XPathNodeIterator.cs

Go to the documentation of this file.

using System.Collections;
using System.Diagnostics;
 
namespace System.Xml.XPath;
 
[DebuggerDisplay("Position={CurrentPosition}, Current={debuggerDisplayProxy}")]
public abstract class XPathNodeIterator : ICloneable, IEnumerable
{
    private sealed class Enumerator : IEnumerator
    {
        private readonly XPathNodeIterator _original;
 
        private XPathNodeIterator _current;
 
        private bool _iterationStarted;
 
        public object Current
        {
            get
            {
                if (_iterationStarted)
                {
                    if (_current == null)
                    {
                        throw new InvalidOperationException(System.SR.Format(System.SR.Sch_EnumFinished, string.Empty));
                    }
                    return _current.Current.Clone();
                }
                throw new InvalidOperationException(System.SR.Format(System.SR.Sch_EnumNotStarted, string.Empty));
            }
        }
 
        public Enumerator(XPathNodeIterator original)
        {
            _original = original.Clone();
        }
 
        public bool MoveNext()
        {
            if (!_iterationStarted)
            {
                _current = _original.Clone();
                _iterationStarted = true;
            }
            if (_current == null || !_current.MoveNext())
            {
                _current = null;
                return false;
            }
            return true;
        }
 
        public void Reset()
        {
            _iterationStarted = false;
        }
    }
 
    internal int count = -1;
 
    public abstract XPathNavigator? Current { get; }
 
    public abstract int CurrentPosition { get; }
 
    public virtual int Count
    {
        get
        {
            if (count == -1)
            {
                XPathNodeIterator xPathNodeIterator = Clone();
                while (xPathNodeIterator.MoveNext())
                {
                }
                count = xPathNodeIterator.CurrentPosition;
            }
            return count;
        }
    }
 
    private object? debuggerDisplayProxy
    {
        get
        {
            if (Current != null)
            {
                return new XPathNavigator.DebuggerDisplayProxy(Current);
            }
            return null;
        }
    }
 
    object ICloneable.Clone()
    {
        return Clone();
    }
 
    public abstract XPathNodeIterator Clone();
 
    public abstract bool MoveNext();
 
    public virtual IEnumerator GetEnumerator()
    {
        return new Enumerator(this);
    }
}