XElementElementsPropertyDescriptor.cs

Go to the documentation of this file.

using System;
using System.Collections.Generic;
using System.Xml.Linq;
 
namespace MS.Internal.Xml.Linq.ComponentModel;
 
internal sealed class XElementElementsPropertyDescriptor : XPropertyDescriptor<XElement, IEnumerable<XElement>>
{
    private XDeferredAxis<XElement> _value;
 
    private object _changeState;
 
    public XElementElementsPropertyDescriptor()
        : base("Elements")
    {
    }
 
    public override object GetValue(object component)
    {
        return _value = new XDeferredAxis<XElement>((XElement e, XName n) => (!(n != null)) ? e.Elements() : e.Elements(n), component as XElement, null);
    }
 
    protected override void OnChanged(object sender, XObjectChangeEventArgs args)
    {
        if (_value == null)
        {
            return;
        }
        switch (args.ObjectChange)
        {
        case XObjectChange.Add:
            if (sender is XElement xElement3 && _value.element == xElement3.Parent && (_value.name == xElement3.Name || _value.name == null))
            {
                OnValueChanged(_value.element, EventArgs.Empty);
            }
            break;
        case XObjectChange.Remove:
            if (sender is XElement xElement2 && _value.element == _changeState as XContainer && (_value.name == xElement2.Name || _value.name == null))
            {
                _changeState = null;
                OnValueChanged(_value.element, EventArgs.Empty);
            }
            break;
        case XObjectChange.Name:
            if (sender is XElement xElement && _value.element == xElement.Parent && _value.name != null && (_value.name == xElement.Name || _value.name == _changeState as XName))
            {
                _changeState = null;
                OnValueChanged(_value.element, EventArgs.Empty);
            }
            break;
        }
    }
 
    protected override void OnChanging(object sender, XObjectChangeEventArgs args)
    {
        if (_value != null)
        {
            switch (args.ObjectChange)
            {
            case XObjectChange.Remove:
                _changeState = (sender as XElement)?.Parent;
                break;
            case XObjectChange.Name:
                _changeState = (sender as XElement)?.Name;
                break;
            }
        }
    }
}