SortQuery.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Xml / System / Xml / XPath / Internal / SortQuery.cs / 1305376 / SortQuery.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
 
namespace MS.Internal.Xml.XPath { 
    using System;
    using System.Xml; 
    using System.Xml.XPath;
    using System.Xml.Xsl;
    using System.Diagnostics;
    using System.Collections; 
    using System.Collections.Generic;
 
    internal sealed class SortQuery : Query { 
        private List results;
        private XPathSortComparer comparer; 
        private Query qyInput;

        public SortQuery(Query qyInput) {
            Debug.Assert(qyInput != null, "Sort Query needs an input query tree to work on"); 
            this.results  = new List();
            this.comparer = new XPathSortComparer(); 
            this.qyInput = qyInput; 
            count = 0;
        } 
        private SortQuery(SortQuery other) : base(other) {
            this.results  = new List(other.results);
            this.comparer = other.comparer.Clone();
            this.qyInput = Clone(other.qyInput); 
            count = 0;
        } 
 
        public override void Reset() { count = 0; }
 
        public override void SetXsltContext(XsltContext xsltContext) {
            qyInput.SetXsltContext(xsltContext);
            if (
                qyInput.StaticType != XPathResultType.NodeSet && 
                qyInput.StaticType != XPathResultType.Any
            ) { 
               throw XPathException.Create(Res.Xp_NodeSetExpected); 
            }
        } 

        private void BuildResultsList() {
            Int32 numSorts = this.comparer.NumSorts;
 
            Debug.Assert(numSorts > 0, "Why was the sort query created?");
 
            XPathNavigator eNext; 
            while ((eNext = qyInput.Advance()) != null) {
                SortKey key = new SortKey(numSorts, /*originalPosition:*/this.results.Count, eNext.Clone()); 

                for (Int32 j = 0; j < numSorts; j++) {
                    key[j] = this.comparer.Expression(j).Evaluate(qyInput);
                } 

                results.Add(key); 
            } 
            results.Sort(this.comparer);
        } 

        public override object Evaluate(XPathNodeIterator context) {
            qyInput.Evaluate(context);
            this.results.Clear(); 
            BuildResultsList();
            count = 0; 
            return this; 
        }
 
        public override XPathNavigator Advance() {
            Debug.Assert(0 <= count && count <= results.Count);
            if (count < this.results.Count) {
                return this.results[count++].Node; 
            }
            return null; 
        } 

        public override XPathNavigator Current { 
            get {
                Debug.Assert(0 <= count && count <= results.Count);
                if (count == 0) {
                    return null; 
                }
                return results[count - 1].Node; 
            } 
        }
 
        internal void AddSort(Query evalQuery, IComparer comparer) {
            this.comparer.AddSort(evalQuery, comparer);
        }
 
        public override XPathNodeIterator Clone() { return new SortQuery(this); }
 
        public override XPathResultType StaticType { get { return XPathResultType.NodeSet; } } 
        public override int CurrentPosition { get { return count; } }
        public override int Count           { get { return results.Count; } } 
        public override QueryProps Properties { get { return QueryProps.Cached | QueryProps.Position | QueryProps.Count; } }

        public override void PrintQuery(XmlWriter w) {
            w.WriteStartElement(this.GetType().Name); 
            qyInput.PrintQuery(w);
            w.WriteElementString("XPathSortComparer", "... PrintTree() not implemented ..."); 
            w.WriteEndElement(); 
        }
    } // class SortQuery 

    internal sealed class SortKey {
        private Int32          numKeys;
        private object[]       keys; 
        private int            originalPosition;
        private XPathNavigator node; 
 
        public SortKey(int numKeys, int originalPosition, XPathNavigator node) {
            this.numKeys          = numKeys; 
            this.keys             = new object[numKeys];
            this.originalPosition = originalPosition;
            this.node             = node;
        } 

        public object this[int index] { 
            get { return this.keys[index]; } 
            set { this.keys[index] = value; }
        } 

        public int NumKeys { get { return this.numKeys; } }
        public int OriginalPosition { get { return this.originalPosition; } }
        public XPathNavigator Node { get { return this.node; } } 
    } // class SortKey
 
    internal sealed class XPathSortComparer : IComparer { 
        private const int   minSize = 3;
        private Query[]    expressions; 
        private IComparer[] comparers;
        private int         numSorts;

        public XPathSortComparer(int size) { 
            if (size <= 0) size = minSize;
            this.expressions   = new Query[   size]; 
            this.comparers     = new IComparer[size]; 
        }
        public XPathSortComparer() : this (minSize) {} 

        public void AddSort(Query evalQuery, IComparer comparer) {
            Debug.Assert(this.expressions.Length == this.comparers.Length);
            Debug.Assert(0 < this.expressions.Length); 
            Debug.Assert(0 <= numSorts && numSorts <= this.expressions.Length);
            // Ajust array sizes if needed. 
            if (numSorts == this.expressions.Length) { 
                Query[]    newExpressions = new Query[   numSorts * 2];
                IComparer[] newComparers   = new IComparer[numSorts * 2]; 
                for (int i = 0; i < numSorts; i ++) {
                    newExpressions[i] = this.expressions[i];
                    newComparers  [i] = this.comparers[i];
                } 
                this.expressions = newExpressions;
                this.comparers   = newComparers; 
            } 
            Debug.Assert(numSorts < this.expressions.Length);
 
            // Fixup expression to handle node-set return type:
            if (evalQuery.StaticType == XPathResultType.NodeSet || evalQuery.StaticType == XPathResultType.Any) {
                evalQuery = new StringFunctions(Function.FunctionType.FuncString, new Query[] { evalQuery });
            } 

            this.expressions[numSorts] = evalQuery; 
            this.comparers[  numSorts] = comparer; 
            numSorts ++;
        } 

        public int NumSorts { get { return numSorts; } }

        public Query Expression(int i) { 
            return this.expressions[i];
        } 
 
        int IComparer.Compare(SortKey x, SortKey y) {
            Debug.Assert(x != null && y != null, "Oops!! what happened?"); 
            int result = 0;
            for (int i = 0; i < x.NumKeys; i++) {
                result = this.comparers[i].Compare(x[i], y[i]);
                if (result != 0) { 
                    return result;
                } 
            } 

            // if after all comparisions, the two sort keys are still equal, preserve the doc order 
            return x.OriginalPosition - y.OriginalPosition;
        }

        internal XPathSortComparer Clone() { 
            XPathSortComparer clone = new XPathSortComparer(this.numSorts);
 
            for (int i = 0; i < this.numSorts; i ++) { 
                clone.comparers[i]   = this.comparers[i];
                clone.expressions[i] = (Query)this.expressions[i].Clone(); // Expressions should be cloned because Query should be cloned 
            }
            clone.numSorts = this.numSorts;
            return clone;
        } 
    } // class XPathSortComparer
} // namespace 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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SortQuery.cs source code in C# .NET

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