source: branches/2817-BinPackingSpeedup/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/SeekableStreamReader.cs @ 15303

//
// SeekableStreamReader.cs
//
// Author:
//       Mike KrÃŒger <mkrueger@xamarin.com>
//
// Copyright (c) 2012 Xamarin Inc. (http://xamarin.com)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using ICSharpCode.NRefactory.Editor;
using System.IO;
using System.Text;

namespace Mono.CSharp
{
  public class SeekableStreamReader : IDisposable
  {
    public const int DefaultReadAheadSize = 2048;

    readonly ITextSource textSource;

    int pos;

    static string GetAllText(Stream stream, Encoding encoding) {
      using (var rdr = new StreamReader(stream, encoding)) {
        return rdr.ReadToEnd();
      }
    }

    public SeekableStreamReader (Stream stream, Encoding encoding, char[] sharedBuffer = null) : this(new StringTextSource(GetAllText(stream, encoding)))
    {
    }

    public SeekableStreamReader (ITextSource source)
    {
      this.textSource = source;
    }


    public void Dispose ()
    {
    }
    
    /// <remarks>
    ///   This value corresponds to the current position in a stream of characters.
    ///   The StreamReader hides its manipulation of the underlying byte stream and all
    ///   character set/decoding issues.  Thus, we cannot use this position to guess at
    ///   the corresponding position in the underlying byte stream even though there is
    ///   a correlation between them.
    /// </remarks>
    public int Position {
      get {
        return pos;
      }
      
      set {
        pos = value;
      }
    }

    public char GetChar (int position)
    {
      return textSource.GetCharAt (position);
    }
    
    public char[] ReadChars (int fromPosition, int toPosition)
    {
      return textSource.GetText (fromPosition, toPosition - fromPosition).ToCharArray ();
    }
    
    public int Peek ()
    {
      if (pos >= textSource.TextLength)
        return -1;
      return textSource.GetCharAt (pos);
    }
    
    public int Read ()
    {
      if (pos >= textSource.TextLength)
        return -1;
      return textSource.GetCharAt (pos++);
    }
  }
}