mirror of
https://github.com/apple/swift.git
synced 2026-06-27 12:25:55 +02:00
Michael Ilseman
1229af8e0f
Use the visitor pattern in most of the opaque-by-hand call sites. Inspecting the compiler output does not show excessive and unanticipated ARC, but there may need to be further tweaks. One downside of the visitor pattern as written is that there's extra shuffling around of registers for the closure CC. Hopefully this will also be fixed soon.
582 lines
22 KiB
Swift
582 lines
22 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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extension String : StringProtocol, RangeReplaceableCollection {
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/// A type that represents the number of steps between two `String.Index`
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/// values, where one value is reachable from the other.
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///
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/// In Swift, *reachability* refers to the ability to produce one value from
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/// the other through zero or more applications of `index(after:)`.
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public typealias IndexDistance = Int
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public typealias SubSequence = Substring
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/// Creates a string representing the given character repeated the specified
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/// number of times.
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///
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/// For example, use this initializer to create a string with ten `"0"`
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/// characters in a row.
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///
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/// let zeroes = String(repeating: "0" as Character, count: 10)
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/// print(zeroes)
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/// // Prints "0000000000"
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///
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/// - Parameters:
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/// - repeatedValue: The character to repeat.
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/// - count: The number of times to repeat `repeatedValue` in the
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/// resulting string.
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@_inlineable // FIXME(sil-serialize-all)
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public init(repeating repeatedValue: Character, count: Int) {
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self.init(repeating: String(repeatedValue), count: count)
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}
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// This initializer disambiguates between the following intitializers, now
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// that String conforms to Collection:
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// - init<T>(_ value: T) where T : LosslessStringConvertible
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// - init<S>(_ characters: S) where S : Sequence, S.Element == Character
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/// Creates a new string containing the characters in the given sequence.
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///
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/// You can use this initializer to create a new string from the result of
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/// one or more collection operations on a string's characters. For example:
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///
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/// let str = "The rain in Spain stays mainly in the plain."
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///
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/// let vowels: Set<Character> = ["a", "e", "i", "o", "u"]
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/// let disemvoweled = String(str.lazy.filter { !vowels.contains($0) })
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///
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/// print(disemvoweled)
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/// // Prints "Th rn n Spn stys mnly n th pln."
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///
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/// - Parameter other: A string instance or another sequence of
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/// characters.
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@_inlineable // FIXME(sil-serialize-all)
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public init<S : Sequence & LosslessStringConvertible>(_ other: S)
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where S.Element == Character {
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self = other.description
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}
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// The defaulted argument prevents this initializer from satisfies the
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// LosslessStringConvertible conformance. You can satisfy a protocol
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// requirement with something that's not yet available, but not with
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// something that has become unavailable. Without this, the code won't
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// compile as Swift 4.
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@_inlineable // FIXME(sil-serialize-all)
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@available(swift, obsoleted: 4, message: "String.init(_:String) is no longer failable")
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public init?(_ other: String, obsoletedInSwift4: () = ()) {
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self.init(other._guts)
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}
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/// The position of the first character in a nonempty string.
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///
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/// In an empty string, `startIndex` is equal to `endIndex`.
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@_inlineable // FIXME(sil-serialize-all)
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public var startIndex: Index { return Index(encodedOffset: 0) }
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/// A string's "past the end" position---that is, the position one greater
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/// than the last valid subscript argument.
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///
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/// In an empty string, `endIndex` is equal to `startIndex`.
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@_inlineable // FIXME(sil-serialize-all)
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public var endIndex: Index { return Index(encodedOffset: _guts.count) }
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@_inlineable
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@_versioned
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@inline(__always)
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internal func _boundsCheck(_ index: Index) {
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_precondition(index.encodedOffset >= 0 && index.encodedOffset < _guts.count,
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"String index is out of bounds")
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}
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@_inlineable
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@_versioned
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@inline(__always)
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internal func _boundsCheck(_ range: Range<Index>) {
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_precondition(
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range.lowerBound.encodedOffset >= 0 &&
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range.upperBound.encodedOffset <= _guts.count,
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"String index range is out of bounds")
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}
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@_inlineable
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@_versioned
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@inline(__always)
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internal func _boundsCheck(_ range: ClosedRange<Index>) {
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_precondition(
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range.lowerBound.encodedOffset >= 0 &&
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range.upperBound.encodedOffset < _guts.count,
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"String index range is out of bounds")
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}
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@_inlineable // FIXME(sil-serialize-all)
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@_versioned // FIXME(sil-serialize-all)
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internal func _index(atEncodedOffset offset: Int) -> Index {
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return _visitGuts(_guts, args: offset,
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ascii: { ascii, offset in return ascii.characterIndex(atOffset: offset) },
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utf16: { utf16, offset in return utf16.characterIndex(atOffset: offset) },
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opaque: { opaque, offset in
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return opaque.characterIndex(atOffset: offset) })
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}
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/// Returns the position immediately after the given index.
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///
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/// - Parameter i: A valid index of the collection. `i` must be less than
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/// `endIndex`.
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/// - Returns: The index value immediately after `i`.
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@_inlineable // FIXME(sil-serialize-all)
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public func index(after i: Index) -> Index {
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return _visitGuts(_guts, args: i,
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ascii: { ascii, i in ascii.characterIndex(after: i) },
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utf16: { utf16, i in utf16.characterIndex(after: i) },
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opaque: { opaque, i in opaque.characterIndex(after: i) })
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}
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/// Returns the position immediately before the given index.
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///
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/// - Parameter i: A valid index of the collection. `i` must be greater than
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/// `startIndex`.
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/// - Returns: The index value immediately before `i`.
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@_inlineable // FIXME(sil-serialize-all)
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public func index(before i: Index) -> Index {
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return _visitGuts(_guts, args: i,
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ascii: { ascii, i in ascii.characterIndex(before: i) },
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utf16: { utf16, i in utf16.characterIndex(before: i) },
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opaque: { opaque, i in opaque.characterIndex(before: i) })
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}
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/// Returns an index that is the specified distance from the given index.
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///
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/// The following example obtains an index advanced four positions from a
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/// string's starting index and then prints the character at that position.
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///
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/// let s = "Swift"
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/// let i = s.index(s.startIndex, offsetBy: 4)
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/// print(s[i])
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/// // Prints "t"
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///
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/// The value passed as `n` must not offset `i` beyond the bounds of the
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/// collection.
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///
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/// - Parameters:
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/// - i: A valid index of the collection.
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/// - n: The distance to offset `i`.
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/// - Returns: An index offset by `n` from the index `i`. If `n` is positive,
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/// this is the same value as the result of `n` calls to `index(after:)`.
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/// If `n` is negative, this is the same value as the result of `-n` calls
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/// to `index(before:)`.
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///
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/// - Complexity: O(*n*), where *n* is the absolute value of `n`.
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@_inlineable // FIXME(sil-serialize-all)
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public func index(_ i: Index, offsetBy n: IndexDistance) -> Index {
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return _visitGuts(_guts, args: (i, n),
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ascii: { ascii, args in let (i, n) = args
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return ascii.characterIndex(i, offsetBy: n) },
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utf16: { utf16, args in let (i, n) = args
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return utf16.characterIndex(i, offsetBy: n) },
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opaque: { opaque, args in let (i, n) = args
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return opaque.characterIndex(i, offsetBy: n) })
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}
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/// Returns an index that is the specified distance from the given index,
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/// unless that distance is beyond a given limiting index.
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///
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/// The following example obtains an index advanced four positions from a
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/// string's starting index and then prints the character at that position.
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/// The operation doesn't require going beyond the limiting `s.endIndex`
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/// value, so it succeeds.
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///
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/// let s = "Swift"
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/// if let i = s.index(s.startIndex, offsetBy: 4, limitedBy: s.endIndex) {
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/// print(s[i])
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/// }
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/// // Prints "t"
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///
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/// The next example attempts to retrieve an index six positions from
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/// `s.startIndex` but fails, because that distance is beyond the index
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/// passed as `limit`.
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///
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/// let j = s.index(s.startIndex, offsetBy: 6, limitedBy: s.endIndex)
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/// print(j)
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/// // Prints "nil"
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///
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/// The value passed as `n` must not offset `i` beyond the bounds of the
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/// collection, unless the index passed as `limit` prevents offsetting
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/// beyond those bounds.
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///
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/// - Parameters:
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/// - i: A valid index of the collection.
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/// - n: The distance to offset `i`.
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/// - limit: A valid index of the collection to use as a limit. If `n > 0`,
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/// a limit that is less than `i` has no effect. Likewise, if `n < 0`, a
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/// limit that is greater than `i` has no effect.
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/// - Returns: An index offset by `n` from the index `i`, unless that index
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/// would be beyond `limit` in the direction of movement. In that case,
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/// the method returns `nil`.
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///
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/// - Complexity: O(*n*), where *n* is the absolute value of `n`.
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@_inlineable // FIXME(sil-serialize-all)
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public func index(
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_ i: Index, offsetBy n: IndexDistance, limitedBy limit: Index
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) -> Index? {
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return _visitGuts(_guts, args: (i, n, limit),
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ascii: { ascii, args in let (i, n, limit) = args
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return ascii.characterIndex(i, offsetBy: n, limitedBy: limit) },
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utf16: { utf16, args in let (i, n, limit) = args
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return utf16.characterIndex(i, offsetBy: n, limitedBy: limit) },
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opaque: { opaque, args in let (i, n, limit) = args
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return opaque.characterIndex(i, offsetBy: n, limitedBy: limit) })
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}
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/// Returns the distance between two indices.
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///
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/// - Parameters:
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/// - start: A valid index of the collection.
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/// - end: Another valid index of the collection. If `end` is equal to
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/// `start`, the result is zero.
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/// - Returns: The distance between `start` and `end`.
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///
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/// - Complexity: O(*n*), where *n* is the resulting distance.
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@_inlineable // FIXME(sil-serialize-all)
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public func distance(from start: Index, to end: Index) -> IndexDistance {
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return _visitGuts(_guts, args: (start, end),
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ascii: { ascii, args in let (start, end) = args
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return ascii.characterDistance(from: start, to: end) },
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utf16: { utf16, args in let (start, end) = args
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return utf16.characterDistance(from: start, to: end) },
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opaque: { opaque, args in let (start, end) = args
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return opaque.characterDistance(from: start, to: end) })
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}
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/// Accesses the character at the given position.
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///
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/// You can use the same indices for subscripting a string and its substring.
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/// For example, this code finds the first letter after the first space:
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///
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/// let str = "Greetings, friend! How are you?"
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/// let firstSpace = str.index(of: " ") ?? str.endIndex
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/// let substr = str[firstSpace...]
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/// if let nextCapital = substr.index(where: { $0 >= "A" && $0 <= "Z" }) {
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/// print("Capital after a space: \(str[nextCapital])")
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/// }
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/// // Prints "Capital after a space: H"
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///
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/// - Parameter i: A valid index of the string. `i` must be less than the
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/// string's end index.
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@_inlineable // FIXME(sil-serialize-all)
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public subscript(i: Index) -> Character {
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return _visitGuts(_guts, args: i,
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ascii: { ascii, i in return ascii.character(at: i) },
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utf16: { utf16, i in return utf16.character(at: i) },
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opaque: { opaque, i in return opaque.character(at: i) })
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}
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}
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extension String {
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/// Creates a new string containing the characters in the given sequence.
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///
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/// You can use this initializer to create a new string from the result of
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/// one or more collection operations on a string's characters. For example:
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///
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/// let str = "The rain in Spain stays mainly in the plain."
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///
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/// let vowels: Set<Character> = ["a", "e", "i", "o", "u"]
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/// let disemvoweled = String(str.lazy.filter { !vowels.contains($0) })
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///
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/// print(disemvoweled)
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/// // Prints "Th rn n Spn stys mnly n th pln."
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///
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/// - Parameter characters: A string instance or another sequence of
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/// characters.
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@_inlineable // FIXME(sil-serialize-all)
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public init<S : Sequence>(_ characters: S)
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where S.Iterator.Element == Character {
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self = ""
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self.append(contentsOf: characters)
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}
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/// Reserves enough space in the string's underlying storage to store the
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/// specified number of ASCII characters.
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///
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/// Because each character in a string can require more than a single ASCII
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/// character's worth of storage, additional allocation may be necessary
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/// when adding characters to a string after a call to
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/// `reserveCapacity(_:)`.
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///
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/// - Parameter n: The minimum number of ASCII character's worth of storage
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/// to allocate.
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///
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/// - Complexity: O(*n*)
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func reserveCapacity(_ n: Int) {
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_guts.reserveCapacity(n)
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}
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/// Appends the given character to the string.
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///
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/// The following example adds an emoji globe to the end of a string.
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///
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/// var globe = "Globe "
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/// globe.append("🌍")
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/// print(globe)
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/// // Prints "Globe 🌍"
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///
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/// - Parameter c: The character to append to the string.
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func append(_ c: Character) {
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if let small = c._smallUTF16 {
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_guts.append(contentsOf: small)
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} else {
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_guts.append(c._largeUTF16!.unmanagedView)
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_fixLifetime(c)
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}
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}
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func append(contentsOf newElements: String) {
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append(newElements)
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}
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func append(contentsOf newElements: Substring) {
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_guts.append(
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newElements._wholeString._guts,
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range: newElements._encodedOffsetRange)
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}
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/// Appends the characters in the given sequence to the string.
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///
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/// - Parameter newElements: A sequence of characters.
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func append<S : Sequence>(contentsOf newElements: S)
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where S.Iterator.Element == Character {
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if _fastPath(newElements is _SwiftStringView) {
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let v = newElements as! _SwiftStringView
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_guts.append(v._wholeString._guts, range: v._encodedOffsetRange)
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return
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}
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_guts.reserveUnusedCapacity(
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newElements.underestimatedCount,
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ascii: _guts.isASCII)
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for c in newElements { self.append(c) }
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}
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/// Replaces the text within the specified bounds with the given characters.
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///
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/// Calling this method invalidates any existing indices for use with this
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/// string.
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///
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/// - Parameters:
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/// - bounds: The range of text to replace. The bounds of the range must be
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/// valid indices of the string.
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/// - newElements: The new characters to add to the string.
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///
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/// - Complexity: O(*m*), where *m* is the combined length of the string and
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/// `newElements`. If the call to `replaceSubrange(_:with:)` simply
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/// removes text at the end of the string, the complexity is O(*n*), where
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/// *n* is equal to `bounds.count`.
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func replaceSubrange<C>(
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_ bounds: Range<Index>,
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with newElements: C
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) where C : Collection, C.Iterator.Element == Character {
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let offsetRange: Range<Int> =
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bounds.lowerBound.encodedOffset ..< bounds.upperBound.encodedOffset
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let lazyUTF16 = newElements.lazy.flatMap { $0.utf16 }
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_guts.replaceSubrange(offsetRange, with: lazyUTF16)
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}
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/// Inserts a new character at the specified position.
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///
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/// Calling this method invalidates any existing indices for use with this
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/// string.
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///
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/// - Parameters:
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/// - newElement: The new character to insert into the string.
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/// - i: A valid index of the string. If `i` is equal to the string's end
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/// index, this methods appends `newElement` to the string.
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///
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/// - Complexity: O(*n*), where *n* is the length of the string.
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func insert(_ newElement: Character, at i: Index) {
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let offset = i.encodedOffset
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_guts.replaceSubrange(offset..<offset, with: newElement.utf16)
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}
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/// Inserts a collection of characters at the specified position.
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///
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/// Calling this method invalidates any existing indices for use with this
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/// string.
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///
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/// - Parameters:
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/// - newElements: A collection of `Character` elements to insert into the
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/// string.
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/// - i: A valid index of the string. If `i` is equal to the string's end
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/// index, this methods appends the contents of `newElements` to the
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/// string.
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///
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/// - Complexity: O(*n*), where *n* is the combined length of the string and
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/// `newElements`.
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@_inlineable // FIXME(sil-serialize-all)
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public mutating func insert<S : Collection>(
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contentsOf newElements: S, at i: Index
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) where S.Iterator.Element == Character {
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let offset = i.encodedOffset
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let utf16 = newElements.lazy.flatMap { $0.utf16 }
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_guts.replaceSubrange(offset..<offset, with: utf16)
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}
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/// Removes and returns the character at the specified position.
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///
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/// All the elements following `i` are moved to close the gap. This example
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/// removes the hyphen from the middle of a string.
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///
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/// var nonempty = "non-empty"
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/// if let i = nonempty.index(of: "-") {
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/// nonempty.remove(at: i)
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/// }
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/// print(nonempty)
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/// // Prints "nonempty"
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///
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/// Calling this method invalidates any existing indices for use with this
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/// string.
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///
|
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/// - Parameter i: The position of the character to remove. `i` must be a
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/// valid index of the string that is not equal to the string's end index.
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/// - Returns: The character that was removed.
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
@discardableResult
|
|
public mutating func remove(at i: Index) -> Character {
|
|
let offset = i.encodedOffset
|
|
let stride = _stride(of: i)
|
|
let range: Range<Int> = offset ..< offset + stride
|
|
let old = Character(_unverified: _guts, range: range)
|
|
_guts.replaceSubrange(range, with: EmptyCollection())
|
|
return old
|
|
}
|
|
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
@_versioned // FIXME(sil-serialize-all)
|
|
internal func _stride(of i: Index) -> Int {
|
|
if case .character(let stride) = i._cache {
|
|
// TODO: should _fastPath the case somehow
|
|
_sanityCheck(stride > 0)
|
|
return Int(stride)
|
|
}
|
|
let offset = i.encodedOffset
|
|
return _visitGuts(_guts, args: offset,
|
|
ascii: { ascii, offset in
|
|
return ascii.characterStride(atOffset: offset) },
|
|
utf16: { utf16, offset in
|
|
return utf16.characterStride(atOffset: offset) },
|
|
opaque: { opaque, offset in
|
|
return opaque.characterStride(atOffset: offset) })
|
|
}
|
|
|
|
/// Removes the characters in the given range.
|
|
///
|
|
/// Calling this method invalidates any existing indices for use with this
|
|
/// string.
|
|
///
|
|
/// - Parameter bounds: The range of the elements to remove. The upper and
|
|
/// lower bounds of `bounds` must be valid indices of the string and not
|
|
/// equal to the string's end index.
|
|
/// - Parameter bounds: The range of the elements to remove. The upper and
|
|
/// lower bounds of `bounds` must be valid indices of the string.
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
public mutating func removeSubrange(_ bounds: Range<Index>) {
|
|
let start = bounds.lowerBound.encodedOffset
|
|
let end = bounds.upperBound.encodedOffset
|
|
_guts.replaceSubrange(start..<end, with: EmptyCollection())
|
|
}
|
|
|
|
/// Replaces this string with the empty string.
|
|
///
|
|
/// Calling this method invalidates any existing indices for use with this
|
|
/// string.
|
|
///
|
|
/// - Parameter keepCapacity: Pass `true` to prevent the release of the
|
|
/// string's allocated storage. Retaining the storage can be a useful
|
|
/// optimization when you're planning to grow the string again. The
|
|
/// default value is `false`.
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
public mutating func removeAll(keepingCapacity keepCapacity: Bool = false) {
|
|
if keepCapacity {
|
|
_guts.replaceSubrange(0..<_guts.count, with: EmptyCollection())
|
|
} else {
|
|
_guts = _StringGuts()
|
|
}
|
|
}
|
|
}
|
|
|
|
extension String {
|
|
// This is needed because of the issue described in SR-4660 which causes
|
|
// source compatibility issues when String becomes a collection
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
@_transparent
|
|
public func max<T : Comparable>(_ x: T, _ y: T) -> T {
|
|
return Swift.max(x,y)
|
|
}
|
|
|
|
// This is needed because of the issue described in SR-4660 which causes
|
|
// source compatibility issues when String becomes a collection
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
@_transparent
|
|
public func min<T : Comparable>(_ x: T, _ y: T) -> T {
|
|
return Swift.min(x,y)
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// The following overloads of flatMap are carefully crafted to allow the code
|
|
// like the following:
|
|
// ["hello"].flatMap { $0 }
|
|
// return an array of strings without any type context in Swift 3 mode, at the
|
|
// same time allowing the following code snippet to compile:
|
|
// [0, 1].flatMap { x in
|
|
// if String(x) == "foo" { return "bar" } else { return nil }
|
|
// }
|
|
// Note that the second overload is declared on a more specific protocol.
|
|
// See: test/stdlib/StringFlatMap.swift for tests.
|
|
extension Sequence {
|
|
@_inlineable // FIXME(sil-serialize-all)
|
|
@available(swift, obsoleted: 4)
|
|
public func flatMap(
|
|
_ transform: (Element) throws -> String
|
|
) rethrows -> [String] {
|
|
return try map(transform)
|
|
}
|
|
}
|
|
|
|
extension Collection {
|
|
@available(swift, deprecated: 4.1, renamed: "compactMap(_:)",
|
|
message: "Please use compactMap(_:) for the case where closure returns an optional value")
|
|
@inline(__always)
|
|
public func flatMap(
|
|
_ transform: (Element) throws -> String?
|
|
) rethrows -> [String] {
|
|
return try _compactMap(transform)
|
|
}
|
|
}
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
extension Sequence where Element == String {
|
|
@available(*, unavailable, message: "Operator '+' cannot be used to append a String to a sequence of strings")
|
|
public static func + (lhs: Self, rhs: String) -> Never {
|
|
fatalError()
|
|
}
|
|
|
|
@available(*, unavailable, message: "Operator '+' cannot be used to append a String to a sequence of strings")
|
|
public static func + (lhs: String, rhs: Self) -> Never {
|
|
fatalError()
|
|
}
|
|
}
|