precedingsibling.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 / precedingsibling.cs / 1 / precedingsibling.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;
    using System.Collections.Generic;
 
    // This class can be rewritten much more efficient.
    // Algorithm could be like one for FollowingSibling: 
    // - Build InputArrays: pares (first, sentinel) 
    // -- Cash all input nodes as sentinel
    // -- Add firts node of its parent for each input node. 
    // -- Sort these pares by first nodes.
    // - Advance algorithm will look like:
    // -- For each row in InputArays we will output first node + all its following nodes which are < sentinel
    // -- Before outputing each node in row #I we will check that it is < first node in row #I+1 
    // --- if true we actualy output it
    // --- if false, we hold with row #I and apply this algorith starting for row #I+1 
    // --- when we done with #I+1 we continue with row #I 

    internal class PreSiblingQuery : CacheAxisQuery { 

        public PreSiblingQuery(Query qyInput, string name, string prefix, XPathNodeType typeTest) : base (qyInput, name, prefix, typeTest) {}
        protected PreSiblingQuery(PreSiblingQuery other) : base(other) {}
 
        private bool NotVisited(XPathNavigator nav, List parentStk){
            XPathNavigator nav1 = nav.Clone(); 
            nav1.MoveToParent(); 
            for (int i = 0; i < parentStk.Count; i++) {
                if (nav1.IsSamePosition(parentStk[i])) { 
                    return false;
                }
            }
            parentStk.Add(nav1); 
            return true;
        } 
 
        public override object Evaluate(XPathNodeIterator context) {
            base.Evaluate(context); 

            // Fill up base.outputBuffer
            List parentStk = new List();
            Stack inputStk = new Stack(); 
            while ((currentNode = qyInput.Advance()) != null) {
                inputStk.Push(currentNode.Clone()); 
            } 
            while (inputStk.Count != 0) {
                XPathNavigator input = inputStk.Pop(); 
                if (input.NodeType == XPathNodeType.Attribute || input.NodeType == XPathNodeType.Namespace) {
                    continue;
                }
                if (NotVisited(input, parentStk)) { 
                    XPathNavigator prev = input.Clone();
                    if (prev.MoveToParent()) { 
                        bool test = prev.MoveToFirstChild(); 
                        Debug.Assert(test, "We just moved to parent, how we can not have first child?");
                        while (!prev.IsSamePosition(input)) { 
                            if (matches(prev)) {
                                Insert(outputBuffer, prev);
                            }
                            if (!prev.MoveToNext()) { 
                                Debug.Fail("We managed to miss sentinel node (input)");
                                break; 
                            } 
                        }
                    } 
                }
            }
            return this;
        } 

        public override XPathNodeIterator Clone() { return new PreSiblingQuery(this); } 
        public override QueryProps Properties { get { return base.Properties | QueryProps.Reverse; } } 
    }
} 

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

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