protected override IEnumerable <EntitySetHandle> OnVisitItems(EvaluationContext evalContext)
{
// The relationship (definition) being accessed
// (don't evaluate in loop for now ... OK while they're just literals)
IEntity relationship = Right.EvaluateEntity(evalContext);
IEntity current = Left.EvaluateEntity(evalContext);
if (current == null)
{
yield break;
}
// Relationship data
IEntityRelationshipCollection <IEntity> values = current.GetRelationships(relationship,
Direction);
foreach (var pair in values)
{
var result = new EntitySetHandle
{
Entity = pair != null ? pair.Entity : null,
Expression = this
};
yield return(result);
}
}
public void AddParent(EntitySetHandle parent)
{
if (Parents == null)
{
Parents = new List <EntitySetHandle>();
}
Parents.Add(parent);
}
protected override IEnumerable <EntitySetHandle> OnVisitItems(EvaluationContext evalContext)
{
EntitySetHandle handle = new EntitySetHandle
{
Expression = this
};
yield return(handle);
}
protected override IEnumerable <EntitySetHandle> OnVisitItems(EvaluationContext evalContext)
{
var result = new EntitySetHandle
{
Entity = evalContext.Settings.ContextEntity,
Expression = this
};
yield return(result);
}
protected override IEnumerable <EntitySetHandle> OnVisitItems(EvaluationContext evalContext)
{
// The instances passed in via the parameter
IEnumerable <IEntity> instances = GetParameterList(evalContext);
foreach (var instance in instances)
{
var result = new EntitySetHandle
{
Entity = instance,
Expression = this
};
yield return(result);
}
}
protected virtual IEnumerable <EntitySetHandle> OnVisitAllItems(EvaluationContext evalContext)
{
// Yes .. this is a hack
// The problem is its not necessarily the case that children should or should not constrain the parent
// The problem is that the tree itself is built wrong.. the root node should be the 'where' node if the overall result set is to be filtered.
bool childrenWillContrainParent = ChildContainer.ChildEntityNodes.Any(node => node is WhereNode);
// Return handle to Visit each entity
IEnumerable <EntitySetHandle> handles = OnVisitItems(evalContext).Select(handle => { handle.Activate(evalContext); return(handle); });
// (Wraps are used to track if any of the joins were non-default-nulls)
var handleWraps = handles.Select(h => new HandleWrap {
Handle = h, IsNotEmpty = !childrenWillContrainParent
});
// And cross-join all child nodes against each other.
// Note: these are effectively left-joined to the parent. (We use the DefaultIfEmpty to ensure that each set returns at least one value, to ensure they act as a left join).
var handlesEx = ChildContainer.ChildEntityNodes.Aggregate
(
seed: handleWraps,
func: (accumHandles, joinNode) => accumHandles.SelectMany(
collectionSelector: handle => AddDefaultRowIfRequired(joinNode.VisitItems(evalContext), evalContext),
resultSelector: (parent, child) =>
{
bool wasEmpty = child == null;
if (wasEmpty)
{
child = new EntitySetHandle {
Expression = joinNode
}
}
;
child.AddParent(parent.Handle);
return(new HandleWrap {
Handle = child, IsNotEmpty = !wasEmpty
});
}
)
);
if (childrenWillContrainParent)
{
handlesEx = handlesEx.Where(hw => hw.IsNotEmpty);
}
return(handlesEx.Select(hw => hw.Handle));
}
protected override IEnumerable <EntitySetHandle> OnVisitItems(EvaluationContext evalContext)
{
IEntity instance = Instance.Entity;
if (instance == null)
{
yield break;
}
var result = new EntitySetHandle
{
Entity = instance,
Expression = this
};
yield return(result);
}
protected override IEnumerable <EntitySetHandle> OnVisitItems(EvaluationContext evalContext)
{
// The type of instances to load
IEntity type = Argument.EvaluateEntity(evalContext);
// Get instances
IEnumerable <IEntity> instances = Entity.GetInstancesOfType(new EntityRef(type.Id), true);
foreach (var instance in instances)
{
var result = new EntitySetHandle
{
Entity = instance,
Expression = this
};
yield return(result);
}
}
