str.pad()

🌀 String + .pad()

⬆️ 需要： Character * Int

// ────────────────────────────────────────────────────────────
// 2022.02.11 / .pad() change parameter order, 
//                     width -> _ width, align -> _ position
//                     remove `char` default argument
//                     PadAlign renamed PadPosition, case names renamed
// ────────────────────────────────────────────────────────────

extension String {
    
    /// ⭐️ position for string padding
    public enum PadPosition {
        case end, both, start
    }
    
    /// ⭐️ pad string with character.
    /// ```
    // "abc".pad("_", 10),       // _______abc
    // "abc".pad("_", 10, .end)  // abc_______
    // "abc".pad("_", 10, .both) // ___abc____
    /// ```
    public func pad(
        _     char: Character,
        _    width: Int,
        _ position: PadPosition = .start
    ) -> String 
    {
        // string longer than or equal to pad places
        if count >= width { return self }
        
        // string short than pad places
        let remainingPlaces = width - count
        let padStr   = char * remainingPlaces
        let leftPad  = remainingPlaces / 2
        let rightPad = remainingPlaces - leftPad
        
        switch position {
        case .end  : return self + padStr
        case .start: return padStr + self
        case .both : return (char * leftPad) + self + (char * rightPad) 
        }
    }
}

💈範例

👉 See: Logger

⬆️ 需要

• Character * Int

⬇️ 應用

• .binary(digits:)

• Logger

👥 相關

• String extension.

History

✏️ archive

1. 2022.02.11

1

// ────────────────────────────────────────────────────────────
// 2022.01.28 * (v.1)          + operator `*`, .pad()
// 2022.01.30 r `String.Align` renamed to `String.PadAlign`
// ────────────────────────────────────────────────────────────

// ┌───────────────────────┐
// │    String + .pad()    │
// └───────────────────────┘

extension String {
    
    /// alignment for string padding
    public enum PadAlign {
        case left, center, right
    }
    
    /// pad string with character
    public func pad(
        width : Int,
        _ char: Character = " ",
        align : PadAlign  = .left
    ) -> String 
    {
        // string longer than or equal to pad places
        if count >= width { return self }
        
        // string short than pad places
        let remainingPlaces = width - count
        let padStr   = char * remainingPlaces
        let leftPad  = remainingPlaces / 2
        let rightPad = remainingPlaces - leftPad
        
        switch align {
        case .left  : return self + padStr
        case .right : return padStr + self
        case .center: return (char * leftPad) + self + (char * rightPad) 
        }
    }
}