internal static IEnumerable <IExpressionPart> GetFluxExpressions(Expression expression, object clause,
QueryGenerationContext context)
{
Arguments.CheckNotNull(expression, nameof(expression));
Arguments.CheckNotNull(clause, nameof(clause));
Arguments.CheckNotNull(context, nameof(context));
var visitor = new QueryExpressionTreeVisitor(clause, context);
visitor.Visit(expression);
return(visitor.GetFluxExpressions());
}
public override void VisitWhereClause(WhereClause whereClause, QueryModel queryModel, int index)
{
base.VisitWhereClause(whereClause, queryModel, index);
var expressions = GetExpressions(whereClause.Predicate, whereClause).ToList();
var rangeFilter = new List <IExpressionPart>();
var tagFilter = new List <IExpressionPart>();
var fieldFilter = new List <IExpressionPart>();
// Map LINQ filter expresion to right place: range, tag filtering, field filtering
foreach (var expression in expressions)
{
switch (expression)
{
// Range
case TimeColumnName _:
rangeFilter.Add(expression);
break;
// Tag
case TagColumnName _:
tagFilter.Add(expression);
break;
// Field
case RecordColumnName _:
fieldFilter.Add(expression);
break;
case NamedField _:
fieldFilter.Add(expression);
break;
case NamedFieldValue _:
fieldFilter.Add(expression);
break;
// Other expressions: binary operator, parenthesis
default:
rangeFilter.Add(expression);
tagFilter.Add(expression);
fieldFilter.Add(expression);
break;
}
}
QueryExpressionTreeVisitor.NormalizeExpressions(rangeFilter);
QueryExpressionTreeVisitor.NormalizeExpressions(tagFilter);
QueryExpressionTreeVisitor.NormalizeExpressions(fieldFilter);
Debug.WriteLine("--- normalized LINQ expressions: ---");
Debug.WriteLine($"range: {ConcatExpression(rangeFilter)}");
Debug.WriteLine($"tag: {ConcatExpression(tagFilter)}");
Debug.WriteLine($"field: {ConcatExpression(fieldFilter)}");
// filter by time
AddFilterByRange(rangeFilter);
// filter by tags
_context.QueryAggregator.AddFilterByTags(ConcatExpression(tagFilter));
// filter by fields
_context.QueryAggregator.AddFilterByFields(ConcatExpression(fieldFilter));
}
private IEnumerable <IExpressionPart> GetExpressions(Expression expression, object clause)
{
return(QueryExpressionTreeVisitor.GetFluxExpressions(expression, clause, _context));
}