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extension Array {
subscript(safe index: Int) -> Element? {
return indices.contains(index) ? self[index] : nil
}
/// Returns the index before i, with wraparound. Assumes i is a valid index.
func indexWrapping(before i: Int) -> Int {
if i == 0 {
return count - 1
}
return i - 1
}
/// Returns the index after i, with wraparound. Assumes i is a valid index.
func indexWrapping(after i: Int) -> Int {
if i == count - 1 {
return 0
}
return i + 1
}
}
extension Array where Element == String {
/// Executes a closure with an array of C string pointers.
func withCStrings<T>(_ body: ([UnsafePointer<Int8>?]) throws -> T) rethrows -> T {
// Handle empty array
if isEmpty {
return try body([])
}
// Recursive helper to process strings
func helper(index: Int, accumulated: [UnsafePointer<Int8>?], body: ([UnsafePointer<Int8>?]) throws -> T) rethrows -> T {
if index == count {
return try body(accumulated)
}
return try self[index].withCString { cStr in
var newAccumulated = accumulated
newAccumulated.append(cStr)
return try helper(index: index + 1, accumulated: newAccumulated, body: body)
}
}
return try helper(index: 0, accumulated: [], body: body)
}
}
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