/// <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);
}