/// <summary>
/// 获取Key的HashCode的值,因为Key的HashCode值有可能是负数所有与0x7FFFFFFF进行与操作确保hashcode值为正数
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public int InitialHashCode(TKey key)
{
return((key == null) ? 0 : comparer.GetHashCode(key) & 0x7FFFFFFF);
}