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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
using System;
using System.Diagnostics;
using System.Globalization;
namespace Tango.Scripting.Editors.Document
{
/// <summary>
/// Represents a line inside a <see cref="TextDocument"/>.
/// </summary>
/// <remarks>
/// <para>
/// The <see cref="TextDocument.Lines"/> collection contains one DocumentLine instance
/// for every line in the document. This collection is read-only to user code and is automatically
/// updated to reflect the current document content.
/// </para>
/// <para>
/// Internally, the DocumentLine instances are arranged in a binary tree that allows for both efficient updates and lookup.
/// Converting between offset and line number is possible in O(lg N) time,
/// and the data structure also updates all offsets in O(lg N) whenever a line is inserted or removed.
/// </para>
/// </remarks>
public sealed partial class DocumentLine : ISegment
{
#region Constructor
#if DEBUG
// Required for thread safety check which is done only in debug builds.
// To save space, we don't store the document reference in release builds as we don't need it there.
readonly TextDocument document;
#endif
internal bool isDeleted;
internal DocumentLine(TextDocument document)
{
#if DEBUG
Debug.Assert(document != null);
this.document = document;
#endif
}
[Conditional("DEBUG")]
void DebugVerifyAccess()
{
#if DEBUG
document.DebugVerifyAccess();
#endif
}
#endregion
#region Events
// /// <summary>
// /// Is raised when the line is deleted.
// /// </summary>
// public event EventHandler Deleted;
//
// /// <summary>
// /// Is raised when the line's text changes.
// /// </summary>
// public event EventHandler TextChanged;
//
// /// <summary>
// /// Raises the Deleted or TextChanged event.
// /// </summary>
// internal void RaiseChanged()
// {
// if (IsDeleted) {
// if (Deleted != null)
// Deleted(this, EventArgs.Empty);
// } else {
// if (TextChanged != null)
// TextChanged(this, EventArgs.Empty);
// }
// }
#endregion
#region Properties stored in tree
/// <summary>
/// Gets if this line was deleted from the document.
/// </summary>
public bool IsDeleted {
get {
DebugVerifyAccess();
return isDeleted;
}
}
/// <summary>
/// Gets the number of this line.
/// Runtime: O(log n)
/// </summary>
/// <exception cref="InvalidOperationException">The line was deleted.</exception>
public int LineNumber {
get {
if (IsDeleted)
throw new InvalidOperationException();
return DocumentLineTree.GetIndexFromNode(this) + 1;
}
}
/// <summary>
/// Gets the starting offset of the line in the document's text.
/// Runtime: O(log n)
/// </summary>
/// <exception cref="InvalidOperationException">The line was deleted.</exception>
public int Offset {
get {
if (IsDeleted)
throw new InvalidOperationException();
return DocumentLineTree.GetOffsetFromNode(this);
}
}
/// <summary>
/// Gets the end offset of the line in the document's text (the offset before the line delimiter).
/// Runtime: O(log n)
/// </summary>
/// <exception cref="InvalidOperationException">The line was deleted.</exception>
/// <remarks>EndOffset = <see cref="Offset"/> + <see cref="Length"/>.</remarks>
public int EndOffset {
get { return this.Offset + this.Length; }
}
#endregion
#region Length
int totalLength;
byte delimiterLength;
/// <summary>
/// Gets the length of this line. The length does not include the line delimiter. O(1)
/// </summary>
/// <remarks>This property is still available even if the line was deleted;
/// in that case, it contains the line's length before the deletion.</remarks>
public int Length {
get {
DebugVerifyAccess();
return totalLength - delimiterLength;
}
}
/// <summary>
/// Gets the length of this line, including the line delimiter. O(1)
/// </summary>
/// <remarks>This property is still available even if the line was deleted;
/// in that case, it contains the line's length before the deletion.</remarks>
public int TotalLength {
get {
DebugVerifyAccess();
return totalLength;
}
internal set {
// this is set by DocumentLineTree
totalLength = value;
}
}
/// <summary>
/// <para>Gets the length of the line delimiter.</para>
/// <para>The value is 1 for single <c>"\r"</c> or <c>"\n"</c>, 2 for the <c>"\r\n"</c> sequence;
/// and 0 for the last line in the document.</para>
/// </summary>
/// <remarks>This property is still available even if the line was deleted;
/// in that case, it contains the line delimiter's length before the deletion.</remarks>
public int DelimiterLength {
get {
DebugVerifyAccess();
return delimiterLength;
}
internal set {
Debug.Assert(value >= 0 && value <= 2);
delimiterLength = (byte)value;
}
}
#endregion
#region Previous / Next Line
/// <summary>
/// Gets the next line in the document.
/// </summary>
/// <returns>The line following this line, or null if this is the last line.</returns>
public DocumentLine NextLine {
get {
DebugVerifyAccess();
if (right != null) {
return right.LeftMost;
} else {
DocumentLine node = this;
DocumentLine oldNode;
do {
oldNode = node;
node = node.parent;
// we are on the way up from the right part, don't output node again
} while (node != null && node.right == oldNode);
return node;
}
}
}
/// <summary>
/// Gets the previous line in the document.
/// </summary>
/// <returns>The line before this line, or null if this is the first line.</returns>
public DocumentLine PreviousLine {
get {
DebugVerifyAccess();
if (left != null) {
return left.RightMost;
} else {
DocumentLine node = this;
DocumentLine oldNode;
do {
oldNode = node;
node = node.parent;
// we are on the way up from the left part, don't output node again
} while (node != null && node.left == oldNode);
return node;
}
}
}
#endregion
#region ToString
/// <summary>
/// Gets a string with debug output showing the line number and offset.
/// Does not include the line's text.
/// </summary>
public override string ToString()
{
if (IsDeleted)
return "[DocumentLine deleted]";
else
return string.Format(
CultureInfo.InvariantCulture,
"[DocumentLine Number={0} Offset={1} Length={2}]", LineNumber, Offset, Length);
}
#endregion
}
}
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