source: stable/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/support.cs

//
// support.cs: Support routines to work around the fact that System.Reflection.Emit
// can not introspect types that are being constructed
//
// Author:
//   Miguel de Icaza (miguel@ximian.com)
//   Marek Safar (marek.safar@gmail.com)
//
// Copyright 2001 Ximian, Inc (http://www.ximian.com)
// Copyright 2003-2009 Novell, Inc
// Copyright 2011 Xamarin Inc
//

using System;
using System.Linq;
using System.IO;
using System.Text;
using System.Collections.Generic;

namespace Mono.CSharp {

  sealed class ReferenceEquality<T> : IEqualityComparer<T> where T : class
  {
    public static readonly IEqualityComparer<T> Default = new ReferenceEquality<T> ();

    private ReferenceEquality ()
    {
    }

    public bool Equals (T x, T y)
    {
      return ReferenceEquals (x, y);
    }

    public int GetHashCode (T obj)
    {
      return System.Runtime.CompilerServices.RuntimeHelpers.GetHashCode (obj);
    }
  }
#if !NET_4_0 && !MOBILE_DYNAMIC
  public class Tuple<T1, T2> : IEquatable<Tuple<T1, T2>>
  {
    public Tuple (T1 item1, T2 item2)
    {
      Item1 = item1;
      Item2 = item2;
    }

    public T1 Item1 { get; private set; }
    public T2 Item2 { get; private set; }

    public override int GetHashCode ()
    {
      return ((object)Item1 ?? 0) .GetHashCode () ^ ((object)Item2 ?? 0).GetHashCode ();
    }

    #region IEquatable<Tuple<T1,T2>> Members

    public bool Equals (Tuple<T1, T2> other)
    {
      return EqualityComparer<T1>.Default.Equals (Item1, other.Item1) &&
        EqualityComparer<T2>.Default.Equals (Item2, other.Item2);
    }

    #endregion
  }

  public class Tuple<T1, T2, T3> : IEquatable<Tuple<T1, T2, T3>>
  {
    public Tuple (T1 item1, T2 item2, T3 item3)
    {
      Item1 = item1;
      Item2 = item2;
      Item3 = item3;
    }

    public T1 Item1 { get; private set; }
    public T2 Item2 { get; private set; }
    public T3 Item3 { get; private set; }

    public override int GetHashCode ()
    {
      return Item1.GetHashCode () ^ Item2.GetHashCode () ^ Item3.GetHashCode ();
    }

    #region IEquatable<Tuple<T1,T2>> Members

    public bool Equals (Tuple<T1, T2, T3> other)
    {
      return EqualityComparer<T1>.Default.Equals (Item1, other.Item1) &&
        EqualityComparer<T2>.Default.Equals (Item2, other.Item2) &&
        EqualityComparer<T3>.Default.Equals (Item3, other.Item3);
    }

    #endregion
  }

  static class Tuple
  {
    public static Tuple<T1, T2> Create<T1, T2> (T1 item1, T2 item2)
    {
      return new Tuple<T1, T2> (item1, item2);
    }

    public static Tuple<T1, T2, T3> Create<T1, T2, T3> (T1 item1, T2 item2, T3 item3)
    {
      return new Tuple<T1, T2, T3> (item1, item2, item3);
    }
  }
#endif

  static class ArrayComparer
  {
    public static bool IsEqual<T> (T[] array1, T[] array2)
    {
      if (array1 == null || array2 == null)
        return array1 == array2;

      var eq = EqualityComparer<T>.Default;

      for (int i = 0; i < array1.Length; ++i) {
        if (!eq.Equals (array1[i], array2[i])) {
          return false;
        }
      }

      return true;
    }
  }
#if !FULL_AST
  /// <summary>
  ///   This is an arbitrarily seekable StreamReader wrapper.
  ///
  ///   It uses a self-tuning buffer to cache the seekable data,
  ///   but if the seek is too far, it may read the underly
  ///   stream all over from the beginning.
  /// </summary>
  public class SeekableStreamReader : IDisposable
  {
    public const int DefaultReadAheadSize =
      4096 / 2;

    StreamReader reader;
    Stream stream;

    char[] buffer;
    int read_ahead_length;  // the length of read buffer
    int buffer_start;       // in chars
    int char_count;         // count of filled characters in buffer[]
    int pos;                // index into buffer[]

    public SeekableStreamReader (Stream stream, Encoding encoding, char[] sharedBuffer = null)
    {
      this.stream = stream;
      this.buffer = sharedBuffer;

      InitializeStream (DefaultReadAheadSize);
      reader = new StreamReader (stream, encoding, true);
    }

    public void Dispose ()
    {
      // Needed to release stream reader buffers
      reader.Dispose ();
    }

    void InitializeStream (int read_length_inc)
    {
      read_ahead_length += read_length_inc;

      int required_buffer_size = read_ahead_length * 2;

      if (buffer == null || buffer.Length < required_buffer_size)
        buffer = new char [required_buffer_size];

      stream.Position = 0;
      buffer_start = char_count = pos = 0;
    }

    /// <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 buffer_start + pos;
      }

      set {
        //
        // If the lookahead was too small, re-read from the beginning. Increase the buffer size while we're at it
        // This should never happen until we are parsing some weird source code
        //
        if (value < buffer_start) {
          InitializeStream (read_ahead_length);

          //
          // Discard buffer data after underlying stream changed position
          // Cannot use handy reader.DiscardBufferedData () because it for
          // some strange reason resets encoding as well
          //
          reader = new StreamReader (stream, reader.CurrentEncoding, true);
        }

        while (value > buffer_start + char_count) {
          pos = char_count;
          if (!ReadBuffer ())
            throw new InternalErrorException ("Seek beyond end of file: " + (buffer_start + char_count - value));
        }

        pos = value - buffer_start;
      }
    }

    bool ReadBuffer ()
    {
      int slack = buffer.Length - char_count;

      //
      // read_ahead_length is only half of the buffer to deal with
      // reads ahead and moves back without re-reading whole buffer
      //
      if (slack <= read_ahead_length) {
        //
        // shift the buffer to make room for read_ahead_length number of characters
        //
        int shift = read_ahead_length - slack;
        Array.Copy (buffer, shift, buffer, 0, char_count - shift);

        // Update all counters
        pos -= shift;
        char_count -= shift;
        buffer_start += shift;
        slack += shift;
      }

      char_count += reader.Read (buffer, char_count, slack);

      return pos < char_count;
    }
    
    public char GetChar (int position)
    {
      if (buffer_start <= position && position < buffer.Length)
        return buffer[position];
      return '\0';
    }
    
    public char[] ReadChars (int fromPosition, int toPosition)
    {
      char[] chars = new char[toPosition - fromPosition];
      if (buffer_start <= fromPosition && toPosition <= buffer_start + buffer.Length) {
        Array.Copy (buffer, fromPosition - buffer_start, chars, 0, chars.Length);
      } else {
        throw new NotImplementedException ();
      }

      return chars;
    }

    public int Peek ()
    {
      if ((pos >= char_count) && !ReadBuffer ())
        return -1;

      return buffer [pos];
    }

    public int Read ()
    {
      if ((pos >= char_count) && !ReadBuffer ())
        return -1;

      return buffer [pos++];
    }
  }
#endif

  public class UnixUtils {
    [System.Runtime.InteropServices.DllImport ("libc", EntryPoint="isatty")]
    extern static int _isatty (int fd);
      
    public static bool isatty (int fd)
    {
      try {
        return _isatty (fd) == 1;
      } catch {
        return false;
      }
    }
  }

  /// <summary>
  ///   An exception used to terminate the compiler resolution phase and provide completions
  /// </summary>
  /// <remarks>
  ///   This is thrown when we want to return the completions or
  ///   terminate the completion process by AST nodes used in
  ///   the completion process.
  /// </remarks>
  public class CompletionResult : Exception {
    string [] result;
    string base_text;
    
    public CompletionResult (string base_text, string [] res)
    {
      if (base_text == null)
        throw new ArgumentNullException ("base_text");
      this.base_text = base_text;

      result = res;
      Array.Sort (result);
    }

    public string [] Result {
      get {
        return result;
      }
    }

    public string BaseText {
      get {
        return base_text;
      }
    }
  }

  struct TypeNameParser
  {
    internal static string Escape(string name)
    {
      if (name == null) {
        return null;
      }
      StringBuilder sb = null;
      for (int pos = 0; pos < name.Length; pos++) {
        char c = name[pos];
        switch (c) {
          case '\\':
          case '+':
          case ',':
          case '[':
          case ']':
          case '*':
          case '&':
            if (sb == null) {
              sb = new StringBuilder(name, 0, pos, name.Length + 3);
            }
            sb.Append("\\").Append(c);
            break;
          default:
            if (sb != null) {
              sb.Append(c);
            }
            break;
        }
      }
      return sb != null ? sb.ToString() : name;
    }
  }
}