SharpDevelop/ICSharpCode.NRefactory/Editor/TextChangeEventArgs.cs

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// 
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using System;

namespace ICSharpCode.NRefactory.Editor
{
	/// <summary>
	/// Describes a change of the document text.
	/// This class is thread-safe.
	/// </summary>
	[Serializable]
	public class TextChangeEventArgs : EventArgs
	{
		readonly int offset;
		readonly string removedText;
		readonly string insertedText;
		
		/// <summary>
		/// The offset at which the change occurs.
		/// </summary>
		public int Offset {
			get { return offset; }
		}
		
		/// <summary>
		/// The text that was removed.
		/// </summary>
		public string RemovedText {
			get { return removedText; }
		}
		
		/// <summary>
		/// The number of characters removed.
		/// </summary>
		public int RemovalLength {
			get { return removedText.Length; }
		}
		
		/// <summary>
		/// The text that was inserted.
		/// </summary>
		public string InsertedText {
			get { return insertedText; }
		}
		
		/// <summary>
		/// The number of characters inserted.
		/// </summary>
		public int InsertionLength {
			get { return insertedText.Length; }
		}
		
		/// <summary>
		/// Creates a new TextChangeEventArgs object.
		/// </summary>
		public TextChangeEventArgs(int offset, string removedText, string insertedText)
		{
			this.offset = offset;
			this.removedText = removedText ?? string.Empty;
			this.insertedText = insertedText ?? string.Empty;
		}
		
		/// <summary>
		/// Gets the new offset where the specified offset moves after this document change.
		/// </summary>
		public virtual int GetNewOffset(int offset, AnchorMovementType movementType = AnchorMovementType.Default)
		{
			if (offset >= this.Offset && offset <= this.Offset + this.RemovalLength) {
				if (movementType == AnchorMovementType.BeforeInsertion)
					return this.Offset;
				else
					return this.Offset + this.InsertionLength;
			} else if (offset > this.Offset) {
				return offset + this.InsertionLength - this.RemovalLength;
			} else {
				return offset;
			}
		}
	}
}