////////////////////////////////////////////////////////////////////////////////
//
//  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 mx.core
{

/**
 *  A deferred instance factory that creates and returns an instance
 *  of a specified class.
 *  An application can use the <code>getInstance()</code> method to
 *  create an instance of the class when it is first needed and get
 *  a reference to the instance thereafter.
 *
 *  @see DeferredInstanceFromFunction
 *  
 *  @langversion 3.0
 *  @playerversion Flash 9
 *  @playerversion AIR 1.1
 *  @productversion Flex 3
 */
public class DeferredInstanceFromClass implements ITransientDeferredInstance
{
    include "../core/Version.as";

    //--------------------------------------------------------------------------
    //
    //  Constructor
    //
    //--------------------------------------------------------------------------

    /**
     *  Constructor.
     *
     *  @param generator The class whose instance the <code>getInstance()</code>
     *  method creates and returns.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */
    public function DeferredInstanceFromClass(generator:Class)
    {
        super();

        this.generator = generator;
    }

    //--------------------------------------------------------------------------
    //
    //  Variables
    //
    //--------------------------------------------------------------------------

    /**
     *  @private
     *  The generator class.
     */
    private var generator:Class;

    /**
     *  @private
     *  The generated value.
     */
    private var instance:Object = null;

    //--------------------------------------------------------------------------
    //
    //  Methods
    //
    //--------------------------------------------------------------------------

    /**
     *  Creates and returns an instance of the class specified in the
     *  DeferredInstanceFromClass constructor, if it does not yet exist;
     *  otherwise, returns the already-created class instance.
     *
     *  @return An instance of the class specified in the
     *  DeferredInstanceFromClass constructor.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */
    public function getInstance():Object
    {
        if (!instance)
            instance = new generator();

        return instance;
    }
    
    /**
     *  Resets the state of our factory to the initial, uninitialized state.
     *  The reference to our cached instance is cleared.
     * 
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 4
     */
    public function reset():void
    {
        instance = null;
    }
}

}