swift-mirror/stdlib/public/core/UnicodeScalarProperties.swift

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 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
//
//===----------------------------------------------------------------------===//
// Exposes advanced properties of Unicode.Scalar defined by the Unicode
// Standard.
//===----------------------------------------------------------------------===//

import SwiftShims

extension Unicode.Scalar {

  /// A value that provides access to properties of a Unicode scalar that are
  /// defined by the Unicode standard.
  public struct Properties: Sendable {
    @usableFromInline
    internal var _scalar: Unicode.Scalar

    internal init(_ scalar: Unicode.Scalar) {
      self._scalar = scalar
    }
  }

  /// Properties of this scalar defined by the Unicode standard.
  ///
  /// Use this property to access the Unicode properties of a Unicode scalar
  /// value. The following code tests whether a string contains any math
  /// symbols:
  ///
  ///     let question = "Which is larger, 3 * 3 * 3 or 10 + 10 + 10?"
  ///     let hasMathSymbols = question.unicodeScalars.contains(where: {
  ///         $0.properties.isMath
  ///     })
  ///     // hasMathSymbols == true
  public var properties: Properties {
    return Properties(self)
  }
}

extension Unicode.Scalar.Properties {
  // This OptionSet represents the 64 bit integer value returned when asking
  // '_swift_stdlib_getBinaryProperties' where each bit indicates a unique
  // Unicode defined binary property of a scalar. For example, bit 8 represents
  // the 'isAlphabetic' property for scalars.
  //
  // WARNING: The values below must be kept in-sync with the generation script.
  // If one should ever update this list below, be it reordering bits, adding
  // new properties, etc., please update the generation script found at:
  // 'utils/gen-unicode-data/Sources/GenScalarProps/BinProps.swift'.
  fileprivate struct _BinaryProperties: OptionSet {
    let rawValue: UInt64

    private init(_ rawValue: UInt64) {
      self.rawValue = rawValue
    }

    // Because we defined the labelless init, we lose the memberwise one
    // generated, so define that here to satisfy the 'OptionSet' requirement.
    init(rawValue: UInt64) {
      self.rawValue = rawValue
    }

    static var changesWhenCaseFolded       : Self { Self(1 &<<  0) }
    static var changesWhenCaseMapped       : Self { Self(1 &<<  1) }
    static var changesWhenLowercased       : Self { Self(1 &<<  2) }
    static var changesWhenNFKCCaseFolded   : Self { Self(1 &<<  3) }
    static var changesWhenTitlecased       : Self { Self(1 &<<  4) }
    static var changesWhenUppercased       : Self { Self(1 &<<  5) }
    static var isASCIIHexDigit             : Self { Self(1 &<<  6) }
    static var isAlphabetic                : Self { Self(1 &<<  7) }
    static var isBidiControl               : Self { Self(1 &<<  8) }
    static var isBidiMirrored              : Self { Self(1 &<<  9) }
    static var isCaseIgnorable             : Self { Self(1 &<< 10) }
    static var isCased                     : Self { Self(1 &<< 11) }
    static var isDash                      : Self { Self(1 &<< 12) }
    static var isDefaultIgnorableCodePoint : Self { Self(1 &<< 13) }
    static var isDeprecated                : Self { Self(1 &<< 14) }
    static var isDiacritic                 : Self { Self(1 &<< 15) }
    static var isEmoji                     : Self { Self(1 &<< 16) }
    static var isEmojiModifier             : Self { Self(1 &<< 17) }
    static var isEmojiModifierBase         : Self { Self(1 &<< 18) }
    static var isEmojiPresentation         : Self { Self(1 &<< 19) }
    static var isExtender                  : Self { Self(1 &<< 20) }
    static var isFullCompositionExclusion  : Self { Self(1 &<< 21) }
    static var isGraphemeBase              : Self { Self(1 &<< 22) }
    static var isGraphemeExtend            : Self { Self(1 &<< 23) }
    static var isHexDigit                  : Self { Self(1 &<< 24) }
    static var isIDContinue                : Self { Self(1 &<< 25) }
    static var isIDSBinaryOperator         : Self { Self(1 &<< 26) }
    static var isIDSTrinaryOperator        : Self { Self(1 &<< 27) }
    static var isIDStart                   : Self { Self(1 &<< 28) }
    static var isIdeographic               : Self { Self(1 &<< 29) }
    static var isJoinControl               : Self { Self(1 &<< 30) }
    static var isLogicalOrderException     : Self { Self(1 &<< 31) }
    static var isLowercase                 : Self { Self(1 &<< 32) }
    static var isMath                      : Self { Self(1 &<< 33) }
    static var isNoncharacterCodePoint     : Self { Self(1 &<< 34) }
    static var isPatternSyntax             : Self { Self(1 &<< 35) }
    static var isPatternWhitespace         : Self { Self(1 &<< 36) }
    static var isQuotationMark             : Self { Self(1 &<< 37) }
    static var isRadical                   : Self { Self(1 &<< 38) }
    static var isSentenceTerminal          : Self { Self(1 &<< 39) }
    static var isSoftDotted                : Self { Self(1 &<< 40) }
    static var isTerminalPunctuation       : Self { Self(1 &<< 41) }
    static var isUnifiedIdeograph          : Self { Self(1 &<< 42) }
    static var isUppercase                 : Self { Self(1 &<< 43) }
    static var isVariationSelector         : Self { Self(1 &<< 44) }
    static var isWhitespace                : Self { Self(1 &<< 45) }
    static var isXIDContinue               : Self { Self(1 &<< 46) }
    static var isXIDStart                  : Self { Self(1 &<< 47) }
  }
}

/// Boolean properties that are defined by the Unicode Standard.
extension Unicode.Scalar.Properties {
  fileprivate var _binaryProperties: _BinaryProperties {
    _BinaryProperties(
      rawValue: _swift_stdlib_getBinaryProperties(_scalar.value)
    )
  }

  /// A Boolean value indicating whether the scalar is alphabetic.
  ///
  /// Alphabetic scalars are the primary units of alphabets and/or syllabaries.
  ///
  /// This property corresponds to the "Alphabetic" and the "Other_Alphabetic"
  /// properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isAlphabetic: Bool {
    _binaryProperties.contains(.isAlphabetic)
  }

  /// A Boolean value indicating whether the scalar is an ASCII character
  /// commonly used for the representation of hexadecimal numbers.
  ///
  /// The only scalars for which this property is `true` are:
  ///
  /// * U+0030...U+0039: DIGIT ZERO...DIGIT NINE
  /// * U+0041...U+0046: LATIN CAPITAL LETTER A...LATIN CAPITAL LETTER F
  /// * U+0061...U+0066: LATIN SMALL LETTER A...LATIN SMALL LETTER F
  ///
  /// This property corresponds to the "ASCII_Hex_Digit" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isASCIIHexDigit: Bool {
    _binaryProperties.contains(.isASCIIHexDigit)
  }

  /// A Boolean value indicating whether the scalar is a format control
  /// character that has a specific function in the Unicode Bidirectional
  /// Algorithm.
  ///
  /// This property corresponds to the "Bidi_Control" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isBidiControl: Bool {
    _binaryProperties.contains(.isBidiControl)
  }

  /// A Boolean value indicating whether the scalar is mirrored in
  /// bidirectional text.
  ///
  /// This property corresponds to the "Bidi_Mirrored" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isBidiMirrored: Bool {
    _binaryProperties.contains(.isBidiMirrored)
  }

  /// A Boolean value indicating whether the scalar is a punctuation
  /// symbol explicitly called out as a dash in the Unicode Standard or a
  /// compatibility equivalent.
  ///
  /// This property corresponds to the "Dash" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isDash: Bool {
    _binaryProperties.contains(.isDash)
  }

  /// A Boolean value indicating whether the scalar is a default-ignorable
  /// code point.
  ///
  /// Default-ignorable code points are those that should be ignored by default
  /// in rendering (unless explicitly supported). They have no visible glyph or
  /// advance width in and of themselves, although they may affect the display,
  /// positioning, or adornment of adjacent or surrounding characters.
  ///
  /// This property corresponds to the "Default_Ignorable_Code_Point" and the
  /// "Other_Default_Ignorable_Code_point" properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isDefaultIgnorableCodePoint: Bool {
    _binaryProperties.contains(.isDefaultIgnorableCodePoint)
  }

  /// A Boolean value indicating whether the scalar is deprecated.
  ///
  /// Scalars are never removed from the Unicode Standard, but the usage of
  /// deprecated scalars is strongly discouraged.
  ///
  /// This property corresponds to the "Deprecated" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isDeprecated: Bool {
    _binaryProperties.contains(.isDeprecated)
  }

  /// A Boolean value indicating whether the scalar is a diacritic.
  ///
  /// Diacritics are scalars that linguistically modify the meaning of another
  /// scalar to which they apply. Scalars for which this property is `true` are
  /// frequently, but not always, combining marks or modifiers.
  ///
  /// This property corresponds to the "Diacritic" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isDiacritic: Bool {
    _binaryProperties.contains(.isDiacritic)
  }

  /// A Boolean value indicating whether the scalar's principal function is
  /// to extend the value or shape of a preceding alphabetic scalar.
  ///
  /// Typical extenders are length and iteration marks.
  ///
  /// This property corresponds to the "Extender" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isExtender: Bool {
    _binaryProperties.contains(.isExtender)
  }

  /// A Boolean value indicating whether the scalar is excluded from
  /// composition when performing Unicode normalization.
  ///
  /// This property corresponds to the "Full_Composition_Exclusion" property in
  /// the [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isFullCompositionExclusion: Bool {
    _binaryProperties.contains(.isFullCompositionExclusion)
  }

  /// A Boolean value indicating whether the scalar is a grapheme base.
  ///
  /// A grapheme base can be thought of as a space-occupying glyph above or
  /// below which other non-spacing modifying glyphs can be applied. For
  /// example, when the character `é` is represented in its decomposed form,
  /// the grapheme base is "e" (U+0065 LATIN SMALL LETTER E) and it is followed
  /// by a single grapheme extender, U+0301 COMBINING ACUTE ACCENT.
  ///
  /// The set of scalars for which `isGraphemeBase` is `true` is disjoint by
  /// definition from the set for which `isGraphemeExtend` is `true`.
  ///
  /// This property corresponds to the "Grapheme_Base" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isGraphemeBase: Bool {
    _binaryProperties.contains(.isGraphemeBase)
  }

  /// A Boolean value indicating whether the scalar is a grapheme extender.
  ///
  /// A grapheme extender can be thought of primarily as a non-spacing glyph
  /// that is applied above or below another glyph. For example, when the
  /// character `é` is represented in its decomposed form, the grapheme base is
  /// "e" (U+0065 LATIN SMALL LETTER E) and it is followed by a single grapheme
  /// extender, U+0301 COMBINING ACUTE ACCENT.
  ///
  /// The set of scalars for which `isGraphemeExtend` is `true` is disjoint by
  /// definition from the set for which `isGraphemeBase` is `true`.
  ///
  /// This property corresponds to the "Grapheme_Extend" and the
  /// "Other_Grapheme_Extend" properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isGraphemeExtend: Bool {
    _binaryProperties.contains(.isGraphemeExtend)
  }

  /// A Boolean value indicating whether the scalar is one that is commonly
  /// used for the representation of hexadecimal numbers or a compatibility
  /// equivalent.
  ///
  /// This property is `true` for all scalars for which `isASCIIHexDigit` is
  /// `true` as well as for their CJK halfwidth and fullwidth variants.
  ///
  /// This property corresponds to the "Hex_Digit" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isHexDigit: Bool {
    _binaryProperties.contains(.isHexDigit)
  }

  /// A Boolean value indicating whether the scalar is one which is
  /// recommended to be allowed to appear in a non-starting position in a
  /// programming language identifier.
  ///
  /// Applications that store identifiers in NFKC normalized form should instead
  /// use `isXIDContinue` to check whether a scalar is a valid identifier
  /// character.
  ///
  /// This property corresponds to the "ID_Continue" and the "Other_ID_Continue"
  /// properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isIDContinue: Bool {
    _binaryProperties.contains(.isIDContinue)
  }

  /// A Boolean value indicating whether the scalar is one which is
  /// recommended to be allowed to appear in a starting position in a
  /// programming language identifier.
  ///
  /// Applications that store identifiers in NFKC normalized form should instead
  /// use `isXIDStart` to check whether a scalar is a valid identifier
  /// character.
  ///
  /// This property corresponds to the "ID_Start" and the "Other_ID_Start"
  /// properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isIDStart: Bool {
    _binaryProperties.contains(.isIDStart)
  }

  /// A Boolean value indicating whether the scalar is considered to be a
  /// CJKV (Chinese, Japanese, Korean, and Vietnamese) or other siniform
  /// (Chinese writing-related) ideograph.
  ///
  /// This property roughly defines the class of "Chinese characters" and does
  /// not include characters of other logographic scripts such as Cuneiform or
  /// Egyptian Hieroglyphs.
  ///
  /// This property corresponds to the "Ideographic" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isIdeographic: Bool {
    _binaryProperties.contains(.isIdeographic)
  }

  /// A Boolean value indicating whether the scalar is an ideographic
  /// description character that determines how the two ideographic characters
  /// or ideographic description sequences that follow it are to be combined to
  /// form a single character.
  ///
  /// Ideographic description characters are technically printable characters,
  /// but advanced rendering engines may use them to approximate ideographs that
  /// are otherwise unrepresentable.
  ///
  /// This property corresponds to the "IDS_Binary_Operator" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isIDSBinaryOperator: Bool {
    _binaryProperties.contains(.isIDSBinaryOperator)
  }

  /// A Boolean value indicating whether the scalar is an ideographic
  /// description character that determines how the three ideographic characters
  /// or ideographic description sequences that follow it are to be combined to
  /// form a single character.
  ///
  /// Ideographic description characters are technically printable characters,
  /// but advanced rendering engines may use them to approximate ideographs that
  /// are otherwise unrepresentable.
  ///
  /// This property corresponds to the "IDS_Trinary_Operator" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isIDSTrinaryOperator: Bool {
    _binaryProperties.contains(.isIDSTrinaryOperator)
  }

  /// A Boolean value indicating whether the scalar is a format control
  /// character that has a specific function in controlling cursive joining and
  /// ligation.
  ///
  /// There are two scalars for which this property is `true`:
  ///
  /// * When U+200C ZERO WIDTH NON-JOINER is inserted between two characters, it
  ///   directs the rendering engine to render them separately/disconnected when
  ///   it might otherwise render them as a ligature. For example, a rendering
  ///   engine might display "fl" in English as a connected glyph; inserting the
  ///   zero width non-joiner would force them to be rendered as disconnected
  ///   glyphs.
  ///
  /// * When U+200D ZERO WIDTH JOINER is inserted between two characters, it
  ///   directs the rendering engine to render them as a connected glyph when it
  ///   would otherwise render them independently. The zero width joiner is also
  ///   used to construct complex emoji from sequences of base emoji characters.
  ///   For example, the various "family" emoji are encoded as sequences of man,
  ///   woman, or child emoji that are interleaved with zero width joiners.
  ///
  /// This property corresponds to the "Join_Control" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isJoinControl: Bool {
    _binaryProperties.contains(.isJoinControl)
  }

  /// A Boolean value indicating whether the scalar requires special handling
  /// for operations involving ordering, such as sorting and searching.
  ///
  /// This property applies to a small number of spacing vowel letters occurring
  /// in some Southeast Asian scripts like Thai and Lao, which use a visual
  /// order display model. Such letters are stored in text ahead of
  /// syllable-initial consonants.
  ///
  /// This property corresponds to the "Logical_Order_Exception" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isLogicalOrderException: Bool {
    _binaryProperties.contains(.isLogicalOrderException)
  }

  /// A Boolean value indicating whether the scalar's letterform is
  /// considered lowercase.
  ///
  /// This property corresponds to the "Lowercase" and the "Other_Lowercase"
  /// properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isLowercase: Bool {
    _binaryProperties.contains(.isLowercase)
  }

  /// A Boolean value indicating whether the scalar is one that naturally
  /// appears in mathematical contexts.
  ///
  /// The set of scalars for which this property is `true` includes mathematical
  /// operators and symbols as well as specific Greek and Hebrew letter
  /// variants that are categorized as symbols. Notably, it does _not_ contain
  /// the standard digits or Latin/Greek letter blocks; instead, it contains the
  /// mathematical Latin, Greek, and Arabic letters and numbers defined in the
  /// Supplemental Multilingual Plane.
  ///
  /// This property corresponds to the "Math" and the "Other_Math" properties in
  /// the [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isMath: Bool {
    _binaryProperties.contains(.isMath)
  }

  /// A Boolean value indicating whether the scalar is permanently reserved
  /// for internal use.
  ///
  /// This property corresponds to the "Noncharacter_Code_Point" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isNoncharacterCodePoint: Bool {
    _binaryProperties.contains(.isNoncharacterCodePoint)
  }

  /// A Boolean value indicating whether the scalar is one that is used in
  /// writing to surround quoted text.
  ///
  /// This property corresponds to the "Quotation_Mark" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isQuotationMark: Bool {
    _binaryProperties.contains(.isQuotationMark)
  }

  /// A Boolean value indicating whether the scalar is a radical component of
  /// CJK characters, Tangut characters, or Yi syllables.
  ///
  /// These scalars are often the components of ideographic description
  /// sequences, as defined by the `isIDSBinaryOperator` and
  /// `isIDSTrinaryOperator` properties.
  ///
  /// This property corresponds to the "Radical" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isRadical: Bool {
    _binaryProperties.contains(.isRadical)
  }

  /// A Boolean value indicating whether the scalar has a "soft dot" that
  /// disappears when a diacritic is placed over the scalar.
  ///
  /// For example, "i" is soft dotted because the dot disappears when adding an
  /// accent mark, as in "í".
  ///
  /// This property corresponds to the "Soft_Dotted" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isSoftDotted: Bool {
    _binaryProperties.contains(.isSoftDotted)
  }

  /// A Boolean value indicating whether the scalar is a punctuation symbol
  /// that typically marks the end of a textual unit.
  ///
  /// This property corresponds to the "Terminal_Punctuation" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isTerminalPunctuation: Bool {
    _binaryProperties.contains(.isTerminalPunctuation)
  }

  /// A Boolean value indicating whether the scalar is one of the unified
  /// CJK ideographs in the Unicode Standard.
  ///
  /// This property is false for CJK punctuation and symbols, as well as for
  /// compatibility ideographs (which canonically decompose to unified
  /// ideographs).
  ///
  /// This property corresponds to the "Unified_Ideograph" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isUnifiedIdeograph: Bool {
    _binaryProperties.contains(.isUnifiedIdeograph)
  }

  /// A Boolean value indicating whether the scalar's letterform is
  /// considered uppercase.
  ///
  /// This property corresponds to the "Uppercase" and the "Other_Uppercase"
  /// properties in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isUppercase: Bool {
    _binaryProperties.contains(.isUppercase)
  }

  /// A Boolean value indicating whether the scalar is a whitespace
  /// character.
  ///
  /// This property is `true` for scalars that are spaces, separator characters,
  /// and other control characters that should be treated as whitespace for the
  /// purposes of parsing text elements.
  ///
  /// This property corresponds to the "White_Space" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isWhitespace: Bool {
    _binaryProperties.contains(.isWhitespace)
  }

  /// A Boolean value indicating whether the scalar is one which is
  /// recommended to be allowed to appear in a non-starting position in a
  /// programming language identifier, with adjustments made for NFKC normalized
  /// form.
  ///
  /// The set of scalars `[:XID_Continue:]` closes the set `[:ID_Continue:]`
  /// under NFKC normalization by removing any scalars whose normalized form is
  /// not of the form `[:ID_Continue:]*`.
  ///
  /// This property corresponds to the "XID_Continue" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isXIDContinue: Bool {
    _binaryProperties.contains(.isXIDContinue)
  }

  /// A Boolean value indicating whether the scalar is one which is
  /// recommended to be allowed to appear in a starting position in a
  /// programming language identifier, with adjustments made for NFKC normalized
  /// form.
  ///
  /// The set of scalars `[:XID_Start:]` closes the set `[:ID_Start:]` under
  /// NFKC normalization by removing any scalars whose normalized form is not of
  /// the form `[:ID_Start:] [:ID_Continue:]*`.
  ///
  /// This property corresponds to the "XID_Start" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isXIDStart: Bool {
    _binaryProperties.contains(.isXIDStart)
  }

  /// A Boolean value indicating whether the scalar is a punctuation mark
  /// that generally marks the end of a sentence.
  ///
  /// This property corresponds to the "Sentence_Terminal" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isSentenceTerminal: Bool {
    _binaryProperties.contains(.isSentenceTerminal)
  }

  /// A Boolean value indicating whether the scalar is a variation selector.
  ///
  /// Variation selectors allow rendering engines that support them to choose
  /// different glyphs to display for a particular code point.
  ///
  /// This property corresponds to the "Variation_Selector" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isVariationSelector: Bool {
    _binaryProperties.contains(.isVariationSelector)
  }

  /// A Boolean value indicating whether the scalar is recommended to have
  /// syntactic usage in patterns represented in source code.
  ///
  /// This property corresponds to the "Pattern_Syntax" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isPatternSyntax: Bool {
    _binaryProperties.contains(.isPatternSyntax)
  }

  /// A Boolean value indicating whether the scalar is recommended to be
  /// treated as whitespace when parsing patterns represented in source code.
  ///
  /// This property corresponds to the "Pattern_White_Space" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isPatternWhitespace: Bool {
    _binaryProperties.contains(.isPatternWhitespace)
  }

  /// A Boolean value indicating whether the scalar is considered to be
  /// either lowercase, uppercase, or titlecase.
  ///
  /// Though similar in name, this property is *not* equivalent to
  /// `changesWhenCaseMapped`. The set of scalars for which `isCased` is `true`
  /// is a superset of those for which `changesWhenCaseMapped` is `true`. For
  /// example, the Latin small capitals that are used by the International
  /// Phonetic Alphabet have a case, but do not change when they are mapped to
  /// any of the other cases.
  ///
  /// This property corresponds to the "Cased" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isCased: Bool {
    _binaryProperties.contains(.isCased)
  }

  /// A Boolean value indicating whether the scalar is ignored for casing
  /// purposes.
  ///
  /// This property corresponds to the "Case_Ignorable" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var isCaseIgnorable: Bool {
    _binaryProperties.contains(.isCaseIgnorable)
  }

  /// A Boolean value indicating whether the scalar's normalized form differs
  /// from the `lowercaseMapping` of each constituent scalar.
  ///
  /// This property corresponds to the "Changes_When_Lowercased" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var changesWhenLowercased: Bool {
    _binaryProperties.contains(.changesWhenLowercased)
  }

  /// A Boolean value indicating whether the scalar's normalized form differs
  /// from the `uppercaseMapping` of each constituent scalar.
  ///
  /// This property corresponds to the "Changes_When_Uppercased" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var changesWhenUppercased: Bool {
    _binaryProperties.contains(.changesWhenUppercased)
  }

  /// A Boolean value indicating whether the scalar's normalized form differs
  /// from the `titlecaseMapping` of each constituent scalar.
  ///
  /// This property corresponds to the "Changes_When_Titlecased" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var changesWhenTitlecased: Bool {
    _binaryProperties.contains(.changesWhenTitlecased)
  }

  /// A Boolean value indicating whether the scalar's normalized form differs
  /// from the case-fold mapping of each constituent scalar.
  ///
  /// This property corresponds to the "Changes_When_Casefolded" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var changesWhenCaseFolded: Bool {
    _binaryProperties.contains(.changesWhenCaseFolded)
  }

  /// A Boolean value indicating whether the scalar may change when it
  /// undergoes case mapping.
  ///
  /// This property is `true` whenever one or more of `changesWhenLowercased`,
  /// `changesWhenUppercased`, or `changesWhenTitlecased` are `true`.
  ///
  /// This property corresponds to the "Changes_When_Casemapped" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var changesWhenCaseMapped: Bool {
    _binaryProperties.contains(.changesWhenCaseMapped)
  }

  /// A Boolean value indicating whether the scalar is one that is not
  /// identical to its NFKC case-fold mapping.
  ///
  /// This property corresponds to the "Changes_When_NFKC_Casefolded" property
  /// in the [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var changesWhenNFKCCaseFolded: Bool {
    _binaryProperties.contains(.changesWhenNFKCCaseFolded)
  }

  /// A Boolean value indicating whether the scalar has an emoji
  /// presentation, whether or not it is the default.
  ///
  /// This property is true for scalars that are rendered as emoji by default
  /// and also for scalars that have a non-default emoji rendering when followed
  /// by U+FE0F VARIATION SELECTOR-16. This includes some scalars that are not
  /// typically considered to be emoji:
  ///
  ///     let scalars: [Unicode.Scalar] = ["😎", "$", "0"]
  ///     for s in scalars {
  ///         print(s, "-->", s.properties.isEmoji)
  ///     }
  ///     // 😎 --> true
  ///     // $ --> false
  ///     // 0 --> true
  ///
  /// The final result is true because the ASCII digits have non-default emoji
  /// presentations; some platforms render these with an alternate appearance.
  ///
  /// Because of this behavior, testing `isEmoji` alone on a single scalar is
  /// insufficient to determine if a unit of text is rendered as an emoji; a
  /// correct test requires inspecting multiple scalars in a `Character`. In
  /// addition to checking whether the base scalar has `isEmoji == true`, you
  /// must also check its default presentation (see `isEmojiPresentation`) and
  /// determine whether it is followed by a variation selector that would modify
  /// the presentation.
  ///
  /// This property corresponds to the "Emoji" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  @available(macOS 10.12.2, iOS 10.2, tvOS 10.1, watchOS 3.1.1, *)
  public var isEmoji: Bool {
    _binaryProperties.contains(.isEmoji)
  }

  /// A Boolean value indicating whether the scalar is one that should be
  /// rendered with an emoji presentation, rather than a text presentation, by
  /// default.
  ///
  /// Scalars that have default to emoji presentation can be followed by
  /// U+FE0E VARIATION SELECTOR-15 to request the text presentation of the
  /// scalar instead. Likewise, scalars that default to text presentation can
  /// be followed by U+FE0F VARIATION SELECTOR-16 to request the emoji
  /// presentation.
  ///
  /// This property corresponds to the "Emoji_Presentation" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  @available(macOS 10.12.2, iOS 10.2, tvOS 10.1, watchOS 3.1.1, *)
  public var isEmojiPresentation: Bool {
    _binaryProperties.contains(.isEmojiPresentation)
  }

  /// A Boolean value indicating whether the scalar is one that can modify
  /// a base emoji that precedes it.
  ///
  /// The Fitzpatrick skin types are examples of emoji modifiers; they change
  /// the appearance of the preceding emoji base (that is, a scalar for which
  /// `isEmojiModifierBase` is true) by rendering it with a different skin tone.
  ///
  /// This property corresponds to the "Emoji_Modifier" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  @available(macOS 10.12.2, iOS 10.2, tvOS 10.1, watchOS 3.1.1, *)
  public var isEmojiModifier: Bool {
    _binaryProperties.contains(.isEmojiModifier)
  }

  /// A Boolean value indicating whether the scalar is one whose appearance
  /// can be changed by an emoji modifier that follows it.
  ///
  /// This property corresponds to the "Emoji_Modifier_Base" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  @available(macOS 10.12.2, iOS 10.2, tvOS 10.1, watchOS 3.1.1, *)
  public var isEmojiModifierBase: Bool {
    _binaryProperties.contains(.isEmojiModifierBase)
  }
}

/// Case mapping properties.
extension Unicode.Scalar.Properties {
  fileprivate struct _CaseMapping {
    let rawValue: UInt8

    static let uppercase = _CaseMapping(rawValue: 0)
    static let lowercase = _CaseMapping(rawValue: 1)
    static let titlecase = _CaseMapping(rawValue: 2)
  }

  fileprivate func _getMapping(_ mapping: _CaseMapping) -> String {
    // First, check if our scalar has a special mapping where it's mapped to
    // more than 1 scalar.
    var specialMappingLength = 0

    let specialMappingPtr = unsafe _swift_stdlib_getSpecialMapping(
      _scalar.value,
      mapping.rawValue,
      &specialMappingLength
    )

    if let specialMapping = unsafe specialMappingPtr, specialMappingLength != 0 {
      let buffer = unsafe UnsafeBufferPointer<UInt8>(
        start: specialMapping,
        count: specialMappingLength
      )

      return unsafe String._uncheckedFromUTF8(buffer, isASCII: false)
    }

    // If we did not have a special mapping, check if we have a direct scalar
    // to scalar mapping.
    let mappingDistance = _swift_stdlib_getMapping(
      _scalar.value,
      mapping.rawValue
    )

    if mappingDistance != 0 {
      let scalar = Unicode.Scalar(
        _unchecked: UInt32(Int(_scalar.value) &+ Int(mappingDistance))
      )
      return String(scalar)
    }

    // We did not have any mapping. Return the scalar as is.
    return String(_scalar)
  }

  /// The lowercase mapping of the scalar.
  ///
  /// This property is a `String`, not a `Unicode.Scalar` or `Character`,
  /// because some mappings may transform a scalar into multiple scalars or
  /// graphemes. For example, the character "İ" (U+0130 LATIN CAPITAL LETTER I
  /// WITH DOT ABOVE) becomes two scalars (U+0069 LATIN SMALL LETTER I, U+0307
  /// COMBINING DOT ABOVE) when converted to lowercase.
  ///
  /// This property corresponds to the "Lowercase_Mapping" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var lowercaseMapping: String {
    _getMapping(.lowercase)
  }

  /// The titlecase mapping of the scalar.
  ///
  /// This property is a `String`, not a `Unicode.Scalar` or `Character`,
  /// because some mappings may transform a scalar into multiple scalars or
  /// graphemes. For example, the ligature "fi" (U+FB01 LATIN SMALL LIGATURE FI)
  /// becomes "Fi" (U+0046 LATIN CAPITAL LETTER F, U+0069 LATIN SMALL LETTER I)
  /// when converted to titlecase.
  ///
  /// This property corresponds to the "Titlecase_Mapping" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var titlecaseMapping: String {
    _getMapping(.titlecase)
  }

  /// The uppercase mapping of the scalar.
  ///
  /// This property is a `String`, not a `Unicode.Scalar` or `Character`,
  /// because some mappings may transform a scalar into multiple scalars or
  /// graphemes. For example, the German letter "ß" (U+00DF LATIN SMALL LETTER
  /// SHARP S) becomes "SS" (U+0053 LATIN CAPITAL LETTER S, U+0053 LATIN CAPITAL
  /// LETTER S) when converted to uppercase.
  ///
  /// This property corresponds to the "Uppercase_Mapping" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var uppercaseMapping: String {
    _getMapping(.uppercase)
  }
}

extension Unicode {

  /// A version of the Unicode Standard represented by its major and minor
  /// components.
  public typealias Version = (major: Int, minor: Int)
}

extension Unicode.Scalar.Properties {

  /// The earliest version of the Unicode Standard in which the scalar was
  /// assigned.
  ///
  /// This value is `nil` for code points that have not yet been assigned.
  ///
  /// This property corresponds to the "Age" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var age: Unicode.Version? {
    let age: UInt16 = _swift_stdlib_getAge(_scalar.value)

    if age == .max {
      return nil
    }

    let major = age & 0xFF
    let minor = (age & 0xFF00) >> 8

    return (major: Int(major), minor: Int(minor))
  }
}

extension Unicode {

  /// The most general classification of a Unicode scalar.
  ///
  /// The general category of a scalar is its "first-order, most usual
  /// categorization". It does not attempt to cover multiple uses of some
  /// scalars, such as the use of letters to represent Roman numerals.
  public enum GeneralCategory: Sendable {

    /// An uppercase letter.
    ///
    /// This value corresponds to the category `Uppercase_Letter` (abbreviated
    /// `Lu`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case uppercaseLetter

    /// A lowercase letter.
    ///
    /// This value corresponds to the category `Lowercase_Letter` (abbreviated
    /// `Ll`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case lowercaseLetter

    /// A digraph character whose first part is uppercase.
    ///
    /// This value corresponds to the category `Titlecase_Letter` (abbreviated
    /// `Lt`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case titlecaseLetter

    /// A modifier letter.
    ///
    /// This value corresponds to the category `Modifier_Letter` (abbreviated
    /// `Lm`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case modifierLetter

    /// Other letters, including syllables and ideographs.
    ///
    /// This value corresponds to the category `Other_Letter` (abbreviated
    /// `Lo`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case otherLetter

    /// A non-spacing combining mark with zero advance width (abbreviated Mn).
    ///
    /// This value corresponds to the category `Nonspacing_Mark` (abbreviated
    /// `Mn`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case nonspacingMark

    /// A spacing combining mark with positive advance width.
    ///
    /// This value corresponds to the category `Spacing_Mark` (abbreviated `Mc`)
    /// in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case spacingMark

    /// An enclosing combining mark.
    ///
    /// This value corresponds to the category `Enclosing_Mark` (abbreviated
    /// `Me`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case enclosingMark

    /// A decimal digit.
    ///
    /// This value corresponds to the category `Decimal_Number` (abbreviated
    /// `Nd`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case decimalNumber

    /// A letter-like numeric character.
    ///
    /// This value corresponds to the category `Letter_Number` (abbreviated
    /// `Nl`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case letterNumber

    /// A numeric character of another type.
    ///
    /// This value corresponds to the category `Other_Number` (abbreviated `No`)
    /// in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case otherNumber

    /// A connecting punctuation mark, like a tie.
    ///
    /// This value corresponds to the category `Connector_Punctuation`
    /// (abbreviated `Pc`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case connectorPunctuation

    /// A dash or hyphen punctuation mark.
    ///
    /// This value corresponds to the category `Dash_Punctuation` (abbreviated
    /// `Pd`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case dashPunctuation

    /// An opening punctuation mark of a pair.
    ///
    /// This value corresponds to the category `Open_Punctuation` (abbreviated
    /// `Ps`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case openPunctuation

    /// A closing punctuation mark of a pair.
    ///
    /// This value corresponds to the category `Close_Punctuation` (abbreviated
    /// `Pe`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case closePunctuation

    /// An initial quotation mark.
    ///
    /// This value corresponds to the category `Initial_Punctuation`
    /// (abbreviated `Pi`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case initialPunctuation

    /// A final quotation mark.
    ///
    /// This value corresponds to the category `Final_Punctuation` (abbreviated
    /// `Pf`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case finalPunctuation

    /// A punctuation mark of another type.
    ///
    /// This value corresponds to the category `Other_Punctuation` (abbreviated
    /// `Po`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case otherPunctuation

    /// A symbol of mathematical use.
    ///
    /// This value corresponds to the category `Math_Symbol` (abbreviated `Sm`)
    /// in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case mathSymbol

    /// A currency sign.
    ///
    /// This value corresponds to the category `Currency_Symbol` (abbreviated
    /// `Sc`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case currencySymbol

    /// A non-letterlike modifier symbol.
    ///
    /// This value corresponds to the category `Modifier_Symbol` (abbreviated
    /// `Sk`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case modifierSymbol

    /// A symbol of another type.
    ///
    /// This value corresponds to the category `Other_Symbol` (abbreviated
    /// `So`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case otherSymbol

    /// A space character of non-zero width.
    ///
    /// This value corresponds to the category `Space_Separator` (abbreviated
    /// `Zs`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case spaceSeparator

    /// A line separator, which is specifically (and only) U+2028 LINE
    /// SEPARATOR.
    ///
    /// This value corresponds to the category `Line_Separator` (abbreviated
    /// `Zl`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case lineSeparator

    /// A paragraph separator, which is specifically (and only) U+2029 PARAGRAPH
    /// SEPARATOR.
    ///
    /// This value corresponds to the category `Paragraph_Separator`
    /// (abbreviated `Zp`) in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case paragraphSeparator

    /// A C0 or C1 control code.
    ///
    /// This value corresponds to the category `Control` (abbreviated `Cc`) in
    /// the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case control

    /// A format control character.
    ///
    /// This value corresponds to the category `Format` (abbreviated `Cf`) in
    /// the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case format

    /// A surrogate code point.
    ///
    /// This value corresponds to the category `Surrogate` (abbreviated `Cs`) in
    /// the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case surrogate

    /// A private-use character.
    ///
    /// This value corresponds to the category `Private_Use` (abbreviated `Co`)
    /// in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case privateUse

    /// A reserved unassigned code point or a non-character.
    ///
    /// This value corresponds to the category `Unassigned` (abbreviated `Cn`)
    /// in the
    /// [Unicode Standard](https://unicode.org/reports/tr44/#General_Category_Values).
    case unassigned

    internal init(rawValue: UInt8) {
      switch rawValue {
      case 0: self = .uppercaseLetter
      case 1: self = .lowercaseLetter
      case 2: self = .titlecaseLetter
      case 3: self = .modifierLetter
      case 4: self = .otherLetter
      case 5: self = .nonspacingMark
      case 6: self = .spacingMark
      case 7: self = .enclosingMark
      case 8: self = .decimalNumber
      case 9: self = .letterNumber
      case 10: self = .otherNumber
      case 11: self = .connectorPunctuation
      case 12: self = .dashPunctuation
      case 13: self = .openPunctuation
      case 14: self = .closePunctuation
      case 15: self = .initialPunctuation
      case 16: self = .finalPunctuation
      case 17: self = .otherPunctuation
      case 18: self = .mathSymbol
      case 19: self = .currencySymbol
      case 20: self = .modifierSymbol
      case 21: self = .otherSymbol
      case 22: self = .spaceSeparator
      case 23: self = .lineSeparator
      case 24: self = .paragraphSeparator
      case 25: self = .control
      case 26: self = .format
      case 27: self = .surrogate
      case 28: self = .privateUse
      case 29: self = .unassigned
      default: fatalError("Unknown general category")
      }
    }
  }
}

// Internal helpers
extension Unicode.GeneralCategory {
  internal var _isSymbol: Bool {
    switch self {
      case .mathSymbol, .currencySymbol, .modifierSymbol, .otherSymbol:
        return true
      default: return false
    }
  }
  internal var _isPunctuation: Bool {
    switch self {
      case .connectorPunctuation, .dashPunctuation, .openPunctuation,
           .closePunctuation, .initialPunctuation, .finalPunctuation,
           .otherPunctuation:
        return true
      default: return false
    }
  }
}

extension Unicode.Scalar.Properties {

  /// The general category (most usual classification) of the scalar.
  ///
  /// This property corresponds to the "General_Category" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var generalCategory: Unicode.GeneralCategory {
    let rawValue = _swift_stdlib_getGeneralCategory(_scalar.value)
    return Unicode.GeneralCategory(rawValue: rawValue)
  }
}

extension Unicode.Scalar.Properties {
  internal func _hangulName() -> String {
    // T = Hangul tail consonants
    let T: (base: UInt32, count: UInt32) = (base: 0x11A7, count: 28)
    // N = Number of precomposed Hangul syllables that start with the same
    //     leading consonant. (There is no base for N).
    let N: (base: UInt32, count: UInt32) = (base: 0x0, count: 588)
    // S = Hangul precomposed syllables
    let S: (base: UInt32, count: UInt32) = (base: 0xAC00, count: 11172)

    let hangulLTable = ["G", "GG", "N", "D", "DD", "R", "M", "B", "BB", "S",
                        "SS", "", "J", "JJ", "C", "K", "T", "P", "H"]

    let hangulVTable = ["A", "AE", "YA", "YAE", "EO", "E", "YEO", "YE", "O",
                        "WA", "WAE", "OE", "YO", "U", "WEO", "WE", "WI", "YU",
                        "EU", "YI", "I"]

    let hangulTTable = ["", "G", "GG", "GS", "N", "NJ", "NH", "D", "L", "LG",
                        "LM", "LB", "LS", "LT", "LP", "LH", "M", "B", "BS", "S",
                        "SS", "NG", "J", "C", "K", "T", "P", "H"]

    let sIdx = _scalar.value &- S.base
    let lIdx = Int(sIdx / N.count)
    let vIdx = Int((sIdx % N.count) / T.count)
    let tIdx = Int(sIdx % T.count)

    let scalarName = hangulLTable[lIdx] + hangulVTable[vIdx] + hangulTTable[tIdx]
    return "HANGUL SYLLABLE \(scalarName)"
  }

  // Used to potentially return a name who can either be represented in a large
  // range or algorithmically. A good example are the Hangul names. Instead of
  // storing those names, we can define an algorithm to generate the name.
  internal func _fastScalarName() -> String? {
    // Define a couple algorithmic names below.

    let scalarName = String(_scalar.value, radix: 16, uppercase: true)

    switch _scalar.value {
    // Hangul Syllable *
    case (0xAC00 ... 0xD7A3):
      return _hangulName()

    // Variation Selector-17 through Variation Selector-256
    case (0xE0100 ... 0xE01EF):
      return "VARIATION SELECTOR-\(_scalar.value - 0xE0100 + 17)"

    case (0x3400 ... 0x4DBF),
         (0x4E00 ... 0x9FFF),
         (0x20000 ... 0x2A6DF),
         (0x2A700 ... 0x2B739),
         (0x2B740 ... 0x2B81D),
         (0x2B820 ... 0x2CEA1),
         (0x2CEB0 ... 0x2EBE0),
         (0x2EBF0 ... 0x2EE5D),
         (0x30000 ... 0x3134A),
         (0x31350 ... 0x323AF):
      return "CJK UNIFIED IDEOGRAPH-\(scalarName)"

    case (0xF900 ... 0xFA6D),
         (0xFA70 ... 0xFAD9),
         (0x2F800 ... 0x2FA1D):
      return "CJK COMPATIBILITY IDEOGRAPH-\(scalarName)"

    case (0x17000 ... 0x187F7),
         (0x18D00 ... 0x18D08):
      return "TANGUT IDEOGRAPH-\(scalarName)"

    case (0x18B00 ... 0x18CD5):
      return "KHITAN SMALL SCRIPT CHARACTER-\(scalarName)"

    case (0x1B170 ... 0x1B2FB):
      return "NUSHU CHARACTER-\(scalarName)"

    case (0x13460 ... 0x143FA):
      return "EGYPTIAN HIEROGLYPH-\(scalarName)"

    // Otherwise, go look it up.
    default:
      return nil
    }
  }

  /// The published name of the scalar.
  ///
  /// Some scalars, such as control characters, do not have a value for this
  /// property in the Unicode Character Database. For such scalars, this
  /// property is `nil`.
  ///
  /// This property corresponds to the "Name" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var name: String? {
    if let fastName = _fastScalarName() {
      return fastName
    }

    // The longest name that Unicode defines is 88 characters long.
    let largestCount = Int(SWIFT_STDLIB_LARGEST_NAME_COUNT)

    let name = unsafe String(_uninitializedCapacity: largestCount) { buffer in
      unsafe _swift_stdlib_getScalarName(
        _scalar.value,
        buffer.baseAddress,
        buffer.count
      )
    }

    return name.isEmpty ? nil : name
  }

  /// The normative formal alias of the scalar.
  ///
  /// The name of a scalar is immutable and never changed in future versions of
  /// the Unicode Standard. The `nameAlias` property is provided to issue
  /// corrections if a name was issued erroneously. For example, the `name` of
  /// U+FE18 is "PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRAKCET"
  /// (note that "BRAKCET" is misspelled). The `nameAlias` property then
  /// contains the corrected name.
  ///
  /// If a scalar has no alias, this property is `nil`.
  ///
  /// This property corresponds to the "Name_Alias" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var nameAlias: String? {
    guard let nameAliasPtr = unsafe _swift_stdlib_getNameAlias(_scalar.value) else {
      return nil
    }

    return unsafe String(cString: nameAliasPtr)
  }
}

extension Unicode {

  /// The classification of a scalar used in the Canonical Ordering Algorithm
  /// defined by the Unicode Standard.
  ///
  /// Canonical combining classes are used by the ordering algorithm to
  /// determine if two sequences of combining marks should be considered
  /// canonically equivalent (that is, identical in interpretation). Two
  /// sequences are canonically equivalent if they are equal when sorting the
  /// scalars in ascending order by their combining class.
  ///
  /// For example, consider the sequence `"\u{0041}\u{0301}\u{0316}"` (LATIN
  /// CAPITAL LETTER A, COMBINING ACUTE ACCENT, COMBINING GRAVE ACCENT BELOW).
  /// The combining classes of these scalars have the numeric values 0, 230, and
  /// 220, respectively. Sorting these scalars by their combining classes yields
  /// `"\u{0041}\u{0316}\u{0301}"`, so two strings that differ only by the
  /// ordering of those scalars would compare as equal:
  ///
  ///     let aboveBeforeBelow = "\u{0041}\u{0301}\u{0316}"
  ///     let belowBeforeAbove = "\u{0041}\u{0316}\u{0301}"
  ///     print(aboveBeforeBelow == belowBeforeAbove)
  ///     // Prints "true"
  ///
  /// Named and Unnamed Combining Classes
  /// ===================================
  ///
  /// Canonical combining classes are defined in the Unicode Standard as
  /// integers in the range `0...254`. For convenience, the standard assigns
  /// symbolic names to a subset of these combining classes.
  ///
  /// The `CanonicalCombiningClass` type conforms to `RawRepresentable` with a
  /// raw value of type `UInt8`. You can create instances of the type by using
  /// the static members named after the symbolic names, or by using the
  /// `init(rawValue:)` initializer.
  ///
  ///     let overlayClass = Unicode.CanonicalCombiningClass(rawValue: 1)
  ///     let overlayClassIsOverlay = overlayClass == .overlay
  ///     // overlayClassIsOverlay == true
  public struct CanonicalCombiningClass:
    Comparable, Hashable, RawRepresentable, Sendable
  {
    /// Base glyphs that occupy their own space and do not combine with others.
    public static let notReordered = CanonicalCombiningClass(rawValue: 0)

    /// Marks that overlay a base letter or symbol.
    public static let overlay = CanonicalCombiningClass(rawValue: 1)

    /// Diacritic nukta marks in Brahmi-derived scripts.
    public static let nukta = CanonicalCombiningClass(rawValue: 7)

    /// Combining marks that are attached to hiragana and katakana to indicate
    /// voicing changes.
    public static let kanaVoicing = CanonicalCombiningClass(rawValue: 8)

    /// Diacritic virama marks in Brahmi-derived scripts.
    public static let virama = CanonicalCombiningClass(rawValue: 9)

    /// Marks attached at the bottom left.
    public static let attachedBelowLeft = CanonicalCombiningClass(rawValue: 200)

    /// Marks attached directly below.
    public static let attachedBelow = CanonicalCombiningClass(rawValue: 202)

    /// Marks attached directly above.
    public static let attachedAbove = CanonicalCombiningClass(rawValue: 214)

    /// Marks attached at the top right.
    public static let attachedAboveRight =
      CanonicalCombiningClass(rawValue: 216)

    /// Distinct marks at the bottom left.
    public static let belowLeft = CanonicalCombiningClass(rawValue: 218)

    /// Distinct marks directly below.
    public static let below = CanonicalCombiningClass(rawValue: 220)

    /// Distinct marks at the bottom right.
    public static let belowRight = CanonicalCombiningClass(rawValue: 222)

    /// Distinct marks to the left.
    public static let left = CanonicalCombiningClass(rawValue: 224)

    /// Distinct marks to the right.
    public static let right = CanonicalCombiningClass(rawValue: 226)

    /// Distinct marks at the top left.
    public static let aboveLeft = CanonicalCombiningClass(rawValue: 228)

    /// Distinct marks directly above.
    public static let above = CanonicalCombiningClass(rawValue: 230)

    /// Distinct marks at the top right.
    public static let aboveRight = CanonicalCombiningClass(rawValue: 232)

    /// Distinct marks subtending two bases.
    public static let doubleBelow = CanonicalCombiningClass(rawValue: 233)

    /// Distinct marks extending above two bases.
    public static let doubleAbove = CanonicalCombiningClass(rawValue: 234)

    /// Greek iota subscript only (U+0345 COMBINING GREEK YPOGEGRAMMENI).
    public static let iotaSubscript = CanonicalCombiningClass(rawValue: 240)

    /// The raw integer value of the canonical combining class.
    public let rawValue: UInt8

    /// Creates a new canonical combining class with the given raw integer
    /// value.
    ///
    /// - Parameter rawValue: The raw integer value of the canonical combining
    ///   class.
    public init(rawValue: UInt8) {
      self.rawValue = rawValue
    }

    public static func == (
      lhs: CanonicalCombiningClass,
      rhs: CanonicalCombiningClass
    ) -> Bool {
      return lhs.rawValue == rhs.rawValue
    }

    public static func < (
      lhs: CanonicalCombiningClass,
      rhs: CanonicalCombiningClass
    ) -> Bool {
      return lhs.rawValue < rhs.rawValue
    }

    public var hashValue: Int {
      return rawValue.hashValue
    }

    public func hash(into hasher: inout Hasher) {
      hasher.combine(rawValue)
    }
  }
}

extension Unicode.Scalar.Properties {

  /// The canonical combining class of the scalar.
  ///
  /// This property corresponds to the "Canonical_Combining_Class" property in
  /// the [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var canonicalCombiningClass: Unicode.CanonicalCombiningClass {
    let normData = Unicode._NormData(_scalar)
    return Unicode.CanonicalCombiningClass(rawValue: normData.ccc)
  }
}

extension Unicode {

  /// The numeric type of a scalar.
  ///
  /// Scalars with a non-nil numeric type include numbers, fractions, numeric
  /// superscripts and subscripts, and circled or otherwise decorated number
  /// glyphs.
  ///
  /// Some letterlike scalars used in numeric systems, such as Greek or Latin
  /// letters, do not have a non-nil numeric type, in order to prevent programs
  /// from incorrectly interpreting them as numbers in non-numeric contexts.
  public enum NumericType: Sendable {

    /// A digit that is commonly understood to form base-10 numbers.
    ///
    /// Specifically, scalars have this numeric type if they occupy a contiguous
    /// range of code points representing numeric values `0...9`.
    case decimal

    /// A digit that does not meet the requirements of the `decimal` numeric
    /// type.
    ///
    /// Scalars with this numeric type are often those that represent a decimal
    /// digit but would not typically be used to write a base-10 number, such
    /// as "④" (U+2463 CIRCLED DIGIT FOUR).
    ///
    /// As of Unicode 6.3, any new scalars that represent numbers but do not
    /// meet the requirements of `decimal` will have numeric type `numeric`,
    /// and programs can treat `digit` and `numeric` equivalently.
    case digit

    /// A digit that does not meet the requirements of the `decimal` numeric
    /// type or a non-digit numeric value.
    ///
    /// This numeric type includes fractions such as "⅕" (U+2155 VULGAR
    /// FRACTION ONE FIFTH), numerical CJK ideographs like "兆" (U+5146 CJK
    /// UNIFIED IDEOGRAPH-5146), and other scalars that are not decimal digits
    /// used positionally in the writing of base-10 numbers.
    ///
    /// As of Unicode 6.3, any new scalars that represent numbers but do not
    /// meet the requirements of `decimal` will have numeric type `numeric`,
    /// and programs can treat `digit` and `numeric` equivalently.
    case numeric

    internal init(rawValue: UInt8) {
      switch rawValue {
      case 0:
        self = .numeric
      case 1:
        self = .digit
      case 2:
        self = .decimal
      default:
        fatalError("Unknown numeric type")
      }
    }
  }
}

/// Numeric properties of scalars.
extension Unicode.Scalar.Properties {

  /// The numeric type of the scalar.
  ///
  /// For scalars that represent a number, `numericType` is the numeric type
  /// of the scalar. For all other scalars, this property is `nil`.
  ///
  ///     let scalars: [Unicode.Scalar] = ["4", "④", "⅕", "X"]
  ///     for scalar in scalars {
  ///         print(scalar, "-->", scalar.properties.numericType)
  ///     }
  ///     // 4 --> Optional(Swift.Unicode.NumericType.decimal)
  ///     // ④ --> Optional(Swift.Unicode.NumericType.digit)
  ///     // ⅕ --> Optional(Swift.Unicode.NumericType.numeric)
  ///     // X --> nil
  ///
  /// This property corresponds to the "Numeric_Type" property in the
  /// [Unicode Standard](http://www.unicode.org/versions/latest/).
  public var numericType: Unicode.NumericType? {
    let rawValue = _swift_stdlib_getNumericType(_scalar.value)

    guard rawValue != .max else {
      return nil
    }

    return Unicode.NumericType(rawValue: rawValue)
  }

  /// The numeric value of the scalar.
  ///
  /// For scalars that represent a numeric value, `numericValue` is the whole
  /// or fractional value. For all other scalars, this property is `nil`.
  ///
  ///     let scalars: [Unicode.Scalar] = ["4", "④", "⅕", "X"]
  ///     for scalar in scalars {
  ///         print(scalar, "-->", scalar.properties.numericValue)
  ///     }
  ///     // 4 --> Optional(4.0)
  ///     // ④ --> Optional(4.0)
  ///     // ⅕ --> Optional(0.2)
  ///     // X --> nil
  ///
  /// This property corresponds to the "Numeric_Value" property in the [Unicode
  /// Standard](http://www.unicode.org/versions/latest/).
  public var numericValue: Double? {
    guard numericType != nil else {
      return nil
    }

    return _swift_stdlib_getNumericValue(_scalar.value)
  }
}