uk.ac.starlink.util

Class ValueWatcher

java.lang.Object

uk.ac.starlink.util.ValueWatcher

public class ValueWatcher
extends Object

Looks out for an unused value in a sequence of submitted numbers. This can be used to identify a suitable 'magic' representation for a bad value.

Since:

22 Jun 2006

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
ValueWatcher(long loBound, long hiBound) Constructs a ValueWatcher which will look out for values in the range covered by loBound and hiBound inclusive.

Method Summary

Modifier and Type	Method and Description
Long	getUnused() Returns a value in the range loBound..hiBound which has never been sumitted to useValue(long).
void	useValue(long val) Takes note of a value.

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueWatcher

public ValueWatcher(long loBound,
                    long hiBound)

Constructs a ValueWatcher which will look out for values in the range covered by loBound and hiBound inclusive. These shouldn't be arbitrarily far apart - storage of up to about one bit per value in the range will be required.

Parameters:

loBound - lower bound to watch for (inclusive)

hiBound - upper bound to watch for (inclusive)

Method Detail

useValue

public void useValue(long val)

Takes note of a value. val will never subsequently be returned from getUnused().

Parameters:

val - value to note

getUnused

public Long getUnused()

Returns a value in the range loBound..hiBound which has never been sumitted to useValue(long). If there is no such value, returns null.

Returns:

unused value in range