collection.columnWidths
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๐พ ็จๅผ๏ผ replit โฌ๏ธ ้่ฆ๏ผ .allElementsSameLength
// โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
// โ Collection + .columnWidths โ
// โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
extension Collection where
Element: Collection, // each element is Collection, e.g. Array.
Element.Index == Int, // each element is Int indexed (column index).
Element.Element: Collection // each cell is Collection (has `count`), e.g. String.
{
/// determine the max length (count) in every column of a 2D array of data.
///
/// ### Explanation:
/// ```
/// typealias Data = [[String]] // Data is Array, which is Collection.
/// typealias Row = [String] // Row == Data.Element, Array (Int indexed).
/// typealias Value = String // Value == Row.Element, String, which is Collection too
/// ```
/// ### Example:
/// - `[["a", "bc", "def"], ["ab", "cde", "f"]].columnWidths == Optional([2, 3, 3])`
/// - `[["a", "b", "c"], ["a"]].columnWidths == nil`
public var columnWidths: [Int]? {
guard
allElementsSameLength, // all rows same length
let firstRow = first, // data must at least have one row
!firstRow.isEmpty // row must at least have one cell
else {
return nil
}
// for each column (at index j), find that column's max string length.
// every column contains at least one string, so max length (max()) can't be nil.
return (0 ..< firstRow.count).map { j in
self // collection of elements (rows)
.map { row in row[j].count } // array of j-th elements' lengths
.max()! // โญ force unwrap (max string length)
}
}
}