管理List的优化

C# List 是个很好用的类型,但是作为数组他有自己的缺陷,插入和删除特别耗,所以,如果这个List需要这样的操作很多,不妨使用UGUI中的LIST,放入项目可以直接使用,如下

namespace UnityEngine.UI.Collections
{
  internal class IndexedSet : IList, ICollection, IEnumerable, IEnumerable
  {
    private readonly List m_List = new List();
    private Dictionary m_Dictionary = new Dictionary();

    public void Add(T item)
    {
      this.m_List.Add(item);
      this.m_Dictionary.Add(item, this.m_List.Count - 1);
    }

    public bool AddUnique(T item)
    {
      if (this.m_Dictionary.ContainsKey(item))
        return false;
      this.m_List.Add(item);
      this.m_Dictionary.Add(item, this.m_List.Count - 1);
      return true;
    }

    public bool Remove(T item)
    {
      int index = -1;
      if (!this.m_Dictionary.TryGetValue(item, out index))
        return false;
      this.RemoveAt(index);
      return true;
    }

    public IEnumerator GetEnumerator()
    {
      throw new NotImplementedException();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
      return (IEnumerator) this.GetEnumerator();
    }

    public void Clear()
    {
      this.m_List.Clear();
      this.m_Dictionary.Clear();
    }

    public bool Contains(T item)
    {
      return this.m_Dictionary.ContainsKey(item);
    }

    public void CopyTo(T[] array, int arrayIndex)
    {
      this.m_List.CopyTo(array, arrayIndex);
    }

    public int Count
    {
      get
      {
        return this.m_List.Count;
      }
    }

    public bool IsReadOnly
    {
      get
      {
        return false;
      }
    }

    public int IndexOf(T item)
    {
      int num = -1;
      this.m_Dictionary.TryGetValue(item, out num);
      return num;
    }

    public void Insert(int index, T item)
    {
      throw new NotSupportedException("Random Insertion is semantically invalid, since this structure does not guarantee ordering.");
    }

    public void RemoveAt(int index)
    {
      this.m_Dictionary.Remove(this.m_List[index]);
      if (index == this.m_List.Count - 1)
      {
        this.m_List.RemoveAt(index);
      }
      else
      {
        int index1 = this.m_List.Count - 1;
        T index2 = this.m_List[index1];
        this.m_List[index] = index2;
        this.m_Dictionary[index2] = index;
        this.m_List.RemoveAt(index1);
      }
    }

    public T this[int index]
    {
      get
      {
        return this.m_List[index];
      }
      set
      {
        T key = this.m_List[index];
        this.m_Dictionary.Remove(key);
        this.m_List[index] = value;
        this.m_Dictionary.Add(key, index);
      }
    }

    public void RemoveAll(Predicate match)
    {
      int index = 0;
      while (index < this.m_List.Count)
      {
        T obj = this.m_List[index];
        if (match(obj))
          this.Remove(obj);
        else
          ++index;
      }
    }

    public void Sort(Comparison sortLayoutFunction)
    {
      this.m_List.Sort(sortLayoutFunction);
      for (int index = 0; index < this.m_List.Count; ++index)
        this.m_Dictionary[this.m_List[index]] = index;
    }
  }
}