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194 lines
6.5 KiB
194 lines
6.5 KiB
// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt) |
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// This code is distributed under the GNU LGPL (for details please see \doc\license.txt) |
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using System; |
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using ICSharpCode.AvalonEdit.Utils; |
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namespace ICSharpCode.AvalonEdit.Document |
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{ |
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/// <summary> |
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/// The TextAnchor class references an offset (a position between two characters). |
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/// It automatically updates the offset when text is inserted/removed in front of the anchor. |
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/// </summary> |
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/// <remarks> |
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/// <para>Use the <see cref="Offset"/> property to get the offset from a text anchor. |
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/// Use the <see cref="TextDocument.CreateAnchor"/> method to create an anchor from an offset. |
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/// </para> |
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/// <para> |
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/// The document will automatically update all text anchors; and because it uses weak references to do so, |
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/// the garbage collector can simply collect the anchor object when you don't need it anymore. |
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/// </para> |
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/// <para>Moreover, the document is able to efficiently update a large number of anchors without having to look |
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/// at each anchor object individually. Updating the offsets of all anchors usually only takes time logarithmic |
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/// to the number of anchors. Retrieving the <see cref="Offset"/> property also runs in O(lg N).</para> |
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/// <inheritdoc cref="IsDeleted" /> |
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/// <inheritdoc cref="MovementType" /> |
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/// <para>If you want to track a segment, you can use the <see cref="AnchorSegment"/> class which |
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/// implements <see cref="ISegment"/> using two text anchors.</para> |
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/// </remarks> |
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/// <example> |
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/// Usage: |
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/// <code>TextAnchor anchor = document.CreateAnchor(offset); |
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/// ChangeMyDocument(); |
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/// int newOffset = anchor.Offset; |
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/// </code> |
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/// </example> |
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public sealed class TextAnchor |
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{ |
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readonly TextDocument document; |
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internal TextAnchorNode node; |
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internal TextAnchor(TextDocument document) |
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{ |
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this.document = document; |
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} |
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/// <summary> |
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/// Gets the document owning the anchor. |
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/// </summary> |
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public TextDocument Document { |
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get { return document; } |
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} |
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/// <summary> |
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/// Controls how the anchor moves. |
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/// </summary> |
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/// <remarks>Anchor movement is ambiguous if text is inserted exactly at the anchor's location. |
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/// Does the anchor stay before the inserted text, or does it move after it? |
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/// The property <see cref="MovementType"/> will be used to determine which of these two options the anchor will choose. |
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/// The default value is <see cref="AnchorMovementType.Default"/>.</remarks> |
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public AnchorMovementType MovementType { get; set; } |
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/// <summary> |
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/// <para> |
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/// Specifies whether the anchor survives deletion of the text containing it. |
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/// </para><para> |
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/// <c>false</c>: The anchor is deleted when the a selection that includes the anchor is deleted. |
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/// <c>true</c>: The anchor is not deleted. |
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/// </para> |
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/// </summary> |
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/// <remarks><inheritdoc cref="IsDeleted" /></remarks> |
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public bool SurviveDeletion { get; set; } |
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/// <summary> |
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/// Gets whether the anchor was deleted. |
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/// </summary> |
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/// <remarks> |
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/// <para>When a piece of text containing an anchor is removed, then that anchor will be deleted. |
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/// First, the <see cref="IsDeleted"/> property is set to true on all deleted anchors, |
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/// then the <see cref="Deleted"/> events are raised. |
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/// You cannot retrieve the offset from an anchor that has been deleted.</para> |
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/// <para>This deletion behavior might be useful when using anchors for building a bookmark feature, |
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/// but in other cases you want to still be able to use the anchor. For those cases, set <c><see cref="SurviveDeletion"/> = true</c>.</para> |
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/// </remarks> |
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public bool IsDeleted { |
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get { |
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document.DebugVerifyAccess(); |
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return node == null; |
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} |
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} |
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/// <summary> |
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/// Occurs after the anchor was deleted. |
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/// </summary> |
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/// <remarks> |
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/// <inheritdoc cref="IsDeleted" /> |
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/// <para>Due to the 'weak reference' nature of TextAnchor, you will receive the Deleted event only |
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/// while your code holds a reference to the TextAnchor object.</para> |
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/// </remarks> |
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public event EventHandler Deleted; |
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internal void OnDeleted(DelayedEvents delayedEvents) |
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{ |
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node = null; |
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delayedEvents.DelayedRaise(Deleted, this, EventArgs.Empty); |
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} |
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/// <summary> |
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/// Gets the offset of the text anchor. |
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/// </summary> |
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/// <exception cref="InvalidOperationException">Thrown when trying to get the Offset from a deleted anchor.</exception> |
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public int Offset { |
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get { |
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document.DebugVerifyAccess(); |
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TextAnchorNode n = this.node; |
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if (n == null) |
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throw new InvalidOperationException(); |
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int offset = n.length; |
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if (n.left != null) |
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offset += n.left.totalLength; |
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while (n.parent != null) { |
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if (n == n.parent.right) { |
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if (n.parent.left != null) |
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offset += n.parent.left.totalLength; |
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offset += n.parent.length; |
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} |
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n = n.parent; |
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} |
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return offset; |
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} |
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} |
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/// <summary> |
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/// Gets the line number of the anchor. |
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/// </summary> |
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/// <exception cref="InvalidOperationException">Thrown when trying to get the Offset from a deleted anchor.</exception> |
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public int Line { |
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get { |
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return document.GetLineByOffset(this.Offset).LineNumber; |
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} |
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} |
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/// <summary> |
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/// Gets the column number of this anchor. |
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/// </summary> |
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/// <exception cref="InvalidOperationException">Thrown when trying to get the Offset from a deleted anchor.</exception> |
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public int Column { |
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get { |
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int offset = this.Offset; |
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return offset - document.GetLineByOffset(offset).Offset + 1; |
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} |
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} |
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/// <summary> |
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/// Gets the text location of this anchor. |
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/// </summary> |
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/// <exception cref="InvalidOperationException">Thrown when trying to get the Offset from a deleted anchor.</exception> |
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public TextLocation Location { |
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get { |
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return document.GetLocation(this.Offset); |
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} |
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} |
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/// <inheritdoc/> |
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public override string ToString() |
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{ |
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return "[TextAnchor Offset=" + Offset + "]"; |
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} |
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} |
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/// <summary> |
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/// Defines how a text anchor moves. |
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/// </summary> |
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public enum AnchorMovementType |
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{ |
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/// <summary> |
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/// When text is inserted at the anchor position, the type of the insertion |
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/// determines where the caret moves to. For normal insertions, the anchor will stay |
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/// behind the inserted text. |
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/// </summary> |
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Default, |
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/// <summary> |
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/// When text is inserted at the anchor position, the anchor will stay |
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/// before the inserted text. |
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/// </summary> |
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BeforeInsertion, |
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/// <summary> |
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/// When text is insered at the anchor position, the anchor will move |
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/// after the inserted text. |
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/// </summary> |
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AfterInsertion |
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} |
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}
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