SortQuery.cs

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using System;
using System.Collections;
using System.Collections.Generic;
using System.Xml.XPath;
using System.Xml.Xsl;
 
namespace MS.Internal.Xml.XPath;
 
internal sealed class SortQuery : Query
{
    private readonly List<SortKey> _results;
 
    private readonly XPathSortComparer _comparer;
 
    private readonly Query _qyInput;
 
    public override XPathNavigator Current
    {
        get
        {
            if (count == 0)
            {
                return null;
            }
            return _results[count - 1].Node;
        }
    }
 
    public override XPathResultType StaticType => XPathResultType.NodeSet;
 
    public override int CurrentPosition => count;
 
    public override int Count => _results.Count;
 
    public override QueryProps Properties => (QueryProps)7;
 
    public SortQuery(Query qyInput)
    {
        _results = new List<SortKey>();
        _comparer = new XPathSortComparer();
        _qyInput = qyInput;
        count = 0;
    }
 
    private SortQuery(SortQuery other)
        : base(other)
    {
        _results = new List<SortKey>(other._results);
        _comparer = other._comparer.Clone();
        _qyInput = Query.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(System.SR.Xp_NodeSetExpected);
        }
    }
 
    private void BuildResultsList()
    {
        int numSorts = _comparer.NumSorts;
        XPathNavigator xPathNavigator;
        while ((xPathNavigator = _qyInput.Advance()) != null)
        {
            SortKey sortKey = new SortKey(numSorts, _results.Count, xPathNavigator.Clone());
            for (int i = 0; i < numSorts; i++)
            {
                sortKey[i] = _comparer.Expression(i).Evaluate(_qyInput);
            }
            _results.Add(sortKey);
        }
        _results.Sort(_comparer);
    }
 
    public override object Evaluate(XPathNodeIterator context)
    {
        _qyInput.Evaluate(context);
        _results.Clear();
        BuildResultsList();
        count = 0;
        return this;
    }
 
    public override XPathNavigator Advance()
    {
        if (count < _results.Count)
        {
            return _results[count++].Node;
        }
        return null;
    }
 
    internal void AddSort(Query evalQuery, IComparer comparer)
    {
        _comparer.AddSort(evalQuery, comparer);
    }
 
    public override XPathNodeIterator Clone()
    {
        return new SortQuery(this);
    }
}