Re: Representing windows of time in a string

in reply to Representing windows of time in a string

Nitrox,
As I mentioned in the CB, The Panther has a section on using bitmap vectors to determine scheduling conflicts. It is just a matter of logically AND-ing the two bitmaps.

Each hour in the week would be one bit. You would be storing a 21 byte bitmap vector. If the bit is set, then there is a problem if the event happens at this hour. The task then is to design a way to parse your range and localtime() into the bitmap vector.

The following is very basic, but it gives you a fully functional framework. Expand it as you see fit.

#!/usr/bin/perl -w
use strict;

my $interval = "Mon 3-4, Mon 8-12, Wed 4-7, Thu 11-18";

my $alert = interval_parse( $interval );
my $alarm = get_current();

print "Page someone\n" if Critical($alert, $alarm);

sub interval_parse {
    my $interval = shift;
    my $bitmap = "";
    my %day_offset = (
        sun => 0, mon => 24, tue => 48, wed => 72, thu => 96, fri => 1
+20, sat => 144
    );
    for my $range (split /,/ , $interval) {
        my ($day, $from, $to) = ($range =~ /([A-Za-z]+)\s+(\d+)-(\d+)/
+);
        my $offset = $day_offset{lc $day};
        $from += $offset;
        $to   += $offset;
        vec( $bitmap, $_, 1 ) = 1 for $from .. $to;
    }
    return $bitmap;
}

sub get_current {
    my ($hour, $day) = (localtime())[2,6];
    my $bitmap = "";
    my $now = $day * 24 + $hour;
    vec ( $bitmap, $now, 1 ) = 1;
    return $bitmap;
}

sub Critical {
    my ($alert, $alarm) = @_;
    my ($combined) = $alert & $alarm;
    my $offset = length ($combined) * 8;
    while (--$offset >= 0) {
        return 1 if vec($combined, $offset, 1);
    }
    return 0;
}
[download]

I hope this helps - L~R

In Section Seekers of Perl Wisdom