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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2024 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
//
//===----------------------------------------------------------------------===//
//
// RUN: %target-run-simple-swift(-parse-as-library)
// REQUIRES: executable_test
// END.
//
//===----------------------------------------------------------------------===//
import StdlibUnittest
@main
final class FlattenDistanceFromToTests {
static func main() {
let tests = FlattenDistanceFromToTests()
let suite = TestSuite("FlattenDistanceFromToTests")
suite.test("EachIndexPair", tests.testEachIndexPair)
if #available(SwiftStdlib 6.0, *) {
// The random access time complexity was fixed in Swift 6.0.
suite.test("MinMaxRandomAccess", tests.testMinMaxRandomAccess)
}
runAllTests()
}
}
//===----------------------------------------------------------------------===//
// MARK: - Each Index Pair
//===----------------------------------------------------------------------===//
extension FlattenDistanceFromToTests {
/// Performs one `action` per lane size case through `limits`.
///
/// limits: [0,1,2,3]
/// ─────────────────
/// [][ ][ ][ ]
/// [][1][ ][ ]
/// [][ ][2 ][ ]
/// [][1][ ][ ]
/// [][ ][2,2][ ]
/// [][1][2,2][ ]
/// [][ ][ ][3 ]
/// ─────────────────
/// [][1][2,2][3,3,3]
///
private func forEachLaneSizeCase(
through limits: [Int],
perform action: ([[Int]]) -> Void
) {
var array = Array(repeating: [Int](), count: limits.count)
var index = array.startIndex
while index < limits.endIndex {
action(array)
if array[index].count < limits[index] {
array[index].append(index)
} else {
while index < limits.endIndex, array[index].count == limits[index] {
array.formIndex(after: &index)
}
if index < limits.endIndex {
array[index].append(index)
while index > array.startIndex {
array.formIndex(before: &index)
array[index].removeAll(keepingCapacity: true)
}
}
}
}
}
/// Performs one `action` per offset-index pair in `collection`.
///
/// collection: [[0],[1,2]].joined()
/// ────────────────────────────────
/// offset: 0, index: 0,0
/// offset: 1, index: 1,0
/// offset: 2, index: 1,1
/// offset: 3, index: 2
///
private func forEachEnumeratedIndexIncludingEndIndex<T>(
in collection: T,
perform action: ((offset: Int, index: T.Index)) -> Void
) where T: Collection {
var state = (offset: 0, index: collection.startIndex)
while true {
action(state)
if state.index == collection.endIndex {
return
}
state.offset += 1
collection.formIndex(after: &state.index)
}
}
/// Checks the distance between each index pair in various cases.
///
/// You need three lanes to exercise the first, the middle, the last region.
/// The past-the-end index is a separate lane, so the middle region contains
/// one additional lane when the past-the-end index is selected.
///
func testEachIndexPair() {
var invocations = 0 as Int
for lanes in 0 ... 3 {
let limits = Array(repeating: 3, count: lanes)
forEachLaneSizeCase(through: limits) { base in
let collection: FlattenSequence = base.joined()
forEachEnumeratedIndexIncludingEndIndex(in: collection) { start in
forEachEnumeratedIndexIncludingEndIndex(in: collection) { end in
let pair = (from: start.offset, to: end.offset)
invocations += 1
expectEqual(
collection.distance(from: start.index, to: end.index),
end.offset - start.offset,
"""
index distance != offset distance for \(pair) in \(base).joined()
"""
)
}
}
}
}
expectEqual(invocations, 2502, "unexpected workload")
}
}
//===----------------------------------------------------------------------===//
// MARK: - Min Max Outputs
//===----------------------------------------------------------------------===//
extension FlattenDistanceFromToTests {
/// Checks some `Int.min` and `Int.max` distances with random access.
///
/// It needs Swift 6.0+ because prior versions find the distance by
/// iterating from one index to the other, which takes way too long.
///
/// - Note: A distance of `Int.min` requires more than `Int.max` elements.
///
@available(SwiftStdlib 6.0, *)
func testMinMaxRandomAccess() {
for s: FlattenSequence in [
[-1..<Int.max/1],
[00..<Int.max/1, 00..<000000001],
[00..<000000001, 01..<Int.max/1, 00..<000000001],
[00..<000000001, 00..<Int.max/2, 00..<Int.max/2, 00..<000000001]
].map({ $0.joined() }) {
let a = s.startIndex, b = s.endIndex
expectEqual(Int.min, s.distance(from: b, to: s.index(a, offsetBy: 00)))
expectEqual(Int.max, s.distance(from: s.index(a, offsetBy: 01), to: b))
expectEqual(Int.min, s.distance(from: s.index(b, offsetBy: 00), to: a))
expectEqual(Int.max, s.distance(from: a, to: s.index(b, offsetBy: -1)))
}
}
}
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