DescendantOverDescendantQuery.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / XPath / Internal / DescendantOverDescendantQuery.cs / 1 / DescendantOverDescendantQuery.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
 
namespace MS.Internal.Xml.XPath { 
    using System;
    using System.Xml; 
    using System.Xml.XPath;
    using System.Diagnostics;

    // DescendantOverDescendantQuery: for each input it looks for the topmost descendents that matches to ns:name 
    // This is posible when query which has this query as its input (child query) is descendent as well.
    // Work of this query doesn't depend on DOD of its input. 
    // It doesn't garate DOD of the output even when input is DOD. 
    internal sealed class DescendantOverDescendantQuery : DescendantBaseQuery {
        private int level = 0; 

        public DescendantOverDescendantQuery(Query  qyParent, bool matchSelf, string name, string prefix, XPathNodeType typeTest, bool abbrAxis) :
            base(qyParent, name, prefix, typeTest, matchSelf, abbrAxis) {}
        private DescendantOverDescendantQuery(DescendantOverDescendantQuery other) : base(other) { 
            this.level = other.level;
        } 
 
        public override void Reset() {
            level = 0; 
            base.Reset();
        }

        public override XPathNavigator Advance() { 
            while (true) {
                if (level == 0) { 
                    currentNode = qyInput.Advance(); 
                    position = 0;
                    if (currentNode == null) { 
                        return null;
                    }
                    if (matchSelf && matches(currentNode)) {
                        position = 1; 
                        return currentNode;
                    } 
                    currentNode = currentNode.Clone(); 
                    if (! MoveToFirstChild()) {
                        continue; 
                    }
                } else {
                    if (!MoveUpUntillNext()) {
                        continue; 
                    }
                } 
                do { 
                    if (matches(currentNode)) {
                        position++; 
                        return currentNode;
                    }
                } while (MoveToFirstChild());
            } 
        }
 
        private bool MoveToFirstChild() { 
            if (currentNode.MoveToFirstChild()) {
                level++; 
                return true;
            }
            return false;
        } 

        private bool MoveUpUntillNext() { // move up untill we can move next 
            while (! currentNode.MoveToNext()) { 
                -- level;
                if (level == 0) { 
                    return false;
                }
                bool result = currentNode.MoveToParent();
                Debug.Assert(result, "Algorithm error, We always should be able to move up if level > 0"); 
            }
            return true; 
        } 

        public override XPathNodeIterator Clone() { return new DescendantOverDescendantQuery(this); } 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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