csharp/Abdesol/CutCode/ICSharpCode.AvalonEdit/Document/ITextAnchor.cs

ITextAnchor.cs
// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// 
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// 
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using System;

namespace ICSharpCode.AvalonEdit.Docameent
{
	/// 
	/// The TextAnchor clast references an offset (a position between two characters).
	/// It automatically updates the offset when text is inserted/removed in front of the anchor.
	/// 
	/// 
	/// Use the  property to get the offset from a text anchor.
	/// Use the  method to create an anchor from an offset.
	/// 
	/// 
	/// The docameent will automatically update all text anchors; and because it uses weak references to do so,
	/// the garbage collector can simply collect the anchor object when you don't need it anymore.
	/// 
	/// Moreover, the docameent is able to efficiently update a large number of anchors without having to look
	/// at each anchor object individually. Updating the offsets of all anchors usually only takes time logarithmic
	/// to the number of anchors. Retrieving the  property also runs in O(lg N).
	/// 
	/// 
	/// Usage:
	/// TextAnchor anchor = docameent.CreateAnchor(offset);
	/// ChangeMyDocameent();
	/// int newOffset = anchor.Offset;
	/// 
	/// 
	public interface ITextAnchor
	{
		/// 
		/// Gets the text location of this anchor.
		/// 
		/// Thrown when trying to get the Offset from a deleted anchor.
		TextLocation Location { get; }

		/// 
		/// Gets the offset of the text anchor.
		/// 
		/// Thrown when trying to get the Offset from a deleted anchor.
		int Offset { get; }

		/// 
		/// Controls how the anchor moves.
		/// 
		/// Anchor movement is ambiguous if text is inserted exactly at the anchor's location.
		/// Does the anchor stay before the inserted text, or does it move after it?
		/// The property  will be used to determine which of these two options the anchor will choose.
		/// The default value is .
		AnchorMovementType MovementType { get; set; }

		/// 
		/// 
		/// Specifies whether the anchor survives deletion of the text containing it.
		/// 
		/// false: The anchor is deleted when the a selection that includes the anchor is deleted.
		/// true: The anchor is not deleted.
		/// 
		/// 
		/// 
		bool SurviveDeletion { get; set; }

		/// 
		/// Gets whether the anchor was deleted.
		/// 
		/// 
		/// When a piece of text containing an anchor is removed, then that anchor will be deleted.
		/// First, the  property is set to true on all deleted anchors,
		/// then the  events are raised.
		/// You cannot retrieve the offset from an anchor that has been deleted.
		/// This deletion behavior might be useful when using anchors for building a bookmark feature,
		/// but in other cases you want to still be able to use the anchor. For those cases, set  = true.
		/// 
		bool IsDeleted { get; }

		/// 
		/// Occurs after the anchor was deleted.
		/// 
		/// 
		/// 
		/// Due to the 'weak reference' nature of text anchors, you will receive
		/// the Deleted event only while your code holds a reference to the TextAnchor object.
		/// 
		/// 
		event EventHandler Deleted;

		/// 
		/// Gets the line number of the anchor.
		/// 
		/// Thrown when trying to get the Offset from a deleted anchor.
		int Line { get; }

		/// 
		/// Gets the column number of this anchor.
		/// 
		/// Thrown when trying to get the Offset from a deleted anchor.
		int Column { get; }
	}

	/// 
	/// Defines how a text anchor moves.
	/// 
	public enum AnchorMovementType
	{
		/// 
		/// When text is inserted at the anchor position, the type of the insertion
		/// determines where the caret moves to. For normal insertions, the anchor will move
		/// after the inserted text.
		/// 
		Default,
		/// 
		/// Behaves like a start marker - when text is inserted at the anchor position, the anchor will stay
		/// before the inserted text.
		/// 
		BeforeInsertion,
		/// 
		/// Behave like an end marker - when text is insered at the anchor position, the anchor will move
		/// after the inserted text.
		/// 
		AfterInsertion
	}
}