FileStreamProvider.cs

/*
 * QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
 * Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
 * 
 * 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.
*/

using System.Collections.Generic;
using System.IO;

namespace QuantConnect.ToolBox
{
    /// <summary>
    /// Provides an implementation of <see cref="IStreamProvider"/> that just returns a file stream
    /// </summary>
    public class FileStreamProvider : IStreamProvider
    {
        private readonly Dictionary<string, FileStream> _files = new Dictionary<string, FileStream>();

        /// <summary>
        /// Opens the specified source as read to be consumed stream
        /// </summary>
        /// <param name="source">The source file to be opened</param>
        /// <returns>The stream representing the specified source</returns>
        public IEnumerable<Stream> Open(string source)
        {
            yield return File.OpenRead(source);
        }

        /// <summary>
        /// Closes the specified source file stream
        /// </summary>
        /// <param name="source">The source file to be closed</param>
        public void Close(string source)
        {
            // it's expected that users will dispose the stream
            // from the open call, this is used to clean up any
            // other resources, for example a ZipFile stream
            // when we returned a ZipEntry stream
            _files.Remove(source);
        }

        /// <summary>
        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            foreach (var kvp in _files)
            {
                kvp.Value.Dispose();
            }
        }
    }
}