private RowHandle VisitElementAt(MethodCallExpression m)
{
Visit(m.Arguments.First());
object argument;
if (!TryExtractConstantValue(m.Arguments.Last(), out argument) || argument.GetType() != typeof(int))
{
throw new NotSupportedException($"The method '{m.Method}' has to be invoked with a single integer constant argument or closure variable");
}
var index = (int)argument;
RowHandle row;
if (OptionalSortDescriptorBuilder == null)
{
var rowPtr = _coreQueryHandle.FindDirect((IntPtr)index);
row = Realm.CreateRowHandle(rowPtr, _realm.SharedRealmHandle);
}
else
{
using (ResultsHandle rh = _realm.MakeResultsForQuery(_coreQueryHandle, OptionalSortDescriptorBuilder))
{
var rowPtr = rh.GetRow(index);
row = Realm.CreateRowHandle(rowPtr, _realm.SharedRealmHandle);
}
}
return(row);
}
/// <summary>
/// Move the iterator to the next related object, starting "before" the first object.
/// </summary>
/// <remarks>
/// Is a factory for RealmObjects, loading a new one and updating <c>Current</c>.
/// </remarks>
/// <returns>True only if can advance.</returns>
public bool MoveNext()
{
if (_enumeratingResults == null)
{
return(false);
}
++_index;
var rowPtr = _enumeratingResults.GetRow(_index);
if (rowPtr == IntPtr.Zero)
{
Current = (T)(object)null;
return(false);
}
Current = (T)(object)_realm.MakeObjectForRow(_schema.Name, rowPtr);
return(true);
}
internal override Expression VisitMethodCall(MethodCallExpression m)
{
if (m.Method.DeclaringType == typeof(Queryable))
{
if (m.Method.Name == nameof(Queryable.Where))
{
this.Visit(m.Arguments[0]);
LambdaExpression lambda = (LambdaExpression)StripQuotes(m.Arguments[1]);
this.Visit(lambda.Body);
return(m);
}
if (m.Method.Name == nameof(Queryable.OrderBy))
{
this.Visit(m.Arguments[0]);
AddSort((LambdaExpression)StripQuotes(m.Arguments[1]), true, true);
return(m);
}
if (m.Method.Name == nameof(Queryable.OrderByDescending))
{
this.Visit(m.Arguments[0]);
AddSort((LambdaExpression)StripQuotes(m.Arguments[1]), true, false);
return(m);
}
if (m.Method.Name == nameof(Queryable.ThenBy))
{
this.Visit(m.Arguments[0]);
AddSort((LambdaExpression)StripQuotes(m.Arguments[1]), false, true);
return(m);
}
if (m.Method.Name == nameof(Queryable.ThenByDescending))
{
this.Visit(m.Arguments[0]);
AddSort((LambdaExpression)StripQuotes(m.Arguments[1]), false, false);
return(m);
}
if (m.Method.Name == nameof(Queryable.Count))
{
RecurseToWhereOrRunLambda(m);
var foundCount = _coreQueryHandle.Count();
return(Expression.Constant(foundCount));
}
if (m.Method.Name == nameof(Queryable.Any))
{
RecurseToWhereOrRunLambda(m);
bool foundAny = _coreQueryHandle.FindDirect(IntPtr.Zero) != IntPtr.Zero;
return(Expression.Constant(foundAny));
}
if (m.Method.Name.StartsWith(nameof(Queryable.First)))
{
RecurseToWhereOrRunLambda(m);
IntPtr firstRowPtr = IntPtr.Zero;
if (OptionalSortDescriptorBuilder == null)
{
firstRowPtr = _coreQueryHandle.FindDirect(IntPtr.Zero);
}
else
{
using (ResultsHandle rh = _realm.MakeResultsForQuery(_coreQueryHandle, OptionalSortDescriptorBuilder))
{
firstRowPtr = rh.GetRow(0);
}
}
if (firstRowPtr != IntPtr.Zero)
{
return(Expression.Constant(_realm.MakeObjectForRow(_metadata, firstRowPtr)));
}
if (m.Method.Name == nameof(Queryable.First))
{
throw new InvalidOperationException("Sequence contains no matching element");
}
Debug.Assert(m.Method.Name == nameof(Queryable.FirstOrDefault));
return(Expression.Constant(null));
}
/*
* // FIXME: See discussion in the test DefaultIfEmptyReturnsDefault
* // kept because it shows part of what might be a viable implementation if can work out architectural issues
*
* if (m.Method.Name == nameof(Queryable.DefaultIfEmpty))
* {
* RecurseToWhereOrRunLambda(m);
* IntPtr firstRowPtr = _coreQueryHandle.FindDirect(IntPtr.Zero);
* if (firstRowPtr != IntPtr.Zero)
* return m; // as if just a "Where"
* var innerType = m.Type.GetGenericArguments()[0];
* var listType = typeof(List<>).MakeGenericType(innerType);
* var singleNullItemList = Activator.CreateInstance(listType);
* ((IList)singleNullItemList).Add(null);
* return Expression.Constant(singleNullItemList);
* }
*/
if (m.Method.Name.StartsWith(nameof(Queryable.Single))) // same as unsorted First with extra checks
{
RecurseToWhereOrRunLambda(m);
var firstRowPtr = _coreQueryHandle.FindDirect(IntPtr.Zero);
if (firstRowPtr == IntPtr.Zero)
{
if (m.Method.Name == nameof(Queryable.Single))
{
throw new InvalidOperationException("Sequence contains no matching element");
}
Debug.Assert(m.Method.Name == nameof(Queryable.SingleOrDefault));
return(Expression.Constant(null));
}
var firstRow = Realm.CreateRowHandle(firstRowPtr, _realm.SharedRealmHandle);
IntPtr nextIndex = (IntPtr)(firstRow.RowIndex + 1);
var nextRowPtr = _coreQueryHandle.FindDirect(nextIndex);
if (nextRowPtr != IntPtr.Zero)
{
throw new InvalidOperationException("Sequence contains more than one matching element");
}
return(Expression.Constant(_realm.MakeObjectForRow(_metadata, firstRow)));
}
if (m.Method.Name.StartsWith(nameof(Queryable.Last)))
{
RecurseToWhereOrRunLambda(m);
var lastRowPtr = IntPtr.Zero;
using (ResultsHandle rh = _realm.MakeResultsForQuery(_coreQueryHandle, OptionalSortDescriptorBuilder))
{
var lastIndex = rh.Count() - 1;
if (lastIndex >= 0)
{
lastRowPtr = rh.GetRow(lastIndex);
}
}
if (lastRowPtr != IntPtr.Zero)
{
return(Expression.Constant(_realm.MakeObjectForRow(_metadata, lastRowPtr)));
}
if (m.Method.Name == nameof(Queryable.Last))
{
throw new InvalidOperationException("Sequence contains no matching element");
}
Debug.Assert(m.Method.Name == nameof(Queryable.LastOrDefault));
return(Expression.Constant(null));
}
if (m.Method.Name.StartsWith(nameof(Queryable.ElementAt)))
{
var row = VisitElementAt(m);
if (row == null || row.IsInvalid)
{
if (m.Method.Name == nameof(Queryable.ElementAt))
{
throw new ArgumentOutOfRangeException();
}
Debug.Assert(m.Method.Name == nameof(Queryable.ElementAtOrDefault));
return(Expression.Constant(null));
}
return(Expression.Constant(_realm.MakeObjectForRow(_metadata, row)));
}
}
if (m.Method.DeclaringType == typeof(string))
{
QueryHandle.Operation <string> queryMethod = null;
if (m.Method == Methods.String.Contains.Value)
{
queryMethod = (q, c, v) => q.StringContains(c, v);
}
else if (m.Method == Methods.String.StartsWith.Value)
{
queryMethod = (q, c, v) => q.StringStartsWith(c, v);
}
else if (m.Method == Methods.String.EndsWith.Value)
{
queryMethod = (q, c, v) => q.StringEndsWith(c, v);
}
else if (m.Method == Methods.String.IsNullOrEmpty.Value)
{
var member = m.Arguments.SingleOrDefault() as MemberExpression;
if (member == null)
{
throw new NotSupportedException($"The method '{m.Method}' has to be invoked with a RealmObject member");
}
var columnIndex = _coreQueryHandle.GetColumnIndex(member.Member.Name);
_coreQueryHandle.GroupBegin();
_coreQueryHandle.NullEqual(columnIndex);
_coreQueryHandle.Or();
_coreQueryHandle.StringEqual(columnIndex, string.Empty);
_coreQueryHandle.GroupEnd();
return(m);
}
if (queryMethod != null)
{
var member = m.Object as MemberExpression;
if (member == null)
{
throw new NotSupportedException($"The method '{m.Method}' has to be invoked on a RealmObject member");
}
var columnIndex = _coreQueryHandle.GetColumnIndex(member.Member.Name);
object argument;
if (!TryExtractConstantValue(m.Arguments.SingleOrDefault(), out argument) || argument.GetType() != typeof(string))
{
throw new NotSupportedException($"The method '{m.Method}' has to be invoked with a single string constant argument or closure variable");
}
queryMethod(_coreQueryHandle, columnIndex, (string)argument);
return(m);
}
}
throw new NotSupportedException($"The method '{m.Method.Name}' is not supported");
}