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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
import Foundation
public extension Array where Element: Comparable {
func sameElements(_ arr: [Element]) -> Bool {
guard self.count == arr.count else { return false }
let sorted = self.sorted(by: <)
let arrSorted = arr.sorted(by: <)
for elements in sorted.zip(arrSorted) where elements.0 != elements.1 {
return false
}
return true
}
}
public extension Array {
func contains(_ x: Element, f: (Element, Element) -> Bool) -> Bool {
for y in self where f(x, y) {
return true
}
return false
}
// Performs a union operator using the result of f(Element) as the value to base uniqueness on.
func union<T: Hashable>(_ arr: [Element], f: (Element) -> T) -> [Element] {
let result = self + arr
return result.unique(f)
}
// Returns unique values in an array using the result of f()
func unique<T: Hashable>(_ f: (Element) -> T) -> [Element] {
var map: [T: Element] = [T: Element]()
return self.compactMap { a in
let t = f(a)
if map[t] == nil {
map[t] = a
return a
} else {
return nil
}
}
}
/// Removes the first element of the Array and returns the rest of the array.
/// If the array is empty, it returns an empty array.
var tail: Array {
return Array(self.dropFirst())
}
}
public extension Sequence where Iterator.Element: Hashable {
/// Return a de-duplicated sequence with the order preserved. `o(N)` complexity.
func uniqued() -> [Iterator.Element] {
var seen: Set<Iterator.Element> = []
return filter { seen.insert($0).inserted }
}
}
public extension Sequence {
func every(_ f: (Self.Iterator.Element) -> Bool) -> Bool {
for x in self where !f(x) {
return false
}
return true
}
}
public extension Collection {
/// Returns the element at the specified index if it is within bounds, otherwise nil.
subscript (safe index: Index) -> Element? {
return indices.contains(index) ? self[index] : nil
}
}
public extension Array where Element: NSAttributedString {
/// If the array is made up of `NSAttributedStrings`, this allows the reduction
/// of the array into a single `NSAttributedString`.
func joined() -> NSAttributedString {
return self.reduce(NSMutableAttributedString()) { result, element in
result.append(element)
return result
}
}
}