java/engine/org/apache/derby/iapi/sql/dictionary/CheckConstraintDescriptor.java

/*

   Derby - Class org.apache.derby.iapi.sql.dictionary.CheckConstraintDescriptor

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to you 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.iapi.sql.dictionary;
import org.apache.derby.catalog.ReferencedColumns;
import org.apache.derby.catalog.UUID;
import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.shared.common.sanity.SanityManager;
import org.apache.derby.iapi.sql.StatementType;
import org.apache.derby.iapi.sql.conn.LanguageConnectionContext;
import org.apache.derby.iapi.store.access.TransactionController;

/**
 * This class represents a check constraint descriptor.
 *
 */
public class CheckConstraintDescriptor extends ConstraintDescriptor
{
	private ReferencedColumns	referencedColumns;
	private String						constraintText;

	CheckConstraintDescriptor(
		    DataDictionary dataDictionary,
			TableDescriptor table,
			String constraintName,
			boolean deferrable,
			boolean initiallyDeferred,
			UUID constraintId,
			String constraintText,
			ReferencedColumns referencedColumns,
			SchemaDescriptor schemaDesc,
			boolean	isEnabled
			)							
	{
		super(dataDictionary, table, constraintName, deferrable,
			  initiallyDeferred, (int []) null,
			  constraintId, schemaDesc, isEnabled);
		this.constraintText = constraintText;
		this.referencedColumns = referencedColumns;
	}

	/**
	 * Does this constraint have a backing index?
	 *
	 * @return boolean	Whether or not there is a backing index for this constraint.
	 */
	public boolean hasBackingIndex()
	{
		return false;
	}

	/**
	 * Gets an identifier telling what type of descriptor it is
	 * (UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK).
	 *
	 * @return	An identifier telling what type of descriptor it is
	 *		(UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK).
	 */
	public int	getConstraintType()
	{
		return DataDictionary.CHECK_CONSTRAINT;
	}

	/**
	 * Get the text of the constraint. (Only non-null/meaningful for check
	 * constraints.)
	 * @return	The constraint text.
	 */
	public String getConstraintText()
	{
		return constraintText;
	}

	/**
	 * Get the UUID of the backing index, if one exists.
	 *
	 * @return The UUID of the backing index, if one exists, else null.
	 */
	public UUID getConglomerateId()
	{
		return null;
	}

	/**
	 * Get the ReferencedColumns.
	 *
	 * @return The ReferencedColumns.
	 */
	public ReferencedColumns getReferencedColumnsDescriptor()
	{
		return referencedColumns;
	}

	/**
	 * Set the ReferencedColumns; used in drop column
	 *
	 * @param	rcd	The new ReferencedColumns.
	 */
	public void setReferencedColumnsDescriptor(ReferencedColumns rcd)
	{
		referencedColumns = rcd;
	}

	/**
	 * Get the referenced columns as an int[] of column ids.
	 *
	 * @return The array of referenced column ids.
	 */
	public int[] getReferencedColumns()
	{
		return referencedColumns.getReferencedColumnPositions();
	}

	/**
	 * Does this constraint need to fire on this type of
	 * DML?  For a check constraint, all inserts, and
	 * appropriate updates
	 *
	 * @param stmtType	the type of DML 
	 * (StatementType.INSERT|StatementType.UPDATE|StatementType.DELETE)
	 * @param modifiedCols	the columns modified, or null for all
	 *
	 * @return true/false
	 */
	public boolean needsToFire(int stmtType, int[] modifiedCols)
	{
		/*
		** If we are disabled, we never fire
		*/
        if (!enforced())
		{
			return false;
		}

		if (stmtType == StatementType.INSERT)
		{
			return true;
		}

		if (stmtType == StatementType.DELETE)
		{
			return false;
		}
	
		// if update, only relevant if columns intersect
		return doColumnsIntersect(modifiedCols, getReferencedColumns());
	}   

	/**
	 * Convert the CheckConstraintDescriptor to a String.
	 *
	 * @return	A String representation of this CheckConstraintDescriptor
	 */

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


}