Examples of jdbm.helper.TupleBrowser

jdbm.helper.TupleBrowser
Browser to traverse a collection of tuples. The browser allows for forward and reverse order traversal. @author Alex Boisvert @version $Id: TupleBrowser.java,v 1.2 2001/05/19 14:02:00 boisvert Exp $

     */
    public Long getLargestPrime()
        throws IOException
     {
        Tuple         tuple;
        TupleBrowser  browser;
        Long          largest = null;


        tuple = new Tuple();
        browser = _primes.browse( null );
        if ( browser.getPrevious( tuple ) ) {
            largest = (Long) tuple.getValue();
            System.out.println( "Largest prime: " + largest );
        } else {
            System.out.println( "No prime number in the database." );
        }

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     */
    boolean isPrime( Long number )
        throws IOException
    {
        Tuple         tuple;
        TupleBrowser  browser;
    Long          largest;
        Long          current;


        if ( number.longValue() <= 0L ) {
            throw new IllegalArgumentException( "Number must be greater than zero" );
        }
        if ( number.longValue() == 1 ) {
        return true;
    }
        tuple = new Tuple();
        browser = _primes.browse();
        while ( browser.getNext( tuple ) ) {
            current = (Long) tuple.getValue();
            if ( current.longValue() != 1 && ( number.longValue() % current.longValue() ) == 0 ) {
                // not a prime because it is divisibe by a prime
                return false;
            }

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     */
    void random( int count ) 
        throws IOException
    {
        Tuple         tuple;
        TupleBrowser  browser;
        Long          largest;
        Long          number;


        tuple = new Tuple();
        largest = getLargestPrime();


        System.out.println( "Looking up " + count + " random primes...." );
        long start = System.currentTimeMillis();
        for ( int i=0; i<count; i++ ) {
            number = new Long( random( 0, largest.longValue() ) );
            browser = _primes.browse( number );
            if ( browser.getNext( tuple ) ) {
                number = (Long) tuple.getValue();
                System.out.print( number );
                System.out.print( ", " );
            }
        }

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        if ( rootPage == null ) {
            return null;
        }


        Tuple tuple = new Tuple( null, null );
        TupleBrowser browser = rootPage.find( _height, key );


        if ( browser.getNext( tuple ) ) {
            // find returns the matching key or the next ordered key, so we must
            // check if we have an exact match
            if ( _comparator.compare( key, tuple.getKey() ) != 0 ) {
                return null;
            } else {

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     */
    public synchronized Tuple findGreaterOrEqual( Object key )
        throws IOException
    {
        Tuple         tuple;
        TupleBrowser  browser;


        if ( key == null ) {
            // there can't be a key greater than or equal to "null"
            // because null is considered an infinite key.
            return null;
        }


        tuple = new Tuple( null, null );
        browser = browse( key );
        if ( browser.getNext( tuple ) ) {
            return tuple;
        } else {
            return null;
        }
    }

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        if ( rootPage == null ) {
            return null;
        }


        Tuple tuple = new Tuple( null, null );
        TupleBrowser browser = rootPage.find( _height, key );


        if ( browser.getNext( tuple ) ) {
            // find returns the matching key or the next ordered key, so we must
            // check if we have an exact match
            if ( _comparator.compare( key, tuple.getKey() ) != 0 ) {
                return null;
            } else {

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     */
    public synchronized Tuple findGreaterOrEqual( Object key )
        throws IOException
    {
        Tuple         tuple;
        TupleBrowser  browser;


        if ( key == null ) {
            // there can't be a key greater than or equal to "null"
            // because null is considered an infinite key.
            return null;
        }


        tuple = new Tuple( null, null );
        browser = browse( key );
        if ( browser.getNext( tuple ) ) {
            return tuple;
        } else {
            return null;
        }
    }

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    {
        BPage rootPage = getRoot();
        if ( rootPage == null ) {
            return EmptyBrowser.INSTANCE;
        }
        TupleBrowser browser = rootPage.findFirst();
        return browser;
    }

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    {
        BPage rootPage = getRoot();
        if ( rootPage == null ) {
            return EmptyBrowser.INSTANCE;
        }
        TupleBrowser browser = rootPage.find( _height, key );
        return browser;
    }

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        assertNotNull( bt.find( "8" ) );
        assertNull( bt.find( "9" ) );


        // browse will position us right after "4" and getNext() will return 8
        // since "5", "6", and "7" do not exist
        TupleBrowser browser = bt.browse( "5" );
        assertNotNull( browser );
        Tuple tuple = new Tuple();
        browser.getNext( tuple );
        assertEquals( "8", tuple.getKey() );


        // browse will position us right after "1" and getNext() will return 2
        // since "2" exists.
        browser = bt.browse( "2" );
        assertNotNull( browser );
        tuple = new Tuple();
        browser.getNext( tuple );
        assertEquals( "2", tuple.getKey() );


        // browse will position us right after "8" and getNext() will null
        // since nothing else exists past 8.  We've come to the end.
        browser = bt.browse( "9" );
        assertNotNull( browser );
        tuple = new Tuple();
        browser.getNext( tuple );
        assertNull( tuple.getKey() );


        // browse will position us right before "1" and getPrevious() will
        // null since nothing else exists before 1.  We've come to the end.
        // getNext() will however return "1".
        browser = bt.browse( "0" );
        assertNotNull( browser );
        tuple = new Tuple();
        browser.getPrevious( tuple );
        assertNull( tuple.getKey() );
        browser.getNext( tuple );
        assertEquals( "1", tuple.getKey() );
    }

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