Struct Engine 

pub struct Engine { /* private fields */ }

The main stateful processor of the Vietnamese Input Method Engine.

It maintains an internal buffer of transformations and produces the correctly marked Vietnamese text.

Implementations

impl Engine

pub fn new(input_method: InputMethod) -> Self

Creates a new engine with the specified input method and default configuration.

pub fn with_config(input_method: InputMethod, config: Config) -> Self

Creates a new engine with a specific input method and configuration.

pub fn config(&self) -> Config

Returns the current configuration of the engine.

pub fn set_config(&mut self, config: Config)

Updates the engine configuration.

pub fn input_method(&self) -> InputMethod

Returns a copy of the current input method.

pub fn process(&mut self, s: &str, mode: Mode) -> String

Processes a string of characters and returns the current active word.

pub fn process_str(&mut self, s: &str, mode: Mode) -> &Self

Processes a string of characters and returns a reference to the engine.

pub fn process_key_delta( &mut self, key: char, mode: Mode, ) -> (usize, usize, &str)

Processes a single key and returns the “delta” change required for a text editor.

This is useful for IMEs to update the preedit text efficiently without rewriting the entire word.

Returns

A tuple containing:

1. backspaces_chars: Number of characters to delete from the end of the previous preedit.
2. backspaces_bytes: Number of UTF-8 bytes to delete.
3. inserted: The new string to append after deletion.

pub fn process_key_delta_into( &mut self, key: char, mode: Mode, inserted: &mut String, ) -> usize

Similar to Self::process_key_delta, but writes the inserted string into a provided buffer.

Returns

The number of backspaces (characters) to perform.

pub fn process_key(&mut self, key: char, mode: Mode)

Processes a single character.

The mode determines whether to apply Vietnamese transformation rules.

pub fn commit(&mut self)

Clears the active syllable buffer and appends it to the committed text.

pub fn output(&self) -> String

Returns the currently active syllable as a string.

pub fn get_processed_str(&self, options: OutputOptions) -> String

Returns the processed string according to the specified options.

This can be used to get the full text (committed + active) or variations like toneless text.

pub fn is_valid(&self, input_is_full_complete: bool) -> bool

Checks if the current composition forms a valid Vietnamese syllable.

pub fn restore_last_word(&mut self, to_vietnamese: bool)

Restores the last word in the composition to its un-transformed state.

If to_vietnamese is true, it attempts to re-apply Vietnamese transformations.

pub fn remove_last_char(&mut self, refresh_last_tone_target: bool)

Removes the last character from the active composition.

pub fn reset(&mut self)

Resets the engine state, clearing committed and active text.