binarylistoperatornode.java

derby database source code.good for you.

/*

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

   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.dictionary.DataDictionary;

import org.apache.derby.iapi.reference.SQLState;

import org.apache.derby.iapi.types.DataTypeDescriptor;
import org.apache.derby.iapi.types.TypeId;
import org.apache.derby.iapi.sql.compile.Visitor;
import org.apache.derby.iapi.sql.compile.Visitable;

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

import org.apache.derby.iapi.store.access.Qualifier;

import org.apache.derby.iapi.util.JBitSet;

import java.util.Vector;

/**
 * A BinaryListOperatorNode represents a built-in "binary" operator with a single
 * operand on the left of the operator and a list of operands on the right.
 * This covers operators such as IN and BETWEEN.
 *
 * @author Jerry Brenner
 */

public abstract class BinaryListOperatorNode extends ValueNode
{
	String	methodName;
	/* operator used for error messages */
	String	operator;

	String		leftInterfaceType;
	String		rightInterfaceType;

	ValueNode		receiver; // used in generation
	ValueNode		leftOperand;
	ValueNodeList	rightOperandList;

	/**
	 * Initializer for a BinaryListOperatorNode
	 *
	 * @param leftOperand		The left operand of the node
	 * @param rightOperandList	The right operand list of the node
	 * @param operator			String representation of operator
	 */

	public void init(Object leftOperand, Object rightOperandList,
					   Object operator, Object methodName)
	{
		this.leftOperand = (ValueNode) leftOperand;
		this.rightOperandList = (ValueNodeList) rightOperandList;
		this.operator = (String) operator;
		this.methodName = (String) methodName;
	}

	/**
	 * Convert this object to a String.  See comments in QueryTreeNode.java
	 * for how this should be done for tree printing.
	 *
	 * @return	This object as a String
	 */

	public String toString()
	{
		if (SanityManager.DEBUG)
		{
			return "operator: " + operator + "\n" +
				   "methodName: " + methodName + "\n" +
				super.toString();
		}
		else
		{
			return "";
		}
	}

	/**
	 * Prints the sub-nodes of this object.  See QueryTreeNode.java for
	 * how tree printing is supposed to work.
	 *
	 * @param depth		The depth of this node in the tree
	 *
	 * @return	Nothing
	 */

	public void printSubNodes(int depth)
	{
		if (SanityManager.DEBUG)
		{
			super.printSubNodes(depth);

			if (leftOperand != null)
			{
				printLabel(depth, "leftOperand: ");
				leftOperand.treePrint(depth + 1);
			}

			if (rightOperandList != null)
			{
				printLabel(depth, "rightOperandList: ");
				rightOperandList.treePrint(depth + 1);
			}
		}
	}

	/**
	 * Set the clause that this node appears in.
	 *
	 * @param clause	The clause that this node appears in.
	 *
	 * @return Nothing.
	 */
	public void setClause(int clause)
	{
		super.setClause(clause);
		leftOperand.setClause(clause);
		rightOperandList.setClause(clause);
	}

	/**
	 * Bind this expression.  This means binding the sub-expressions,
	 * as well as figuring out what the return type is for this expression.
	 *
	 * @param fromList		The FROM list for the query this
	 *				expression is in, for binding columns.
	 * @param subqueryList		The subquery list being built as we find SubqueryNodes
	 * @param aggregateVector	The aggregate vector being built as we find AggregateNodes
	 *
	 * @return	The new top of the expression tree.
	 *
	 * @exception StandardException		Thrown on error
	 */

	public ValueNode bindExpression(
		FromList fromList, SubqueryList subqueryList,
		Vector	aggregateVector) 
			throws StandardException
	{
		leftOperand = leftOperand.bindExpression(fromList, subqueryList, aggregateVector);
		rightOperandList.bindExpression(fromList, subqueryList, aggregateVector);

		/* Is there a ? parameter on the left? */
		if (leftOperand.isParameterNode())
		{
			ValueNode rightOperand = (ValueNode) rightOperandList.elementAt(0);

			/*
			** It's an error if both operands are all ? parameters.
			*/
			if (rightOperandList.containsAllParameterNodes())
			{
				throw StandardException.newException(SQLState.LANG_BINARY_OPERANDS_BOTH_PARMS, 
																	operator);
			}

			/* Set the left operand to the type of right parameter. */
			((ParameterNode) leftOperand).setDescriptor(rightOperandList.getTypeServices());
		}

		/* Is there a ? parameter on the right? */
		if (rightOperandList.containsParameterNode())
		{
			/* Set the right operand to the type of the left parameter. */
			rightOperandList.setParameterDescriptor(leftOperand.getTypeServices());
		}

		/* If the left operand is not a built-in type, then generate a conversion
		 * tree to a built-in type.
		 */
		if (! leftOperand.getTypeId().systemBuiltIn())
		{
			leftOperand = leftOperand.genSQLJavaSQLTree();
		}

		/* Generate bound conversion trees for those elements in the rightOperandList
		 * that are not built-in types.
		 */
		rightOperandList.genSQLJavaSQLTrees();

		/* Test type compatability and set type info for this node */
		bindComparisonOperator();

		return this;
	}

	/**
	 * Test the type compatability of the operands and set the type info
	 * for this node.  This method is useful both during binding and
	 * when we generate nodes within the language module outside of the parser.
	 *
	 * @return	Nothing
	 *
	 * @exception StandardException		Thrown on error
	 */
	public void bindComparisonOperator()
			throws StandardException
	{
		boolean				nullableResult;

		/* Can the types be compared to each other? */
		rightOperandList.comparable(leftOperand);

		/*
		** Set the result type of this comparison operator based on the
		** operands.  The result type is always SQLBoolean - the only question
		** is whether it is nullable or not.  If either the leftOperand or
		** any of the elements in the rightOperandList is
		** nullable, the result of the comparison must be nullable, too, so
		** we can represent the unknown truth value.
		*/
		nullableResult = leftOperand.getTypeServices().isNullable() ||
							rightOperandList.isNullable();
		setType(new DataTypeDescriptor(TypeId.BOOLEAN_ID, nullableResult));
	}

	/**
	 * 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	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
	{
		leftOperand = leftOperand.preprocess(numTables,
											 outerFromList, outerSubqueryList,
											 outerPredicateList);
 		rightOperandList.preprocess(numTables,
									outerFromList, outerSubqueryList,
									outerPredicateList);
		return this;
	}

	/**
	 * Set the leftOperand to the specified ValueNode
	 *
	 * @param newLeftOperand	The new leftOperand
	 *
	 * @return None.
	 */
	public void setLeftOperand(ValueNode newLeftOperand)
	{
		leftOperand = newLeftOperand;
	}

	/**
	 * Get the leftOperand
	 *
	 * @return The current leftOperand.
	 */
	public ValueNode getLeftOperand()
	{
		return leftOperand;
	}

	/**
	 * Set the rightOperandList to the specified ValueNodeList
	 *
	 * @param newRightOperandList	The new rightOperandList
	 *
	 * @return None.
	 */
	public void setRightOperandList(ValueNodeList newRightOperandList)
	{
		rightOperandList = newRightOperandList;
	}

	/**
	 * Get the rightOperandList
	 *
	 * @return The current rightOperandList.
	 */
	public ValueNodeList getRightOperandList()
	{
		return rightOperandList;
	}

	/**
	 * Categorize this predicate.  Initially, this means
	 * building a bit map of the referenced tables for each predicate.
	 * If the source of this ColumnReference (at the next underlying level) 
	 * is not a ColumnReference or a VirtualColumnNode then this predicate
	 * will not be pushed down.
	 *
	 * For example, in:
	 *		select * from (select 1 from s) a (x) where x = 1
	 * we will not push down x = 1.
	 * NOTE: It would be easy to handle the case of a constant, but if the
	 * inner SELECT returns an arbitrary expression, then we would have to copy
	 * that tree into the pushed predicate, and that tree could contain
	 * subqueries and method calls.
	 * RESOLVE - revisit this issue once we have views.
	 *
	 * @param referencedTabs	JBitSet with bit map of referenced FromTables
	 * @param simplePredsOnly	Whether or not to consider method
	 *							calls, field references and conditional nodes
	 *							when building bit map
	 *
	 * @return boolean		Whether or not source.expression is a ColumnReference
	 *						or a VirtualColumnNode.
	 * @exception StandardException			Thrown on error
	 */
	public boolean categorize(JBitSet referencedTabs, boolean simplePredsOnly)
		throws StandardException
	{
		boolean pushable;
		pushable = leftOperand.categorize(referencedTabs, simplePredsOnly);
		pushable = (rightOperandList.categorize(referencedTabs, simplePredsOnly) && pushable);
		return pushable;
	}

	/**
	 * Remap all ColumnReferences in this tree to be clones of the
	 * underlying expression.
	 *
	 * @return ValueNode			The remapped expression tree.
	 *
	 * @exception StandardException			Thrown on error
	 */
	public ValueNode remapColumnReferencesToExpressions()
		throws StandardException
	{
		// we need to assign back because a new object may be returned, beetle 4983
		leftOperand = leftOperand.remapColumnReferencesToExpressions();
		rightOperandList.remapColumnReferencesToExpressions();
		return this;
	}

	/**
	 * Return whether or not this expression tree represents a constant expression.
	 *
	 * @return	Whether or not this expression tree represents a constant expression.
	 */
	public boolean isConstantExpression()
	{
		return (leftOperand.isConstantExpression() &&
				rightOperandList.isConstantExpression());
	}

	/** @see ValueNode#constantExpression */
	public boolean constantExpression(PredicateList whereClause)
	{
		return (leftOperand.constantExpression(whereClause) &&
				rightOperandList.constantExpression(whereClause));
	}

	/**
	 * Return the variant type for the underlying expression.
	 * The variant type can be:
	 *		VARIANT				- variant within a scan
	 *							  (method calls and non-static field access)
	 *		SCAN_INVARIANT		- invariant within a scan
	 *							  (column references from outer tables)
	 *		QUERY_INVARIANT		- invariant within the life of a query
	 *		CONSTANT			- immutable
	 *
	 * @return	The variant type for the underlying expression.
	 * @exception StandardException	thrown on error
	 */
	protected int getOrderableVariantType() throws StandardException
	{
		int leftType = leftOperand.getOrderableVariantType();
		int rightType = rightOperandList.getOrderableVariantType();

		return Math.min(leftType, rightType);
	}

	/**
	 * Accept a visitor, and call v.visit()
	 * on child nodes as necessary.  
	 * 
	 * @param v the visitor
	 *
	 * @exception StandardException on error
	 */
	public Visitable accept(Visitor v) 
		throws StandardException
	{
		Visitable		returnNode = v.visit(this);

		if (v.skipChildren(this))
		{
			return returnNode;
		}

		if (leftOperand != null && !v.stopTraversal())
		{
			leftOperand = (ValueNode)leftOperand.accept(v);
		}
			
		if (rightOperandList != null && !v.stopTraversal())
		{
			rightOperandList = (ValueNodeList)rightOperandList.accept(v);
		}
			
		return returnNode;
	}
}