CompiledXpathExpr.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / XPath / Internal / CompiledXpathExpr.cs / 1 / CompiledXpathExpr.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.Globalization;
    using System.Collections; 
    using System.Xml.Xsl;
 
    internal class CompiledXpathExpr : XPathExpression { 
        Query query;
        string expr; 
        bool needContext;

        internal CompiledXpathExpr(Query query, string expression, bool needContext) {
            this.query = query; 
            this.expr = expression;
            this.needContext = needContext; 
        } 

        internal Query QueryTree { 
            get {
                if (needContext) {
                    throw XPathException.Create(Res.Xp_NoContext);
                } 
                return query;
            } 
        } 

        public override string Expression { 
            get { return expr; }
        }

        public virtual void CheckErrors() { 
            Debug.Assert(query != null, "In case of error in XPath we create ErrorXPathExpression");
        } 
 
        public override void AddSort(object expr, IComparer comparer) {
            // sort makes sense only when we are dealing with a query that 
            // returns a nodeset.
 	        Query evalExpr;
            if (expr is string) {
                evalExpr = new QueryBuilder().Build((string)expr, out needContext); // this will throw if expr is invalid 
            } else if (expr is CompiledXpathExpr) {
                evalExpr = ((CompiledXpathExpr)expr).QueryTree; 
	        } else { 
                throw XPathException.Create(Res.Xp_BadQueryObject);
            } 
            SortQuery sortQuery = query as SortQuery;
            if (sortQuery == null) {
                query = sortQuery = new SortQuery(query);
            } 
            sortQuery.AddSort(evalExpr, comparer);
        } 
 
        public override void AddSort(object expr, XmlSortOrder order, XmlCaseOrder caseOrder, string lang, XmlDataType dataType) {
            AddSort(expr, new XPathComparerHelper(order, caseOrder, lang, dataType)); 
        }

        public override XPathExpression Clone() {
            return new CompiledXpathExpr(Query.Clone(query), expr, needContext); 
        }
 
        public override void SetContext(XmlNamespaceManager nsManager) { 
            XsltContext xsltContext = nsManager as XsltContext;
            if(xsltContext == null) { 
                if(nsManager == null) {
                    nsManager = new XmlNamespaceManager(new NameTable());
                }
                xsltContext = new UndefinedXsltContext(nsManager); 
            }
            query.SetXsltContext(xsltContext); 
 
            needContext = false;
        } 

        public override void SetContext(IXmlNamespaceResolver nsResolver) {
            XmlNamespaceManager nsManager = nsResolver as XmlNamespaceManager;
            if (nsManager == null) { 
                if (nsResolver != null) {
                    nsManager = new XmlNamespaceManager(new NameTable()); 
                } 
            }
            SetContext(nsManager); 
        }

        public override XPathResultType ReturnType { get { return query.StaticType; } }
 
        private class UndefinedXsltContext : XsltContext {
            private XmlNamespaceManager nsManager; 
 
            public UndefinedXsltContext(XmlNamespaceManager nsManager) : base(/*dummy*/false) {
                this.nsManager = nsManager; 
            }
            //----- Namespace support -----
            public override string DefaultNamespace {
                get { return string.Empty; } 
            }
            public override string LookupNamespace(string prefix) { 
                Debug.Assert(prefix != null); 
                if(prefix.Length == 0) {
                    return string.Empty; 
                }
                string ns = this.nsManager.LookupNamespace(prefix);
                if(ns == null) {
                    throw XPathException.Create(Res.XmlUndefinedAlias, prefix); 
                }
                Debug.Assert(ns.Length != 0, "No XPath prefix can be mapped to 'null namespace'"); 
                return ns; 
            }
            //----- XsltContext support ----- 
            public override IXsltContextVariable ResolveVariable(string prefix, string name) {
                throw XPathException.Create(Res.Xp_UndefinedXsltContext);
            }
            public override IXsltContextFunction ResolveFunction(string prefix, string name, XPathResultType[] ArgTypes) { 
                throw XPathException.Create(Res.Xp_UndefinedXsltContext);
            } 
            public override bool Whitespace { get{ return false; } } 
            public override bool PreserveWhitespace(XPathNavigator node) { return false; }
            public override int CompareDocument (string baseUri, string nextbaseUri) { 
                return string.CompareOrdinal(baseUri, nextbaseUri);
            }
        }
    } 

    internal sealed class XPathComparerHelper : IComparer { 
        private XmlSortOrder order; 
        private XmlCaseOrder caseOrder;
        private CultureInfo  cinfo; 
        private XmlDataType  dataType;

        public XPathComparerHelper(XmlSortOrder order, XmlCaseOrder caseOrder, string lang, XmlDataType dataType) {
            if (lang == null) { 
                this.cinfo = System.Threading.Thread.CurrentThread.CurrentCulture;
            } else { 
                try { 
                    this.cinfo = new CultureInfo(lang);
                } 
                catch (System.ArgumentException) {
                    throw;  // Throwing an XsltException would be a breaking change
				}
            } 

            if (order == XmlSortOrder.Descending) { 
                if (caseOrder == XmlCaseOrder.LowerFirst) { 
                    caseOrder = XmlCaseOrder.UpperFirst;
                } 
                else if (caseOrder == XmlCaseOrder.UpperFirst) {
                    caseOrder = XmlCaseOrder.LowerFirst;
                }
            } 

            this.order     = order; 
            this.caseOrder = caseOrder; 
            this.dataType  = dataType;
        } 

        public Int32 Compare(object x, object y) {
            Int32 sortOrder = (this.order == XmlSortOrder.Ascending) ? 1 : -1;
            switch(this.dataType) { 
            case XmlDataType.Text:
                string s1 = Convert.ToString(x, this.cinfo); 
                string s2 = Convert.ToString(y, this.cinfo); 
                Int32 result = string.Compare(s1, s2, (this.caseOrder == XmlCaseOrder.None) ? false : true, this.cinfo);
                if (result != 0 || this.caseOrder == XmlCaseOrder.None) 
                    return (sortOrder * result);

                // If we came this far, it means that strings s1 and s2 are
                // equal to each other when case is ignored. Now it's time to check 
                // and see if they differ in case only and take into account the user
                // requested case order for sorting purposes. 
                Int32 caseOrder = (this.caseOrder == XmlCaseOrder.LowerFirst) ? 1 : -1; 
                result = string.Compare(s1, s2, false, this.cinfo);
                return (caseOrder * result); 

            case XmlDataType.Number:
                double r1 = XmlConvert.ToXPathDouble(x);
                double r2 = XmlConvert.ToXPathDouble(y); 

                // trying to return the result of (r1 - r2) casted down 
                // to an Int32 can be dangerous. E.g 100.01 - 100.00 would result 
                // erroneously in zero when casted down to Int32.
                if (r1 > r2) { 
                    return (1*sortOrder);
                }
                else if (r1 < r2) {
                    return (-1*sortOrder); 
                }
                else { 
                    if (r1 == r2) { 
                        return 0;
                    } 
                    if (Double.IsNaN(r1)) {
                        if (Double.IsNaN(r2)) {
                            return 0;
                        } 
                        //r2 is not NaN .NaN comes before any other number
                        return (-1*sortOrder); 
                    } 
                    //r2 is NaN. So it should come after r1
                    return (1*sortOrder); 
                }
            default:
                // dataType doesn't support any other value
                throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) ); 
            } // switch
        } // Compare () 
    } // class XPathComparerHelper 
}

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

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