protected override void LeaveObject(IFieldSelection selection)
{
if (selection.Field.Member is PropertyInfo member)
{
SelectionClosure closure = Closures.Pop();
MemberInitExpression memberInit = closure.CreateMemberInit();
MemberExpression property = Expression.Property(
Closures.Peek().Instance.Peek(), member);
Expression withNullCheck = Expression.Condition(
Expression.Equal(property, Expression.Constant(null)),
Expression.Default(memberInit.Type),
memberInit);
Closures.Peek().Projections[selection.Field.Name] =
Expression.Bind(selection.Field.Member, withNullCheck);
base.LeaveObject(selection);
}
else
{
throw new QueryException(
ErrorBuilder.New()
.SetMessage(
string.Format(
"UseSelection is in a invalid state. Field {0}" +
" should never have been visited!",
selection.Field.Name))
.Build());
}
}
protected override void LeaveLeaf(IFieldSelection selection)
{
if (selection.Field.Member is PropertyInfo member)
{
SelectionClosure closure = Closures.Peek();
closure.Projections[member.Name] = Expression.Bind(
member, Expression.Property(closure.Instance.Peek(), member));
}
base.LeaveLeaf(selection);
}
protected override bool EnterObject(IFieldSelection selection)
{
if (selection.Field.Member is PropertyInfo property)
{
var nextClosure =
new SelectionClosure(
selection.Field.ClrType, "e" + Closures.Count);
nextClosure.Instance.Push(
Expression.Property(
Closures.Peek().Instance.Peek(), property));
Closures.Push(nextClosure);
return(base.EnterObject(selection));
}
return(false);
}
protected override void LeaveList(IFieldSelection selection)
{
if (selection.Field.Member is PropertyInfo propertyInfo)
{
SelectionClosure closure = Closures.Pop();
Expression body =
Expression.Property(
Closures.Peek().Instance.Peek(), propertyInfo);
if (selection is FieldSelection fieldSelection)
{
var context = new SelectionVisitorContext(
Context,
_converter,
fieldSelection,
_selectionMiddlewareContext);
for (var i = 0; i < _listHandler.Count; i++)
{
body = _listHandler[i].HandleLeave(context, selection, body);
}
}
Expression select = closure.CreateSelection(body, propertyInfo.PropertyType);
Closures.Peek().Projections[selection.Field.Name] =
Expression.Bind(selection.Field.Member, select);
base.LeaveList(selection);
}
else
{
throw new QueryException(
ErrorBuilder.New()
.SetMessage(
string.Format(
"UseSelection is in a invalid state. Field {0}" +
" should never have been visited!",
selection.Field.Name))
.Build());
}
}