/*

   Derby - Class org.apache.derby.iapi.services.context.ContextImpl

   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.services.context;

/**
 * Contexts are created and used to manage the execution
 * environment. They provide a convenient location for
 * storing globals organized by the module using the
 * globals. 
 * 

 * We provide this abstract class for other implementations
 * to use so that they can simply add fields and operations on
 * them. To be usable by the context manager, the subclasses
 * must define CleanupOnError and call super() in any constructor.
 * 

 * Contexts assist in cleanup
 * when errors are caught in the outer block.
 * 

 * Contexts implement the sanity interface to check and provide
 * information about their contents.
 */
public abstract class ContextImpl 
	implements Context
{
	private final String myIdName;
	private final ContextManager myContextManager;

	/*
	 * class interface
	 */
	protected ContextImpl(ContextManager cm, String id) {
		myIdName = id;
		myContextManager = cm;
		cm.pushContext(this);
	}

	/*
	 * Context interface
	 */
	/**
	 * @see org.apache.derby.iapi.services.context.Context#getContextManager
	 */
	final public ContextManager getContextManager()
	{
		return myContextManager;
	}

	/**
	 * @see org.apache.derby.iapi.services.context.Context#getIdName
	 */
	final public String getIdName()
	{
		return myIdName;
	}

	final public void pushMe() {
		getContextManager().pushContext(this);
	}

	/** @see Context#popMe */
	final public void popMe() {
		getContextManager().popContext(this);
	}

	/**
	 * @see Context#isLastHandler
	 */
	public boolean isLastHandler(int severity)
	{
		return false;
	}

	public StringBuffer appendErrorInfo() {
		return null;
	}
}