NAME
Bitmask::Data - Handle unlimited length bitmasks in an easy and flexible way
SYNOPSIS
# Create a simple bitmask class
package MyBitmask;
use base qw(Bitmask::Data);
__PACKAGE__->bitmask_length(18);
__PACKAGE__->bitmask_default('0b000000000000000011');
__PACKAGE__->init(
'value1' => '0b000000000000000001',
'value2' => '0b000000000000000010',
'value2' => '0b000000000000000100',
'value4' => '0b000000000000001000',
'value5' => '0b000000000000010000',
...
);
## Somewhere else in your code
use MyBitmask;
my $bm1 = MyBitmask->new('value1','value3');
my $bm2 = MyBitmask->new('0b000000000000010010');
$bm1->add('value3');
my $bm3 = $bm1 | $bm2;
$bm3->string;DESCRIPTION
This package helps you dealing with bitmasks. First you need to subclass Bitmask::Data and set the bitmask values and length. (If you are only working with a single bitmask in a simple application you might also initialize the bitmask directly in the Bitmask::Data module).
After the initialization you can create an arbitrary number of bitmask objects which can be accessed and manipulated with convenient methods and overloaded arithmetic and bit operators.
Bitmask::Data does not store bitmasks as integers internally, but as strings conststing of \0 and \1, hence makinging unlimited length bitmasks possible.
METHODS
Class Methods
bitmask_length
Set/Get the length of the bitmask. Do not change this value after the initialization.
Bitmask length is unlimited.
Default: 16
bitmask_default
Set/Get the default bitmask for empty Bitmask::Data objects.
Default: undef
bitmask_lazyinit
If true warning for lazy initialization are disabled. (Lazy initialization = call of init without bitmask bit values).
Default: 0
__PACKAGE__->bitmask_lazyinit(1);
__PACKAGE__->bitmask_length(6);
__PACKAGE__->init(
'value1', # will be 0b000001
'value2', # will be 0b000010
'value3' # will be 0b000100
);If bitmask_lazyinit is 2 then bit values will be filled from left to right, otherwise from right to left
__PACKAGE__->bitmask_lazyinit(2);
__PACKAGE__->bitmask_length(6);
__PACKAGE__->init(
'value1', # will be 0b100000
'value2', # will be 0b010000
'value3' # will be 0b001000
);bitmask_items
HASHREF of all bitmask items, with values as keys and bitmask as values.
init
CLASS->init(LIST of VALUES);Initializes the bitmask class. You can supply a list of possible values. Optionally you can also specify the bits for the mask by adding bit values after the value.
CLASS->init(
'value1' => 0b000001,
'value2' => 0b000010,
'value3' => 0b001000,
'value4' => 0b010000,
);With bitmask_lazyinit enabled you can also skip the bitmask bit values
CLASS->bitmask_lazyinit(1);
CLASS->init(
'value1',
'value2',
'value3',
'value4',
);Bits may be supplied as integers, strings or Math::BigInt objects (not recommended).
CLASS->init(
'value1' => 0b000001, # integer
'value2' => 2, # integer
'value3' => '0b000100' # string starting with '0b'
'value4' => '0B001000' # string starting with '0B'
'value5' => '\0\1\0\0\0\0' # string consisting of \0 and \1
'value6' => Math::BigInt->new("32") # Math::BigInt object
);int2bit
my $bitmask_string = CLASS->int2bit(INTEGER);Helper method that turns an integer into the internal bitmask representation
string2bit
my $bitmask_string = CLASS->string2bit(STRING);Helper method that takes a string like '0B001010' or '0b010101' and turns it into the internal bitmask representation
any2bitmask
my $bitmask_string = CLASS->any2bitmask(ANYTHING);Helper method that tries to turn arbitrary arguments into the internal bitmask representation. This method can hanle
any Bitmask::Data object
Math::BigInt object
a string matching on of the bitmask values
a bitmask string consisting of \0 and \1 characters
a bitmask string starting with '0b' or '0B' and containing only 0 and 1
an integer
_parse_params
my $bitmask_string = CLASS->_parse_params(LIST)Helper method for parsing params passed to various methods.
Overloaded operators
Bitmask::Data uses overload by default.
Numeric context
Returns bitmask integer value (see integer method). For large bitmasks (> 40 bits) this will always be a Math::BigInt object (hence using this method is not recommended).
Scalar context
Returns bitmask string representation (see string method)
==, eq, <=>, cmp
Works like 'has_any'
~~
Works like has_any.
$bm = Somebitmask->new('v1','v2'); $bm ~~ ['v1','v3'] # true, because 'v1' matches even if 'v3' is not set+, -
Adds/Removes bits to/from the bitmask without changing the current object. The result is returned as a new Bitmask::Data object.
-=, +=
Adds/Removes bits to/from the current bitmask object.
~, ^, &, |
Performs the bitwise operations without changing the current object. The result is returned as a new Bitmask::Data object.
^=, &=, |=
Performs the bitwise operations on the current bitmask object.
Constructors
new
my $bm = MyBitmask->new();
my $bm = MyBitmask->new('value1');
my $bm = MyBitmask->new('0b00010000010000');
my $bm = MyBitmask->new(124);
my $bm = MyBitmask->new(0b00010000010000);
my $bm = MyBitmask->new(0x2);
my $bm = MyBitmask->new($another_bm_object);
my $bm = MyBitmask->new("\0\1\0\0\1");
my $bm = MyBitmask->new('value2', 'value3');
my $bm = MyBitmask->new([32, 'value1', 0b00010000010000]);Create a new bitmask object. You can supply almost any combination of ARRAYREFS, bits, integers, Bitmask::Data objects, Math::BigInt objects, bitmasks and values, even mix different types. See any2bitmask for details on possible formats.
new_from_bitmask
my $bm = MyBitmask->new_from_bitmask($bitmask_string);Create a new bitmask object from a bitmask string (as returned by many helper methods).
Public Methods
clone
my $bm_new = $bm->clone();Clones an existing Bitmask::Data object and returns it.
set
$bm->set(PARAMS);This method resets the current bitmask and sets the supplied arguments. Takes the same arguments as new.
Returns the object.
remove
$bm->remove(PARAMS)Removes the given values/bits from the bitmask. Takes the same arguments as new.
Returns the object.
add
$bm->add(PARAMS)Adds the given values/bits to the bitmask. Takes the same arguments as new.
Returns the object.
reset
$bm->reset()Resets the bitmask to the default (or empty) bitmask.
Returns the object.
set_all
$bm->set_all()Sets all defined bits in the bitmask.
Returns the object.
neg
$bm->neg()Negates/Inverts the bitmask
Returns the object.
list
my @values = $bm->list();
OR
my $values = $bm->list();In list context, this returns a list of the set values in scalar context, this returns an array reference to the list of values.
length
my $length = $bm->length();Number of set bitmask values.
first
my $value = $bm->first()Returns the first set value. The order is determined by the bit value.
integer
my $integer = $bm->integer();Returns the bitmask as an integer. For bitmasks with a length > 40 this will always be a Math::BigInt object.
string
my $string = $bm->string();Returns the bitmask as a string of 0 and 1.
bitmask
my $string = $bm->bitmask();Returns the bitmask in the internal representation: A string of \0 and \1
sqlfilter_all
This method can be used for database searches in conjunction with SQL::Abstract an POSTGRESQL (SQL::Abstract is used by DBIx::Class for generating searches). The search will find all database rows with bitmask that have at least the given values set. (use the sql method for an exact match)
Example how to use sqlfilter with SQL::Abstract:
my($stmt, @bind) = $sql->select(
'mytable',
\@fields,
{
$bm->sqlfilter_all('mytable.bitmaskfield'),
}
);Example how to use sqlfilter with DBIx::Class:
my $list = $resultset->search(
{
$bm->sqlfilter_all('me.bitmaskfield'),
},
);sqlfilter_any
Works like sqlfilter_all but checks for any bit matching
sqlstring
Returns the bitmask as a quoted string as needed by PostgreSQL:
B'0000000000000001'::bit(16)has_all
if ($bm->has_all(PARAMS)) {
# Do something
}Checks if all requestes bits/values are set and returns true or false. This method takes the same arguments as new.
has_exact
if ($bm->has_exact(PARAMS)) {
# Do something
}Checks if the set bits/values excactly match the supplied bits/values and returns true or false. This method takes the same arguments as new.
has_any
if ($bm->has_any(PARAMS)) {
# Do something
}Checks if at least one set value/bit matches the supplied bits/values and returns true or false. This method takes the same arguments as new.
CAVEATS
Since Bitmask::Data is very liberal with input data you cannot use numbers as bitmask values. (It would think that you are supplying an integer bitmask and not a value)
Bitmask::Data adds a considerable processing overhead to bitmask manipulations. If you either don't need the extra comfort or use bitmasks with less that 32 bits that you should consider using just the perl built in bit operators on simple integer values.
SUBCLASSING
Bitmask::Data was designed to be subclassed.
package MyBitmask;
use parent qw(Bitmask::Data);
__PACKAGE__->bitmask_length(20); # Default length is 16
__PACKAGE__->init(
'value1' => 0b000000000000000001,
'value2' => 0x2,
'value2' => 4,
'value4', # lazy initlialization
'value5', # lazy initlialization
);WORKING WITH DATABASES
This module comes with support for PostgreSQL databases (patches for other database vendors are welcome).
First you need to create the correct column types:
CREATE TABLE bitmaskexample (
id integer DEFAULT nextval('pkey_seq'::regclass) NOT NULL,
bitmask bit(14),
otherfields character varying
);The length of the bitmask field must match CLASS->bitmask_length.
This module provides three convenient methods to work with databases:
sqlfilter_all: Search for matching bitmasks
sqlfilter_any: Search for bitmasks with matching bits
string: Print the bitmask string as used by the database
If you are working with l<DBIx::Class> you might also install in- and deflators for Bitmask::Data objects:
__PACKAGE__->inflate_column('fieldname',{
inflate => sub {
my $value = shift;
return MyBitmask->new($value);
},
deflate => sub {
my $value = shift;
undef $value
unless ref($value) && $value->isa('MyBitmask');
$value //= MyBitmask->new();
return $value->string;
},
});SUPPORT
Please report any bugs or feature requests to bug-bitmask-data@rt.cpan.org, or through the web interface at http://rt.cpan.org/Public/Bug/Report.html?Queue=Bitmask::Data. I will be notified and then you'll automatically be notified of the progress on your report as I make changes.
AUTHOR
Klaus Ita
koki [at] worstofall.com
Maroš Kollár
CPAN ID: MAROS
maros [at] k-1.com
L<http://www.k-1.com>ACKNOWLEDGEMENTS
This module was originally written by Klaus Ita (Koki) for Revdev http://www.revdev.at, a nice litte software company I (Maros) run with Koki and Domm (http://search.cpan.org/~domm/).
COPYRIGHT & LICENSE
Bitmask::Data is Copyright (c) 2008 Klaus Ita, Maroš Kollár - http://www.revdev.at
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included with this module.