frameworks/projects/framework/src/mx/utils/DescribeTypeCache.as

////////////////////////////////////////////////////////////////////////////////
//
//  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.utils
{

import flash.utils.describeType;
import flash.utils.getDefinitionByName;
import flash.utils.getQualifiedClassName;
import mx.binding.BindabilityInfo;

[ExcludeClass]

/**
 *  @private
 *  DescribeTypeCache is a convenience class that is used to
 *  cache the return values of <code>flash.utils.describeType()</code>
 *  so that calls made subsequent times return faster.
 *
 *  This class also lets you set handler functions for specific value types.
 *  These will get called when the user tries to access these values on
 *  the <code>DescribeTypeCacheRecord</code> class.
 *
 *  @see mx.utils.DescribeTypeCacheRecord
 */
public class DescribeTypeCache
{
    include "../core/Version.as";

    //--------------------------------------------------------------------------
    //
    //  Class initialization
    //
    //--------------------------------------------------------------------------

    registerCacheHandler("bindabilityInfo", bindabilityInfoHandler);

    //--------------------------------------------------------------------------
    //
    //  Class variables
    //
    //--------------------------------------------------------------------------

    /**
     *  @private
     */
    private static var typeCache:Object = {};

    /**
     *  @private
     */
    private static var cacheHandlers:Object = {};

    //--------------------------------------------------------------------------
    //
    //  Class methods
    //
    //--------------------------------------------------------------------------

    /**
     *  Calls <code>flash.utils.describeType()</code> for the first time and caches
         *  the return value so that subsequent calls return faster.
         *
         *  @param o Can be either a string describing a fully qualified class name or any
         *  ActionScript value, including all available ActionScript types, object instances,
         *  primitive types (such as <code>uint</code>), and class objects.
         *
         *  @return Returns the cached record.
         *
         *  @see flash.utils#describeType()
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */
    public static function describeType(o:*):DescribeTypeCacheRecord
    {
        var className:String;
        var cacheKey:String;

        if (o is String)
            cacheKey = className = o;
        else
            cacheKey = className = getQualifiedClassName(o);

        //Need separate entries for describeType(Foo) and describeType(myFoo)
        if (o is Class)
            cacheKey += "$";

        if (cacheKey in typeCache)
        {
            return typeCache[cacheKey];
        }
        else
        {
            if (o is String)
            {
                try
                {
                    o = getDefinitionByName(o);
                }
                catch (error:ReferenceError)
                {
                    // The o parameter doesn't refer to an ActionScript 
                    // definition, it's just a string value.
                }
            }
            var typeDescription:XML = flash.utils.describeType(o);
            var record:DescribeTypeCacheRecord = new DescribeTypeCacheRecord();
            record.typeDescription = typeDescription;
            record.typeName = className;
            typeCache[cacheKey] = record;

            return record;
        }
    }

    /**
     *  registerCacheHandler lets you add function handler for specific strings.
         *  These functions get called when the user refers to these values on a
         *  instance of <code>DescribeTypeCacheRecord</code>.
     *
     *  @param valueName String that specifies the value for which the handler must be set.
         *  @param handler Function that should be called when user references valueName.
     *  
     *  @langversion 3.0
     *  @playerversion Flash 9
     *  @playerversion AIR 1.1
     *  @productversion Flex 3
     */
    public static function registerCacheHandler(valueName:String, handler:Function):void
    {
        cacheHandlers[valueName] = handler;
    }

    /**
     *  @private
     */
    internal static function extractValue(valueName:String, record:DescribeTypeCacheRecord):*
    {
        if (valueName in cacheHandlers)
            return cacheHandlers[valueName](record);

        return undefined;
    }

    /**
     *  @private
     */
    private static function bindabilityInfoHandler(record:DescribeTypeCacheRecord):*
    {
        return new BindabilityInfo(record.typeDescription);
    }
}

}