levelcollection.cs

详细讲述了数据库编程

		/// <returns>An <see cref="Enumerator"/> for the entire <c>LevelCollection</c>.</returns>
		public virtual ILevelCollectionEnumerator GetEnumerator()
		{
			return new Enumerator(this);
		}

		#endregion

		#region Public helpers (just to mimic some nice features of ArrayList)
		
		/// <summary>
		/// Gets or sets the number of elements the <c>LevelCollection</c> can contain.
		/// </summary>
		public virtual int Capacity
		{
			get 
			{ 
				return m_array.Length; 
			}
			set
			{
				if (value < m_count)
				{
					value = m_count;
				}

				if (value != m_array.Length)
				{
					if (value > 0)
					{
						Level[] temp = new Level[value];
						Array.Copy(m_array, 0, temp, 0, m_count);
						m_array = temp;
					}
					else
					{
						m_array = new Level[DEFAULT_CAPACITY];
					}
				}
			}
		}

		/// <summary>
		/// Adds the elements of another <c>LevelCollection</c> to the current <c>LevelCollection</c>.
		/// </summary>
		/// <param name="x">The <c>LevelCollection</c> whose elements should be added to the end of the current <c>LevelCollection</c>.</param>
		/// <returns>The new <see cref="LevelCollection.Count"/> of the <c>LevelCollection</c>.</returns>
		public virtual int AddRange(LevelCollection x)
		{
			if (m_count + x.Count >= m_array.Length)
			{
				EnsureCapacity(m_count + x.Count);
			}
			
			Array.Copy(x.m_array, 0, m_array, m_count, x.Count);
			m_count += x.Count;
			m_version++;

			return m_count;
		}

		/// <summary>
		/// Adds the elements of a <see cref="Level"/> array to the current <c>LevelCollection</c>.
		/// </summary>
		/// <param name="x">The <see cref="Level"/> array whose elements should be added to the end of the <c>LevelCollection</c>.</param>
		/// <returns>The new <see cref="LevelCollection.Count"/> of the <c>LevelCollection</c>.</returns>
		public virtual int AddRange(Level[] x)
		{
			if (m_count + x.Length >= m_array.Length)
			{
				EnsureCapacity(m_count + x.Length);
			}

			Array.Copy(x, 0, m_array, m_count, x.Length);
			m_count += x.Length;
			m_version++;

			return m_count;
		}

		/// <summary>
		/// Adds the elements of a <see cref="Level"/> collection to the current <c>LevelCollection</c>.
		/// </summary>
		/// <param name="col">The <see cref="Level"/> collection whose elements should be added to the end of the <c>LevelCollection</c>.</param>
		/// <returns>The new <see cref="LevelCollection.Count"/> of the <c>LevelCollection</c>.</returns>
		public virtual int AddRange(ICollection col)
		{
			if (m_count + col.Count >= m_array.Length)
			{
				EnsureCapacity(m_count + col.Count);
			}

			foreach(object item in col)
			{
				Add((Level)item);
			}

			return m_count;
		}
		
		/// <summary>
		/// Sets the capacity to the actual number of elements.
		/// </summary>
		public virtual void TrimToSize()
		{
			this.Capacity = m_count;
		}

		#endregion

		#region Implementation (helpers)

		/// <exception cref="ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is less than zero</para>
		/// <para>-or-</para>
		/// <para><paramref name="index"/> is equal to or greater than <see cref="LevelCollection.Count"/>.</para>
		/// </exception>
		private void ValidateIndex(int i)
		{
			ValidateIndex(i, false);
		}

		/// <exception cref="ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is less than zero</para>
		/// <para>-or-</para>
		/// <para><paramref name="index"/> is equal to or greater than <see cref="LevelCollection.Count"/>.</para>
		/// </exception>
		private void ValidateIndex(int i, bool allowEqualEnd)
		{
			int max = (allowEqualEnd) ? (m_count) : (m_count-1);
			if (i < 0 || i > max)
			{
				throw log4net.Util.SystemInfo.CreateArgumentOutOfRangeException("i", (object)i, "Index was out of range. Must be non-negative and less than the size of the collection. [" + (object)i + "] Specified argument was out of the range of valid values.");
			}
		}

		private void EnsureCapacity(int min)
		{
			int newCapacity = ((m_array.Length == 0) ? DEFAULT_CAPACITY : m_array.Length * 2);
			if (newCapacity < min)
			{
				newCapacity = min;
			}

			this.Capacity = newCapacity;
		}

		#endregion
		
		#region Implementation (ICollection)

		void ICollection.CopyTo(Array array, int start)
		{
			Array.Copy(m_array, 0, array, start, m_count);
		}

		#endregion

		#region Implementation (IList)

		object IList.this[int i]
		{
			get { return (object)this[i]; }
			set { this[i] = (Level)value; }
		}

		int IList.Add(object x)
		{
			return this.Add((Level)x);
		}

		bool IList.Contains(object x)
		{
			return this.Contains((Level)x);
		}

		int IList.IndexOf(object x)
		{
			return this.IndexOf((Level)x);
		}

		void IList.Insert(int pos, object x)
		{
			this.Insert(pos, (Level)x);
		}

		void IList.Remove(object x)
		{
			this.Remove((Level)x);
		}

		void IList.RemoveAt(int pos)
		{
			this.RemoveAt(pos);
		}

		#endregion

		#region Implementation (IEnumerable)

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

		#endregion

		#region Nested enumerator class

		/// <summary>
		/// Supports simple iteration over a <see cref="LevelCollection"/>.
		/// </summary>
		private sealed class Enumerator : IEnumerator, ILevelCollectionEnumerator
		{
			#region Implementation (data)
			
			private readonly LevelCollection m_collection;
			private int m_index;
			private int m_version;
			
			#endregion
		
			#region Construction
			
			/// <summary>
			/// Initializes a new instance of the <c>Enumerator</c> class.
			/// </summary>
			/// <param name="tc"></param>
			internal Enumerator(LevelCollection tc)
			{
				m_collection = tc;
				m_index = -1;
				m_version = tc.m_version;
			}
			
			#endregion
	
			#region Operations (type-safe IEnumerator)
			
			/// <summary>
			/// Gets the current element in the collection.
			/// </summary>
			public Level Current
			{
				get { return m_collection[m_index]; }
			}

			/// <summary>
			/// Advances the enumerator to the next element in the collection.
			/// </summary>
			/// <returns>
			/// <c>true</c> if the enumerator was successfully advanced to the next element; 
			/// <c>false</c> if the enumerator has passed the end of the collection.
			/// </returns>
			/// <exception cref="InvalidOperationException">
			/// The collection was modified after the enumerator was created.
			/// </exception>
			public bool MoveNext()
			{
				if (m_version != m_collection.m_version)
				{
					throw new System.InvalidOperationException("Collection was modified; enumeration operation may not execute.");
				}

				++m_index;
				return (m_index < m_collection.Count);
			}

			/// <summary>
			/// Sets the enumerator to its initial position, before the first element in the collection.
			/// </summary>
			public void Reset()
			{
				m_index = -1;
			}

			#endregion
	
			#region Implementation (IEnumerator)
			
			object IEnumerator.Current
			{
				get { return this.Current; }
			}
			
			#endregion
		}

		#endregion

		#region Nested Read Only Wrapper class

		private sealed class ReadOnlyLevelCollection : LevelCollection
		{
			#region Implementation (data)

			private readonly LevelCollection m_collection;

			#endregion

			#region Construction

			internal ReadOnlyLevelCollection(LevelCollection list) : base(Tag.Default)
			{
				m_collection = list;
			}

			#endregion

			#region Type-safe ICollection

			public override void CopyTo(Level[] array)
			{
				m_collection.CopyTo(array);
			}

			public override void CopyTo(Level[] array, int start)
			{
				m_collection.CopyTo(array,start);
			}
			public override int Count
			{
				get { return m_collection.Count; }
			}

			public override bool IsSynchronized
			{
				get { return m_collection.IsSynchronized; }
			}

			public override object SyncRoot
			{
				get { return this.m_collection.SyncRoot; }
			}

			#endregion

			#region Type-safe IList

			public override Level this[int i]
			{
				get { return m_collection[i]; }
				set { throw new NotSupportedException("This is a Read Only Collection and can not be modified"); }
			}

			public override int Add(Level x)
			{
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			public override void Clear()
			{
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			public override bool Contains(Level x)
			{
				return m_collection.Contains(x);
			}

			public override int IndexOf(Level x)
			{
				return m_collection.IndexOf(x);
			}

			public override void Insert(int pos, Level x)
			{
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			public override void Remove(Level x)
			{           
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			public override void RemoveAt(int pos)
			{
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			public override bool IsFixedSize
			{
				get { return true; }
			}

			public override bool IsReadOnly
			{
				get { return true; }
			}

			#endregion

			#region Type-safe IEnumerable

			public override ILevelCollectionEnumerator GetEnumerator()
			{
				return m_collection.GetEnumerator();
			}

			#endregion

			#region Public Helpers

			// (just to mimic some nice features of ArrayList)
			public override int Capacity
			{
				get { return m_collection.Capacity; }
				set { throw new NotSupportedException("This is a Read Only Collection and can not be modified"); }
			}

			public override int AddRange(LevelCollection x)
			{
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			public override int AddRange(Level[] x)
			{
				throw new NotSupportedException("This is a Read Only Collection and can not be modified");
			}

			#endregion
		}

		#endregion
	}

}