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[SR-1516][stdlib] Implement SE-0045 prefix(while:) and drop(while:) #3600

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Merged
merged 1 commit into from
Aug 16, 2016
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[SR-1516][stdlib] Implement SE-0045 prefix(while:) and drop(while:) #3600

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3 changes: 3 additions & 0 deletions stdlib/private/StdlibCollectionUnittest/CheckCollectionType.swift.gyb
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Expand Up @@ -486,6 +486,9 @@ internal func _product<C1 : Collection, C2 : Collection>(
return '''
C : %(protocol)s,
CollectionWithEquatableElement : %(protocol)s,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element,
C.SubSequence : %(protocol)s,
C.SubSequence.Iterator.Element == C.Iterator.Element,
C.SubSequence.Index == C.Index,
Expand Down
9 changes: 9 additions & 0 deletions stdlib/private/StdlibCollectionUnittest/CheckMutableCollectionType.swift.gyb
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Expand Up @@ -115,6 +115,9 @@ extension TestSuite {
C.Indices.Index == C.Index,
C.Indices.SubSequence == C.Indices,
CollectionWithEquatableElement.Iterator.Element : Equatable,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element,
CollectionWithComparableElement.Iterator.Element : Comparable {

var testNamePrefix = testNamePrefix
Expand Down Expand Up @@ -705,6 +708,9 @@ self.test("\(testNamePrefix).partition/InvalidOrderings") {
C.Indices.Index == C.Index,
C.Indices.SubSequence == C.Indices,
CollectionWithEquatableElement.Iterator.Element : Equatable,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element,
CollectionWithComparableElement.Iterator.Element : Comparable {

var testNamePrefix = testNamePrefix
Expand Down Expand Up @@ -858,6 +864,9 @@ self.test("\(testNamePrefix).partition/DispatchesThrough_withUnsafeMutableBuffer
C.Indices.Index == C.Index,
C.Indices.SubSequence == C.Indices,
CollectionWithEquatableElement.Iterator.Element : Equatable,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element,
CollectionWithComparableElement.Iterator.Element : Comparable,
CollectionWithComparableElement.SubSequence.Indices.Iterator.Element == CollectionWithComparableElement.Index {

Expand Down
15 changes: 12 additions & 3 deletions stdlib/private/StdlibCollectionUnittest/CheckRangeReplaceableCollectionType.swift
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Expand Up @@ -471,7 +471,10 @@ extension TestSuite {
C.Indices.Iterator.Element == C.Index,
C.Indices.Index == C.Index,
C.Indices.SubSequence == C.Indices,
CollectionWithEquatableElement.Iterator.Element : Equatable {
CollectionWithEquatableElement.Iterator.Element : Equatable,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element {

var testNamePrefix = testNamePrefix

Expand Down Expand Up @@ -1182,7 +1185,10 @@ self.test("\(testNamePrefix).OperatorPlus") {
C.Indices.Iterator.Element == C.Index,
C.Indices.Index == C.Index,
C.Indices.SubSequence == C.Indices,
CollectionWithEquatableElement.Iterator.Element : Equatable {
CollectionWithEquatableElement.Iterator.Element : Equatable,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element {

var testNamePrefix = testNamePrefix

Expand Down Expand Up @@ -1311,7 +1317,10 @@ self.test("\(testNamePrefix).removeLast(n: Int)/whereIndexIsBidirectional/remove
C.Indices.Iterator.Element == C.Index,
C.Indices.Index == C.Index,
C.Indices.SubSequence == C.Indices,
CollectionWithEquatableElement.Iterator.Element : Equatable {
CollectionWithEquatableElement.Iterator.Element : Equatable,
CollectionWithEquatableElement.SubSequence : Collection,
CollectionWithEquatableElement.SubSequence.Iterator.Element
== CollectionWithEquatableElement.Iterator.Element {

var testNamePrefix = testNamePrefix

Expand Down
41 changes: 41 additions & 0 deletions stdlib/private/StdlibCollectionUnittest/CheckSequenceType.swift
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Expand Up @@ -1463,6 +1463,9 @@ extension TestSuite {
resiliencyChecks: CollectionMisuseResiliencyChecks = .all
) where
SequenceWithEquatableElement.Iterator.Element : Equatable,
SequenceWithEquatableElement.SubSequence : Sequence,
SequenceWithEquatableElement.SubSequence.Iterator.Element
== SequenceWithEquatableElement.Iterator.Element,
S.SubSequence : Sequence,
S.SubSequence.Iterator.Element == S.Iterator.Element,
S.SubSequence.SubSequence == S.SubSequence {
Expand Down Expand Up @@ -1615,6 +1618,25 @@ self.test("\(testNamePrefix).dropLast/semantics/negative") {
_ = s.dropLast(-1)
}

//===----------------------------------------------------------------------===//
// drop(while:)
//===----------------------------------------------------------------------===//

self.test("\(testNamePrefix).drop(while:)/semantics").forEach(in: findTests) {
test in
let s = makeWrappedSequenceWithEquatableElement(test.sequence)
let closureLifetimeTracker = LifetimeTracked(0)
let remainingSequence = s.drop {
_blackHole(closureLifetimeTracker)
return $0 != wrapValueIntoEquatable(test.element)
}
let remaining = Array(remainingSequence)
let expectedSuffix = test.sequence.suffix(
from: test.expected ?? test.sequence.endIndex)
expectEqual(expectedSuffix.count, remaining.count)
expectEqualSequence(expectedSuffix.map(wrapValueIntoEquatable), remaining)
}

//===----------------------------------------------------------------------===//
// prefix()
//===----------------------------------------------------------------------===//
Expand Down Expand Up @@ -1654,6 +1676,25 @@ self.test("\(testNamePrefix).prefix/semantics/negative") {
_ = s.prefix(-1)
}

//===----------------------------------------------------------------------===//
// prefix(while:)
//===----------------------------------------------------------------------===//

self.test("\(testNamePrefix).prefix(while:)/semantics").forEach(in: findTests) {
test in
let s = makeWrappedSequenceWithEquatableElement(test.sequence)
let closureLifetimeTracker = LifetimeTracked(0)
let remainingSequence = s.prefix {
_blackHole(closureLifetimeTracker)
return $0 != wrapValueIntoEquatable(test.element)
}
let expectedPrefix = test.sequence.prefix(
upTo: test.expected ?? test.sequence.endIndex)
let remaining = Array(remainingSequence)
expectEqual(expectedPrefix.count, remaining.count)
expectEqualSequence(expectedPrefix.map(wrapValueIntoEquatable), remaining)
}

//===----------------------------------------------------------------------===//
// suffix()
//===----------------------------------------------------------------------===//
Expand Down
16 changes: 16 additions & 0 deletions stdlib/private/StdlibCollectionUnittest/LoggingWrappers.swift.gyb
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Expand Up @@ -85,6 +85,8 @@ public class SequenceLog {
public static var first = TypeIndexed(0)
public static var dropFirst = TypeIndexed(0)
public static var dropLast = TypeIndexed(0)
public static var dropWhile = TypeIndexed(0)
public static var prefixWhile = TypeIndexed(0)
public static var prefixMaxLength = TypeIndexed(0)
public static var suffixMaxLength = TypeIndexed(0)
public static var split = TypeIndexed(0)
Expand Down Expand Up @@ -262,11 +264,25 @@ public struct ${Self}<
Log.dropLast[selfType] += 1
return base.dropLast(n)
}

public func drop(
while predicate: @noescape (Base.Iterator.Element) throws -> Bool
) rethrows -> SubSequence {
Log.dropWhile[selfType] += 1
return try base.drop(while: predicate)
}

public func prefix(_ maxLength: Int) -> SubSequence {
Log.prefixMaxLength[selfType] += 1
return base.prefix(maxLength)
}

public func prefix(
while predicate: @noescape (Base.Iterator.Element) throws -> Bool
) rethrows -> SubSequence {
Log.prefixWhile[selfType] += 1
return try base.prefix(while: predicate)
}

public func suffix(_ maxLength: Int) -> SubSequence {
Log.suffixMaxLength[selfType] += 1
Expand Down
2 changes: 2 additions & 0 deletions stdlib/public/core/CMakeLists.txt
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Expand Up @@ -44,6 +44,7 @@ set(SWIFTLIB_ESSENTIAL
CString.swift
CTypes.swift
DebuggerSupport.swift
DropWhile.swift.gyb
EmptyCollection.swift
Equatable.swift
ErrorType.swift
Expand Down Expand Up @@ -88,6 +89,7 @@ set(SWIFTLIB_ESSENTIAL
OutputStream.swift
Pointer.swift
Policy.swift
PrefixWhile.swift.gyb
Print.swift
RandomAccessCollection.swift
Range.swift.gyb
Expand Down
38 changes: 38 additions & 0 deletions stdlib/public/core/Collection.swift
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Expand Up @@ -1319,6 +1319,25 @@ extension Collection {
offsetBy: numericCast(amount), limitedBy: endIndex) ?? endIndex
return self[startIndex..<end]
}

/// Returns a subsequence by skipping elements while `predicate` returns
/// `true` and returning the remaining elements.
///
/// - Parameter predicate: A closure that takes an element of the
/// sequence as its argument and returns `true` if the element should
/// be skipped or `false` if it should be included. Once the predicate
/// returns `false` it will not be called again.
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@gribozavr gribozavr Jul 21, 2016 •
edited
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Please also add algorithmic complexity documentation in every doc comment. (O(N))

///
/// - Complexity: O(*n*), where *n* is the length of the collection.
public func drop(
while predicate: @noescape (Iterator.Element) throws -> Bool
) rethrows -> SubSequence {
var start = startIndex
while try start != endIndex && predicate(self[start]) {
formIndex(after: &start)
}
return self[start..<endIndex]
}

/// Returns a subsequence, up to the specified maximum length, containing
/// the initial elements of the collection.
Expand All @@ -1344,6 +1363,25 @@ extension Collection {
offsetBy: numericCast(maxLength), limitedBy: endIndex) ?? endIndex
return self[startIndex..<end]
}

/// Returns a subsequence containing the initial elements until `predicate`
/// returns `false` and skipping the remaining elements.
///
/// - Parameter predicate: A closure that takes an element of the
/// sequence as its argument and returns `true` if the element should
/// be included or `false` if it should be excluded. Once the predicate
/// returns `false` it will not be called again.
///
/// - Complexity: O(*n*), where *n* is the length of the collection.
public func prefix(
while predicate: @noescape (Iterator.Element) throws -> Bool
) rethrows -> SubSequence {
var end = startIndex
while try end != endIndex && predicate(self[end]) {
formIndex(after: &end)
}
return self[startIndex..<end]
}

/// Returns a subsequence, up to the given maximum length, containing the
/// final elements of the collection.
Expand Down
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