UnionExpr.cs source code in C# .NET

                        Code:
                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / XPath / Internal / UnionExpr.cs / 1 / UnionExpr.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.Xml.Xsl;
 
    internal sealed class UnionExpr : Query {
        internal Query qy1, qy2; 
        private bool advance1, advance2; 
        private XPathNavigator currentNode;
        private XPathNavigator nextNode; 

        public UnionExpr(Query query1, Query query2) {
            this.qy1 = query1;
            this.qy2 = query2; 
            this.advance1 = true;
            this.advance2 = true; 
        } 
        private UnionExpr(UnionExpr other) : base(other) {
            this.qy1 = Clone(other.qy1); 
            this.qy2 = Clone(other.qy2);
            this.advance1 = other.advance1;
            this.advance2 = other.advance2;
            this.currentNode = Clone(other.currentNode); 
            this.nextNode    = Clone(other.nextNode);
        } 
 
        public override void Reset() {
            qy1.Reset(); 
            qy2.Reset();
            advance1 = true;
            advance2 = true;
            nextNode = null; 
        }
 
        public override void SetXsltContext(XsltContext xsltContext) { 
            qy1.SetXsltContext(xsltContext);
            qy2.SetXsltContext(xsltContext); 
        }

        public override object Evaluate(XPathNodeIterator context) {
            qy1.Evaluate(context); 
            qy2.Evaluate(context);
            advance1 = true; 
            advance2 = true; 
            nextNode = null;
            base.ResetCount(); 
            return this;
        }

        private XPathNavigator ProcessSamePosition(XPathNavigator result){ 
           currentNode = result;
           advance1 = advance2 = true; 
           return result; 
        }
 
        private XPathNavigator ProcessBeforePosition(XPathNavigator res1, XPathNavigator res2){
            nextNode = res2;
            advance2 = false;
            advance1 = true; 
            currentNode = res1;
            return res1; 
        } 

        private XPathNavigator ProcessAfterPosition(XPathNavigator res1, XPathNavigator res2){ 
            nextNode = res1;
            advance1 = false;
            advance2 = true;
            currentNode = res2; 
            return res2;
        } 
 
        public override XPathNavigator Advance() {
            XPathNavigator res1, res2; 
            XmlNodeOrder order = 0;
            if (advance1) {
                res1 = qy1.Advance();
            } else { 
                res1 = nextNode;
            } 
            if (advance2) { 
                res2 = qy2.Advance();
            } else { 
                res2 = nextNode;
            }
            if (res1 != null && res2 != null) {
                order = CompareNodes(res1, res2); 
            } else if (res2 == null) {
                advance1 = true; 
                advance2 = false; 
                currentNode = res1;
                nextNode = null; 
                return res1;
            } else {
                advance1 = false;
                advance2 = true; 
                currentNode = res2;
                nextNode = null; 
                return res2; 
            }
 
            if (order == XmlNodeOrder.Before) {
                return ProcessBeforePosition(res1, res2);
            } else if (order == XmlNodeOrder.After) {
                return ProcessAfterPosition(res1, res2); 
            } else {
                // BugBug. In case of Unknown we sorting as the same. 
                return ProcessSamePosition(res1); 
            }
        } 

        public override XPathNavigator MatchNode(XPathNavigator xsltContext) {
            if (xsltContext != null) {
                XPathNavigator result = qy1.MatchNode(xsltContext); 
                if (result != null) {
                    return result; 
                } 
                return qy2.MatchNode(xsltContext);
            } 
            return null;
        }

        public override XPathResultType StaticType { get { return XPathResultType.NodeSet; } } 

        public override XPathNodeIterator Clone() { return new UnionExpr(this); } 
 
        public override XPathNavigator Current { get { return currentNode; } }
        public override int CurrentPosition { get { throw new InvalidOperationException(); } } 

        public override void PrintQuery(XmlWriter w) {
            w.WriteStartElement(this.GetType().Name);
            if (qy1 != null) { 
                qy1.PrintQuery(w);
            } 
            if (qy2 != null) { 
                qy2.PrintQuery(w);
            } 
            w.WriteEndElement();
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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UnionExpr.cs source code in C# .NET

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