com.sun.tools.javac.util
Class Bits

java.lang.Object
  com.sun.tools.javac.util.Bits

public class Bits
extends java.lang.Object

A class for extensible, mutable bit sets.

This is NOT part of any API supported by Sun Microsystems. If you write code that depends on this, you do so at your own risk. This code and its internal interfaces are subject to change or deletion without notice.

Field Summary

private int[]	bits
private static int	wordlen
private static int	wordmask
private static int	wordshift

Constructor Summary

Bits()
Construct an initially empty set.

Bits(int[] bits)
Construct a set consisting initially of given bit vector.

Bits(int start, int limit)
Construct a set consisting initially of given range.

Method Summary

Bits	andSet(Bits xs) this set = this set & xs.
void	clear() This set = {}.
Bits	diffSet(Bits xs) this set = this set \ xs.
Bits	dup() Return a copy of this set.
void	excl(int x) Exclude x from this set.
void	incl(int x) Include x in this set.
void	inclRange(int start, int limit) Include [start..limit) in this set.
boolean	isMember(int x) Is x an element of this set?
static void	main(java.lang.String[] args) Test Bits.nextBit(int).
int	nextBit(int x) Return the index of the least bit position >= x that is set.
Bits	orSet(Bits xs) this set = this set | xs.
private void	sizeTo(int len)
java.lang.String	toString() a string representation of this set.
private static int	trailingZeroBits(int x) Count trailing zero bits in an int.
Bits	xorSet(Bits xs) this set = this set ^ xs.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

wordlen

private static final int wordlen

See Also:

Constant Field Values

wordshift

private static final int wordshift

See Also:

Constant Field Values

wordmask

private static final int wordmask

See Also:

Constant Field Values

bits

private int[] bits

Constructor Detail

Bits

public Bits()

Construct an initially empty set.

Bits

public Bits(int[] bits)

Construct a set consisting initially of given bit vector.

Bits

public Bits(int start,
            int limit)

Construct a set consisting initially of given range.

Method Detail

sizeTo

private void sizeTo(int len)

clear

public void clear()

This set = {}.

dup

public Bits dup()

Return a copy of this set.

incl

public void incl(int x)

Include x in this set.

inclRange

public void inclRange(int start,
                      int limit)

Include [start..limit) in this set.

excl

public void excl(int x)

Exclude x from this set.

isMember

public boolean isMember(int x)

Is x an element of this set?

andSet

public Bits andSet(Bits xs)

this set = this set & xs.

orSet

public Bits orSet(Bits xs)

this set = this set | xs.

diffSet

public Bits diffSet(Bits xs)

this set = this set \ xs.

xorSet

public Bits xorSet(Bits xs)

this set = this set ^ xs.

trailingZeroBits

private static int trailingZeroBits(int x)

Count trailing zero bits in an int. Algorithm from "Hacker's Delight" by Henry S. Warren Jr. (figure 5-13)

nextBit

public int nextBit(int x)

Return the index of the least bit position >= x that is set. If none are set, returns -1. This provides a nice way to iterate over the members of a bit set:

  for (int i = bits.nextBit(0); i>=0; i = bits.nextBit(i+1)) ...
  

toString

public java.lang.String toString()

a string representation of this set.

Overrides:

toString in class java.lang.Object

main

public static void main(java.lang.String[] args)

Test Bits.nextBit(int).