/
Combinatorics.swift
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/
Combinatorics.swift
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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2021 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
//
//===----------------------------------------------------------------------===//
/// Run the supplied closure with all values in `items` in a loop,
/// recording the current value in the current test trace stack.
public func withEvery<Element>(
_ label: String,
by generator: () -> Element?,
file: StaticString = #file,
line: UInt = #line,
run body: (Element) throws -> Void
) rethrows {
let context = TestContext.current
while let item = generator() {
let entry = context.push("\(label): \(item)", file: file, line: line)
var done = false
defer {
context.pop(entry)
if !done {
print(context.currentTrace(title: "Throwing trace"))
}
}
try body(item)
done = true
}
}
/// Run the supplied closure with all values in `items` in a loop,
/// recording the current value in the current test trace stack.
public func withEvery<S: Sequence>(
_ label: String,
in items: S,
file: StaticString = #file,
line: UInt = #line,
run body: (S.Element) throws -> Void
) rethrows {
let context = TestContext.current
for item in items {
let entry = context.push("\(label): \(item)", file: file, line: line)
var done = false
defer {
context.pop(entry)
if !done {
print(context.currentTrace(title: "Throwing trace"))
}
}
try body(item)
done = true
}
}
public func withEveryRange<T: Strideable>(
_ label: String,
in bounds: Range<T>,
file: StaticString = #file,
line: UInt = #line,
run body: (Range<T>) throws -> Void
) rethrows where T.Stride == Int {
let context = TestContext.current
for lowerBound in bounds.lowerBound ... bounds.upperBound {
for upperBound in lowerBound ... bounds.upperBound {
let range = lowerBound ..< upperBound
let entry = context.push("\(label): \(range)", file: file, line: line)
var done = false
defer {
context.pop(entry)
if !done {
print(context.currentTrace(title: "Throwing trace"))
}
}
try body(range)
done = true
}
}
}
internal func _samples<C: Collection>(from items: C) -> [C.Element] {
let c = items.count
guard c > 7 else { return Array(items) }
let offsets = [0, 1, c / 2 - 1, c / 2, c / 2 + 1, c - 2, c - 1]
var offset = 0
var index = items.startIndex
var result: [C.Element] = []
result.reserveCapacity(7)
for o in offsets {
items.formIndex(&index, offsetBy: o - offset)
offset = o
result.append(items[index])
}
return result
}
/// Run the supplied closure with all values in `items` in a loop,
/// recording the current value in the current test trace stack.
public func withSome<C: Collection>(
_ label: String,
in items: C,
maxSamples: Int? = nil,
file: StaticString = #file,
line: UInt = #line,
run body: (C.Element) throws -> Void
) rethrows {
let context = TestContext.current
func check(item: C.Element) throws {
let entry = context.push("\(label): \(item)", file: file, line: line)
var done = false
defer {
if !done {
print(context.currentTrace(title: "Throwing trace"))
}
context.pop(entry)
}
try body(item)
done = true
}
let c = items.count
if let maxSamples = maxSamples, c > maxSamples {
// FIXME: Use randomSample() from swift-algorithms to eliminate dupes
for _ in 0 ..< maxSamples {
let r = Int.random(in: 0 ..< c)
let i = items.index(items.startIndex, offsetBy: r)
try check(item: items[i])
}
} else {
for item in items {
try check(item: item)
}
}
}
public func withSomeRanges<T: Strideable>(
_ label: String,
in bounds: Range<T>,
maxSamples: Int? = nil,
file: StaticString = #file,
line: UInt = #line,
run body: (Range<T>) throws -> Void
) rethrows where T.Stride == Int {
try withSome(
label,
in: IndexRangeCollection(bounds: bounds),
maxSamples: maxSamples,
run: body)
}
/// Utility function for testing mutations with value semantics.
///
/// Calls `body` with on given collection value, while optionally keeping
/// hidden a hidden copy of it around. Once `body` returns, checks that the copy
/// remain unchanged.
///
/// - Parameters:
/// - `enabled`: if `false`, then no copies are made -- the values are passed to `body` with no processing.
/// - `value`: The collection value that is being tested.
/// - `checker`: An optional function that is used to check the consistency of the hidden copy.
/// - `body`: A closure performing a mutation on `value`.
public func withHiddenCopies<S: Sequence, R>(
if enabled: Bool,
of value: inout S,
checker: (S) -> Void = { _ in },
file: StaticString = #file, line: UInt = #line,
_ body: (inout S) throws -> R
) rethrows -> R where S.Element: Equatable {
guard enabled else { return try body(&value) }
let copy = value
let expected = Array(value)
let result = try body(&value)
expectEqualElements(copy, expected, file: file, line: line)
checker(copy)
return result
}
/// Utility function for testing mutations with value semantics.
///
/// Calls `body` with on given collection value, while optionally keeping
/// hidden a hidden copy of it around. Once `body` returns, checks that the copy
/// remain unchanged.
///
/// - Parameters:
/// - `enabled`: if `false`, then no copies are made -- the values are passed to `body` with no processing.
/// - `value`: The collection value that is being tested.
/// - `checker`: An optional function that is used to check the consistency of the hidden copy.
/// - `body`: A closure performing a mutation on `value`.
public func withHiddenCopies<
S: Sequence,
Key: Equatable,
Value: Equatable,
R
>(
if enabled: Bool,
of value: inout S,
checker: (S) -> Void = { _ in },
file: StaticString = #file, line: UInt = #line,
_ body: (inout S) throws -> R
) rethrows -> R where S.Element == (key: Key, value: Value) {
guard enabled else { return try body(&value) }
let copy = value
let expected = Array(value)
let result = try body(&value)
expectEqualElements(copy, expected, file: file, line: line)
checker(copy)
return result
}