// Optimization that speeds up the common case (single selection)
private static IEnumerable <IList <ModelProperty> > GetFirstProperties(PropertyExpander expander)
{
IEnumerator <IEnumerable <ModelProperty> > propertyContainers = expander.GetEnumerator();
propertyContainers.MoveNext();
if (propertyContainers.Current != null)
{
foreach (ModelProperty property in propertyContainers.Current)
{
yield return(new ModelProperty[] { property });
}
}
}
// Optimization that speeds up the common case (single selection)
private static IEnumerable <IList <ModelProperty> > GetMergedPropertiesHelper(PropertyExpander expander)
{
// Check empty list
if (expander == null || expander.ContainerCount == 0)
{
return(EmptyCollection);
}
if (expander.ContainerCount == 1)
{
// Corner case - one object selected, don't bother with merging
return(GetFirstProperties(expander));
}
else
{
// Calculate the list anew
return(GetMergedPropertiesCore(expander));
}
}
private static IEnumerable <IList <ModelProperty> > GetMergedPropertiesCore(PropertyExpander expander)
{
Dictionary <string, IList <ModelProperty> > counter = new Dictionary <string, IList <ModelProperty> >();
int containerCounter = 0;
foreach (IEnumerable <ModelProperty> properties in expander)
{
if (properties == null)
{
yield break;
}
foreach (ModelProperty property in properties)
{
IList <ModelProperty> existingModelPropertiesForProperty;
if (!counter.TryGetValue(property.Name, out existingModelPropertiesForProperty))
{
if (containerCounter == 0)
{
existingModelPropertiesForProperty = new List <ModelProperty>(expander.ContainerCount);
counter[property.Name] = existingModelPropertiesForProperty;
}
else
{
// This property has not been encountered yet in the previous objects,
// so skip it altogether.
continue;
}
}
if (existingModelPropertiesForProperty.Count < containerCounter)
{
// There has been a ModelItem in the list that didn't have this property,
// so delete any record of it and skip it in the future.
counter.Remove(property.Name);
continue;
}
// Verify that the properties are equivalent
if (containerCounter > 0 &&
!ModelUtilities.AreEquivalent(
existingModelPropertiesForProperty[containerCounter - 1], property))
{
// They are not, so scrap this property altogether
counter.Remove(property.Name);
continue;
}
existingModelPropertiesForProperty.Add(property);
}
containerCounter++;
}
foreach (KeyValuePair <string, IList <ModelProperty> > pair in counter)
{
// Once again, if there is a property that is not shared by all
// selected items, ignore it
if (pair.Value.Count < containerCounter)
{
continue;
}
// We should not set the same instance to multiple properties,
// so ignore types that are not value type or string in case of multi-selection
if (pair.Value.Count > 1 && !(pair.Value[0].PropertyType.IsValueType || pair.Value[0].PropertyType.Equals(typeof(string))))
{
continue;
}
yield return((IList <ModelProperty>)pair.Value);
}
}
