testconstraintnode.java

derby database source code.good for you.

/*

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

   Copyright 2000, 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.compile.C_NodeTypes;

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

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

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

import org.apache.derby.impl.sql.compile.ExpressionClassBuilder;
import org.apache.derby.iapi.services.classfile.VMOpcode;

import java.util.Vector;

/**
 * A TestConstraintNode is used to determine when a constraint
 * has been violated.
 *
 * @author jeff
 */

public class TestConstraintNode extends UnaryLogicalOperatorNode
{
	private String sqlState;
	private String tableName;
	private String constraintName;

	/**
	 * Initializer for a TestConstraintNode
	 *
	 * @param operand	The operand of the constraint test
	 * @param sqlState	The SQLState of the exception to throw if the
	 *					constraint has failed
	 * @param tableName	The name of the table that the constraint is on
	 * @param constraintName	The name of the constraint being checked
	 */

	public void init(Object booleanValue,
					 Object sqlState,
					 Object tableName,
					 Object constraintName)
	{
		super.init(booleanValue, "throwExceptionIfFalse");
		this.sqlState = (String) sqlState;
		this.tableName = (String) tableName;
		this.constraintName = (String) constraintName;
	}

	/**
	 * 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
	{
		bindUnaryOperator(fromList, subqueryList, aggregateVector);

		/*
		** If the operand is not boolean, cast it.
		*/

		if ( ! operand.getTypeServices().getTypeId().getSQLTypeName().equals(
														TypeId.BOOLEAN_NAME))
		{
			operand = (ValueNode)
				getNodeFactory().getNode(
					C_NodeTypes.CAST_NODE,
					operand,
					new DataTypeDescriptor(TypeId.BOOLEAN_ID, true),
					getContextManager());
			((CastNode) operand).bindCastNodeOnly();
		}

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

		return this;
	}

	/**
	 * Do code generation for the TestConstraint operator.
	 *
	 * @param acb	The ExpressionClassBuilder for the class we're generating
	 * @param mb	The method the expression will go into
	 *
	 *
	 * @exception StandardException		Thrown on error
	 */

	public void generateExpression(ExpressionClassBuilder acb,
											MethodBuilder mb)
									throws StandardException
	{

		/*
		** This generates the following code:
		**
		** operand.testConstraint(sqlState, tableName, constraintName)
		*/

		operand.generateExpression(acb, mb);

		mb.push(sqlState);
		mb.push(tableName);
		mb.push(constraintName);

		mb.callMethod(VMOpcode.INVOKEINTERFACE, ClassName.BooleanDataValue,
				"throwExceptionIfFalse", ClassName.BooleanDataValue, 3);

	}
}