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diff --git a/third_party/rust/unicode-linebreak/src/shared.rs b/third_party/rust/unicode-linebreak/src/shared.rs
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+++ b/third_party/rust/unicode-linebreak/src/shared.rs
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+/// Unicode line breaking class.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+#[repr(u8)]
+pub enum BreakClass {
+    // Non-tailorable
+    /// Cause a line break (after)
+    Mandatory,
+    /// Cause a line break (after), except between CR and LF
+    CarriageReturn,
+    /// Cause a line break (after)
+    LineFeed,
+    /// Prohibit a line break between the character and the preceding character
+    CombiningMark,
+    /// Cause a line break (after)
+    NextLine,
+    /// Do not occur in well-formed text
+    Surrogate,
+    /// Prohibit line breaks before and after
+    WordJoiner,
+    /// Provide a break opportunity
+    ZeroWidthSpace,
+    /// Prohibit line breaks before and after
+    NonBreakingGlue,
+    /// Enable indirect line breaks
+    Space,
+    /// Prohibit line breaks within joiner sequences
+    ZeroWidthJoiner,
+    // Break opportunities
+    /// Provide a line break opportunity before and after the character
+    BeforeAndAfter,
+    /// Generally provide a line break opportunity after the character
+    After,
+    /// Generally provide a line break opportunity before the character
+    Before,
+    /// Provide a line break opportunity after the character, except in numeric context
+    Hyphen,
+    /// Provide a line break opportunity contingent on additional information
+    Contingent,
+    // Characters prohibiting certain breaks
+    /// Prohibit line breaks before
+    ClosePunctuation,
+    /// Prohibit line breaks before
+    CloseParenthesis,
+    /// Prohibit line breaks before
+    Exclamation,
+    /// Allow only indirect line breaks between pairs
+    Inseparable,
+    /// Allow only indirect line breaks before
+    NonStarter,
+    /// Prohibit line breaks after
+    OpenPunctuation,
+    /// Act like they are both opening and closing
+    Quotation,
+    // Numeric context
+    /// Prevent breaks after any and before numeric
+    InfixSeparator,
+    /// Form numeric expressions for line breaking purposes
+    Numeric,
+    /// Do not break following a numeric expression
+    Postfix,
+    /// Do not break in front of a numeric expression
+    Prefix,
+    /// Prevent a break before, and allow a break after
+    Symbol,
+    // Other characters
+    /// Act like AL when the resolved EAW is N; otherwise, act as ID
+    Ambiguous,
+    /// Are alphabetic characters or symbols that are used with alphabetic characters
+    Alphabetic,
+    /// Treat as NS or ID for strict or normal breaking.
+    ConditionalJapaneseStarter,
+    /// Do not break from following Emoji Modifier
+    EmojiBase,
+    /// Do not break from preceding Emoji Base
+    EmojiModifier,
+    /// Form Korean syllable blocks
+    HangulLvSyllable,
+    /// Form Korean syllable blocks
+    HangulLvtSyllable,
+    /// Do not break around a following hyphen; otherwise act as Alphabetic
+    HebrewLetter,
+    /// Break before or after, except in some numeric context
+    Ideographic,
+    /// Form Korean syllable blocks
+    HangulLJamo,
+    /// Form Korean syllable blocks
+    HangulVJamo,
+    /// Form Korean syllable blocks
+    HangulTJamo,
+    /// Keep pairs together. For pairs, break before and after other classes
+    RegionalIndicator,
+    /// Provide a line break opportunity contingent on additional, language-specific context analysis
+    ComplexContext,
+    /// Have as yet unknown line breaking behavior or unassigned code positions
+    Unknown,
+}
+
+use BreakClass::{
+    After as BA, Alphabetic as AL, Ambiguous as AI, Before as BB, BeforeAndAfter as B2,
+    CarriageReturn as CR, CloseParenthesis as CP, ClosePunctuation as CL, CombiningMark as CM,
+    ComplexContext as SA, ConditionalJapaneseStarter as CJ, Contingent as CB, EmojiBase as EB,
+    EmojiModifier as EM, Exclamation as EX, HangulLJamo as JL, HangulLvSyllable as H2,
+    HangulLvtSyllable as H3, HangulTJamo as JT, HangulVJamo as JV, HebrewLetter as HL,
+    Hyphen as HY, Ideographic as ID, InfixSeparator as IS, Inseparable as IN, LineFeed as LF,
+    Mandatory as BK, NextLine as NL, NonBreakingGlue as GL, NonStarter as NS, Numeric as NU,
+    OpenPunctuation as OP, Postfix as PO, Prefix as PR, Quotation as QU, RegionalIndicator as RI,
+    Space as SP, Surrogate as SG, Symbol as SY, Unknown as XX, WordJoiner as WJ,
+    ZeroWidthJoiner as ZWJ, ZeroWidthSpace as ZW,
+};
+
+/// Ceiling for code points in the Basic Multilingual Place (BMP).
+const BMP_LIMIT: u32 = 0x10000;
+
+/// Shift size for getting index-3 table offset.
+const SHIFT_3: u32 = 4;
+/// Shift size for getting index-2 table offset.
+const SHIFT_2: u32 = 5 + SHIFT_3;
+/// Shift size for getting index-1 table offset.
+const SHIFT_1: u32 = 5 + SHIFT_2;
+/// Shift size for getting BMP block start.
+const BMP_SHIFT: u32 = 6;
+
+const INDEX_2_BLOCK_LENGTH: u32 = 1 << (SHIFT_1 - SHIFT_2);
+const INDEX_3_BLOCK_LENGTH: u32 = 1 << (SHIFT_2 - SHIFT_3);
+const SMALL_DATA_BLOCK_LENGTH: u32 = 1 << SHIFT_3;
+const BMP_DATA_BLOCK_LENGTH: u32 = 1 << BMP_SHIFT;
+
+const ALLOWED_BREAK_BIT: u8 = 0x80;
+const MANDATORY_BREAK_BIT: u8 = 0x40;
+
+#[allow(non_upper_case_globals)]
+const eot: u8 = 43;
+#[allow(non_upper_case_globals)]
+const sot: u8 = 44;