betweenoperatornode.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.sql.compile.BetweenOperatorNode

   Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable.

   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.apache.derby.impl.sql.compile;

import org.apache.derby.iapi.error.StandardException;

import org.apache.derby.iapi.sql.conn.LanguageConnectionContext;

import org.apache.derby.iapi.sql.dictionary.DataDictionary;

import org.apache.derby.iapi.sql.compile.C_NodeTypes;

import org.apache.derby.iapi.services.compiler.MethodBuilder;

import org.apache.derby.iapi.services.sanity.SanityManager;

import org.apache.derby.impl.sql.compile.ExpressionClassBuilder;
import org.apache.derby.impl.sql.compile.ActivationClassBuilder;
import org.apache.derby.iapi.sql.compile.NodeFactory;
import org.apache.derby.iapi.services.context.ContextManager;

/**
 * A BetweenOperatorNode represents a BETWEEN clause. The between values are
 * represented as a 2 element list in order to take advantage of code reuse.
 *
 * @author Jerry Brenner
 */

public class BetweenOperatorNode extends BinaryListOperatorNode
{
	/**
	 * Initializer for a BetweenOperatorNode
	 *
	 * @param leftOperand		The left operand of the node
	 * @param betweenValues		The between values in list form
	 */

	public void init(Object leftOperand, Object betweenValues)
	{
		if (SanityManager.DEBUG)
		{
			ValueNodeList betweenVals = (ValueNodeList) betweenValues;

			SanityManager.ASSERT(betweenVals.size() == 2,
				"betweenValues.size() (" +
				betweenVals.size()	+
				") is expected to be 2");
		}

		super.init(leftOperand, betweenValues, "BETWEEN", null);
	}

	/**
	 * Eliminate NotNodes in the current query block.  We traverse the tree, 
	 * inverting ANDs and ORs and eliminating NOTs as we go.  We stop at 
	 * ComparisonOperators and boolean expressions.  We invert 
	 * ComparisonOperators and replace boolean expressions with 
	 * boolean expression = false.
	 * NOTE: Since we do not recurse under ComparisonOperators, there
	 * still could be NotNodes left in the tree.
	 *
	 * @param	underNotNode		Whether or not we are under a NotNode.
	 *							
	 *
	 * @return		The modified expression
	 *
	 * @exception StandardException		Thrown on error
	 */
	ValueNode eliminateNots(boolean underNotNode) 
					throws StandardException
	{
		BinaryComparisonOperatorNode leftBCO;
		BinaryComparisonOperatorNode rightBCO;
		OrNode						 newOr;

		if (SanityManager.DEBUG)
		SanityManager.ASSERT(rightOperandList.size() == 2,
			"rightOperandList.size() (" +
			rightOperandList.size()	+
			") is expected to be 2");

		if (! underNotNode)
		{
			return this;
		}

		/* we want to convert the BETWEEN  * into < OR > 
		   as described below.
		*/		

		/* Convert:
		 *		leftO between rightOList.elementAt(0) and rightOList.elementAt(1)
		 * to:
		 *		leftO < rightOList.elementAt(0) or leftO > rightOList.elementAt(1)
		 * NOTE - We do the conversion here since ORs will eventually be
		 * optimizable and there's no benefit for the optimizer to see NOT BETWEEN
		 */

		NodeFactory nodeFactory = getNodeFactory();
		ContextManager cm = getContextManager();

		/* leftO < rightOList.elementAt(0) */
		leftBCO = (BinaryComparisonOperatorNode) 
					nodeFactory.getNode(
									C_NodeTypes.BINARY_LESS_THAN_OPERATOR_NODE,
									leftOperand, 
								 	rightOperandList.elementAt(0),
									cm);
		/* Set type info for the operator node */
		leftBCO.bindComparisonOperator();

		/* leftO > rightOList.elementAt(1) */
		rightBCO = (BinaryComparisonOperatorNode) 
					nodeFactory.getNode(
								C_NodeTypes.BINARY_GREATER_THAN_OPERATOR_NODE,
								leftOperand, 
								rightOperandList.elementAt(1),
								cm);
		/* Set type info for the operator node */
		rightBCO.bindComparisonOperator();

		/* Create and return the OR */
		newOr = (OrNode) nodeFactory.getNode(
												C_NodeTypes.OR_NODE,
												leftBCO,
												rightBCO,
												cm);
		newOr.postBindFixup();

		/* Tell optimizer to use the between selectivity instead of >= * <= selectivities */
		leftBCO.setBetweenSelectivity();
		rightBCO.setBetweenSelectivity();

		return newOr;
	}

	/**
	 * Preprocess an expression tree.  We do a number of transformations
	 * here (including subqueries, IN lists, LIKE and BETWEEN) plus
	 * subquery flattening.
	 * NOTE: This is done before the outer ResultSetNode is preprocessed.
	 *
	 * @param	dataDictionary		DataDictionary to use.
	 * @param	numTables			Number of tables in the DML Statement
	 * @param	outerFromList		FromList from outer query block
	 * @param	outerSubqueryList	SubqueryList from outer query block
	 * @param	outerPredicateList	PredicateList from outer query block
	 *
	 * @return		The modified expression
	 *
	 * @exception StandardException		Thrown on error
	 */
	public ValueNode preprocess(int numTables,
								FromList outerFromList,
								SubqueryList outerSubqueryList,
								PredicateList outerPredicateList) 
					throws StandardException
	{
		ValueNode	leftClone1;
		ValueNode	rightOperand;

		/* We must 1st preprocess the component parts */
		super.preprocess(numTables,
						 outerFromList, outerSubqueryList,
						 outerPredicateList);

		/* This is where we do the transformation for BETWEEN to make it optimizable.
		 * c1 BETWEEN value1 AND value2 -> c1 >= value1 AND c1 <= value2
		 * This transformation is only done if the leftOperand is a ColumnReference.
		 */
		if (!(leftOperand instanceof ColumnReference))
		{
			return this;
		}

		/* For some unknown reason we need to clone the leftOperand if it is
		 * a ColumnReference because reusing them in Qualifiers for a scan
		 * does not work.  
		 */
		leftClone1 = leftOperand.getClone();

		/* The transformed tree has to be normalized:
		 *				AND
		 *			   /   \
		 *			  >=    AND
		 *				   /   \
		 *				  <=    TRUE
		 */

		NodeFactory nodeFactory = getNodeFactory();
		ContextManager cm = getContextManager();

        QueryTreeNode trueNode = nodeFactory.getNode(
											C_NodeTypes.BOOLEAN_CONSTANT_NODE,
											Boolean.TRUE,
											cm);

		/* Create the AND <= */
		BinaryComparisonOperatorNode lessEqual = 
			(BinaryComparisonOperatorNode) nodeFactory.getNode(
						C_NodeTypes.BINARY_LESS_EQUALS_OPERATOR_NODE,
						leftClone1, 
						rightOperandList.elementAt(1),
						cm);

		/* Set type info for the operator node */
		lessEqual.bindComparisonOperator();

		/* Create the AND */
		AndNode newAnd = (AndNode) nodeFactory.getNode(
												C_NodeTypes.AND_NODE,
												lessEqual,
												trueNode,
												cm);
		newAnd.postBindFixup();

		/* Create the AND >= */
		BinaryComparisonOperatorNode greaterEqual = 
			(BinaryComparisonOperatorNode) nodeFactory.getNode(
					C_NodeTypes.BINARY_GREATER_EQUALS_OPERATOR_NODE,
					leftOperand, 
					rightOperandList.elementAt(0),
					cm);

		/* Set type info for the operator node */
		greaterEqual.bindComparisonOperator();

		/* Create the AND */
		newAnd = (AndNode) nodeFactory.getNode(
												C_NodeTypes.AND_NODE,
												greaterEqual,
												newAnd,
												cm);
		newAnd.postBindFixup();

		/* Tell optimizer to use the between selectivity instead of >= * <= selectivities */
		lessEqual.setBetweenSelectivity();
		greaterEqual.setBetweenSelectivity();

		return newAnd;
	}
 
	/**
	 * Do code generation for this BETWEEN operator.
	 *
	 * @param acb	The ExpressionClassBuilder for the class we're generating
	 * @param mb	The method the code to place the code
	 *
	 *
	 * @exception StandardException		Thrown on error
	 */

	public void generateExpression(ExpressionClassBuilder acb,
											MethodBuilder mb)
		throws StandardException
	{
		AndNode						 newAnd;
		BinaryComparisonOperatorNode leftBCO;
		BinaryComparisonOperatorNode rightBCO;

		if (SanityManager.DEBUG)
		SanityManager.ASSERT(rightOperandList.size() == 2,
			"rightOperandList.size() (" +
			rightOperandList.size()	+
			") is expected to be 2");

		/* Convert:
		 *		leftO between rightOList.elementAt(0) and rightOList.elementAt(1)
		 * to:
		 *		leftO >= rightOList.elementAt(0) and leftO <= rightOList.elementAt(1) 
		 */

		NodeFactory nodeFactory = getNodeFactory();
		ContextManager cm = getContextManager();

		/* leftO >= rightOList.elementAt(0) */
		leftBCO = (BinaryComparisonOperatorNode) 
					nodeFactory.getNode(
							C_NodeTypes.BINARY_GREATER_EQUALS_OPERATOR_NODE,
							leftOperand, 
							rightOperandList.elementAt(0),
							cm);
		/* Set type info for the operator node */
		leftBCO.bindComparisonOperator();

		/* leftO <= rightOList.elementAt(1) */
		rightBCO = (BinaryComparisonOperatorNode) 
					nodeFactory.getNode(
						C_NodeTypes.BINARY_LESS_EQUALS_OPERATOR_NODE,
						leftOperand, 
						rightOperandList.elementAt(1),
						cm);
		/* Set type info for the operator node */
		rightBCO.bindComparisonOperator();

		/* Create and return the AND */
		newAnd = (AndNode) nodeFactory.getNode(
												C_NodeTypes.AND_NODE,
												leftBCO,
												rightBCO,
												cm);
		newAnd.postBindFixup();
		newAnd.generateExpression(acb, mb);
	}
}