unarylogicaloperatornode.java

derby database source code.good for you.

/*

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

   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.sql.dictionary.DataDictionary;

import org.apache.derby.iapi.types.TypeId;

import org.apache.derby.iapi.reference.SQLState;
import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.types.DataTypeDescriptor;

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

import java.util.Vector;

public abstract class UnaryLogicalOperatorNode extends UnaryOperatorNode
{
	/**
	 * Initializer for a UnaryLogicalOperatorNode
	 *
	 * @param operand	The operand of the operator
	 * @param methodName	The name of the method to call in the generated
	 *						class.  In this case, it's actually an operator
	 *						name.
	 */

	public void init(
				Object	operand,
				Object		methodName)
	{
		/* For logical operators, the operator and method names are the same */
		super.init(operand, methodName, methodName);
	}

	/**
	 * Bind this logical operator.  All that has to be done for binding
	 * a logical operator is to bind the operand, check that the operand
	 * is SQLBoolean, and set the result type to SQLBoolean.
	 *
	 * @param fromList			The query's FROM list
	 * @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
	{
		super.bindExpression(fromList, subqueryList,
							 aggregateVector);

		/*
		** Logical operators work only on booleans.  If the operand 
		** is not boolean, throw an exception.
		**
		** For now, this exception will never happen, because the grammar
		** does not allow arbitrary expressions with NOT.  But when
		** we start allowing generalized boolean expressions, we will modify
		** the grammar, so this test will become useful.
		*/

		if ( ! operand.getTypeServices().getTypeId().equals(TypeId.BOOLEAN_ID))
		{
operand.treePrint();
			throw StandardException.newException(SQLState.LANG_UNARY_LOGICAL_NON_BOOLEAN);
		}

		/* Set the type info */
		setFullTypeInfo();

		return this;
	}
		
	/**
	 * Set all of the type info (nullability and DataTypeServices) for
	 * this node.  Extracts out tasks that must be done by both bind()
	 * and post-bind() AndNode generation.
	 *
	 * @return	None.
	 *
	 * @exception StandardException		Thrown on error
	 */
	protected void setFullTypeInfo()
		throws StandardException
	{
		boolean nullableResult;

		/*
		** 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 of the operands is
		** nullable, the result of the comparison must be nullable, too, so
		** we can represent the unknown truth value.
		*/
		nullableResult = operand.getTypeServices().isNullable();
		setType(new DataTypeDescriptor(TypeId.BOOLEAN_ID, nullableResult));
	}
}