private IASTNode CreateProjection(SqlServerCommandParser.ProjectionContext context, AliasSegment alias)
{
IASTNode projection = Visit(context.expr());
if (projection is AggregationProjectionSegment aggregationProjectionSegment)
{
aggregationProjectionSegment.SetAlias(alias);
return(projection);
}
if (projection is ExpressionProjectionSegment expressionProjectionSegment)
{
expressionProjectionSegment.SetAlias(alias);
return(projection);
}
if (projection is CommonExpressionSegment commonExpressionSegment)
{
ExpressionProjectionSegment commonResult = new ExpressionProjectionSegment(commonExpressionSegment.GetStartIndex(), commonExpressionSegment.GetStopIndex(), commonExpressionSegment.GetText());
commonResult.SetAlias(alias);
return(commonResult);
}
// FIXME :For DISTINCT()
if (projection is ColumnSegment columnSegment)
{
ExpressionProjectionSegment columnResult = new ExpressionProjectionSegment(context.Start.StartIndex, context.Stop.StopIndex, context.GetText());
columnResult.SetAlias(alias);
return(columnResult);
}
if (projection is SubQueryExpressionSegment subQueryExpressionSegment)
{
SubQueryProjectionSegment subQueryResult = new SubQueryProjectionSegment(subQueryExpressionSegment.SubQuery);
subQueryResult.SetAlias(alias);
return(subQueryResult);
}
LiteralExpressionSegment column = (LiteralExpressionSegment)projection;
ExpressionProjectionSegment result = null == alias ? new ExpressionProjectionSegment(column.GetStartIndex(), column.GetStopIndex(), column.GetLiterals()?.ToString())
: new ExpressionProjectionSegment(column.GetStartIndex(), context.alias().Stop.StopIndex, column.GetLiterals()?.ToString());
result.SetAlias(alias);
return(result);
}
