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 $

        bt.insert( 0, 3, true );
        bt.insert( 30, 3, true );
        bt.insert( 25, 3, true );


        Tuple tuple = new Tuple();
        TupleBrowser browser = bt.browse( null );
        assertTrue( browser.getPrevious( tuple ) );
        //noinspection AssertEqualsBetweenInconvertibleTypes
        assertEquals( 30, tuple.getKey() );


        assertTrue( browser.getPrevious( tuple ) );
        //noinspection AssertEqualsBetweenInconvertibleTypes
        assertEquals( 25, tuple.getKey() );


        assertTrue( browser.getNext( tuple ) );
        //noinspection AssertEqualsBetweenInconvertibleTypes
        assertEquals( "If this works the jdbm bug is gone: will start to return " +
            "30 instead as expected for correct operation", 25, tuple.getKey() );
    }

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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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             * key argument supplied.  We use this key to advance a browser to
             * that tuple and scan down to lesser Tuples until we hit one
             * that is less than the key argument supplied.  Usually this will
             * be the previous tuple if it exists.
             */
            TupleBrowser browser = bt.browse( tuple.getKey() );
            if ( browser.getPrevious( tuple ) )
            {
                return true;
            }
        }

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    @SuppressWarnings("unchecked")
    private boolean btreeHas( BTree tree, V key, boolean isGreaterThan ) throws IOException
    {
        jdbm.helper.Tuple tuple = new jdbm.helper.Tuple();
        
        TupleBrowser browser = tree.browse( key );
        if ( isGreaterThan )
        {
            return browser.getNext( tuple );
        }
        else
        {
            if ( browser.getPrevious( tuple ) )
            {
                return true;
            }
            else
            {
                /*
                 * getPrevious() above fails which means the browser has is
                 * before the first Tuple of the btree.  A call to getNext()
                 * should work every time.
                 */
                browser.getNext( tuple );


                /*
                 * Since the browser is positioned now on the Tuple with the
                 * smallest key we just need to check if it equals this key
                 * which is the only chance for returning true.

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    @SuppressWarnings("unchecked")
    private ArrayTree<V> convertToArrayTree( BTree bTree ) throws IOException
    {
        ArrayTree<V> avlTree = new ArrayTree<V>( valueComparator );
        TupleBrowser browser = bTree.browse();
        jdbm.helper.Tuple tuple = new jdbm.helper.Tuple();
        
        while ( browser.getNext( tuple ) )
        {
            avlTree.insert( ( V ) tuple.getKey() );
        }


        return avlTree;

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            }
    
            // Less than searches occur below and are not as efficient or easy.
            // We need to scan up from the begining if findGreaterOrEqual failed
            // or scan down if findGreaterOrEqual succeed.
            TupleBrowser browser = null;
            if ( null == tuple ) 
            {
                // findGreaterOrEqual failed so we create a tuple and scan from
                // the lowest values up via getNext comparing each key to key
                tuple = new jdbm.helper.Tuple();
                browser = bt.browse();
    
                // We should at most have to read one key.  If 1st key is not
                // less than or equal to key then all keys are > key
                // since the keys are assorted in ascending order based on the
                // comparator.
                while ( browser.getNext( tuple ) ) 
                {
                    if ( comparator.compareKey( tuple.getKey(), key ) 
                        <= 0 )
                    {
                        return true;
                    } 


                    return false;
                }
            } 
            else 
            {
                // findGreaterOrEqual succeeded so use the existing tuple and
                // scan the down from the highest key less than key via
                // getPrevious while comparing each key to key.
                browser = bt.browse( tuple.getKey() );
    
                // The above call positions the browser just before the given
                // key so we need to step forward once then back.  Remember this
                // key represents a key greater than or equal to key.
                if ( comparator.compareKey( tuple.getKey(), key ) <= 0 ) 
                {
                    return true;
                }
                
                browser.getNext( tuple );
    
                // We should at most have to read one key, but we don't short
                // the search as in the search above first because the chance of
                // unneccessarily looping is nil since values get smaller.
                while ( browser.getPrevious( tuple ) ) 
                {
                    if ( comparator.compareKey( tuple.getKey(), key ) 
                        <= 0 )
                    {
                        return true;

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                 * key.  If it does then we do nothing feeding in the browser
                 * to the NoDupsCursor.  If it does not we call getPrevious and
                 * pass it into the NoDupsCursor constructor.
                 */
                jdbm.helper.Tuple tuple = new jdbm.helper.Tuple();
                TupleBrowser browser = bt.browse( key ); 
                
                if ( browser.getNext( tuple ) ) 
                {
                    Object greaterKey = tuple.getKey();
                    
                    if ( 0 != comparator.compareKey( key, greaterKey ) ) 
                    {
                        // Make sure we don't return greaterKey in cursor
                        browser.getPrevious( tuple );
                    }
                }


                // If greaterKey != key above then it will not be returned.
                list = new NoDupsEnumeration(

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   @Override
   Set<Object> getChildrenNames0(Fqn name) throws IOException
   {
      Fqn name2 = withDepth(name, name.size() + 1);
      TupleBrowser browser = tree.browse(name2);
      Tuple t = new Tuple();


      Set<Object> set = new HashSet<Object>();


      while (browser.getNext(t))
      {
         Fqn fqn = (Fqn) t.getKey();
         if (!fqn.isChildOf(name2))
         {
            break;

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                 * key.  If it does then we do nothing feeding in the browser
                 * to the NoDupsCursor.  If it does not we call getPrevious and
                 * pass it into the NoDupsCursor constructor.
                 */
                jdbm.helper.Tuple tuple = new jdbm.helper.Tuple();
                TupleBrowser browser = bt.browse( key ); 
                
                if ( browser.getNext( tuple ) ) 
                {
                    Object greaterKey = tuple.getKey();
                    
                    if ( 0 != comparator.compareKey( key, greaterKey ) ) 
                    {
                        // Make sure we don't return greaterKey in cursor
                        browser.getPrevious( tuple );
                    }
                }


                // If greaterKey != key above then it will not be returned.
                list = new NoDupsEnumeration(

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            }
    
            // Less than searches occur below and are not as efficient or easy.
            // We need to scan up from the begining if findGreaterOrEqual failed
            // or scan down if findGreaterOrEqual succeed.
            TupleBrowser browser = null;
            if ( null == tuple ) 
            {
                // findGreaterOrEqual failed so we create a tuple and scan from
                // the lowest values up via getNext comparing each key to key
                tuple = new jdbm.helper.Tuple();
                browser = bt.browse();
    
                // We should at most have to read one key.  If 1st key is not
                // less than or equal to key then all keys are > key
                // since the keys are assorted in ascending order based on the
                // comparator.
                while ( browser.getNext( tuple ) ) 
                {
                    if ( comparator.compareKey( tuple.getKey(), key ) 
                        <= 0 )
                    {
                        return true;
                    } 


                    return false;
                }
            } 
            else 
            {
                // findGreaterOrEqual succeeded so use the existing tuple and
                // scan the down from the highest key less than key via
                // getPrevious while comparing each key to key.
                browser = bt.browse( tuple.getKey() );
    
                // The above call positions the browser just before the given
                // key so we need to step forward once then back.  Remember this
                // key represents a key greater than or equal to key.
                if ( comparator.compareKey( tuple.getKey(), key ) <= 0 ) 
                {
                    return true;
                }
                
                browser.getNext( tuple );
    
                // We should at most have to read one key, but we don't short
                // the search as in the search above first because the chance of
                // unneccessarily looping is nil since values get smaller.
                while ( browser.getPrevious( tuple ) ) 
                {
                    if ( comparator.compareKey( tuple.getKey(), key ) 
                        <= 0 )
                    {
                        return true;

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