HelperVocabularycheck.cs

// -- FreeBSD License ---------------------------------------------------------
// Copyright (c) 2012, Gerhard Fobe
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;

namespace Vsr.Hawaii.EmotionmlLib
{
    class HelperVocabularycheck
    {
        /// <summary>
        /// enables caching when loading a vocabulary by URL (default = true)
        /// </summary>
        public static bool enableCaching = true;

        /// <summary>
        /// cache for already readed vocabularies List<uri, vocabulary>
        /// </summary>
        private static SortedList<string,List<Vocabulary>> vocabularyCache = new SortedList<string,List<Vocabulary>>();
        

        /// <summary>
        /// load a vocabulary list from a URL
        /// </summary>
        /// <param name="uri">URI for emotionml vocabulary ressource</param>
        /// <returns>list of emotionml vocabularies</returns>
        public static List<Vocabulary> loadVocabularyListFromUrl(Uri uri) {
            string emotionmlString = null;
            List<Vocabulary> vocabularies = null;

            //read from cache
            //OPTIMIZE: use memory cache with garbage collection: http://msdn.microsoft.com/de-de/library/system.runtime.caching.memorycache.aspx
            if (vocabularyCache.Keys.Contains(uri.AbsoluteUri))
            {
                return vocabularyCache[uri.AbsoluteUri];
            }

            //normal processing
            if ("http://www.w3.org/TR/emotion-voc/xml" == uri.AbsoluteUri)
            {
                //use internal ressource if we use the W3C example
                //OPTIMIZE: how to deal between changes in W3C-list and easy to use with internal ressource -> @see cache?
                emotionmlString = Helper.loadInternalResource("vocabularies.emotionml");
            }
            else
            {
                List<KeyValuePair<string, string>> headers = new List<KeyValuePair<string, string>>();
                headers.Add(
                    // http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
                    new KeyValuePair<string, string>("Accept", EmotionML.MIME_TYPE)
                );

                emotionmlString = Helper.doGetRequest(uri);
            }

            //load vocabularies
            Parser parser = new Parser(emotionmlString);
            vocabularies = parser.getVocabularies();

            //store it in cache:
            if (enableCaching)
            {
                if (vocabularyCache.ContainsKey(uri.AbsoluteUri))
                {
                    vocabularyCache[uri.AbsoluteUri] = vocabularies;
                }
                else
                {
                    vocabularyCache.Add(uri.AbsoluteUri, vocabularies);
                }
            }

            return vocabularies;
        }

        /// <summary>
        /// flushes the cache dealing with loaded vocabularies
        /// </summary>
        public static void flushCache()
        {
            vocabularyCache = new SortedList<string, List<Vocabulary>>();
        }
    }
}