ddidderr
126da77a37
rustfmt.toml sets group_imports, imports_granularity and imports_layout, which are nightly-only; agents formatted with stable rustfmt, which ignored them. This is a formatting-only pass with `cargo +nightly fmt`. Test Plan: - cargo clippy --workspace --all-targets -- -D warnings - cargo test --workspace
500 lines
17 KiB
Rust
500 lines
17 KiB
Rust
//! Grapheme break detection (`grapheme.zig`), backed by uucode's
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//! `x.grapheme.computeGraphemeBreakNoControl` precomputed for every
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//! combination of state and break properties.
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use crate::{props::GraphemeBreakNoControl as Gb, props_table::table};
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/// State carried between sequential [`grapheme_break`] calls
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/// (`uucode.grapheme.BreakState`).
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
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#[repr(u8)]
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pub enum BreakState {
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#[default]
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Default = 0,
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RegionalIndicator,
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ExtendedPictographic,
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IndicConjunctBreakConsonant,
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IndicConjunctBreakLinker,
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}
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const ALL_STATES: [BreakState; 5] = [
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BreakState::Default,
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BreakState::RegionalIndicator,
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BreakState::ExtendedPictographic,
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BreakState::IndicConjunctBreakConsonant,
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BreakState::IndicConjunctBreakLinker,
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];
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const ALL_GB: [Gb; Gb::COUNT] = [
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Gb::Other,
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Gb::Prepend,
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Gb::RegionalIndicator,
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Gb::SpacingMark,
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Gb::L,
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Gb::V,
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Gb::T,
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Gb::Lv,
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Gb::Lvt,
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Gb::Zwj,
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Gb::Zwnj,
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Gb::ExtendedPictographic,
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Gb::EmojiModifierBase,
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Gb::EmojiModifier,
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Gb::IndicConjunctBreakExtend,
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Gb::IndicConjunctBreakLinker,
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Gb::IndicConjunctBreakConsonant,
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];
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const fn is_indic_conjunct_break_extend(gb: Gb) -> bool {
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matches!(gb, Gb::IndicConjunctBreakExtend | Gb::Zwj)
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}
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// Despite `emoji_modifier` being `extend` according to
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// GraphemeBreakProperty.txt and UAX #29 (in addition to tests in
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// GraphemeBreakTest.txt), UTS #51 states: `emoji_modifier_sequence :=
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// emoji_modifier_base emoji_modifier` in ED-13 (emoji modifier sequence) under
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// 1.4.4 (Emoji Modifiers), and: "When used alone, the default representation
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// of these modifier characters is a color swatch... To have an effect on an
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// emoji, an emoji modifier must immediately follow that base emoji
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// character." in 2.4 (Diversity). Additionally it states "Skin tone
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// modifiers and hair components should be displayed even in isolation" in
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// ED-20 (basic emoji set) under 1.4.6 (Emoji Sets). Here we decide to diverge
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// from the grapheme break spec, which is allowed under "tailored" grapheme
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// clusters.
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const fn is_extend(gb: Gb) -> bool {
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matches!(
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gb,
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Gb::Zwnj | Gb::IndicConjunctBreakExtend | Gb::IndicConjunctBreakLinker
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)
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}
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const fn is_extended_pictographic(gb: Gb) -> bool {
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matches!(gb, Gb::ExtendedPictographic | Gb::EmojiModifierBase)
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}
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/// Port of uucode `x.grapheme.computeGraphemeBreakNoControl`: the rules for
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/// `control`, `cr`, and `lf` are ignored, since they are assumed to have been
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/// handled prior or stripped from the input.
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#[must_use]
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pub const fn compute_grapheme_break_no_control(gb1: Gb, gb2: Gb, state: &mut BreakState) -> bool {
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// Set state back to default when `gb1` or `gb2` is not expected in sequence.
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match *state {
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BreakState::RegionalIndicator => {
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if !matches!(gb1, Gb::RegionalIndicator) || !matches!(gb2, Gb::RegionalIndicator) {
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*state = BreakState::Default;
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}
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}
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BreakState::ExtendedPictographic => {
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if !matches!(
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gb1,
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Gb::IndicConjunctBreakExtend
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| Gb::IndicConjunctBreakLinker
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| Gb::Zwnj
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| Gb::Zwj
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| Gb::ExtendedPictographic
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| Gb::EmojiModifierBase
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| Gb::EmojiModifier
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) {
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*state = BreakState::Default;
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}
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if !matches!(
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gb2,
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Gb::IndicConjunctBreakExtend
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| Gb::IndicConjunctBreakLinker
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| Gb::Zwnj
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| Gb::Zwj
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| Gb::ExtendedPictographic
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| Gb::EmojiModifierBase
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| Gb::EmojiModifier
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) {
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*state = BreakState::Default;
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}
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}
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BreakState::IndicConjunctBreakConsonant | BreakState::IndicConjunctBreakLinker => {
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if !matches!(
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gb1,
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Gb::IndicConjunctBreakConsonant
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| Gb::IndicConjunctBreakLinker
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| Gb::IndicConjunctBreakExtend
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| Gb::Zwj
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) {
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*state = BreakState::Default;
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}
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if !matches!(
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gb2,
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Gb::IndicConjunctBreakConsonant
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| Gb::IndicConjunctBreakLinker
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| Gb::IndicConjunctBreakExtend
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| Gb::Zwj
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) {
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*state = BreakState::Default;
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}
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}
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BreakState::Default => {}
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}
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// GB6: L x (L | V | LV | VT)
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if matches!(gb1, Gb::L) && matches!(gb2, Gb::L | Gb::V | Gb::Lv | Gb::Lvt) {
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return false;
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}
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// GB7: (LV | V) x (V | T)
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if matches!(gb1, Gb::Lv | Gb::V) && matches!(gb2, Gb::V | Gb::T) {
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return false;
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}
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// GB8: (LVT | T) x T
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if matches!(gb1, Gb::Lvt | Gb::T) && matches!(gb2, Gb::T) {
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return false;
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}
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// Handle GB9 (Extend | ZWJ) later, since it can also match the start of
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// GB9c (Indic) and GB11 (Emoji ZWJ)
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// GB9a: SpacingMark
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if matches!(gb2, Gb::SpacingMark) {
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return false;
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}
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// GB9b: Prepend
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if matches!(gb1, Gb::Prepend) {
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return false;
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}
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// GB9c: Indic
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if matches!(gb1, Gb::IndicConjunctBreakConsonant) {
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// start of sequence:
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if is_indic_conjunct_break_extend(gb2) {
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*state = BreakState::IndicConjunctBreakConsonant;
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return false;
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} else if matches!(gb2, Gb::IndicConjunctBreakLinker) {
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// jump straight to linker state
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*state = BreakState::IndicConjunctBreakLinker;
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return false;
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}
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// else, not an Indic sequence
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} else if matches!(*state, BreakState::IndicConjunctBreakConsonant) {
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// consonant state:
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if matches!(gb2, Gb::IndicConjunctBreakLinker) {
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// consonant -> linker transition
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*state = BreakState::IndicConjunctBreakLinker;
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return false;
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} else if is_indic_conjunct_break_extend(gb2) {
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// continue [extend]* sequence
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return false;
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}
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// Not a valid Indic sequence
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*state = BreakState::Default;
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} else if matches!(*state, BreakState::IndicConjunctBreakLinker) {
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// linker state:
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if matches!(gb2, Gb::IndicConjunctBreakLinker) || is_indic_conjunct_break_extend(gb2) {
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// continue [extend linker]* sequence
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return false;
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} else if matches!(gb2, Gb::IndicConjunctBreakConsonant) {
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// linker -> end of sequence
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*state = BreakState::Default;
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return false;
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}
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// Not a valid Indic sequence
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*state = BreakState::Default;
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}
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// GB11: Emoji ZWJ sequence and Emoji modifier sequence
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if is_extended_pictographic(gb1) {
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// start of sequence:
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if is_extend(gb2) || matches!(gb2, Gb::Zwj) {
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*state = BreakState::ExtendedPictographic;
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return false;
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}
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// The `emoji_modifier_sequence` case is described in the comment for
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// `is_extend` above, from UTS #51.
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if matches!(gb1, Gb::EmojiModifierBase) && matches!(gb2, Gb::EmojiModifier) {
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*state = BreakState::ExtendedPictographic;
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return false;
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}
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// else, not an Emoji ZWJ sequence
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} else if matches!(*state, BreakState::ExtendedPictographic) {
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// continue or end sequence:
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if (is_extend(gb1) || matches!(gb1, Gb::EmojiModifier))
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&& (is_extend(gb2) || matches!(gb2, Gb::Zwj))
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{
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// continue extend* ZWJ sequence
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return false;
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} else if matches!(gb1, Gb::Zwj) && is_extended_pictographic(gb2) {
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// ZWJ -> end of sequence
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*state = BreakState::Default;
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return false;
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}
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// Not a valid Emoji ZWJ sequence
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*state = BreakState::Default;
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}
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// GB12 and GB13: Regional Indicator
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if matches!(gb1, Gb::RegionalIndicator) && matches!(gb2, Gb::RegionalIndicator) {
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if matches!(*state, BreakState::Default) {
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*state = BreakState::RegionalIndicator;
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return false;
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}
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*state = BreakState::Default;
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return true;
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}
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// GB9: x (Extend | ZWJ)
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if is_extend(gb2) || matches!(gb2, Gb::Zwj) {
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return false;
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}
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// GB999: Otherwise, break everywhere
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true
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}
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/// Result of one table lookup: the break decision and the next state.
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#[derive(Debug, Clone, Copy)]
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struct Value {
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result: bool,
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state: BreakState,
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}
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const N_GB: usize = Gb::COUNT;
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const N_STATE: usize = 5;
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/// Precomputed lookup table for all possible permutations of state and
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/// grapheme break properties (5 states x 17 x 17 = 1445 entries).
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static PRECOMPUTE: [Value; N_STATE * N_GB * N_GB] = {
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let mut data = [Value {
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result: false,
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state: BreakState::Default,
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}; N_STATE * N_GB * N_GB];
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let mut s = 0;
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while s < N_STATE {
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let mut a = 0;
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while a < N_GB {
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let mut b = 0;
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while b < N_GB {
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let mut state = ALL_STATES[s];
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let result = compute_grapheme_break_no_control(ALL_GB[a], ALL_GB[b], &mut state);
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data[index(ALL_GB[a], ALL_GB[b], ALL_STATES[s])] = Value { result, state };
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b += 1;
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}
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a += 1;
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}
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s += 1;
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}
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data
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};
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const fn index(gb1: Gb, gb2: Gb, state: BreakState) -> usize {
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(state as usize) * N_GB * N_GB + (gb1 as usize) * N_GB + (gb2 as usize)
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}
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/// Determines if there is a grapheme break between two codepoints. This
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/// must be called sequentially maintaining the state between calls.
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///
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/// This function does NOT work with control characters. Control characters,
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/// line feeds, and carriage returns are expected to be filtered out before
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/// calling this function. This is because this function is tuned for
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/// Ghostty.
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#[inline]
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pub fn grapheme_break(cp1: u32, cp2: u32, state: &mut BreakState) -> bool {
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let t = table();
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grapheme_break_props(t.get(cp1).grapheme_break, t.get(cp2).grapheme_break, state)
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}
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/// Same as [`grapheme_break`] but with already-looked-up break properties.
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#[inline]
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pub fn grapheme_break_props(gb1: Gb, gb2: Gb, state: &mut BreakState) -> bool {
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let value = PRECOMPUTE[index(gb1, gb2, *state)];
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*state = value.state;
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value.result
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}
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#[cfg(test)]
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mod tests {
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use std::path::Path;
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use super::*;
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#[test]
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fn grapheme_break_emoji_modifier() {
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// Emoji and modifier
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{
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let mut state = BreakState::Default;
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assert!(!grapheme_break(0x261D, 0x1F3FF, &mut state));
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}
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// Non-emoji and emoji modifier
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{
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let mut state = BreakState::Default;
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assert!(grapheme_break(0x22, 0x1F3FF, &mut state));
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}
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}
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#[test]
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fn long_emoji_zwj_sequences() {
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let mut state = BreakState::Default;
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// (family: woman, woman, girl, boy)
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let cps: Vec<u32> = "\u{1F469}\u{200D}\u{1F469}\u{200D}\u{1F467}\u{200D}\u{1F466}_"
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.chars()
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.map(|c| c as u32)
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.collect();
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assert_eq!(cps[0], 0x1F469);
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for (i, pair) in cps.windows(2).enumerate() {
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let brk = grapheme_break(pair[0], pair[1], &mut state);
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// Only the break between the last emoji and `_` is a break.
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assert_eq!(brk, i == 6, "index {i}");
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}
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}
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fn breaks(s: &str) -> Vec<&str> {
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let mut out = Vec::new();
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let mut state = BreakState::Default;
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let mut start = 0;
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let mut it = s.char_indices().peekable();
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while let Some((i, c)) = it.next() {
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let end = i + c.len_utf8();
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match it.peek() {
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None => {
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out.push(&s[start..end]);
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}
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Some(&(_, n)) => {
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if grapheme_break(c as u32, n as u32, &mut state) {
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out.push(&s[start..end]);
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start = end;
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}
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}
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}
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}
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out
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}
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#[test]
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fn grapheme_clusters() {
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assert_eq!(breaks("abc"), ["a", "b", "c"]);
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// Combining mark
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assert_eq!(breaks("e\u{301}x"), ["e\u{301}", "x"]);
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// VS15 / VS16
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assert_eq!(breaks("\u{2764}\u{FE0F}x"), ["\u{2764}\u{FE0F}", "x"]);
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assert_eq!(breaks("\u{2764}\u{FE0E}x"), ["\u{2764}\u{FE0E}", "x"]);
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// Keycap
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assert_eq!(breaks("1\u{FE0F}\u{20E3}2"), ["1\u{FE0F}\u{20E3}", "2"]);
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// Skin tone and ZWJ with rocket
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assert_eq!(breaks("👩🏽🚀🇨🇭👨🏻🍼"), ["👩🏽🚀", "🇨🇭", "👨🏻🍼"]);
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// Sequence of regional indicators: pairs.
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assert_eq!(
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breaks("\u{1F1FA}\u{1F1F8}\u{1F1E6}\u{1F1F9}\u{1F1FC}_\u{1F1F3}_"),
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[
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"\u{1F1FA}\u{1F1F8}",
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"\u{1F1E6}\u{1F1F9}",
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"\u{1F1FC}",
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"_",
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"\u{1F1F3}",
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"_"
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]
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);
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// Kiss: man, man, light skin tone, dark skin tone (with modifiers).
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assert_eq!(
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breaks(
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"\u{1F468}\u{1F3FB}\u{200D}\u{2764}\u{FE0F}\u{200D}\u{1F48B}\u{200D}\u{1F468}\u{1F3FF}_"
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),
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[
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"\u{1F468}\u{1F3FB}\u{200D}\u{2764}\u{FE0F}\u{200D}\u{1F48B}\u{200D}\u{1F468}\u{1F3FF}",
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"_"
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]
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);
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// Lone emoji modifier after non-base breaks.
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assert_eq!(breaks("a\u{1F3FB}"), ["a", "\u{1F3FB}"]);
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// Hangul syllable sequence L V T
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assert_eq!(
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breaks("\u{1100}\u{1161}\u{11A8}"),
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["\u{1100}\u{1161}\u{11A8}"]
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);
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// Prepend
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assert_eq!(breaks("\u{0600}a"), ["\u{0600}a"]);
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// Devanagari conjunct (GB9c): KA + virama + SSA
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assert_eq!(
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breaks("\u{0915}\u{094D}\u{0937}"),
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["\u{0915}\u{094D}\u{0937}"]
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);
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// Devanagari no virama: break
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assert_eq!(breaks("\u{0915}\u{0937}"), ["\u{0915}", "\u{0937}"]);
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}
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/// Runs the official GraphemeBreakTest.txt (with controls skipped and the
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/// emoji-modifier tailoring applied, as in uucode's own test).
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#[test]
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fn grapheme_break_test_txt() {
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let path =
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Path::new(env!("CARGO_MANIFEST_DIR")).join("ucd/auxiliary/GraphemeBreakTest.txt");
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let content = std::fs::read_to_string(path).unwrap();
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let t = table();
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let mut checked = 0;
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'lines: for (ln, line) in content.lines().enumerate() {
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let line = line.split('#').next().unwrap().trim();
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if line.is_empty() {
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continue;
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}
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let mut toks = line.split(' ');
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assert_eq!(toks.next(), Some("÷"));
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// Tokens: cp op cp op cp ... op(÷)
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let mut cps = Vec::new();
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let mut ops = Vec::new();
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while let Some(cp) = toks.next() {
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cps.push(u32::from_str_radix(cp, 16).unwrap());
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ops.push(toks.next().unwrap());
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}
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assert_eq!(*ops.last().unwrap(), "÷");
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// Skip lines with control/CR/LF (their break property was folded
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// into `other`; handled by the caller in Ghostty).
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for &cp in &cps {
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if cp == 0x0D
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|| cp == 0x0A
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|| (cp < 0x20)
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|| (0x7F..0xA0).contains(&cp)
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|| [0x2028, 0x2029].contains(&cp)
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|| is_gb_control(cp)
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{
|
|
continue 'lines;
|
|
}
|
|
}
|
|
let mut state = BreakState::Default;
|
|
for i in 0..cps.len() - 1 {
|
|
let gb1 = t.get(cps[i]).grapheme_break;
|
|
let gb2 = t.get(cps[i + 1]).grapheme_break;
|
|
let mut expected = ops[i] == "÷";
|
|
// Ghostty/uucode diverge from UAX #29 for emoji modifiers.
|
|
if gb2 == Gb::EmojiModifier && gb1 != Gb::EmojiModifierBase {
|
|
assert!(!expected);
|
|
expected = true;
|
|
}
|
|
let actual = grapheme_break(cps[i], cps[i + 1], &mut state);
|
|
assert_eq!(actual, expected, "line {} idx {i}: {line}", ln + 1);
|
|
checked += 1;
|
|
}
|
|
}
|
|
assert!(checked > 800, "checked {checked}");
|
|
}
|
|
|
|
/// Codepoints whose original Grapheme_Cluster_Break is Control.
|
|
fn is_gb_control(cp: u32) -> bool {
|
|
// Cc, Zl/Zp, and format characters (excluding ZWNJ/ZWJ and prepend)
|
|
// that are `Control` in GraphemeBreakProperty.txt.
|
|
matches!(cp, 0x00AD | 0x061C | 0x180E | 0x200B | 0x200E | 0x200F | 0x202A..=0x202E | 0x2060..=0x206F | 0xFEFF | 0xFFF0..=0xFFFB | 0x13430..=0x1343F | 0x1BCA0..=0x1BCA3 | 0x1D173..=0x1D17A | 0xE0000..=0xE001F | 0xE0080..=0xE00FF | 0xE01F0..=0xE0FFF)
|
|
}
|
|
|
|
#[test]
|
|
fn precompute_matches_compute() {
|
|
for &s in &ALL_STATES {
|
|
for &a in &ALL_GB {
|
|
for &b in &ALL_GB {
|
|
let mut s1 = s;
|
|
let r1 = compute_grapheme_break_no_control(a, b, &mut s1);
|
|
let mut s2 = s;
|
|
let r2 = grapheme_break_props(a, b, &mut s2);
|
|
assert_eq!((r1, s1), (r2, s2));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|