| //===----------------------------------------------------------------------===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| /// A single extended grapheme cluster that approximates a user-perceived |
| /// character. |
| /// |
| /// The `Character` type represents a character made up of one or more Unicode |
| /// scalar values, grouped by a Unicode boundary algorithm. Generally, a |
| /// `Character` instance matches what the reader of a string will perceive as |
| /// a single character. Strings are collections of `Character` instances, so |
| /// the number of visible characters is generally the most natural way to |
| /// count the length of a string. |
| /// |
| /// let greeting = "Hello! π₯" |
| /// print("Length: \(greeting.count)") |
| /// // Prints "Length: 8" |
| /// |
| /// Because each character in a string can be made up of one or more Unicode |
| /// scalar values, the number of characters in a string may not match the |
| /// length of the Unicode scalar value representation or the length of the |
| /// string in a particular binary representation. |
| /// |
| /// print("Unicode scalar value count: \(greeting.unicodeScalars.count)") |
| /// // Prints "Unicode scalar value count: 15" |
| /// |
| /// print("UTF-8 representation count: \(greeting.utf8.count)") |
| /// // Prints "UTF-8 representation count: 18" |
| /// |
| /// Every `Character` instance is composed of one or more Unicode scalar values |
| /// that are grouped together as an *extended grapheme cluster*. The way these |
| /// scalar values are grouped is defined by a canonical, localized, or |
| /// otherwise tailored Unicode segmentation algorithm. |
| /// |
| /// For example, a country's Unicode flag character is made up of two regional |
| /// indicator scalar values that correspond to that country's ISO 3166-1 |
| /// alpha-2 code. The alpha-2 code for The United States is "US", so its flag |
| /// character is made up of the Unicode scalar values `"\u{1F1FA}"` (REGIONAL |
| /// INDICATOR SYMBOL LETTER U) and `"\u{1F1F8}"` (REGIONAL INDICATOR SYMBOL |
| /// LETTER S). When placed next to each other in a string literal, these two |
| /// scalar values are combined into a single grapheme cluster, represented by |
| /// a `Character` instance in Swift. |
| /// |
| /// let usFlag: Character = "\u{1F1FA}\u{1F1F8}" |
| /// print(usFlag) |
| /// // Prints "πΊπΈ" |
| /// |
| /// For more information about the Unicode terms used in this discussion, see |
| /// the [Unicode.org glossary][glossary]. In particular, this discussion |
| /// mentions [extended grapheme clusters][clusters] and [Unicode scalar |
| /// values][scalars]. |
| /// |
| /// [glossary]: http://www.unicode.org/glossary/ |
| /// [clusters]: http://www.unicode.org/glossary/#extended_grapheme_cluster |
| /// [scalars]: http://www.unicode.org/glossary/#unicode_scalar_value |
| @_fixed_layout |
| public struct Character : |
| _ExpressibleByBuiltinUTF16ExtendedGraphemeClusterLiteral, |
| ExpressibleByExtendedGraphemeClusterLiteral, Hashable { |
| |
| // Fundamentally, it is just a String, but it is optimized for the common case |
| // where the UTF-16 representation fits in 63 bits. The remaining bit is used |
| // to discriminate between small and large representations. Since a grapheme |
| // cluster cannot have U+0000 anywhere but in its first scalar, we can store |
| // zero in empty code units above the first one. |
| @_versioned |
| internal enum Representation { |
| case smallUTF16(Builtin.Int63) |
| case large(_StringBuffer._Storage) |
| } |
| |
| /// Creates a character containing the given Unicode scalar value. |
| /// |
| /// - Parameter content: The Unicode scalar value to convert into a character. |
| public init(_ content: Unicode.Scalar) { |
| let content16 = UTF16.encode(content)._unsafelyUnwrappedUnchecked |
| _representation = .smallUTF16( |
| Builtin.zext_Int32_Int63(content16._storage._value)) |
| } |
| |
| @effects(readonly) |
| public init(_builtinUnicodeScalarLiteral value: Builtin.Int32) { |
| self = Character( |
| String._fromWellFormedCodeUnitSequence( |
| UTF32.self, input: CollectionOfOne(UInt32(value)))) |
| } |
| |
| // Inlining ensures that the whole constructor can be folded away to a single |
| // integer constant in case of small character literals. |
| @inline(__always) |
| @effects(readonly) |
| public init( |
| _builtinExtendedGraphemeClusterLiteral start: Builtin.RawPointer, |
| utf8CodeUnitCount: Builtin.Word, |
| isASCII: Builtin.Int1 |
| ) { |
| let utf8 = UnsafeBufferPointer( |
| start: UnsafePointer<Unicode.UTF8.CodeUnit>(start), |
| count: Int(utf8CodeUnitCount)) |
| |
| if utf8.count == 1 { |
| _representation = .smallUTF16( |
| Builtin.zext_Int8_Int63(utf8.first._unsafelyUnwrappedUnchecked._value)) |
| return |
| } |
| |
| FastPath: |
| repeat { |
| var shift = 0 |
| let maxShift = 64 - 16 |
| var bits: UInt64 = 0 |
| |
| for s8 in Unicode._ParsingIterator( |
| codeUnits: utf8.makeIterator(), parser: UTF8.ForwardParser()) { |
| |
| let s16 |
| = UTF16.transcode(s8, from: UTF8.self)._unsafelyUnwrappedUnchecked |
| |
| for u16 in s16 { |
| guard _fastPath(shift <= maxShift) else { break FastPath } |
| bits |= UInt64(u16) &<< shift |
| shift += 16 |
| } |
| } |
| guard _fastPath(Int64(truncatingIfNeeded: bits) >= 0) else { |
| break FastPath |
| } |
| _representation = .smallUTF16(Builtin.trunc_Int64_Int63(bits._value)) |
| return |
| } |
| while false |
| |
| // For anything that doesn't fit in 63 bits, build the large |
| // representation. |
| self = Character(_largeRepresentationString: |
| String( |
| _builtinExtendedGraphemeClusterLiteral: start, |
| utf8CodeUnitCount: utf8CodeUnitCount, |
| isASCII: isASCII)) |
| } |
| |
| // Inlining ensures that the whole constructor can be folded away to a single |
| // integer constant in case of small character literals. |
| @inline(__always) |
| @effects(readonly) |
| public init( |
| _builtinExtendedGraphemeClusterLiteral start: Builtin.RawPointer, |
| utf16CodeUnitCount: Builtin.Word |
| ) { |
| let utf16 = UnsafeBufferPointer( |
| start: UnsafePointer<Unicode.UTF16.CodeUnit>(start), |
| count: Int(utf16CodeUnitCount)) |
| |
| switch utf16.count { |
| case 1: |
| _representation = .smallUTF16(Builtin.zext_Int16_Int63(utf16[0]._value)) |
| case 2: |
| let bits = UInt32(utf16[0]) | UInt32(utf16[1]) &<< 16 |
| _representation = .smallUTF16(Builtin.zext_Int32_Int63(bits._value)) |
| case 3: |
| let bits = UInt64(utf16[0]) |
| | UInt64(utf16[1]) &<< 16 |
| | UInt64(utf16[2]) &<< 32 |
| _representation = .smallUTF16(Builtin.trunc_Int64_Int63(bits._value)) |
| case 4 where utf16[3] < 0x8000: |
| let bits = UInt64(utf16[0]) |
| | UInt64(utf16[1]) &<< 16 |
| | UInt64(utf16[2]) &<< 32 |
| | UInt64(utf16[3]) &<< 48 |
| _representation = .smallUTF16(Builtin.trunc_Int64_Int63(bits._value)) |
| default: |
| _representation = Character( |
| _largeRepresentationString: String( |
| _StringCore( |
| baseAddress: UnsafeMutableRawPointer(start), |
| count: utf16.count, |
| elementShift: 1, |
| hasCocoaBuffer: false, |
| owner: nil) |
| ))._representation |
| } |
| } |
| |
| /// Creates a character with the specified value. |
| /// |
| /// Do not call this initalizer directly. It is used by the compiler when |
| /// you use a string literal to initialize a `Character` instance. For |
| /// example: |
| /// |
| /// let oBreve: Character = "o\u{306}" |
| /// print(oBreve) |
| /// // Prints "Ε" |
| /// |
| /// The assignment to the `oBreve` constant calls this initializer behind the |
| /// scenes. |
| public init(extendedGraphemeClusterLiteral value: Character) { |
| self = value |
| } |
| |
| /// Creates a character from a single-character string. |
| /// |
| /// The following example creates a new character from the uppercase version |
| /// of a string that only holds one character. |
| /// |
| /// let a = "a" |
| /// let capitalA = Character(a.uppercased()) |
| /// |
| /// - Parameter s: The single-character string to convert to a `Character` |
| /// instance. `s` must contain exactly one extended grapheme cluster. |
| public init(_ s: String) { |
| _precondition( |
| s._core.count != 0, "Can't form a Character from an empty String") |
| _debugPrecondition( |
| s.index(after: s.startIndex) == s.endIndex, |
| "Can't form a Character from a String containing more than one extended grapheme cluster") |
| |
| if _fastPath(s._core.count <= 4) { |
| let b = _UIntBuffer<UInt64, Unicode.UTF16.CodeUnit>(s._core) |
| if _fastPath(Int64(truncatingIfNeeded: b._storage) >= 0) { |
| _representation = .smallUTF16( |
| Builtin.trunc_Int64_Int63(b._storage._value)) |
| return |
| } |
| } |
| self = Character(_largeRepresentationString: s) |
| } |
| |
| /// Creates a Character from a String that is already known to require the |
| /// large representation. |
| /// |
| /// - Note: `s` should contain only a single grapheme, but we can't require |
| /// that formally because of grapheme cluster literals and the shifting |
| /// sands of Unicode. https://bugs.swift.org/browse/SR-4955 |
| @_versioned |
| internal init(_largeRepresentationString s: String) { |
| if let native = s._core.nativeBuffer, |
| native.start == s._core._baseAddress!, |
| native.usedCount == s._core.count { |
| _representation = .large(native._storage) |
| return |
| } |
| var nativeString = "" |
| nativeString.append(s) |
| _representation = .large(nativeString._core.nativeBuffer!._storage) |
| } |
| |
| static func _smallValue(_ value: Builtin.Int63) -> UInt64 { |
| return UInt64(Builtin.zext_Int63_Int64(value)) |
| } |
| |
| /// The character's hash value. |
| /// |
| /// Hash values are not guaranteed to be equal across different executions of |
| /// your program. Do not save hash values to use during a future execution. |
| public var hashValue: Int { |
| // FIXME(performance): constructing a temporary string is extremely |
| // wasteful and inefficient. |
| return String(self).hashValue |
| } |
| |
| typealias UTF16View = String.UTF16View |
| var utf16: UTF16View { |
| return String(self).utf16 |
| } |
| |
| @_versioned |
| internal var _representation: Representation |
| } |
| |
| extension Character : CustomStringConvertible { |
| public var description: String { |
| return String(describing: self) |
| } |
| } |
| |
| extension Character : LosslessStringConvertible {} |
| |
| extension Character : CustomDebugStringConvertible { |
| /// A textual representation of the character, suitable for debugging. |
| public var debugDescription: String { |
| return String(self).debugDescription |
| } |
| } |
| |
| extension Character { |
| @_versioned |
| internal var _smallUTF16 : _UIntBuffer<UInt64, Unicode.UTF16.CodeUnit>? { |
| guard case .smallUTF16(let _63bits) = _representation else { return nil } |
| _onFastPath() |
| let bits = UInt64(Builtin.zext_Int63_Int64(_63bits)) |
| let minBitWidth = type(of: bits).bitWidth - bits.leadingZeroBitCount |
| return _UIntBuffer<UInt64, Unicode.UTF16.CodeUnit>( |
| _storage: bits, |
| _bitCount: UInt8( |
| truncatingIfNeeded: 16 * Swift.max(1, (minBitWidth + 15) / 16)) |
| ) |
| } |
| |
| @_versioned |
| internal var _largeUTF16 : _StringCore? { |
| guard case .large(let storage) = _representation else { return nil } |
| return _StringCore(_StringBuffer(storage)) |
| } |
| } |
| |
| extension String { |
| /// Creates a string containing the given character. |
| /// |
| /// - Parameter c: The character to convert to a string. |
| public init(_ c: Character) { |
| if let utf16 = c._smallUTF16 { |
| self = String(decoding: utf16, as: Unicode.UTF16.self) |
| } |
| else { |
| self = String(c._largeUTF16!) |
| } |
| } |
| } |
| |
| /// `.small` characters are stored in an Int63 with their UTF-8 representation, |
| /// with any unused bytes set to 0xFF. ASCII characters will have all bytes set |
| /// to 0xFF except for the lowest byte, which will store the ASCII value. Since |
| /// 0x7FFFFFFFFFFFFF80 or greater is an invalid UTF-8 sequence, we know if a |
| /// value is ASCII by checking if it is greater than or equal to |
| /// 0x7FFFFFFFFFFFFF00. |
| internal var _minASCIICharReprBuiltin: Builtin.Int63 { |
| @inline(__always) get { |
| let x: Int64 = 0x7FFFFFFFFFFFFF00 |
| return Builtin.truncOrBitCast_Int64_Int63(x._value) |
| } |
| } |
| |
| extension Character : Equatable { |
| @_inlineable |
| @inline(__always) |
| public static func == (lhs: Character, rhs: Character) -> Bool { |
| let l0 = lhs._smallUTF16 |
| if _fastPath(l0 != nil), let l = l0?._storage { |
| let r0 = rhs._smallUTF16 |
| if _fastPath(r0 != nil), let r = r0?._storage { |
| if (l | r) < 0x300 { return l == r } |
| if l == r { return true } |
| } |
| } |
| |
| // FIXME(performance): constructing two temporary strings is extremely |
| // wasteful and inefficient. |
| return String(lhs) == String(rhs) |
| } |
| } |
| |
| extension Character : Comparable { |
| @_inlineable |
| @inline(__always) |
| public static func < (lhs: Character, rhs: Character) -> Bool { |
| let l0 = lhs._smallUTF16 |
| if _fastPath(l0 != nil), let l = l0?._storage { |
| let r0 = rhs._smallUTF16 |
| if _fastPath(r0 != nil), let r = r0?._storage { |
| if (l | r) < 0x80 { return l < r } |
| if l == r { return false } |
| } |
| } |
| // FIXME(performance): constructing two temporary strings is extremely |
| // wasteful and inefficient. |
| return String(lhs) < String(rhs) |
| } |
| } |