JoinPredicate.java

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 * See the COPYRIGHT.txt file distributed with this work for information
 * regarding copyright ownership.  Some portions may be licensed
 * to Red Hat, Inc. under one or more contributor license agreements.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

package org.teiid.query.sql.lang;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.teiid.core.util.EquivalenceUtil;
import org.teiid.core.util.HashCodeUtil;
import org.teiid.query.sql.LanguageVisitor;
import org.teiid.query.sql.symbol.GroupSymbol;


/**
 * Represents a subpart of the FROM clause specifying a join within the FROM.  It may
 * optionally specify criteria for the join, depending on the join type.  For example,
 * these are some representations of JoinPredicates:
 * <OL>
 * <LI>GroupA CROSS JOIN GroupB</LI>
 * <LI>GroupA JOIN GroupB ON GroupA.E1=GroupB.E1 AND GroupA.E2=GroupB.E2</LI>
 * <LI>GroupA RIGHT OUTER JOIN (GroupB JOIN GroupC ON GroupB.E1=GroupC.E1) ON GroupA.E1=GroupB.E1</LI>
 * </OL>
 */
public class JoinPredicate extends FromClause {

	private FromClause leftClause;
	private FromClause rightClause;
	private JoinType joinType = JoinType.JOIN_INNER;
	private List joinCriteria;
	
	/**
	 * Construct a JoinPredicate
	 */
	public JoinPredicate() {
        this.joinCriteria = new ArrayList();
	}
	
	/**
	 * Construct a JoinPredicate between two clauses of the specified type.
	 * @param leftClause Left from clause
	 * @param rightClause Right from clause
	 * @param type Type of join
	 */
	public JoinPredicate(FromClause leftClause, FromClause rightClause, JoinType type) {
		this.leftClause = leftClause;
		this.rightClause = rightClause;
		this.joinType = type;
	 	this.joinCriteria = new ArrayList();
	}

	/**
	 * Construct a JoinPredicate between two clauses of the specified type.
	 * @param leftClause Left from clause
	 * @param rightClause Right from clause
	 * @param type Type of join
	 * @param criteria List of Criteria for this join predicate
	 */
	public JoinPredicate(FromClause leftClause, FromClause rightClause, JoinType type, List criteria) {
		this.leftClause = leftClause;
		this.rightClause = rightClause;
		this.joinType = type;
		this.joinCriteria = criteria;
	}
    
    /**
     * Construct a JoinPredicate between two clauses of the specified type.
     * @param leftClause Left from clause
     * @param rightClause Right from clause
     * @param type Type of join
     * @param criteria List of Criteria for this join predicate
     */
    public JoinPredicate(FromClause leftClause, FromClause rightClause, JoinType type, Criteria criteria) {
        this.leftClause = leftClause;
        this.rightClause = rightClause;
        this.joinType = type;
        this.joinCriteria = Criteria.separateCriteriaByAnd(criteria);
    }

	/**
	 * Set left clause 
	 * @param predicate Left clause to set
	 */
	public void setLeftClause(FromClause predicate) {
		this.leftClause = predicate;
	}
	
	/**
	 * Get left clause
	 * @return Left clause
	 */
	public FromClause getLeftClause() {
		return this.leftClause;
	}
	
	/**
	 * Set right clause 
	 * @param predicate Right clause to set
	 */
	public void setRightClause(FromClause predicate) {
		this.rightClause = predicate;
	}
	
	/**
	 * Get right clause
	 * @return Right clause
	 */
	public FromClause getRightClause() {
		return this.rightClause;
	}
	
	/**
	 * Set join type for this predicate
	 * @param type Type of join
	 */
	public void setJoinType(JoinType type) { 
		this.joinType = type;
	}
	
	/**
	 * Get join type for this predicate
	 * @return Type of join
	 */
	public JoinType getJoinType() {
		return this.joinType;
	}				
	
	/**
	 * Set join criteria for this predicate
	 * @param criteria List of {@link Criteria} set on this predicate
	 */
	public void setJoinCriteria(List criteria) {
		this.joinCriteria = criteria;
	}
	
	/**
	 * Get join criteria for this predicate
	 * @return List of {@link Criteria} 
	 */
	public List getJoinCriteria() {
		return this.joinCriteria;
	}
		
    /**
     * Collect all GroupSymbols for this from clause.
     * @param groups Groups to add to
     */
    public void collectGroups(Collection<GroupSymbol> groups) {
        if(this.leftClause != null) { 
            this.leftClause.collectGroups(groups);
        } 
        if(this.rightClause != null) {
            this.rightClause.collectGroups(groups);
        }
    }

    public void acceptVisitor(LanguageVisitor visitor) {
        visitor.visit(this);
    }

	/**
	 * Compare this object to another
	 * @param obj Other object
	 * @return True if equal
	 */
	public boolean equals(Object obj) {
		if (!super.equals(obj)) {
		    return false;
        }
        
		if(!(obj instanceof JoinPredicate)) { 
			return false;
		}		
		JoinPredicate other = (JoinPredicate) obj;

		List thisCrit = this.getJoinCriteria();
		if(thisCrit != null && thisCrit.size() == 0) { 
			thisCrit = null;
		}
		List otherCrit = other.getJoinCriteria();
		if(otherCrit != null && otherCrit.size() == 0) {
			otherCrit = null;
		}	

		return EquivalenceUtil.areEqual(other.getJoinType(), this.getJoinType()) &&
               EquivalenceUtil.areEqual(other.getLeftClause(), this.getLeftClause()) &&
               EquivalenceUtil.areEqual(other.getRightClause(), this.getRightClause()) &&
               EquivalenceUtil.areEqual(otherCrit, thisCrit);
	}
	
	/**
	 * Get hash code for object
	 * @return Hash code
	 */
	public int hashCode() {
		int hash = HashCodeUtil.hashCode(0, getLeftClause());
		hash = HashCodeUtil.hashCode(hash, getJoinType().getTypeCode());
		hash = HashCodeUtil.hashCode(hash, getRightClause());
		return hash;
	}
	
	/**
	 * Return deep clone for object
	 * @return Deep clone
	 */
	protected FromClause cloneDirect() {
	    FromClause copyLeft = null;
	    if(this.leftClause != null) { 
	        copyLeft = this.leftClause.clone();
	    }	

	    FromClause copyRight = null;
	    if(this.rightClause != null) { 
	        copyRight = this.rightClause.clone();
	    }	
	    
		List copyCrits = null;
		if(this.joinCriteria != null) { 
			copyCrits = new ArrayList(joinCriteria.size());
			Iterator iter = this.joinCriteria.iterator();
			while(iter.hasNext()) { 
				Criteria crit = (Criteria) iter.next();
				copyCrits.add(crit.clone());    
			}    
		}
	    	    
        JoinPredicate clonedJoinPredicate = new JoinPredicate(copyLeft, copyRight, this.joinType, copyCrits);
        return clonedJoinPredicate;
	}

}