Deveel.Data.Sql.Query.RangeSelectNode.Evaluate C# (CSharp) Method

        public override ITable Evaluate(IRequest context)
        {
            var t = Child.Evaluate(context);

            var exp = Expression;

            // Assert that all variables in the expression are identical.
            var columnNames = exp.DiscoverReferences();
            ObjectName columnName = null;
            foreach (var cv in columnNames) {
                if (columnName != null && !cv.Equals(columnName))
                    throw new InvalidOperationException("Range plan does not contain common column.");

                columnName = cv;
            }

            // Find the variable field in the table.
            var col = t.IndexOfColumn(columnName);
            if (col == -1)
                throw new InvalidOperationException("Could not find column reference in table: " + columnName);

            var field = t.TableInfo[col];

            // Calculate the range
            var range = new IndexRangeSet();
            var calculator = new RangeSetCalculator(context, field, range);
            range = calculator.Calculate(exp);

            // Select the range from the table
            var ranges = range.ToArray();
            return t.SelectRange(columnName, ranges);
        }