DocumentOrderComparer.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / XmlUtils / System / Xml / Xsl / Runtime / DocumentOrderComparer.cs / 1305376 / DocumentOrderComparer.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
using System; 
using System.Collections; 
using System.Collections.Generic;
using System.Xml; 
using System.Xml.XPath;
using System.Diagnostics;

namespace System.Xml.Xsl.Runtime { 

    ///  
    /// 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. 
    /// 
    internal class DocumentOrderComparer : IComparer {
        private List roots;
 
        /// 
        /// Return: 
        ///     -1 if navThis is positioned before navThat 
        ///      0 if navThis has the same position as navThat
        ///      1 if navThis is positioned after navThat 
        /// 
        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();

            Debug.Assert(GetDocumentIndex(navThis) != GetDocumentIndex(navThat)); 
            return GetDocumentIndex(navThis) < GetDocumentIndex(navThat) ? -1 : 1;
        } 
 
        /// 
        /// 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. 
        /// 
        public int GetDocumentIndex(XPathNavigator nav) { 
            XPathNavigator navRoot; 

            // Use this.roots to impose stable ordering 
            if (this.roots == null)
                this.roots = new List();

            // 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; 
        }
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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