AreaStream.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    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;
using System.IO;

namespace Deveel.Data.Store {
    public sealed class AreaStream : Stream {
        private readonly IArea area;

        public AreaStream(IArea area) {
            if (area == null)
                throw new ArgumentNullException("area");

            this.area = area;
        }

        public override void Flush() {
            area.Flush();
        }

        public override long Seek(long offset, SeekOrigin origin) {
            if (origin == SeekOrigin.Begin) {
                if (offset >= Length)
                    throw new ArgumentOutOfRangeException("offset");

                area.Position = (int) offset;
            } else if (origin == SeekOrigin.Current) {
                var pos = area.Position;
                var length = area.Length;
                if (pos + offset >= length)
                    throw new ArgumentOutOfRangeException("offset");

                area.Position = pos + (int)offset;
            } else {
                var length = area.Length;
                var newPos = length - offset;
                if (newPos < 0)
                    throw new ArgumentOutOfRangeException("offset");

                area.Position = (int)newPos;
            }

            return area.Position;
        }

        public override void SetLength(long value) {
            throw new NotSupportedException();
        }

        public override int Read(byte[] buffer, int offset, int count) {
            return area.Read(buffer, offset, count);
        }

        public override void Write(byte[] buffer, int offset, int count) {
            area.Write(buffer, offset, count);
        }

        public override bool CanRead {
            get { return true; }
        }

        public override bool CanSeek {
            get { return true; }
        }

        public override bool CanWrite {
            get { return !area.IsReadOnly; }
        }

        public override long Length {
            get { return area.Length; }
        }

        public override long Position {
            get { return area.Position; }
            set { Seek(value, SeekOrigin.Begin); }
        }
    }
}