public Tuple prev()

in mavibot/src/main/java/org/apache/directory/mavibot/btree/TupleCursor.java [539:618]
58 lines of code
15 McCabe index (conditional complexity)

    public Tuple<K, V> prev() throws EndOfFileExceededException, IOException
    {
        // First check that we have elements in the BTree
        if ( ( stack == null ) || ( stack.length == 0 ) )
        {
            throw new NoSuchElementException( "No more tuple present" );
        }

        ParentPos<K, V> parentPos = stack[depth];

        if ( ( parentPos.page == null ) || ( parentPos.pos == BEFORE_FIRST ) )
        {
            // This is the end : no more value
            throw new NoSuchElementException( "No more tuples present" );
        }

        if ( ( parentPos.pos == 0 ) && ( !parentPos.valueCursor.hasPrev() ) )
        {
            // End of the leaf. We have to go back into the stack up to the
            // parent, and down to the leaf
            parentPos = findPrevParentPos();

            // we also need to check for the type of page cause
            // findPrevParentPos will never return a null ParentPos
            if ( ( parentPos == null ) || ( parentPos.page == null ) )
            {
                // This is the end : no more value
                throw new NoSuchElementException( "No more tuples present" );
            }
        }

        V value = null;

        if ( parentPos.valueCursor.hasPrev() )
        {
            // Deal with the AfterLast case
            if ( parentPos.pos == AFTER_LAST )
            {
                parentPos.pos = parentPos.page.getNbElems() - 1;
            }

            value = parentPos.valueCursor.prev();
        }
        else
        {
            if ( parentPos.pos == 0 )
            {
                parentPos = findPrevParentPos();

                if ( ( parentPos == null ) || ( parentPos.page == null ) )
                {
                    // This is the end : no more value
                    throw new NoSuchElementException( "No more tuples present" );
                }
            }
            else
            {
                parentPos.pos--;

                try
                {
                    ValueHolder<V> valueHolder = ( ( AbstractPage<K, V> ) parentPos.page ).getValue( parentPos.pos );

                    parentPos.valueCursor = valueHolder.getCursor();
                    parentPos.valueCursor.afterLast();

                    value = parentPos.valueCursor.prev();
                }
                catch ( IllegalArgumentException e )
                {
                    e.printStackTrace();
                }
            }
        }

        AbstractPage<K, V> leaf = ( AbstractPage<K, V> ) ( parentPos.page );
        Tuple<K, V> tuple = new Tuple<K, V>( leaf.getKey( parentPos.pos ), value );

        return tuple;
    }