columnordering.java

derby database source code.good for you.

/*

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

   Copyright 1999, 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.RowOrdering;
import org.apache.derby.iapi.sql.compile.Optimizable;

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

import java.util.Vector;

class ColumnOrdering {

	/* See RowOrdering for possible values */
	int	myDirection;

	/* A vector of column numbers (Integers) */
	Vector columns = new Vector();

	/*
	** A vector of table numbers (Integers), corresponding to the column
	** vector by position.
	*/
	Vector tables = new Vector();

	/**
	 * @param direction	See RowOrdering for possible values
	 */
	ColumnOrdering(int direction) {
		myDirection = direction;
	}

	/**
	 * Does this ColumnOrdering contain the given column in the given table
	 * in the right direction?
	 *
	 * @param direction		See RowOrdering for possible values
	 * @param tableNumber	The number of the table in question
	 * @param columnNumber	The column number in the table (one-based)
	 *
	 * @return	true if the column is found here in the right direction
	 */
	boolean ordered(int direction, int tableNumber, int columnNumber) {
		/*
		** Check the direction only if the direction isn't DONTCARE
		*/
		if (direction != RowOrdering.DONTCARE) {
			if (direction != myDirection)
				return false;
		}

		/* The direction matches - see if the column is in this ordering */
		return contains(tableNumber, columnNumber);
	}

	/**
	 * Does this ColumnOrdering contain the given column?
	 *
	 * @param tableNumber	The number of table in question
	 * @param columnNumber	The column number in the table (one-based)
	 *
	 * @return	true if the column is found here in the right direction
	 */
	boolean contains(int tableNumber, int columnNumber)
	{
		for (int i = 0; i < columns.size(); i++) {
			Integer col = (Integer) columns.elementAt(i);
			Integer tab = (Integer) tables.elementAt(i);

			if (tab.intValue() == tableNumber &&
				col.intValue() == columnNumber) {

				return true;
			}
		}

		return false;
	}

	/**
	 * Get the direction of this ColumnOrdering
	 */
	int direction()
	{
		return myDirection;
	}

	/**
	 * Add a column in a table to this ColumnOrdering
	 *
	 * @param tableNumber	The number of table in question
	 * @param columnNumber	The column number in the table (one-based)
	 */
	void addColumn(int tableNumber, int columnNumber)
	{
		tables.addElement(new Integer(tableNumber));
		columns.addElement(new Integer(columnNumber));
	}

	/**
	 * Remove all columns with the given table number
	 */
	void removeColumns(int tableNumber)
	{
		/*
		** Walk the list backwards, so we can remove elements
		** by position.
		*/
		for (int i = tables.size() - 1; i >= 0; i--)
		{
			Integer tab = (Integer) tables.elementAt(i);
			if (tab.intValue() == tableNumber)
			{
				tables.removeElementAt(i);
				columns.removeElementAt(i);
			}
		}
	}

	/**
	 * Tell whether this ColumnOrdering has no elements.
	 */
	boolean empty()
	{
		return (tables.size() == 0);
	}

	/** Return a clone of this ColumnOrdering */
	ColumnOrdering cloneMe() {
		ColumnOrdering retval = new ColumnOrdering(myDirection);

		for (int i = 0; i < columns.size(); i++) {
			/* Integers are immutable, so just copy the pointers */
			retval.columns.addElement(columns.elementAt(i));
			retval.tables.addElement(tables.elementAt(i));
		}

		return retval;
	}

	/** Is the given table number in this ColumnOrdering? */
	boolean hasTable(int tableNumber) {
		if (tables.size() == 0)
			return false;

		for (int i = 0; i < tables.size(); i++) {
			Integer tab = (Integer) tables.elementAt(i);
			
			if (tab.intValue() == tableNumber)
				return true;
		}

		return false;
	}

	/** Is there any table other than the given one in this ColumnOrdering? */
	boolean hasAnyOtherTable(int tableNumber) {
		if (tables.size() == 0)
			return false;

		for (int i = 0; i < tables.size(); i++) {
			Integer tab = (Integer) tables.elementAt(i);
			
			if (tab.intValue() != tableNumber)
				return true;
		}

		return false;
	}

	public String toString() {
		String retval = "";

		if (SanityManager.DEBUG) {
			retval += "Direction: " + myDirection;

			for (int i = 0; i < columns.size(); i++) {
				retval += " Table " + tables.elementAt(i) +
							", Column " + columns.elementAt(i);
			}
		}

		return retval;
	}
}