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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
extension Collection {
public func divide(into pieces: Int) -> [SubSequence] {
func range(of piece: Int) -> Range<Index> {
let start = index(startIndex, offsetBy: count * piece / pieces)
let end = index(startIndex, offsetBy: count * (piece + 1) / pieces)
return start..<end
}
return (0..<pieces).map {piece in self[range(of: piece)]}
}
public func divide<T: Equatable>(by comparison: (Element) -> T) -> [SubSequence] {
var working = self[...]
var result = [SubSequence]()
while let first = working.first {
let firstValue = comparison(first)
let partition = working.prefix{ comparison($0) == firstValue }
result.append(partition)
working = working.dropFirst(partition.count)
}
return result
}
}
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