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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021-2022 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
//
//===----------------------------------------------------------------------===//
// MARK: `CollectionConsumer` algorithms
extension Collection {
func _trimmingPrefix<Consumer: CollectionConsumer>(
_ consumer: Consumer
) -> SubSequence where Consumer.Consumed == Self {
let start = consumer.consuming(self) ?? startIndex
return self[start...]
}
}
extension Collection where SubSequence == Self {
mutating func _trimPrefix<Consumer: CollectionConsumer>(
_ consumer: Consumer
) where Consumer.Consumed == Self {
_ = consumer.consume(&self)
}
}
extension RangeReplaceableCollection {
// NOTE: Disfavored because the `Collection with SubSequence == Self` overload
// should be preferred whenever both are available
@_disfavoredOverload
mutating func _trimPrefix<Consumer: CollectionConsumer>(
_ consumer: Consumer
) where Consumer.Consumed == Self {
if let start = consumer.consuming(self) {
removeSubrange(..<start)
}
}
}
// MARK: Predicate algorithms
extension Collection {
fileprivate func _endOfPrefix(while predicate: (Element) throws -> Bool) rethrows -> Index {
try firstIndex(where: { try !predicate($0) }) ?? endIndex
}
@available(SwiftStdlib 5.7, *)
public func trimmingPrefix(
while predicate: (Element) throws -> Bool
) rethrows -> SubSequence {
let end = try _endOfPrefix(while: predicate)
return self[end...]
}
}
extension Collection where SubSequence == Self {
@available(SwiftStdlib 5.7, *)
public mutating func trimPrefix(
while predicate: (Element) throws -> Bool
) throws {
let end = try _endOfPrefix(while: predicate)
self = self[end...]
}
}
extension RangeReplaceableCollection {
@_disfavoredOverload
@available(SwiftStdlib 5.7, *)
public mutating func trimPrefix(
while predicate: (Element) throws -> Bool
) rethrows {
let end = try _endOfPrefix(while: predicate)
removeSubrange(startIndex..<end)
}
}
// MARK: Fixed pattern algorithms
extension Collection where Element: Equatable {
/// Returns a new collection of the same type by removing `prefix` from the start
/// of the collection.
/// - Parameter prefix: The collection to remove from this collection.
/// - Returns: A collection containing the elements of the collection that are
/// not removed by `prefix`.
@available(SwiftStdlib 5.7, *)
public func trimmingPrefix<Prefix: Sequence>(
_ prefix: Prefix
) -> SubSequence where Prefix.Element == Element {
_trimmingPrefix(FixedPatternConsumer(pattern: prefix))
}
}
extension Collection where SubSequence == Self, Element: Equatable {
/// Removes `prefix` from the start of the collection.
/// - Parameter prefix: The collection to remove from this collection.
@available(SwiftStdlib 5.7, *)
public mutating func trimPrefix<Prefix: Sequence>(
_ prefix: Prefix
) where Prefix.Element == Element {
_trimPrefix(FixedPatternConsumer<SubSequence, Prefix>(pattern: prefix))
}
}
extension RangeReplaceableCollection where Element: Equatable {
/// Removes `prefix` from the start of the collection.
/// - Parameter prefix: The collection to remove from this collection.
@available(SwiftStdlib 5.7, *)
public mutating func trimPrefix<Prefix: Sequence>(
_ prefix: Prefix
) where Prefix.Element == Element {
_trimPrefix(FixedPatternConsumer(pattern: prefix))
}
}
// MARK: Regex algorithms
extension BidirectionalCollection where SubSequence == Substring {
/// Returns a new collection of the same type by removing the initial elements
/// that matches the given regex.
/// - Parameter regex: The regex to remove from this collection.
/// - Returns: A collection containing the elements that does not match
/// `regex` from the start.
@_disfavoredOverload
@available(SwiftStdlib 5.7, *)
public func trimmingPrefix(_ regex: some RegexComponent) -> SubSequence {
let s = self[...]
guard let prefix = try? regex.regex.prefixMatch(in: s) else {
return s
}
return s[prefix.range.upperBound...]
}
}
extension RangeReplaceableCollection
where Self: BidirectionalCollection, SubSequence == Substring
{
/// Removes the initial elements that matches the given regex.
/// - Parameter regex: The regex to remove from this collection.
@_disfavoredOverload
@available(SwiftStdlib 5.7, *)
public mutating func trimPrefix(_ regex: some RegexComponent) {
let s = self[...]
guard let prefix = try? regex.regex.prefixMatch(in: s) else {
return
}
self.removeSubrange(prefix.range)
}
}
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