StringInd.swift

StringInd.swift

public struct Ind {
    private let s: String
    public let index: String.Index

    public init(_ s: String, _ index: String.Index) {
        self.s = s
        self.index = index
    }

    public init(_ s: String, _ f: (String) -> String.Index) {
        self.init(s, f(s))
    }

    public var start: Self { .init(s, s.startIndex) }
    public var end: Self { .init(s, s.endIndex) }
    public var prev: Self { .init(s, s.index(before: index)) }
    public var next: Self { .init(s, s.index(after: index)) }

    public func offset(by distance: Int) -> Self {
        .init(s, s.index(index, offsetBy: distance))
    }

    public func offset(by distance: Int, limitedBy limit: String.Index) -> Self? {
        s.index(index, offsetBy: distance, limitedBy: limit)
            .map { .init(s, $0) }
    }

    public func offset(by distance: Int, limit f: (String) -> String.Index) -> Self? {
        offset(by: distance, limitedBy: f(s))
    }
}