value otherwise.

   equality_checker returns 1 if both sets are equal, else 0.

TECHNICAL IMPLEMENTATION OF SETS
   For formula_checker and formula_calcul
   --------------------------------------
   All formula operands must be highest level keys of a hash of hashes,
   that is named in example below as %HoH_sets.
   Lowest level keys of this hash of hashes form corresponding sets.
   Values of lowest level hashes are irrelevant (can be undefined).

   Name convention for formula operands: begin with a character, optionally
   following by any amount of characters, digits, underlines.
   Operand names are case sensitive.

   For equality_checker
   --------------------
   Operands are sets, written in keys of one dimensional hashes.

EXAMPLES
   use Set::Formula;

   @A{qw (bisque  red      blue  yellow)} = ();
   @B{qw (bisque  brown    white yellow)} = ();
   @C{qw (magenta pink     green       )} = ();
   @D{qw (magenta pink     rose        )} = ();
   @E{qw (bisque  honeydew             )} = ();
   %HoH_sets = ( A=>\%A, B=>\%B, C=>\%C, D=>\%D, E=>\%E );

   # or alternatively
   %HoH_sets = (
   A => { bisque  => 0,  red      => 0,  blue  => 0,  yellow => 0, },
   B => { bisque  => 0,  brown    => 0,  white => 0,  yellow => 0, },
   C => { magenta => 0,  pink     => 0,  green => 0,               },
   D => { grey    => 0,  pink     => 0,  rose  => 0,               },
   E => { bisque  => 0,  honeydew => 0,                            }
   );
   #  A, B, C, D, F are operands. Every of them is a set, written in keys of sublev

   $formula  = "A ^ ( B + (C ^ D) ) - E";
   %result = ();  # this hash must be declared, but it must not be emptied before
   # call of formula_calcul()

   # Usage of formula_checker() before formula_calcul() is recommended,
   # but is not mandatory
   formula_checker ($formula)                       || die "Error in formula\n";
   formula_calcul  ($formula, \%result, \%HoH_sets) || die "Error in formula\n";

   for (keys %result) {print "$_\n"}   # prints result of formula calculation

   @expected_result{qw (magenta yellow)} = ();
   if (equality_checker (\%result, \%expected_result)) { print "equal\n" }
   else                                                { print "not equal\n" }

EXPORT
   formula_checker,
   formula_calcul,
   equality_checker.

SEE ALSO
   Part "Basic operations" - http://en.wikipedia.org/wiki/Set_(mathematics)
   Infix notation          - http://en.wikipedia.org/wiki/Infix_notation

AUTHOR
   Mart Rivilis, rivilism@cpan.com

INSTALLATION

To install this module, run the following commands:

	perl Makefile.PL
	make
	make test
	make install

SUPPORT AND DOCUMENTATION

After installing, you can find documentation for this module with the
perldoc command.

    perldoc Set::Formula

You can also look for information at:

    RT, CPAN's request tracker (report bugs here)
        http://rt.cpan.org/NoAuth/Bugs.html?Dist=Set-Formula

    AnnoCPAN, Annotated CPAN documentation
        http://annocpan.org/dist/Set-Formula

    CPAN Ratings
        http://cpanratings.perl.org/d/Set-Formula

    Search CPAN
        http://search.cpan.org/dist/Set-Formula/


LICENSE AND COPYRIGHT

Copyright (C) 2013 Mart Rivilis

This program is free software; you can redistribute it and/or modify it
under the terms of the the Artistic License (2.0). You may obtain a
copy of the full license at:

L<http://www.perlfoundation.org/artistic_license_2_0>

Any use, modification, and distribution of the Standard or Modified
Versions is governed by this Artistic License. By using, modifying or
distributing the Package, you accept this license. Do not use, modify,
or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made
by someone other than you, you are nevertheless required to ensure that
your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service
mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge
patent license to make, have made, use, offer to sell, sell, import and
otherwise transfer the Package with respect to any patent claims
licensable by the Copyright Holder that are necessarily infringed by the
Package. If you institute patent litigation (including a cross-claim or
counterclaim) against any party alleging that the Package constitutes
direct or contributory patent infringement, then this Artistic License
to you shall terminate on the date that such litigation is filed.

Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER
AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES.
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