Method getSortedTable

engine/engine.go:456–503

(orderByCommand *ast.OrderByCommand, table *Table, copyOfTable *Table, tableName string)

}

func (engine *DbEngine) getSortedTable(orderByCommand *ast.OrderByCommand, table *Table, copyOfTable *Table, tableName string) (*Table, error) {
	sortPatterns := orderByCommand.SortPatterns

	columnNames := make([]string, 0)
	for _, sortPattern := range sortPatterns {
		columnNames = append(columnNames, sortPattern.ColumnName.Literal)
	}

	missingColName := engine.getMissingColumnName(columnNames, table)
	if missingColName != "" {
		return nil, &ColumnDoesNotExistError{
			tableName:  tableName,
			columnName: missingColName,
		}
	}

	rows := MapTableToRows(table).rows

	sort.Slice(rows, func(i, j int) bool {
		howDeepWeSort := 0
		sortingType := sortPatterns[howDeepWeSort].Order.Type
		columnToSort := sortPatterns[howDeepWeSort].ColumnName.Literal

		for rows[i][columnToSort].IsEqual(rows[j][columnToSort]) {
			howDeepWeSort++
			sortingType = sortPatterns[howDeepWeSort].Order.Type

			if howDeepWeSort >= len(orderByCommand.SortPatterns) {
				return true
			}
			columnToSort = sortPatterns[howDeepWeSort].ColumnName.Literal
		}

		if sortingType == token.DESC {
			return rows[i][columnToSort].isGreaterThan(rows[j][columnToSort])
		}

		return rows[i][columnToSort].isSmallerThan(rows[j][columnToSort])
	})

	for _, row := range rows {
		for _, newColumn := range copyOfTable.Columns {
			value := row[newColumn.Name]
			newColumn.Values = append(newColumn.Values, value)
		}
	}
	return copyOfTable, nil
}

func (engine *DbEngine) getMissingColumnName(columnNames []string, table *Table) string {
	for _, columnName := range columnNames {