Struct JapaneseEngine 

pub struct JapaneseEngine { /* private fields */ }

JP engine. One per session. Cheap to construct — all data is in const tables in crate::romaji and crate::kanji.

Implementations

impl JapaneseEngine

pub fn new() -> Self

pub fn handle_letter(&mut self, c: u8) -> bool

Push one ASCII letter into the buffer and re-render candidates. Returns true if the letter was accepted; rejected letters leave state unchanged so the IME controller can route the byte elsewhere (locale punct mapping, raw passthrough).

Accepted bytes:

• a-z, A-Z (the romaji alphabet — lowercased on push)
• - only when the buffer is non-empty — chōonpu (ー / long-vowel mark). romaji::TABLE maps - to ー so a buffer of "koohi-" renders as コーヒー. Empty-buffer - is rejected so a stranded hyphen still routes to the host as ASCII punctuation rather than becoming a leading ー with no preceding syllable. User-reported 2026-05-27: - must be typeable as JP chōonpu, otherwise long- vowel words like コーヒー are unreachable.

pub fn backspace(&mut self) -> bool

Pop one byte off the buffer. Returns true if a byte was removed (i.e. buffer was non-empty), false if there was nothing to pop.

pub fn escape(&mut self) -> bool

Drop the buffer entirely. Returns true if something was dropped, false if buffer was already empty.

pub fn preedit(&self) -> &str

Read-only buffer view as a string (for the preedit display).

pub fn is_composing(&self) -> bool

pub fn candidates(&self) -> &[Candidate]

pub fn commit_index(&mut self, index: usize) -> Option<String>

Commit the candidate at index. Returns the committed text and clears the buffer. None if index is out of range (state unchanged).

Trait Implementations

impl Default for JapaneseEngine

fn default() -> Self

Returns the “default value” for a type.