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Bit::Vector::Overload(User Contributed Perl DocumentatBit::Vector::Overload(3)

NAME
       Bit::Vector::Overload - Overloaded operators add-on for Bit::Vector

USAGE
       Note that you do	not need to ""use Bit::Vector;"" in addition to	this
       module.

       Simply ""use Bit::Vector::Overload;"" INSTEAD of	""use Bit::Vector;"".
       You can still use all the methods from the "Bit::Vector"	module in
       addition	to the overloaded operators and	methods	provided here after
       that.

SYNOPSIS
	 Configuration
	     $config = Bit::Vector->Configuration();
	     Bit::Vector->Configuration($config);
	     $oldconfig	= Bit::Vector->Configuration($newconfig);

	 String	Conversion
	     $string = "$vector";	      #	 depending on configuration
	     print "\$vector = '$vector'\n";

	 Emptyness
	     if	($vector)  #  if not empty (non-zero)
	     if	(! $vector)  #	if empty (zero)
	     unless ($vector)  #  if empty (zero)

	 Complement (one's complement)
	     $vector2 =	~$vector1;
	     $vector = ~$vector;

	 Negation (two's complement)
	     $vector2 =	-$vector1;
	     $vector = -$vector;

	 Norm
	     $norm = abs($vector);  #  depending on configuration

	 Absolute
	     $vector2 =	abs($vector1);	#  depending on	configuration

	 Concatenation
	     $vector3 =	$vector1 . $vector2;
	     $vector1 .= $vector2;
	     $vector1 =	$vector2 . $vector1;
	     $vector2 =	$vector1 . $scalar;  #	depending on configuration
	     $vector2 =	$scalar	. $vector1;
	     $vector .=	$scalar;

	 Duplication
	     $vector2 =	$vector1 x $factor;
	     $vector x=	$factor;

	 Shift Left
	     $vector2 =	$vector1 << $bits;
	     $vector <<= $bits;

	 Shift Right
	     $vector2 =	$vector1 >> $bits;
	     $vector >>= $bits;

	 Union
	     $vector3 =	$vector1 | $vector2;
	     $vector1 |= $vector2;
	     $vector2 =	$vector1 | $scalar;
	     $vector |=	$scalar;

	     $vector3 =	$vector1 + $vector2;  #	 depending on configuration
	     $vector1 += $vector2;
	     $vector2 =	$vector1 + $scalar;
	     $vector +=	$scalar;

	 Intersection
	     $vector3 =	$vector1 & $vector2;
	     $vector1 &= $vector2;
	     $vector2 =	$vector1 & $scalar;
	     $vector &=	$scalar;

	     $vector3 =	$vector1 * $vector2;  #	 depending on configuration
	     $vector1 *= $vector2;
	     $vector2 =	$vector1 * $scalar;
	     $vector *=	$scalar;

	 ExclusiveOr
	     $vector3 =	$vector1 ^ $vector2;
	     $vector1 ^= $vector2;
	     $vector2 =	$vector1 ^ $scalar;
	     $vector ^=	$scalar;

	 Set Difference
	     $vector3 =	$vector1 - $vector2;  #	 depending on configuration
	     $vector1 -= $vector2;
	     $vector1 =	$vector2 - $vector1;
	     $vector2 =	$vector1 - $scalar;
	     $vector2 =	$scalar	- $vector1;
	     $vector -=	$scalar;

	 Addition
	     $vector3 =	$vector1 + $vector2;  #	 depending on configuration
	     $vector1 += $vector2;
	     $vector2 =	$vector1 + $scalar;
	     $vector +=	$scalar;

	 Subtraction
	     $vector3 =	$vector1 - $vector2;  #	 depending on configuration
	     $vector1 -= $vector2;
	     $vector1 =	$vector2 - $vector1;
	     $vector2 =	$vector1 - $scalar;
	     $vector2 =	$scalar	- $vector1;
	     $vector -=	$scalar;

	 Multiplication
	     $vector3 =	$vector1 * $vector2;  #	 depending on configuration
	     $vector1 *= $vector2;
	     $vector2 =	$vector1 * $scalar;
	     $vector *=	$scalar;

	 Division
	     $vector3 =	$vector1 / $vector2;
	     $vector1 /= $vector2;
	     $vector1 =	$vector2 / $vector1;
	     $vector2 =	$vector1 / $scalar;
	     $vector2 =	$scalar	/ $vector1;
	     $vector /=	$scalar;

	 Modulo
	     $vector3 =	$vector1 % $vector2;
	     $vector1 %= $vector2;
	     $vector1 =	$vector2 % $vector1;
	     $vector2 =	$vector1 % $scalar;
	     $vector2 =	$scalar	% $vector1;
	     $vector %=	$scalar;

	 Exponentiation
	     $vector3 =	$vector1 ** $vector2;
	     $vector1 **= $vector2;
	     $vector2 =	$vector1 ** $scalar;
	     $vector2 =	$scalar	** $vector1;
	     $vector **= $scalar;

	 Increment
	     ++$vector;
	     $vector++;

	 Decrement
	     --$vector;
	     $vector--;

	 Lexical Comparison (unsigned)
	     $cmp = $vector1 cmp $vector2;
	     if	($vector1 lt $vector2)
	     if	($vector1 le $vector2)
	     if	($vector1 gt $vector2)
	     if	($vector1 ge $vector2)

	     $cmp = $vector cmp	$scalar;
	     if	($vector lt $scalar)
	     if	($vector le $scalar)
	     if	($vector gt $scalar)
	     if	($vector ge $scalar)

	 Comparison (signed)
	     $cmp = $vector1 <=> $vector2;
	     if	($vector1 < $vector2)  #  depending on configuration
	     if	($vector1 <= $vector2)
	     if	($vector1 > $vector2)
	     if	($vector1 >= $vector2)

	     $cmp = $vector <=>	$scalar;
	     if	($vector < $scalar)  #	depending on configuration
	     if	($vector <= $scalar)
	     if	($vector > $scalar)
	     if	($vector >= $scalar)

	 Equality
	     if	($vector1 eq $vector2)
	     if	($vector1 ne $vector2)
	     if	($vector eq $scalar)
	     if	($vector ne $scalar)

	     if	($vector1 == $vector2)
	     if	($vector1 != $vector2)
	     if	($vector == $scalar)
	     if	($vector != $scalar)

	 Subset	Relationship
	     if	($vector1 <= $vector2)	#  depending on	configuration

	 True Subset Relationship
	     if	($vector1 < $vector2)  #  depending on configuration

	 Superset Relationship
	     if	($vector1 >= $vector2)	#  depending on	configuration

	 True Superset Relationship
	     if	($vector1 > $vector2)  #  depending on configuration

IMPORTANT NOTES
       o Boolean values

	 Boolean values	in this	module are always a numeric zero ("0") for
	 "false" and a numeric one ("1") for "true".

       o Negative numbers

	 Numeric factors (as needed for	the ""<<"", "">>"" and ""x""
	 operators) and	bit numbers are	always regarded	as being UNSIGNED.

	 As a consequence, whenever you	pass a negative	number for such	a
	 factor	or bit number, it will be treated as a (usually	very large)
	 positive number due to	its internal two's complement binary
	 representation, usually resulting in malfunctions or an "index	out of
	 range"	error message and program abortion.

	 Note that this	does not apply to "big integer"	decimal	numbers, which
	 are (usually) passed as strings, and which may	of course be negative
	 (see also the section "Big integers" a	little further below).

       o Overloaded operators configuration

	 Note that the behaviour of certain overloaded operators can be
	 changed in various ways by means of the ""Configuration()"" method
	 (for more details, see	the description	of this	method further below).

	 For instance, scalars (i.e., numbers and strings) provided as
	 operands to overloaded	operators are automatically converted to bit
	 vectors, internally.

	 These scalars are thereby automatically assumed to be indices or to
	 be in hexadecimal, binary, decimal or enumeration format, depending
	 on the	configuration.

	 Similarly, when converting bit	vectors	to strings using double	quotes
	 (""), the output format will also depend on the previously chosen
	 configuration.

	 Finally, some overloaded operators may	have different semantics
	 depending on the proper configuration;	for instance, the operator "+"
	 can be	the "union" operator from set theory or	the arithmetic "add"
	 operator.

	 In all	cases (input, output and operator semantics), the defaults
	 have been chosen in such a way	so that	the behaviour of the module is
	 backward compatible with previous versions.

       o "Big integers"

	 As long as "big integers" (for	"big integer" arithmetic) are small
	 enough	so that	Perl doesn't need scientific notation (exponents) to
	 be able to represent them internally, you can provide these "big
	 integer" constants to the overloaded operators	of this	module (or to
	 the method ""from_Dec()"") in numeric form (i.e., either as a numeric
	 constant or expression	or as a	Perl variable containing a numeric
	 value).

	 Note that you will get	an error message (resulting in program
	 abortion) if your "big	integer" numbers exceed	that limit.

	 Because this limit is machine-dependent and not obvious to find out,
	 it is strongly	recommended that you enclose ALL your "big integer"
	 constants in your programs in (double or single) quotes.

	 Examples:

	     $vector /=	10;  #	ok because number is small

	     $vector /=	-10;  #	 ok for	same reason

	     $vector /=	"10";  #  always correct

	     $vector +=	"1152921504606846976";	#  quotes probably required here

	 All examples assume

	     Bit::Vector->Configuration("input=decimal");

	 having	been set beforehand.

	 Note also that	this module does not support scientific	notation
	 (exponents) for "big integer" decimal numbers because you can always
	 make the bit vector large enough for the whole	number to fit without
	 loss of precision (as it would	occur if scientific notation were
	 used).

	 Finally, note that the	only characters	allowed	in "big	integer"
	 constant strings are the digits 0..9 and an optional leading sign
	 (""+""	or ""-"").

	 All other characters produce a	syntax error.

       o Valid operands	for overloaded operators

	 All overloaded	operators expect at least one bit vector operand, in
	 order for the operator	to "know" that not the usual operation is to
	 be carried out, but rather the	overloaded variant.

	 This is especially true for all unary operators:

			     "$vector"
			     if	($vector)
			     if	(!$vector)
			     ~$vector
			     -$vector
			     abs($vector)
			     ++$vector
			     $vector++
			     --$vector
			     $vector--

	 For obvious reasons the left operand (the "lvalue") of	all assignment
	 operators is also required to be a bit	vector:

				 .=
				 x=
				 <<=
				 >>=
				 |=
				 &=
				 ^=
				 +=
				 -=
				 *=
				 /=
				 %=
				**=

	 In the	case of	three special operators, namely	""<<"",	"">>"" and
	 ""x"",	as well	as their related assignment variants, ""<<="", "">>=""
	 and ""x="", the left operand is ALWAYS	a bit vector and the right
	 operand is ALWAYS a number (which is the factor indicating how	many
	 times the operator is to be applied).

	 In all	truly binary operators,	i.e.,

				 .
				 |
				 &
				 ^
				 +
				 -
				 *
				 /
				 %
				**
			     <=>   cmp
			      ==    eq
			      !=    ne
			      <	    lt
			      <=    le
			      >	    gt
			      >=    ge

	 one of	either operands	may be replaced	by a Perl scalar, i.e.,	a
	 number	or a string, either as a Perl constant,	a Perl expression or a
	 Perl variable yielding	a number or a string.

	 The same applies to the right side operand (the "rvalue") of the
	 remaining assignment operators, i.e.,

				 .=
				 |=
				 &=
				 ^=
				 +=
				 -=
				 *=
				 /=
				 %=
				**=

	 Note that this	Perl scalar should be of the correct type, i.e.,
	 numeric or string, for	the chosen configuration, because otherwise a
	 warning message will occur if your program runs under the ""-w""
	 switch	of Perl.

	 The acceptable	scalar types for each possible configuration are the
	 following:

	     input = bit indices    (default)  :    numeric
	     input = hexadecimal	       :    string
	     input = binary		       :    string
	     input = decimal		       :    string     (in general)
	     input = decimal		       :    numeric    (if small enough)
	     input = enumeration	       :    string

	 NOTE ALSO THAT	THESE SCALAR OPERANDS ARE CONVERTED TO BIT VECTORS OF
	 THE SAME SIZE AS THE BIT VECTOR WHICH IS THE OTHER OPERAND.

	 The only exception from this rule is the concatenation	operator
	 (""."") and its assignment variant ("".=""):

	 If one	of the two operands of the concatenation operator (""."") is
	 not a bit vector object but a Perl scalar, the	contents of the
	 remaining bit vector operand are converted into a string (the format
	 of which depends on the configuration set with	the
	 ""Configuration()"" method), which is then concatenated in the	proper
	 order (i.e., as indicated by the order	of the two operands) with the
	 Perl scalar (in other words, a	string is returned in such a case
	 instead of a bit vector object!).

	 If the	right side operand (the	"rvalue") of the assignment variant
	 ("".="") of the concatenation operator	is a Perl scalar, it is
	 converted internally to a bit vector of the same size as the left
	 side operand provided that the	configuration states that scalars are
	 to be regarded	as indices, decimal strings or enumerations.

	 If the	configuration states that scalars are to be regarded as
	 hexadecimal or	boolean	strings, however, these	strings	are converted
	 to bit	vectors	of a size matching the length of the input string,
	 i.e., four times the length for hexadecimal strings (because each
	 hexadecimal digit is worth 4 bits) and	once the length	for binary
	 strings.

	 If a decimal number ("big integer") is	too large to be	stored in a
	 bit vector of the given size, a "numeric overflow error" occurs.

	 If a bit index	is out of range	for the	given bit vector, an "index
	 out of	range" error occurs.

	 If a scalar operand cannot be converted successfully due to invalid
	 syntax, a fatal "input	string syntax error" is	issued.

	 If the	two operands of	the operator ""<<"", "">>"" or ""x"" are
	 reversed, a fatal "reversed operands error" occurs.

	 If an operand is neither a bit	vector nor a scalar, then a fatal
	 "illegal operand type error" occurs.

       o Bit order

	 Note that bit vectors are stored least	order bit and least order word
	 first internally.

	 I.e., bit #0 of any given bit vector corresponds to bit #0 of word #0
	 in the	array of machine words representing the	bit vector.

	 (Where	word #0	comes first in memory, i.e., it	is stored at the least
	 memory	address	in the allocated block of memory holding the given bit
	 vector.)

	 Note however that machine words can be	stored least order byte	first
	 or last, depending on your system's implementation.

	 Note further that whenever bit	vectors	are converted to and from
	 (binary or hexadecimal) strings, the RIGHTMOST	bit is always the
	 LEAST SIGNIFICANT one,	and the	LEFTMOST bit is	always the MOST
	 SIGNIFICANT bit.

	 This is because in our	western	culture, numbers are always
	 represented in	this way (least	significant to most significant	digits
	 go from right to left).

	 Of course this	requires an internal reversion of order, which the
	 corresponding conversion methods perform automatically	(without any
	 additional overhead, it's just	a matter of starting the internal loop
	 at the	bottom or the top end).

       o Matching sizes

	 In general, for methods involving several bit vectors at the same
	 time, all bit vector arguments	must have identical sizes (number of
	 bits),	or a fatal "size mismatch" error will occur.

	 Exceptions from this rule are the methods ""Concat()"",
	 ""Concat_List()"", ""Copy()"",	""Interval_Copy()"" and
	 ""Interval_Substitute()"", where no conditions	at all are imposed on
	 the size of their bit vector arguments.

	 In method ""Multiply()"", all three bit vector	arguments must in
	 principle obey	the rule of matching sizes, but	the bit	vector in
	 which the result of the multiplication	is to be stored	may be larger
	 than the two bit vector arguments containing the factors for the
	 multiplication.

	 In method ""Power()"",	the bit	vector for the result must be the same
	 size or greater than the base of the exponentiation term. The
	 exponent can be any size.

	 The same applies to the corresponding overloaded operators.

       o Index ranges

	 All indices for any given bits	must lie between "0" and
	 ""$vector->Size()-1"",	or a fatal "index out of range"	error will
	 occur.

DESCRIPTION
       o "$config = Bit::Vector->Configuration();"

       o "Bit::Vector->Configuration($config);"

       o "$oldconfig = Bit::Vector->Configuration($newconfig);"

	 This method serves to alter the semantics (i.e., behaviour) of
	 certain overloaded operators (which are all implemented in Perl, by
	 the way).

	 It does not have any effect whatsoever	on anything else. In
	 particular, it	does not affect	the methods implemented	in C.

	 The method accepts an (optional) string as input in which certain
	 keywords are expected,	which influence	some or	almost all of the
	 overloaded operators in several possible ways.

	 The method always returns a string (which you do not need to take
	 care of, i.e.,	to store, in case you aren't interested	in keeping it)
	 which is a complete representation of the current configuration
	 (i.e.,	BEFORE any modifications are applied) and which	can be fed
	 back to this method later in order to restore the previous
	 configuration.

	 There are three aspects of the	way certain overloaded operators
	 behave	which can be controlled	with this method:

	   +  the way scalar operands (replacing one of	the two
	      bit vector object	operands) are automatically
	      converted	internally into	a bit vector object of
	      their own,

	   +  the operation certain overloaded operators perform,
	      i.e., an operation with sets or an arithmetic
	      operation,

	   +  the format to which bit vectors are converted
	      automatically when they are enclosed in double
	      quotes.

	 The input string may contain any number of assignments, each of which
	 controls one of these three aspects.

	 Each assignment has the form ""<which>=<value>"".

	 ""<which>"" and ""<value>"" thereby consist of	letters	("[a-zA-Z]")
	 and white space.

	 Multiple assignments have to be separated by one or more comma	(","),
	 semi-colon (";"), colon (":"),	vertical bar ("|"), slash ("/"),
	 newline ("\n"), ampersand ("&"), plus ("+") or	dash ("-").

	 Empty lines or	statements (only white space) are allowed but will be
	 ignored.

	 ""<which>"" has to contain one	or more	keywords from one of three
	 groups, each group representing one of	the three aspects that the
	 ""Configuration()"" method controls:

	   +  "^scalar", "^input", "^in$"

	   +  "^operator", "^semantic",	"^ops$"

	   +  "^string", "^output", "^out$"

	 The character "^" thereby denotes the beginning of a word, and	"$"
	 denotes the end. Case is ignored (!).

	 Using these keywords, you can build any phrase	you like to select one
	 of the	three aspects (see also	examples given below).

	 The only condition is that no other keyword from any of the other two
	 groups	may match - otherwise a	syntax error will occur	(i.e.,
	 ambiguities are forbidden). A syntax error also occurs	if none	of the
	 keywords matches.

	 This same principle applies to	""<value>"":

	 Depending on which aspect you specified for ""<which>"", there	are
	 different groups of keywords that determine the value the selected
	 aspect	will be	set to:

	   +  "<which>"	= "^scalar", "^input", "^in$":

		"<value>" =

		*  "^bit$", "^index", "^indice"
		*  "^hex"
		*  "^bin"
		*  "^dec"
		*  "^enum"

	   +  "<which>"	= "^operator", "^semantic", "^ops$":

		"<value>" =

		*  "^set$"
		*  "^arithmetic"

	   +  "<which>"	= "^string", "^output",	"^out$":

		"<value>" =

		*  "^hex"
		*  "^bin"
		*  "^dec"
		*  "^enum"

	 Examples:

	   "Any	scalar input I provide should be considered to be = a bit index"

	   "I want to have operator semantics suitable for = arithmetics"

	   "Any	bit vector in double quotes is to be output as = an enumeration"

	 SCALAR	INPUT:

	 In the	case of	scalar input, ""^bit$"", ""^index"", or	""^indice""
	 all cause scalar input	to be considered to represent a	bit index,
	 i.e., ""$vector ^= 5;"" will flip bit #5 in the given bit vector
	 (this is essentially the same as ""$vector->bit_flip(5);"").

	 Note that "bit	indices" is the	default	setting	for "scalar input".

	 The keyword ""^hex"" will cause scalar	input to be considered as
	 being in hexadecimal, i.e., ""$vector ^= 5;"" will flip bit #0	and
	 bit #2	(because hexadecimal "5" is binary "0101").

	 (Note though that hexadecimal input should always be enclosed in
	 quotes, otherwise it will be interpreted as a decimal number by Perl!
	 The example relies on the fact	that hexadecimal "0-9" and decimal
	 "0-9" are the same.)

	 The keyword ""^bin"" will cause scalar	input to be considered as
	 being in binary format. All characters	except "0" and "1" are
	 forbidden in this case	(i.e., produce a syntax	error).

	 ""$vector ^= '0101';"", for instance, will flip bit #0	and bit	#2.

	 The keyword ""^dec"" causes scalar input to be	considered as integers
	 in decimal format, i.e., ""$vector ^= 5;"" will flip bit #0 and bit
	 #2 (because decimal "5" is binary "0101").

	 (Note though that all decimal input should be enclosed	in quotes,
	 because for large numbers, Perl will use scientific notation
	 internally for	representing them, which produces a syntax error
	 because scientific notation is	neither	supported by this module nor
	 needed.)

	 Finally, the keyword ""^enum""	causes scalar input to be considered
	 as being a list ("enumeration") of indices and	ranges of (contiguous)
	 indices, i.e.,	""$vector |= '2,3,5,7-13,17-23';"" will	cause bits #2,
	 #3, #5, #7 through #13	and #17	through	#23 to be set.

	 OPERATOR SEMANTICS:

	 Several overloaded operators can have two distinct functions
	 depending on this setting.

	 The affected operators	are: ""+"", ""-"", ""*"", ""<"", ""<="", "">""
	 and "">="".

	 With the default setting, "set	operations", these operators perform:

	   +	   set union			       ( set1  u   set2	)
	   -	   set difference		       ( set1  \   set2	)
	   *	   set intersection		       ( set1  n   set2	)
	   <	   true	subset relationship	       ( set1  <   set2	)
	   <=	   subset relationship		       ( set1  <=  set2	)
	   >	   true	superset relationship	       ( set1  >   set2	)
	   >=	   superset relationship	       ( set1  >=  set2	)

	 With the alternative setting, "arithmetic operations",	these
	 operators perform:

	   +	   addition			       ( num1  +   num2	)
	   -	   subtraction			       ( num1  -   num2	)
	   *	   multiplication		       ( num1  *   num2	)
	   <	   "less than" comparison	       ( num1  <   num2	)
	   <=	   "less than or equal"	comparison     ( num1  <=  num2	)
	   >	   "greater than" comparison	       ( num1  >   num2	)
	   >=	   "greater than or equal" comparison  ( num1  >=  num2	)

	 Note that these latter	comparison operators (""<"", ""<="", "">"" and
	 "">="") regard	their operands as being	SIGNED.

	 To perform comparisons	with UNSIGNED operands,	use the	operators
	 ""lt"", ""le"", ""gt""	and ""ge"" instead (in contrast	to the
	 operators above, these	operators are NOT affected by the "operator
	 semantics" setting).

	 STRING	OUTPUT:

	 There are four	methods	which convert the contents of a	given bit
	 vector	into a string: ""to_Hex()"", ""to_Bin()"", ""to_Dec()""	and
	 ""to_Enum()"" (not counting ""Block_Read()"", since this method does
	 not return a human-readable string).

	 (For conversion to octal, see the description of the method
	 ""Chunk_List_Read()"".)

	 Therefore, there are four possible formats into which a bit vector
	 can be	converted when it is enclosed in double	quotes,	for example:

	   print "\$vector = '$vector'\n";
	   $string = "$vector";

	 Hence you can set "string output" to four different values: To	"hex"
	 for hexadecimal format	(which is the default),	to "bin" for binary
	 format, to "dec" for conversion to decimal numbers and	to "enum" for
	 conversion to enumerations (".newsrc" style sets).

	 BEWARE	that the conversion to decimal numbers is inherently slow; it
	 can easily take up several seconds for	a single large bit vector!

	 Therefore you should store the	decimal	strings	returned to you	rather
	 than converting a given bit vector again.

	 EXAMPLES:

	 The default setting as	returned by the	method ""Configuration()"" is:

		 Scalar	Input	    = Bit Index
		 Operator Semantics = Set Operators
		 String	Output	    = Hexadecimal

	 Performing a statement	such as:

	   Bit::Vector->Configuration("in=bin,ops=arithmetic,out=bin");
	   print Bit::Vector->Configuration(), "\n";

	 yields	the following output:

		 Scalar	Input	    = Binary
		 Operator Semantics = Arithmetic Operators
		 String	Output	    = Binary

	 Note that you can always feed this output back	into the
	 ""Configuration()"" method to restore that setting later.

	 This also means that you can enter the	same given setting with	almost
	 any degree of verbosity you like (as long as the required keywords
	 appear	and no ambiguities arise).

	 Note further that any aspect you do not specify is not	changed, i.e.,
	 the statement

	   Bit::Vector->Configuration("operators = arithmetic");

	 leaves	all other aspects unchanged.

       o "$vector"

	 Remember that variables enclosed in double quotes are always
	 interpolated in Perl.

	 Whenever a Perl variable containing the reference of a	"Bit::Vector"
	 object	is enclosed in double quotes (either alone or together with
	 other text and/or variables), the contents of the corresponding bit
	 vector	are converted into a printable string.

	 Since there are several conversion methods available in this module
	 (see the description of the methods ""to_Hex()"", ""to_Bin()"",
	 ""to_Dec()"" and ""to_Enum()""), it is	of course desirable to be able
	 to choose which of these methods should be applied in this case.

	 This can actually be done by changing the configuration of this
	 module	using the method ""Configure()"" (see the previous chapter,
	 immediately above).

	 The default is	conversion to hexadecimal.

       o "if ($vector)"

	 It is possible	to use a Perl variable containing the reference	of a
	 "Bit::Vector" object as a boolean expression.

	 The condition above is	true if	the corresponding bit vector contains
	 at least one set bit, and it is false if ALL bits of the
	 corresponding bit vector are cleared.

       o "if (!$vector)"

	 Since it is possible to use a Perl variable containing	the reference
	 of a "Bit::Vector" object as a	boolean	expression, you	can of course
	 also negate this boolean expression.

	 The condition above is	true if	ALL bits of the	corresponding bit
	 vector	are cleared, and it is false if	the corresponding bit vector
	 contains at least one set bit.

	 Note that this	is NOT the same	as using the method ""is_full()"",
	 which returns true if ALL bits	of the corresponding bit vector	are
	 SET.

       o "~$vector"

	 This term returns a new bit vector object which is the	one's
	 complement of the given bit vector.

	 This is equivalent to inverting all bits.

       o "-$vector" (unary minus)

	 This term returns a new bit vector object which is the	two's
	 complement of the given bit vector.

	 This is equivalent to inverting all bits and incrementing the result
	 by one.

	 (This is the same as changing the sign	of a number in two's
	 complement binary representation.)

       o "abs($vector)"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns the
	 number	of set bits in the given bit vector (this is the same as
	 calculating the number	of elements which are contained	in the given
	 set) -	which is the default behaviour,	or it returns a	new bit	vector
	 object	which contains the absolute value of the number	stored in the
	 given bit vector.

       o "$vector1 . $vector2"

	 This term usually returns a new bit vector object which is the	result
	 of the	concatenation of the two bit vector operands.

	 The left operand becomes the most significant,	and the	right operand
	 becomes the least significant part of the new bit vector object.

	 If one	of the two operands is not a bit vector	object but a Perl
	 scalar, however, the contents of the remaining	bit vector operand are
	 converted into	a string (the format of	which depends on the
	 configuration set with	the ""Configuration()""	method), which is then
	 concatenated in the proper order (i.e., as indicated by the order of
	 the two operands) with	the Perl scalar.

	 In other words, a string is returned in such a	case instead of	a bit
	 vector	object!

       o "$vector x $factor"

	 This term returns a new bit vector object which is the	concatenation
	 of as many copies of the given	bit vector operand (the	left operand)
	 as the	factor (the right operand) specifies.

	 If the	factor is zero,	a bit vector object with a length of zero bits
	 is returned.

	 If the	factor is one, just a new copy of the given bit	vector is
	 returned.

	 Note that a fatal "reversed operands error" occurs if the two
	 operands are swapped.

       o "$vector << $bits"

	 This term returns a new bit vector object which is a copy of the
	 given bit vector (the left operand), which is then shifted left
	 (towards the most significant bit) by as many places as the right
	 operand, "$bits", specifies.

	 This means that the "$bits" most significant bits are lost, all other
	 bits move up by "$bits" positions, and	the "$bits" least significant
	 bits that have	been left unoccupied by	this shift are all set to
	 zero.

	 If "$bits" is greater than the	number of bits of the given bit
	 vector, this term returns an empty bit	vector (i.e., with all bits
	 cleared) of the same size as the given	bit vector.

	 Note that a fatal "reversed operands error" occurs if the two
	 operands are swapped.

       o "$vector >> $bits"

	 This term returns a new bit vector object which is a copy of the
	 given bit vector (the left operand), which is then shifted right
	 (towards the least significant	bit) by	as many	places as the right
	 operand, "$bits", specifies.

	 This means that the "$bits" least significant bits are	lost, all
	 other bits move down by "$bits" positions, and	the "$bits" most
	 significant bits that have been left unoccupied by this shift are all
	 set to	zero.

	 If "$bits" is greater than the	number of bits of the given bit
	 vector, this term returns an empty bit	vector (i.e., with all bits
	 cleared) of the same size as the given	bit vector.

	 Note that a fatal "reversed operands error" occurs if the two
	 operands are swapped.

       o "$vector1 | $vector2"

	 This term returns a new bit vector object which is the	result of a
	 bitwise OR operation between the two bit vector operands.

	 This is the same as calculating the union of two sets.

       o "$vector1 & $vector2"

	 This term returns a new bit vector object which is the	result of a
	 bitwise AND operation between the two bit vector operands.

	 This is the same as calculating the intersection of two sets.

       o "$vector1 ^ $vector2"

	 This term returns a new bit vector object which is the	result of a
	 bitwise XOR (exclusive-or) operation between the two bit vector
	 operands.

	 This is the same as calculating the symmetric difference of two sets.

       o "$vector1 + $vector2"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns a new
	 bit vector object which is the	result of a bitwise OR operation
	 between the two bit vector operands (this is the same as calculating
	 the union of two sets)	- which	is the default behaviour, or it
	 returns a new bit vector object which contains	the sum	of the two
	 numbers stored	in the two bit vector operands.

       o "$vector1 - $vector2"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns a new
	 bit vector object which is the	set difference of the two sets
	 represented in	the two	bit vector operands - which is the default
	 behaviour, or it returns a new	bit vector object which	contains the
	 difference of the two numbers stored in the two bit vector operands.

       o "$vector1 * $vector2"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns a new
	 bit vector object which is the	result of a bitwise AND	operation
	 between the two bit vector operands (this is the same as calculating
	 the intersection of two sets) - which is the default behaviour, or it
	 returns a new bit vector object which contains	the product of the two
	 numbers stored	in the two bit vector operands.

       o "$vector1 / $vector2"

	 This term returns a new bit vector object containing the result of
	 the division of the two numbers stored	in the two bit vector
	 operands.

       o "$vector1 % $vector2"

	 This term returns a new bit vector object containing the remainder of
	 the division of the two numbers stored	in the two bit vector
	 operands.

       o "$vector1 ** $vector2"

	 This term returns a new bit vector object containing the result of
	 the exponentiation of the left	bit vector elevated to the right bit
	 vector's power.

       o "$vector1 .= $vector2;"

	 This statement	"appends" the right bit	vector operand (the "rvalue")
	 to the	left one (the "lvalue").

	 The former contents of	the left operand become	the most significant
	 part of the resulting bit vector, and the right operand becomes the
	 least significant part.

	 Since bit vectors are stored in "least	order bit first" order,	this
	 actually requires the left operand to be shifted "up" by the length
	 of the	right operand, which is	then copied to the now freed least
	 significant part of the left operand.

	 If the	right operand is a Perl	scalar,	it is first converted to a bit
	 vector	of the same size as the	left operand, provided that the
	 configuration states that scalars are to be regarded as indices,
	 decimal strings or enumerations.

	 If the	configuration states that scalars are to be regarded as
	 hexadecimal or	boolean	strings, however, these	strings	are converted
	 to bit	vectors	of a size matching the length of the input string,
	 i.e., four times the length for hexadecimal strings (because each
	 hexadecimal digit is worth 4 bits) and	once the length	for binary
	 strings.

       o "$vector x= $factor;"

	 This statement	replaces the given bit vector by a concatenation of as
	 many copies of	the original contents of the given bit vector as the
	 factor	(the right operand) specifies.

	 If the	factor is zero,	the given bit vector is	resized	to a length of
	 zero bits.

	 If the	factor is one, the given bit vector is not changed at all.

       o "$vector <<= $bits;"

	 This statement	moves the contents of the given	bit vector left	by
	 "$bits" positions (towards the	most significant bit).

	 This means that the "$bits" most significant bits are lost, all other
	 bits move up by "$bits" positions, and	the "$bits" least significant
	 bits that have	been left unoccupied by	this shift are all set to
	 zero.

	 If "$bits" is greater than the	number of bits of the given bit
	 vector, the given bit vector is erased	completely (i.e., all bits are
	 cleared).

       o "$vector >>= $bits;"

	 This statement	moves the contents of the given	bit vector right by
	 "$bits" positions (towards the	least significant bit).

	 This means that the "$bits" least significant bits are	lost, all
	 other bits move down by "$bits" positions, and	the "$bits" most
	 significant bits that have been left unoccupied by this shift are all
	 set to	zero.

	 If "$bits" is greater than the	number of bits of the given bit
	 vector, the given bit vector is erased	completely (i.e., all bits are
	 cleared).

       o "$vector1 |= $vector2;"

	 This statement	performs a bitwise OR operation	between	the two	bit
	 vector	operands and stores the	result in the left operand.

	 This is the same as calculating the union of two sets.

       o "$vector1 &= $vector2;"

	 This statement	performs a bitwise AND operation between the two bit
	 vector	operands and stores the	result in the left operand.

	 This is the same as calculating the intersection of two sets.

       o "$vector1 ^= $vector2;"

	 This statement	performs a bitwise XOR (exclusive-or) operation
	 between the two bit vector operands and stores	the result in the left
	 operand.

	 This is the same as calculating the symmetric difference of two sets.

       o "$vector1 += $vector2;"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this statement either performs
	 a bitwise OR operation	between	the two	bit vector operands (this is
	 the same as calculating the union of two sets)	- which	is the default
	 behaviour, or it calculates the sum of	the two	numbers	stored in the
	 two bit vector	operands.

	 The result of this operation is stored	in the left operand.

       o "$vector1 -= $vector2;"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this statement either
	 calculates the	set difference of the two sets represented in the two
	 bit vector operands - which is	the default behaviour, or it
	 calculates the	difference of the two numbers stored in	the two	bit
	 vector	operands.

	 The result of this operation is stored	in the left operand.

       o "$vector1 *= $vector2;"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this statement either performs
	 a bitwise AND operation between the two bit vector operands (this is
	 the same as calculating the intersection of two sets) - which is the
	 default behaviour, or it calculates the product of the	two numbers
	 stored	in the two bit vector operands.

	 The result of this operation is stored	in the left operand.

       o "$vector1 /= $vector2;"

	 This statement	puts the result	of the division	of the two numbers
	 stored	in the two bit vector operands into the	left operand.

       o "$vector1 %= $vector2;"

	 This statement	puts the remainder of the division of the two numbers
	 stored	in the two bit vector operands into the	left operand.

       o "$vector1 **= $vector2;"

	 This statement	puts the result	of the exponentiation of the left
	 operand elevated to the right operand's power into the	left operand.

       o "++$vector", "$vector++"

	 This operator performs	pre- and post-incrementation of	the given bit
	 vector.

	 The value returned by this term is a reference	of the given bit
	 vector	object (after or before	the incrementation, respectively).

       o "--$vector", "$vector--"

	 This operator performs	pre- and post-decrementation of	the given bit
	 vector.

	 The value returned by this term is a reference	of the given bit
	 vector	object (after or before	the decrementation, respectively).

       o "($vector1 cmp	$vector2)"

	 This term returns ""-1"" if "$vector1"	is less	than "$vector2", "0"
	 if "$vector1" and "$vector2" are the same, and	"1" if "$vector1" is
	 greater than "$vector2".

	 This comparison assumes UNSIGNED bit vectors.

       o "($vector1 eq $vector2)"

	 This term returns true	("1") if the contents of the two bit vector
	 operands are the same and false ("0") otherwise.

       o "($vector1 ne $vector2)"

	 This term returns true	("1") if the two bit vector operands differ
	 and false ("0") otherwise.

       o "($vector1 lt $vector2)"

	 This term returns true	("1") if "$vector1" is less than "$vector2",
	 and false ("0") otherwise.

	 This comparison assumes UNSIGNED bit vectors.

       o "($vector1 le $vector2)"

	 This term returns true	("1") if "$vector1" is less than or equal to
	 "$vector2", and false ("0") otherwise.

	 This comparison assumes UNSIGNED bit vectors.

       o "($vector1 gt $vector2)"

	 This term returns true	("1") if "$vector1" is greater than
	 "$vector2", and false ("0") otherwise.

	 This comparison assumes UNSIGNED bit vectors.

       o "($vector1 ge $vector2)"

	 This term returns true	("1") if "$vector1" is greater than or equal
	 to "$vector2",	and false ("0")	otherwise.

	 This comparison assumes UNSIGNED bit vectors.

       o "($vector1 <=>	$vector2)"

	 This term returns ""-1"" if "$vector1"	is less	than "$vector2", "0"
	 if "$vector1" and "$vector2" are the same, and	"1" if "$vector1" is
	 greater than "$vector2".

	 This comparison assumes SIGNED	bit vectors.

       o "($vector1 == $vector2)"

	 This term returns true	("1") if the contents of the two bit vector
	 operands are the same and false ("0") otherwise.

       o "($vector1 != $vector2)"

	 This term returns true	("1") if the two bit vector operands differ
	 and false ("0") otherwise.

       o "($vector1 < $vector2)"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns true
	 ("1") if "$vector1" is	a true subset of "$vector2" (and false ("0")
	 otherwise) - which is the default behaviour, or it returns true ("1")
	 if "$vector1" is less than "$vector2" (and false ("0")	otherwise).

	 The latter comparison assumes SIGNED bit vectors.

       o "($vector1 <= $vector2)"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns true
	 ("1") if "$vector1" is	a subset of "$vector2" (and false ("0")
	 otherwise) - which is the default behaviour, or it returns true ("1")
	 if "$vector1" is less than or equal to	"$vector2" (and	false ("0")
	 otherwise).

	 The latter comparison assumes SIGNED bit vectors.

       o "($vector1 > $vector2)"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns true
	 ("1") if "$vector1" is	a true superset	of "$vector2" (and false ("0")
	 otherwise) - which is the default behaviour, or it returns true ("1")
	 if "$vector1" is greater than "$vector2" (and false ("0") otherwise).

	 The latter comparison assumes SIGNED bit vectors.

       o "($vector1 >= $vector2)"

	 Depending on the configuration	(see the description of	the method
	 ""Configuration()"" for more details),	this term either returns true
	 ("1") if "$vector1" is	a superset of "$vector2" (and false ("0")
	 otherwise) - which is the default behaviour, or it returns true ("1")
	 if "$vector1" is greater than or equal	to "$vector2" (and false ("0")
	 otherwise).

	 The latter comparison assumes SIGNED bit vectors.

SEE ALSO
       Bit::Vector(3), Bit::Vector::String(3).

VERSION
       This man	page documents "Bit::Vector::Overload" version 7.4.

AUTHOR
	 Steffen Beyer
	 mailto:STBEY@cpan.org
	 http://www.engelschall.com/u/sb/download/

COPYRIGHT
       Copyright (c) 2000 - 2013 by Steffen Beyer. All rights reserved.

LICENSE
       This package is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself, i.e., under	the terms of the
       "Artistic License" or the "GNU General Public License".

       The C library at	the core of this Perl module can additionally be
       redistributed and/or modified under the terms of	the "GNU Library
       General Public License".

       Please refer to the files "Artistic.txt", "GNU_GPL.txt" and
       "GNU_LGPL.txt" in this distribution for details!

DISCLAIMER
       This package is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A	PARTICULAR PURPOSE.

       See the "GNU General Public License" for	more details.

perl v5.32.0			  2013-09-03	      Bit::Vector::Overload(3)

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