1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
|
//
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.
//
// This file contain implementations details that are subject to change without notice.
// Use at your own risk.
//
using System;
using System.Threading;
namespace Microsoft.VisualStudio.Text.Implementation
{
/// <summary>
/// An immutable variation on the StringBuilder class.
/// </summary>
internal class TextImageVersion : ITextImageVersion
{
public TextImageVersion(int length)
: this(versionNumber: 0, reiteratedVersionNumber: 0, length: length, identifier: new object())
{
}
private TextImageVersion(int versionNumber, int reiteratedVersionNumber, int length, object identifier)
{
this.VersionNumber = versionNumber;
this.ReiteratedVersionNumber = reiteratedVersionNumber;
this.Identifier = identifier;
this.Length = length;
}
internal TextImageVersion CreateNext(int reiteratedVersionNumber, int length, INormalizedTextChangeCollection changes)
{
int newVersionNumber = this.VersionNumber + 1;
if (reiteratedVersionNumber < 0)
{
// If there are no changes (e.g. readonly region edit or content type change), then
// we consider this a reiteration of the current version. changes can be null in the special case
// of doing a reload (at which point the reload code will call SetChanges after computing the diff).
reiteratedVersionNumber = ((changes != null) && (changes.Count == 0)) ? this.ReiteratedVersionNumber : newVersionNumber;
}
else if (reiteratedVersionNumber > newVersionNumber)
{
throw new ArgumentOutOfRangeException(nameof(reiteratedVersionNumber));
}
if (length == -1)
{
length = this.Length;
int changeCount = changes.Count;
for (int c = 0; c < changeCount; ++c)
{
length += changes[c].Delta;
}
}
var newVersion = new TextImageVersion(newVersionNumber, reiteratedVersionNumber, length, this.Identifier);
// Arguably this should happen as an atomic operation but it is unlikely to cause a race condition
// because, in general, people won't even be looking at these properties until they get a change event
// (which happens after everything has been set).
this.SetChanges(changes);
this.Next = newVersion;
return newVersion;
}
// The length needs to be set after the creation of the version in some cases (projection, for example).
internal void SetLength(int length)
{
if (this.Length != 0)
throw new InvalidOperationException("Not allowed to SetLength twice");
this.Length = length;
}
internal void SetChanges(INormalizedTextChangeCollection changes)
{
if (this.Changes != null)
throw new InvalidOperationException("Not allowed to SetChanges twice");
this.Changes = changes;
}
#region ITextImageVersion members
public ITextImageVersion Next { get; private set; }
public int Length { get; private set; }
public INormalizedTextChangeCollection Changes { get; private set; }
public int VersionNumber { get; }
public int ReiteratedVersionNumber { get; }
public object Identifier { get; }
public int TrackTo(VersionedPosition other, PointTrackingMode mode)
{
if (other.Version == null)
throw new ArgumentException(nameof(other) + " version cannot be null");
if (other.Version.VersionNumber == this.VersionNumber)
return other.Position;
if (other.Version.VersionNumber > this.VersionNumber)
return Tracking.TrackPositionForwardInTime(mode, other.Position, this, other.Version);
else
return Tracking.TrackPositionBackwardInTime(mode, other.Position, this, other.Version);
}
public Span TrackTo(VersionedSpan span, SpanTrackingMode mode)
{
if (span.Version == null)
throw new ArgumentException(nameof(span) + " version cannot be null");
if (span.Version.VersionNumber == this.VersionNumber)
return span.Span;
if (span.Version.VersionNumber > this.VersionNumber)
return Tracking.TrackSpanForwardInTime(mode, span.Span, this, span.Version);
else
return Tracking.TrackSpanBackwardInTime(mode, span.Span, this, span.Version);
}
#endregion
}
}
|
