/// <summary>
/// Sets the value of the model content associated to this <see cref="GraphNodeViewModel"/>. The value is actually modified only if the new value is different from the previous value.
/// </summary>
/// <returns><c>True</c> if the value has been modified, <c>false</c> otherwise.</returns>
protected virtual bool SetModelContentValue(IContentNode node, object newValue)
{
var oldValue = node.Retrieve(Index);
if (!Equals(oldValue, newValue))
{
node.Update(newValue, Index);
return(true);
}
return(false);
}
protected static bool UpdateCollection(IContentNode node, object value, Index index)
{
if (IsIndexExisting(node, index))
{
node.Update(value, index);
return(true);
}
if (IsIndexValid(node, index))
{
node.Add(value, index);
return(true);
}
return(false);
}
public override Task Execute(IContentNode content, Index index, object parameter)
{
var hasIndex = content.Indices == null || content.Indices.Contains(index);
var currentValue = hasIndex ? content.Retrieve(index) : (content.Type.IsValueType ? Activator.CreateInstance(content.Type) : null);
var newValue = ChangeValue(currentValue, parameter);
if (hasIndex)
{
if (!Equals(newValue, currentValue))
{
content.Update(newValue, index);
}
}
else
{
content.Add(newValue, index);
}
return(Task.FromResult(0));
}