/// <summary>
/// Process the grouping operator. We have to sort through the items, group them, and then
/// create an object we can be translated later to access the items or the Key. We need to return
/// an IEnumerable<IGrouping<TKey, TElement>>... As a result, this is one of those operators that has
/// a fair amount of implementation in other parts of the re-linq structure.
/// </summary>
/// <param name="resultOperator"></param>
/// <param name="queryModel"></param>
/// <param name="gc"></param>
/// <param name="cc"></param>
/// <param name="container"></param>
/// <returns></returns>
/// <remarks>
/// re-linq blog post that shows the format of the query we are dealing with: https://www.re-motion.org/blogs/mix/2009/09/01/re-linq-how-to-support-ldquogroup-intordquo-with-aggregates
/// Not as useful:
/// Code for the result operator (including in-memory execution): https://svn.re-motion.org/svn/Remotion/trunk/Relinq/Core/Clauses/ResultOperators/GroupResultOperator.cs
/// Unit tests for the result operator: https://www.re-motion.org/fisheye/browse/~raw,r=17871/Remotion/trunk/Remotion/Data/Linq.UnitTests/Linq/SqlBackend/SqlPreparation/ResultOperatorHandlers/GroupResultOperatorHandlerTest.cs
/// </remarks>
System.Linq.Expressions.Expression IQVScalarResultOperator.ProcessResultOperator(ResultOperatorBase resultOperator, QueryModel queryModel, IGeneratedQueryCode gc, ICodeContext cc, CompositionContainer container)
{
//
// Basic checks
//
var groupOp = resultOperator as GroupResultOperator;
if (groupOp == null)
{
throw new ArgumentNullException("resultOperator");
}
if (!groupOp.KeySelector.Type.IsNumberType())
{
throw new InvalidOperationException(string.Format("Don't know how to group by type '{0}'.", groupOp.KeySelector.Type.Name));
}
//
// First, record all the indicies and the values. This is what we are going to be grouping.
//
var mapRecord = DeclarableParameter.CreateDeclarableParameterMapExpression(groupOp.KeySelector.Type, typeof(int).MakeArrayType());
gc.AddOutsideLoop(mapRecord);
var savePairValues = new StatementRecordPairValues(mapRecord,
ExpressionToCPP.GetExpression(groupOp.KeySelector, gc, cc, container),
ExpressionToCPP.GetExpression(cc.LoopIndexVariable.AsExpression(), gc, cc, container));
gc.Add(savePairValues);
gc.Pop();
//
// Now create the object that will be handed back for later parsing. This should contain the info that is needed to do the
// actual looping over the groups when it is requested.
//
var t_return = typeof(GroupByTypeTagEnum <int, int>).GetGenericTypeDefinition().MakeGenericType(new Type[] { groupOp.KeySelector.Type, groupOp.ElementSelector.Type });
var ctor = t_return.GetConstructor(new Type[] { });
var o = ctor.Invoke(new object[] { }) as BaseGroupInfo;
o.MapRecord = mapRecord;
o.TargetExpression = groupOp.ElementSelector;
o.TargetExpressionLoopVariable = cc.LoopIndexVariable;
return(Expression.Constant(o, t_return));
}
/// <summary>
/// Sort the current stream of the query. To do this we run through all the results, sort them,
/// and then start a new loop.
/// </summary>
/// <param name="ordering"></param>
/// <param name="queryModel"></param>
/// <param name="orderByClause"></param>
/// <param name="index"></param>
public override void VisitOrdering(Ordering ordering, QueryModel queryModel, OrderByClause orderByClause, int index)
{
//
// Only number types can be sorted.
//
if (!ordering.Expression.Type.IsNumberType())
{
throw new InvalidOperationException(string.Format("Don't know how to sort query by type '{0}'.", ordering.Expression.Type.Name));
}
//
// First, record all the indicies and the values. This is what we are going to be sorting.
//
var mapRecord = DeclarableParameter.CreateDeclarableParameterMapExpression(ordering.Expression.Type, _codeContext.LoopIndexVariable.Type.MakeArrayType());
_codeEnv.AddOutsideLoop(mapRecord);
var savePairValues = new StatementRecordPairValues(mapRecord,
ExpressionToCPP.GetExpression(ordering.Expression, _codeEnv, _codeContext, MEFContainer),
ExpressionToCPP.GetExpression(_codeContext.LoopIndexVariable.AsExpression(), _codeEnv, _codeContext, MEFContainer));
_codeEnv.Add(savePairValues);
var otherSavers = _codeEnv.GetUsedQuerySourceVariables(savePairValues, _codeContext.LoopIndexVariable)
.Select(v =>
{
var mr = DeclarableParameter.CreateDeclarableParameterMapExpression(ordering.Expression.Type, v.Type.MakeArrayType());
_codeEnv.AddOutsideLoop(mr);
savePairValues.AddSaver(mr, v);
return(Tuple.Create(v, mr));
})
.ToArray();
// Get back to the results level now, where we do the sorting!
_codeEnv.PopToResultsLevel();
//
// Now, we need to sort and loop over the variables in the map. This is a bit of a messy
// multi-line statement, and it is a compound statement.
//
var sortAndRunLoop = new StatementLoopOverSortedPairValue(mapRecord, ordering.OrderingDirection == OrderingDirection.Asc);
_codeEnv.Add(sortAndRunLoop);
var pindex = sortAndRunLoop.IndexVariable;
var lv = _codeContext.LoopIndexVariable.RawValue;
_codeContext.Add(lv, pindex);
foreach (var savers in otherSavers)
{
var newVarName = sortAndRunLoop.RestoreOtherSaver(savers.Item2);
_codeContext.Add(savers.Item1.RawValue, newVarName);
}
_codeContext.SetLoopVariable(_codeContext.LoopVariable.ReplaceSubExpression(_codeContext.LoopIndexVariable.AsExpression(), pindex), pindex);
}
public void CreateDeclarableParameterMapExpressionTest()
{
var r = DeclarableParameter.CreateDeclarableParameterMapExpression(typeof(int), typeof(double));
Assert.AreEqual(typeof(Dictionary <int, double>), r.Type, "map type not right");
}
