/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.directory.server.xdbm.search.impl;
import org.apache.directory.server.core.entry.ServerEntry;
import org.apache.directory.server.i18n.I18n;
import org.apache.directory.server.xdbm.AbstractIndexCursor;
import org.apache.directory.server.xdbm.ForwardIndexEntry;
import org.apache.directory.server.xdbm.Index;
import org.apache.directory.server.xdbm.IndexCursor;
import org.apache.directory.server.xdbm.IndexEntry;
import org.apache.directory.server.xdbm.Store;
import org.apache.directory.shared.ldap.cursor.InvalidCursorPositionException;
/**
* A Cursor over entry candidates matching a LessEq assertion filter. This
* Cursor operates in two modes. The first is when an index exists for the
* attribute the assertion is built on. The second is when the user index for
* the assertion attribute does not exist. Different Cursors are used in each
* of these cases where the other remains null.
*
* @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
* @version $$Rev$$
*/
public class LessEqCursor<V, ID> extends AbstractIndexCursor<V, ServerEntry, ID>
{
private static final String UNSUPPORTED_MSG = I18n.err( I18n.ERR_716 );
/** An less eq evaluator for candidates */
private final LessEqEvaluator<V, ID> lessEqEvaluator;
/** Cursor over attribute entry matching filter: set when index present */
private final IndexCursor<V, ServerEntry, ID> userIdxCursor;
/** NDN Cursor on all entries in (set when no index on user attribute) */
private final IndexCursor<V, ServerEntry, ID> ndnIdxCursor;
/**
* Used to store indexEntry from ndnCandidate so it can be saved after
* call to evaluate() which changes the value so it's not referring to
* the NDN but to the value of the attribute instead.
*/
IndexEntry<V, ServerEntry, ID> ndnCandidate;
/** used in both modes */
private boolean available = false;
@SuppressWarnings("unchecked")
public LessEqCursor( Store<ServerEntry, ID> db, LessEqEvaluator<V, ID> lessEqEvaluator ) throws Exception
{
this.lessEqEvaluator = lessEqEvaluator;
String attribute = lessEqEvaluator.getExpression().getAttribute();
if ( db.hasIndexOn( attribute ) )
{
userIdxCursor = ( ( Index<V, ServerEntry, ID> ) db.getIndex( attribute ) ).forwardCursor();
ndnIdxCursor = null;
}
else
{
ndnIdxCursor = ( IndexCursor<V, ServerEntry, ID> ) db.getNdnIndex().forwardCursor();
userIdxCursor = null;
}
}
public boolean available()
{
return available;
}
public void beforeValue( ID id, V value ) throws Exception
{
checkNotClosed( "beforeValue()" );
if ( userIdxCursor != null )
{
/*
* First we need to check and make sure this element is within
* bounds as mandated by the assertion node. To do so we compare
* it's value with the value of the expression node. If the
* element's value is greater than this upper bound then we
* position the userIdxCursor after the last node.
*
* If the element's value is equal to this upper bound then we
* position the userIdxCursor right before the last node.
*
* If the element's value is smaller, then we delegate to the
* before() method of the userIdxCursor.
*/
//noinspection unchecked
int compareValue = lessEqEvaluator.getLdapComparator().compare( value,
lessEqEvaluator.getExpression().getValue().get() );
if ( compareValue > 0 )
{
afterLast();
return;
}
else if ( compareValue == 0 )
{
last();
previous();
available = false;
return;
}
userIdxCursor.beforeValue( id, value );
available = false;
}
else
{
throw new UnsupportedOperationException( UNSUPPORTED_MSG );
}
}
public void before( IndexEntry<V, ServerEntry, ID> element ) throws Exception
{
checkNotClosed( "before()" );
if ( userIdxCursor != null )
{
/*
* First we need to check and make sure this element is within
* bounds as mandated by the assertion node. To do so we compare
* it's value with the value of the expression node. If the
* element's value is greater than this upper bound then we
* position the userIdxCursor after the last node.
*
* If the element's value is equal to this upper bound then we
* position the userIdxCursor right before the last node.
*
* If the element's value is smaller, then we delegate to the
* before() method of the userIdxCursor.
*/
int compareValue = lessEqEvaluator.getLdapComparator().compare( element.getValue(),
lessEqEvaluator.getExpression().getValue().get() );
if ( compareValue > 0 )
{
afterLast();
return;
}
else if ( compareValue == 0 )
{
last();
previous();
available = false;
return;
}
userIdxCursor.before( element );
available = false;
}
else
{
throw new UnsupportedOperationException( UNSUPPORTED_MSG );
}
}
public void afterValue( ID id, V value ) throws Exception
{
checkNotClosed( "afterValue()" );
if ( userIdxCursor != null )
{
int comparedValue = lessEqEvaluator.getLdapComparator().compare( value,
lessEqEvaluator.getExpression().getValue().get() );
/*
* First we need to check and make sure this element is within
* bounds as mandated by the assertion node. To do so we compare
* it's value with the value of the expression node.
*
* If the element's value is equal to or greater than this upper
* bound then we position the userIdxCursor after the last node.
*
* If the element's value is smaller, then we delegate to the
* after() method of the userIdxCursor.
*/
if ( comparedValue >= 0 )
{
afterLast();
return;
}
// Element is in the valid range as specified by assertion
userIdxCursor.afterValue( id, value );
available = false;
}
else
{
throw new UnsupportedOperationException( UNSUPPORTED_MSG );
}
}
public void after( IndexEntry<V, ServerEntry, ID> element ) throws Exception
{
checkNotClosed( "after()" );
if ( userIdxCursor != null )
{
int comparedValue = lessEqEvaluator.getLdapComparator().compare( element.getValue(),
lessEqEvaluator.getExpression().getValue().get() );
/*
* First we need to check and make sure this element is within
* bounds as mandated by the assertion node. To do so we compare
* it's value with the value of the expression node.
*
* If the element's value is equal to or greater than this upper
* bound then we position the userIdxCursor after the last node.
*
* If the element's value is smaller, then we delegate to the
* after() method of the userIdxCursor.
*/
if ( comparedValue >= 0 )
{
afterLast();
return;
}
// Element is in the valid range as specified by assertion
userIdxCursor.after( element );
available = false;
}
else
{
throw new UnsupportedOperationException( UNSUPPORTED_MSG );
}
}
public void beforeFirst() throws Exception
{
checkNotClosed( "beforeFirst()" );
if ( userIdxCursor != null )
{
userIdxCursor.beforeFirst();
}
else
{
ndnIdxCursor.beforeFirst();
ndnCandidate = null;
}
available = false;
}
public void afterLast() throws Exception
{
checkNotClosed( "afterLast()" );
if ( userIdxCursor != null )
{
IndexEntry<V, ServerEntry, ID> advanceTo = new ForwardIndexEntry<V, ServerEntry, ID>();
//noinspection unchecked
advanceTo.setValue( ( V ) lessEqEvaluator.getExpression().getValue().get() );
userIdxCursor.after( advanceTo );
}
else
{
ndnIdxCursor.afterLast();
ndnCandidate = null;
}
available = false;
}
public boolean first() throws Exception
{
beforeFirst();
return next();
}
public boolean last() throws Exception
{
afterLast();
return previous();
}
public boolean previous() throws Exception
{
checkNotClosed( "previous()" );
if ( userIdxCursor != null )
{
/*
* No need to do the same check that is done in next() since
* values are decreasing with calls to previous(). We will
* always have lesser values.
*/
return available = userIdxCursor.previous();
}
while ( ndnIdxCursor.previous() )
{
checkNotClosed( "previous()" );
ndnCandidate = ndnIdxCursor.get();
if ( lessEqEvaluator.evaluate( ndnCandidate ) )
{
return available = true;
}
else
{
ndnCandidate = null;
}
}
return available = false;
}
public boolean next() throws Exception
{
checkNotClosed( "next()" );
if ( userIdxCursor != null )
{
/*
* We have to check and make sure the next value complies by
* being less than or eq to the expression node's value. We need
* to do this since values are increasing and we must limit to our
* upper bound.
*/
while ( userIdxCursor.next() )
{
checkNotClosed( "next()" );
IndexEntry<?, ServerEntry, ID> candidate = userIdxCursor.get();
if ( lessEqEvaluator.getLdapComparator().compare( candidate.getValue(),
lessEqEvaluator.getExpression().getValue().get() ) <= 0 )
{
return available = true;
}
}
return available = false;
}
while ( ndnIdxCursor.next() )
{
checkNotClosed( "next()" );
ndnCandidate = ndnIdxCursor.get();
if ( lessEqEvaluator.evaluate( ndnCandidate ) )
{
return available = true;
}
else
{
ndnCandidate = null;
}
}
return available = false;
}
public IndexEntry<V, ServerEntry, ID> get() throws Exception
{
checkNotClosed( "get()" );
if ( userIdxCursor != null )
{
if ( available )
{
return userIdxCursor.get();
}
throw new InvalidCursorPositionException( I18n.err( I18n.ERR_708 ) );
}
if ( available )
{
return ndnCandidate;
}
throw new InvalidCursorPositionException( I18n.err( I18n.ERR_708 ) );
}
public boolean isElementReused()
{
if ( userIdxCursor != null )
{
return userIdxCursor.isElementReused();
}
return ndnIdxCursor.isElementReused();
}
public void close() throws Exception
{
super.close();
if ( userIdxCursor != null )
{
userIdxCursor.close();
}
else
{
ndnIdxCursor.close();
ndnCandidate = null;
}
}
}