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
|
//------------------------------------------------------------------------------
// <copyright file="DocumentOrderComparer.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
using System;
using System.Collections;
using System.Collections.Generic;
using System.Xml;
using System.Xml.XPath;
using System.Diagnostics;
namespace System.Xml.Xsl.Runtime {
/// <summary>
/// IComparer implementation that orders navigators based on ComparePosition. When ComparePosition returns
/// XmlNodeOrder.Unknown, a stable order between documents is maintained by an ordered list mapping each root node
/// to an ordering index.
/// </summary>
internal class DocumentOrderComparer : IComparer<XPathNavigator> {
private List<XPathNavigator> roots;
/// <summary>
/// Return:
/// -1 if navThis is positioned before navThat
/// 0 if navThis has the same position as navThat
/// 1 if navThis is positioned after navThat
/// </summary>
public int Compare(XPathNavigator navThis, XPathNavigator navThat) {
switch (navThis.ComparePosition(navThat)) {
case XmlNodeOrder.Before: return -1;
case XmlNodeOrder.Same: return 0;
case XmlNodeOrder.After: return 1;
}
// Use this.roots to impose stable ordering
if (this.roots == null)
this.roots = new List<XPathNavigator>();
Debug.Assert(GetDocumentIndex(navThis) != GetDocumentIndex(navThat));
return GetDocumentIndex(navThis) < GetDocumentIndex(navThat) ? -1 : 1;
}
/// <summary>
/// Map navigator's document to a unique index.
/// When consecutive calls are made to GetIndexOfNavigator for navThis and navThat, it is not possible
/// for them to return the same index. navThis compared to navThat is always XmlNodeOrder.Unknown.
/// Therefore, no matter where navThis is inserted in the list, navThat will never be inserted just
/// before navThis, and therefore will never have the same index.
/// </summary>
public int GetDocumentIndex(XPathNavigator nav) {
XPathNavigator navRoot;
// Use this.roots to impose stable ordering
if (this.roots == null)
this.roots = new List<XPathNavigator>();
// Position navigator to root
navRoot = nav.Clone();
navRoot.MoveToRoot();
for (int idx = 0; idx < this.roots.Count; idx++) {
if (navRoot.IsSamePosition(this.roots[idx])) {
// navigator's document was previously mapped to a unique index
return idx;
}
}
// Add navigator to this.roots mapping
this.roots.Add(navRoot);
return this.roots.Count - 1;
}
}
}
|
