Chapter 19, Bronze Challenge Solution

Swift Programming (3rd Edition) 19. Protocols
1

I moved the columnWidths[j] - item.count calculation into a constant, widthDelta. I then used the ternary operator to evaluate whether widthDelta has a negative value. If the column label’s width is less than the item’s width, then no padding is needed, and I assign 0 to paddingNeeded.

func printTable(_ dataSource: TabularDataSource &
                CustomStringConvertible) {
    print("Table: \(dataSource)")
    // Create a header row containing column headers
    var headerRow = "|"
    
    // Also keep track of the width of each column
    var columnWidths = [Int]()
    
    for i in 0 ..< dataSource.numberOfColumns {
        let columnLabel = dataSource.label(forColumn: i)
        let columnHeader = " \(columnLabel) |"
        headerRow += columnHeader
        columnWidths.append(columnLabel.count)
    }
    print(headerRow)
    
    for i in 0 ..< dataSource.numberOfRows {
        // Start the output string
        var out = "|"
        
        // Append each item in this row to the string
        for j in 0 ..< dataSource.numberOfColumns {
            let item = dataSource.itemFor(row: i, column: j)
            
            // Bronze challenge
            let widthDelta = columnWidths[j] - item.count
            let paddingNeeded = widthDelta > 0 ? widthDelta : 0
            
            let padding = repeatElement(" ", count:
                                            paddingNeeded).joined(separator: "")
            out += " \(padding)\(item) |"
        }
        
        // Done - print it!
        print(out)
    }
}