package org.drools.reteoo;
/*
* $Id: Builder.java,v 1.72 2005/02/02 00:23:21 mproctor Exp $
*
* Copyright 2001-2003 (C) The Werken Company. All Rights Reserved.
*
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided that the
* following conditions are met:
*
* 1. Redistributions of source code must retain copyright statements and
* notices. Redistributions must also contain a copy of this document.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The name "drools" must not be used to endorse or promote products derived
* from this Software without prior written permission of The Werken Company.
* For written permission, please contact bob@werken.com.
*
* 4. Products derived from this Software may not be called "drools" nor may
* "drools" appear in their names without prior written permission of The Werken
* Company. "drools" is a trademark of The Werken Company.
*
* 5. Due credit should be given to The Werken Company. (http://werken.com/)
*
* THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE WERKEN COMPANY OR ITS CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.drools.RuleBase;
import org.drools.RuleIntegrationException;
import org.drools.RuleSetIntegrationException;
import org.drools.conflict.DefaultConflictResolver;
import org.drools.rule.Declaration;
import org.drools.rule.Rule;
import org.drools.rule.RuleSet;
import org.drools.spi.Condition;
import org.drools.spi.ConflictResolver;
import org.drools.spi.RuleBaseContext;
/**
* Builds the Rete-OO network for a <code>RuleSet</code>.
*
* @see org.drools.rule.RuleSet
*
* @author <a href="mailto:bob@werken.com">bob mcwhirter </a>
*
* TODO Make joinForCondition actually be intelligent enough to build optimal
* joins. Currently using forgy's original description of 2-input nodes, which I
* feel (but don't know for sure, is sub-optimal.
*/
public class Builder
{
// ------------------------------------------------------------
// Instance members
// ------------------------------------------------------------
/** Rete network to build against. */
private Rete rete;
/** Rule-sets added. */
private List ruleSets;
/** Nodes that have been attached. */
private Map attachedNodes;
private Map applicationData;
private FactHandleFactory factHandleFactory;
private ConflictResolver conflictResolver;
private RuleBaseContext ruleBaseContext;
// ------------------------------------------------------------
// Constructors
// ------------------------------------------------------------
/**
* Construct a <code>Builder</code> against an existing <code>Rete</code>
* network.
*/
public Builder()
{
reset( );
this.ruleBaseContext = new RuleBaseContext( );
}
/**
* Construct a <code>Builder</code> against an existing <code>Rete</code>
* network.
*/
public Builder(RuleBaseContext ruleBaseContext)
{
reset( );
this.ruleBaseContext = ruleBaseContext;
}
// ------------------------------------------------------------
// Instance methods
// ------------------------------------------------------------
/**
* Build the <code>RuleBase</code>.
*
* @return The rule-base.
*/
public RuleBase buildRuleBase()
{
RuleBase ruleBase = new RuleBaseImpl( this.rete,
this.conflictResolver,
this.factHandleFactory,
this.ruleSets,
this.applicationData,
this.ruleBaseContext );
reset( );
return ruleBase;
}
/**
* Set the <code>FactHandleFactory</code>.
*
* @param factHandleFactory
* The fact handle factory.
*/
public void setFactHandleFactory(FactHandleFactory factHandleFactory)
{
this.factHandleFactory = factHandleFactory;
}
/**
* Set the <code>ConflictResolver</code>.
*
* @param conflictResolver
* The conflict resolver.
*/
public void setConflictResolver(ConflictResolver conflictResolver)
{
this.conflictResolver = conflictResolver;
}
/**
* Add a <code>RuleSet</code> to the network.
*
* @param ruleSet
* The rule-set to add.
*
* @throws RuleIntegrationException
* if an error prevents complete construction of the network for
* the <code>Rule</code>.
*/
public void addRuleSet(RuleSet ruleSet) throws RuleIntegrationException,
RuleSetIntegrationException
{
this.ruleSets.add( ruleSet );
Map newApplicationData = ruleSet.getApplicationData( );
Iterator it = newApplicationData.keySet( ).iterator( );
String identifier;
Class type;
while ( it.hasNext( ) )
{
identifier = (String) it.next( );
type = (Class) newApplicationData.get( identifier );
if ( this.applicationData.containsKey( identifier ) && !this.applicationData.get( identifier ).equals( type ) )
{
throw new RuleSetIntegrationException( ruleSet );
}
}
this.applicationData.putAll( newApplicationData );
Rule[] rules = ruleSet.getRules( );
for ( int i = 0; i < rules.length; ++i )
{
addRule( rules[i] );
}
}
/**
* Add a <code>Rule</code> to the network.
*
* @param rule
* The rule to add.
*
* @throws RuleIntegrationException
* if an error prevents complete construction of the network for
* the <code>Rule</code>.
*/
protected void addRule(Rule rule) throws RuleIntegrationException
{
List conds = new LinkedList( rule.getConditions( ) );
List leafNodes = createParameterNodes( rule );
boolean performedJoin;
boolean joinedForCondition;
while ( true )
{
joinedForCondition = false;
if ( !conds.isEmpty( ) )
{
attachConditions( rule,
conds,
leafNodes );
}
performedJoin = createJoinNodes( leafNodes );
if ( !performedJoin && !conds.isEmpty( ) )
{
joinedForCondition = joinForCondition( conds,
leafNodes );
}
if ( joinedForCondition )
{
continue;
}
if ( leafNodes.size( ) > 1 )
{
if ( !performedJoin )
{
joinArbitrary( leafNodes );
}
}
else
{
break;
}
}
if ( leafNodes.size( ) != 1 )
{
throw new RuleIntegrationException( rule );
}
TupleSource lastNode = (TupleSource) leafNodes.iterator( ).next( );
TerminalNode terminal = new TerminalNode( lastNode,
rule );
}
/**
* Create the <code>ParameterNode</code> s for the <code>Rule</code>,
* and link into the network.
*
* @param rule
* The rule.
*
* @return A <code>Set</code> of <code>ParameterNodes</code> created and
* linked into the network.
*/
List createParameterNodes(Rule rule)
{
List leafNodes = new LinkedList( );
Iterator declIter = rule.getParameterDeclarations( ).iterator( );
Declaration eachDecl;
while ( declIter.hasNext( ) )
{
eachDecl = (Declaration) declIter.next( );
attachNode( new ParameterNode( this.rete.getOrCreateObjectTypeNode( eachDecl.getObjectType( ) ),
eachDecl ),
leafNodes );
}
return leafNodes;
}
/**
* Attaches a node into the network. If a node already exists that could
* substitute, it is used instead.
*
* @param candidate
* The node to attach.
* @param leafNodes
* The list to which the newly added node will be added.
*/
private void attachNode(TupleSource candidate,
List leafNodes)
{
TupleSource node = (TupleSource) this.attachedNodes.get( candidate );
if ( node == null )
{
candidate.attach( );
this.attachedNodes.put( candidate,
candidate );
node = candidate;
}
leafNodes.add( node );
}
/**
* Create and attach <code>Condition</code> s to the network.
*
* <p>
* It may not be possible to satisfy all filder conditions on the first
* pass. This method removes satisfied conditions from the
* <code>Condition</code> parameter, and leaves unsatisfied ones in the
* <code>Set</code>.
* </p>
*
* @param rule
* The rule.
* @param conds
* Set of <code>Conditions</code> to attempt attaching.
* @param leafNodes
* The leaf node.
*/
private void attachConditions(Rule rule,
List conds,
List leafNodes)
{
Iterator condIter = conds.iterator( );
Condition eachCond;
TupleSource tupleSource;
while ( condIter.hasNext( ) )
{
eachCond = (Condition) condIter.next( );
tupleSource = findMatchingTupleSourceForCondition( eachCond,
leafNodes );
if ( tupleSource == null )
{
continue;
}
condIter.remove( );
attachNode( new ConditionNode( rule,
tupleSource,
eachCond ),
leafNodes );
}
}
/**
* Join two arbitrary leaves in order to satisfy a filter that currently
* cannot be applied.
*
* @param conds
* The filter conditions remaining.
* @param leafNodes
* Available leaf nodes.
*
* @return <code>true</code> if a join was possible, otherwise,
* <code>false</code>.
*/
private boolean joinForCondition(List conds,
List leafNodes)
{
return joinArbitrary( leafNodes );
}
/**
* Join two arbitrary leaves in order to satisfy a filter that currently
* cannot be applied.
*
* @param leafNodes
* Available leaf nodes.
*
* @return <code>true</code> if successfully joined some nodes, otherwise
* <code>false</code>.
*/
private boolean joinArbitrary(List leafNodes)
{
Iterator leafIter = leafNodes.iterator( );
TupleSource left = (TupleSource) leafIter.next( );
if ( !leafIter.hasNext( ) )
{
return false;
}
leafIter.remove( );
TupleSource right = (TupleSource) leafIter.next( );
leafIter.remove( );
attachNode( new JoinNode( left,
right ),
leafNodes );
return true;
}
/**
* Create and attach <code>JoinNode</code> s to the network.
*
* <p>
* It may not be possible to join all <code>leafNodes</code>.
* </p>
*
* <p>
* Any <code>leafNodes</code> member that particiates in a <i>join </i> is
* removed from the <code>leafNodes</code> collection, and replaced by the
* joining <code>JoinNode</code>.
* </p>
*
* @param leafNodes
* The current attachable leaf nodes of the network.
*
* @return <code>true</code> if at least one <code>JoinNode</code> was
* created, else <code>false</code>.
*/
private boolean createJoinNodes(List leafNodes)
{
boolean performedJoin = false;
Object[] nodesArray = leafNodes.toArray( );
TupleSource left;
TupleSource right;
for ( int i = 0; i < nodesArray.length; ++i )
{
left = (TupleSource) nodesArray[i];
if ( leafNodes.contains( left ) )
{
for ( int j = i + 1; j < nodesArray.length; ++j )
{
right = (TupleSource) nodesArray[j];
if ( leafNodes.contains( right ) && canBeJoined( left,
right ) )
{
leafNodes.remove( left );
leafNodes.remove( right );
attachNode( new JoinNode( left,
right ),
leafNodes );
performedJoin = true;
break;
}
}
}
}
return performedJoin;
}
/**
* Determine if two <code>TupleSource</code> s can be joined.
*
* @param left
* The left tuple source
* @param right
* The right tuple source
*
* @return <code>true</code> if they can be joined (they share at least
* one common member declaration), else <code>false</code>.
*/
private boolean canBeJoined(TupleSource left,
TupleSource right)
{
Set leftDecls = left.getTupleDeclarations( );
Iterator rightDeclIter = right.getTupleDeclarations( ).iterator( );
while ( rightDeclIter.hasNext( ) )
{
if ( leftDecls.contains( rightDeclIter.next( ) ) )
{
return true;
}
}
return false;
}
/**
* Locate a <code>TupleSource</code> suitable for attaching the
* <code>Condition</code> and remove it.
*
* @param condition
* The <code>Condition</code> to attach.
* @param sources
* Candidate <code>TupleSources</code>.
*
* @return Matching <code>TupleSource</code> if a suitable one can be
* found, else <code>null</code>.
*/
TupleSource findMatchingTupleSourceForCondition(Condition condition,
List sources)
{
Iterator sourceIter = sources.iterator( );
TupleSource eachSource;
while ( sourceIter.hasNext( ) )
{
eachSource = (TupleSource) sourceIter.next( );
if ( matches( condition,
eachSource.getTupleDeclarations( ) ) )
{
sourceIter.remove( );
return eachSource;
}
}
return null;
}
/**
* Determine if a set of <code>Declarations</code> match those required by
* a <code>Condition</code>.
*
* @param condition
* The <code>Condition</code>.
* @param declarations
* The set of <code>Declarations</code> to compare against.
*
* @return <code>true</code> if the set of <code>Declarations</code> is
* a super-set of the <code>Declarations</code> required by the
* <code>Condition</code>.
*/
boolean matches(Condition condition,
Set declarations)
{
return containsAll( declarations,
condition.getRequiredTupleMembers( ) );
}
/**
* Determine if a set of <code>Declarations</code> is a super set of
* required <code>Declarations</code>
*
* @param declarations
* The set of <code>Declarations</code> to compare against.
*
* @param requiredDecls
* The required <code>Declarations</code>.
* @return <code>true</code> if the set of <code>Declarations</code> is
* a super-set of the <code>Declarations</code> required by the
* <code>Condition</code>.
*/
private boolean containsAll(Set declarations,
Declaration[] requiredDecls)
{
for ( int i = requiredDecls.length - 1; i >= 0; i-- )
{
if ( !declarations.contains( requiredDecls[i] ) )
{
return false;
}
}
return true;
}
/**
* Reset the internal state.
*/
private void reset()
{
this.rete = new Rete( );
this.ruleSets = new ArrayList( );
this.attachedNodes = new HashMap( );
this.applicationData = new HashMap( );
this.factHandleFactory = new DefaultFactHandleFactory( );
this.conflictResolver = DefaultConflictResolver.getInstance( );
}
}