IfStatement.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
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 */

package org.teiid.query.sql.proc;

import org.teiid.core.util.EquivalenceUtil;
import org.teiid.core.util.HashCodeUtil;
import org.teiid.query.sql.LanguageVisitor;
import org.teiid.query.sql.lang.Criteria;


/**
 * <p> This class represents an if-else statement in the storedprocedure language.
 * It extends the <code>Statement</code> that could part of a block.  This statement has
 * an IF block and an optional ELSE block, it also holds reference to the criteria that
 * determines which block should be executed..</p>
 */
public class IfStatement extends Statement  {

	// the IF block
	private Block ifBlock;
	
	// the ELSE block
	private Block elseBlock;
	
	// criteria on the if block
	private Criteria condition;

	/**
	 * Constructor for IfStatement.
	 */
	public IfStatement() {
		super();
	}

	/**
	 * Constructor for IfStatement.
	 * @param criteria The criteria determining which bleck should be executed
	 * @param ifBlock The IF <code>Block</code> object.
	 * @param ifBlock The ELSE <code>Block</code> object.
	 */
	public IfStatement(Criteria criteria, Block ifBlock, Block elseBlock) {
		this.ifBlock = ifBlock;
		this.elseBlock = elseBlock;
		this.condition = criteria;
	}

	/**
	 * Constructor for IfStatement.
	 * @param criteria The criteria determining which bleck should be executed
	 * @param ifBlock The IF <code>Block</code> object.
	 */
	public IfStatement(Criteria criteria, Block ifBlock) {
		this(criteria, ifBlock, null);
	}

	/**
	 * Get the statement's IF block.
	 * @return The IF <code>Block</code> object.
	 */
	public Block getIfBlock() {
		return ifBlock;
	}
	
	/**
	 * Set the statement's IF block.
	 * @param block The IF <code>Block</code> object.
	 */
	public void setIfBlock(Block block) {
		this.ifBlock = block;
	}

	/**
	 * Get the statement's ELSE block.
	 * @return The ELSE <code>Block</code> object.
	 */
	public Block getElseBlock() {
		return elseBlock;
	}
	
	/**
	 * Set the statement's ELSE block.
	 * @param block The ELSE <code>Block</code> object.
	 */
	public void setElseBlock(Block block) {
		elseBlock = block;
	}
	
	/**
	 * Return a boolean indicating if the statement has an else block.
	 * @return A boolean indicating if the statement has an else block
	 */
	public boolean hasElseBlock() {
		return (elseBlock != null);
	}

	/**
	 * Get the condition that determines which block needs to be executed.
	 * @return The <code>Criteria</code> to determine block execution
	 */
	public Criteria getCondition() {
		return condition;
	}
	
	/**
	 * Set the condition that determines which block needs to be executed.
	 * @param criteria The <code>Criteria</code> to determine block execution
	 */
	public void setCondition(Criteria criteria) {
		this.condition = criteria;
	}
	
	/**
	 * Return the type for this statement, this is one of the types
	 * defined on the statement object.
	 * @return The statement type
	 */
	public int getType() {
		return Statement.TYPE_IF;
	}	

    // =========================================================================
    //                  P R O C E S S I N G     M E T H O D S
    // =========================================================================
    
    public void acceptVisitor(LanguageVisitor visitor) {
        visitor.visit(this);
    }
	
	/**
	 * Deep clone statement to produce a new identical statement.
	 * @return Deep clone 
	 */
	public Object clone() {
		Block otherIf = this.ifBlock.clone();
		Criteria otherCrit = (Criteria) this.condition.clone();		
		Block otherElse = null;
		if(this.hasElseBlock()) {
			otherElse = this.elseBlock.clone();	
		}

		return new IfStatement(otherCrit, otherIf, otherElse);
	}
	
    /**
     * Compare two IfStatements for equality.  They will only evaluate to equal if
     * they are IDENTICAL: their if, else blocks are same and the condition on the
     * ifBlock is same.
     * @param obj Other object
     * @return True if equal
     */
    public boolean equals(Object obj) {
    	// Quick same object test
    	if(this == obj) {
    		return true;
		}

		// Quick fail tests		
    	if(!(obj instanceof IfStatement)) {
    		return false;
		}

		IfStatement other = (IfStatement) obj;
		
        return 
    		// Compare the condition
    		EquivalenceUtil.areEqual(getCondition(), other.getCondition()) &&
            // Compare the if block
            EquivalenceUtil.areEqual(getIfBlock(), other.getIfBlock()) &&
            // Compare the else block
    		EquivalenceUtil.areEqual(this.getElseBlock(), other.getElseBlock());
    }

    /**
     * Get hashcode for IfStatement.  WARNING: This hash code relies on the
     * hash codes of the if-else blocks anf the criteria determining the block
     * on this statement. Hash code is only valid after the block has been
     * completely constructed.
     * @return Hash code
     */
    public int hashCode() {
    	// This hash code relies on the blocks and criteria for this statement
    	int myHash = 0;
    	myHash = HashCodeUtil.hashCode(myHash, this.getCondition());
    	myHash = HashCodeUtil.hashCode(myHash, this.getIfBlock());
    	myHash = HashCodeUtil.hashCode(myHash, this.getElseBlock());
		return myHash;
	}

} // END CLASS