source: branches/2929_PrioritizedGrammarEnumeration/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Utils/Deque.cs @ 16452

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// 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
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// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Generic;
using System.Diagnostics;

namespace ICSharpCode.AvalonEdit.Utils
{
  /// <summary>
  /// Double-ended queue.
  /// </summary>
  [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix")]
  [Serializable]
  public sealed class Deque<T> : ICollection<T>
  {
    T[] arr = Empty<T>.Array;
    int size, head, tail;
    
    /// <inheritdoc/>
    public int Count {
      get { return size; }
    }
    
    /// <inheritdoc/>
    public void Clear()
    {
      arr = Empty<T>.Array;
      size = 0;
      head = 0;
      tail = 0;
    }
    
    /// <summary>
    /// Gets/Sets an element inside the deque.
    /// </summary>
    public T this[int index] {
      get {
        ThrowUtil.CheckInRangeInclusive(index, "index", 0, size - 1);
        return arr[(head + index) % arr.Length];
      }
      set {
        ThrowUtil.CheckInRangeInclusive(index, "index", 0, size - 1);
        arr[(head + index) % arr.Length] = value;
      }
    }
    
    /// <summary>
    /// Adds an element to the end of the deque.
    /// </summary>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1702:CompoundWordsShouldBeCasedCorrectly", MessageId = "PushBack")]
    public void PushBack(T item)
    {
      if (size == arr.Length)
        SetCapacity(Math.Max(4, arr.Length * 2));
      arr[tail++] = item;
      if (tail == arr.Length) tail = 0;
      size++;
    }
    
    /// <summary>
    /// Pops an element from the end of the deque.
    /// </summary>
    public T PopBack()
    {
      if (size == 0)
        throw new InvalidOperationException();
      if (tail == 0)
        tail = arr.Length - 1;
      else
        tail--;
      T val = arr[tail];
      arr[tail] = default(T); // allow GC to collect the element
      size--;
      return val;
    }
    
    /// <summary>
    /// Adds an element to the front of the deque.
    /// </summary>
    public void PushFront(T item)
    {
      if (size == arr.Length)
        SetCapacity(Math.Max(4, arr.Length * 2));
      if (head == 0)
        head = arr.Length - 1;
      else
        head--;
      arr[head] = item;
      size++;
    }
    
    /// <summary>
    /// Pops an element from the end of the deque.
    /// </summary>
    public T PopFront()
    {
      if (size == 0)
        throw new InvalidOperationException();
      T val = arr[head];
      arr[head] = default(T); // allow GC to collect the element
      head++;
      if (head == arr.Length) head = 0;
      size--;
      return val;
    }
    
    void SetCapacity(int capacity)
    {
      T[] newArr = new T[capacity];
      CopyTo(newArr, 0);
      head = 0;
      tail = (size == capacity) ? 0 : size;
      arr = newArr;
    }
    
    /// <inheritdoc/>
    public IEnumerator<T> GetEnumerator()
    {
      if (head < tail) {
        for (int i = head; i < tail; i++)
          yield return arr[i];
      } else {
        for (int i = head; i < arr.Length; i++)
          yield return arr[i];
        for (int i = 0; i < tail; i++)
          yield return arr[i];
      }
    }
    
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
      return this.GetEnumerator();
    }
    
    bool ICollection<T>.IsReadOnly {
      get { return false; }
    }
    
    void ICollection<T>.Add(T item)
    {
      PushBack(item);
    }
    
    /// <inheritdoc/>
    public bool Contains(T item)
    {
      EqualityComparer<T> comparer = EqualityComparer<T>.Default;
      foreach (T element in this)
        if (comparer.Equals(item, element))
          return true;
      return false;
    }
    
    /// <inheritdoc/>
    public void CopyTo(T[] array, int arrayIndex)
    {
      if (array == null)
        throw new ArgumentNullException("array");
      if (head < tail) {
        Array.Copy(arr, head, array, arrayIndex, tail - head);
      } else {
        int num1 = arr.Length - head;
        Array.Copy(arr, head, array, arrayIndex, num1);
        Array.Copy(arr, 0, array, arrayIndex + num1, tail);
      }
    }
    
    bool ICollection<T>.Remove(T item)
    {
      throw new NotSupportedException();
    }
  }
}