/*
* Copyright 2006 JBoss Inc
*
* Licensed 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.drools.common;
import org.drools.reteoo.ReteTuple;
import org.drools.rule.ContextEntry;
import org.drools.rule.Declaration;
import org.drools.spi.BetaNodeFieldConstraint;
/**
* Checks if one tuple is the start subtuple of other tuple.
* For instance, if we have two tuples:
*
* T1 = [ a, b, c ]
* T2 = [ a, b, c, d, e]
*
* This constraint will evaluate to true as T1 is the starting subtuple
* of T2. On the other hand, if we have:
*
* T1 = [ a, c, b ]
* T2 = [ a, b, c, d, e ]
*
* This constraint will evaluate to false, as T1 is not the starting subtuple
* of T2. Besides having the same elements, the order is different.
*
* This constraint is used when joining subnetworks back into the main
* network.
*
* @author etirelli
*
*/
public class TupleStartEqualsConstraint
implements
BetaNodeFieldConstraint {
private static final long serialVersionUID = 400L;
private final Declaration[] declarations = new Declaration[0];
private static final TupleStartEqualsConstraint INSTANCE = new TupleStartEqualsConstraint();
// this is a stateless constraint, so we can make it a singleton
private TupleStartEqualsConstraint() {
}
public static TupleStartEqualsConstraint getInstance() {
return INSTANCE;
}
public Declaration[] getRequiredDeclarations() {
return this.declarations;
}
public void replaceDeclaration(Declaration oldDecl,
Declaration newDecl) {
}
public ContextEntry getContextEntry() {
return new TupleStartEqualsConstraintContextEntry();
}
public boolean isAllowedCachedLeft(final ContextEntry context,
final Object object) {
// object MUST be a ReteTuple
final ReteTuple tuple = ((ReteTuple) object).getSubTuple( ((TupleStartEqualsConstraintContextEntry) context).compareSize );
return ((TupleStartEqualsConstraintContextEntry) context).left.equals( tuple );
}
public boolean isAllowedCachedRight(final ReteTuple tuple,
final ContextEntry context) {
return tuple.equals( ((TupleStartEqualsConstraintContextEntry) context).right.getSubTuple( tuple.size() ) );
}
public String toString() {
return "[ TupleStartEqualsConstraint ]";
}
public int hashCode() {
return 10;
}
public boolean equals(final Object object) {
if ( object instanceof TupleStartEqualsConstraint ) {
return true;
}
return false;
}
public static class TupleStartEqualsConstraintContextEntry
implements
ContextEntry {
private static final long serialVersionUID = 400L;
public ReteTuple left;
public ReteTuple right;
// the size of the tuple to compare
public int compareSize;
private ContextEntry entry;
public TupleStartEqualsConstraintContextEntry() {
}
public ContextEntry getNext() {
return this.entry;
}
public void setNext(final ContextEntry entry) {
this.entry = entry;
}
public void updateFromTuple(final InternalWorkingMemory workingMemory,
final ReteTuple tuple) {
this.left = tuple;
this.compareSize = tuple.size();
}
public void updateFromFactHandle(final InternalWorkingMemory workingMemory,
final InternalFactHandle handle) {
// if it is not a rete tuple, then there is a bug in the engine...
// it MUST be a rete tuple
this.right = (ReteTuple) handle.getObject();
}
}
}