Bamboo Core (Rust)

A high-performance Vietnamese input method engine (IME) core written in Rust, ported from bamboo-core (Go).

Features

• Telex, VNI, VIQR input methods with custom input method support
• Hybrid engine: Rule-based transformations + Lazy JIT DFA caching
• Zero heap allocation in core processing path (stack-allocated buffers)
• O(1) backspace via snapshot stack
• O(N) single-pass spelling validation
• FFI for C/C++ integration and WASM bindings

Installation

[dependencies]
bamboo-core = "0.3.12"

Quick Start

use bamboo_core::{Engine, Mode, InputMethod};

let mut engine = Engine::new(InputMethod::telex());

let word = engine.process("tieengs", Mode::Vietnamese);
assert_eq!(word, "tiếng");

engine.reset();
let word2 = engine.process("vieetj", Mode::Vietnamese);
assert_eq!(word2, "việt");

Incremental Processing

Process keystrokes one at a time for IME integration:

use bamboo_core::{Engine, Mode, InputMethod};

let mut engine = Engine::new(InputMethod::telex());

engine.process_key('t', Mode::Vietnamese);
engine.process_key('i', Mode::Vietnamese);
engine.process_key('e', Mode::Vietnamese);
engine.process_key('e', Mode::Vietnamese);
engine.process_key('n', Mode::Vietnamese);
engine.process_key('g', Mode::Vietnamese);
engine.process_key('s', Mode::Vietnamese);
assert_eq!(engine.output(), "tiếng");

Delta Updates

For efficient text editor integration, use process_key_delta to get a 3-way diff:

use bamboo_core::{Engine, Mode, InputMethod};

let mut engine = Engine::new(InputMethod::telex());

let (bs, _, ins) = engine.process_key_delta('a', Mode::Vietnamese);
assert_eq!(bs, 0);
assert_eq!(ins, "a");

// previous = "a", new = "á"
let (bs, _, ins) = engine.process_key_delta('s', Mode::Vietnamese);
assert_eq!(bs, 1);     // delete 1 char ("a")
assert_eq!(ins, "á");  // insert "á"
// result: "" + "á" = "á"

Contract:

previous = [common_prefix] + [backspace_count chars to delete]
new      = [common_prefix] + [inserted_suffix]

Frontend does not need to compute LCP — the engine does it.

Backspace

use bamboo_core::{Engine, Mode, InputMethod};

let mut engine = Engine::new(InputMethod::telex());
engine.process_str("chuyeenr", Mode::Vietnamese);
assert_eq!(engine.output(), "chuyển");

engine.remove_last_char(true);
assert_eq!(engine.output(), "chuyên");

Output Customization

use bamboo_core::{Engine, Mode, InputMethod, OutputOptions};

let mut engine = Engine::new(InputMethod::telex());
engine.process_str("Trangws", Mode::Vietnamese);

// Toneless
assert_eq!(engine.get_processed_str(OutputOptions::TONE_LESS), "Trăng");

// Full text (committed + active)
assert_eq!(engine.get_processed_str(OutputOptions::FULL_TEXT), "Trăng");

Benchmarks

Benchmarked against uvie v2.1.1 on the same machine. Lower is better.

Core Operations

Backspace

Real-world Scenarios

Note: Bamboo's cold start (first keystroke) is slower (~17 µs vs ~1.5 µs) due to Engine + DFA allocation. After warmup, the DFA fast path dominates.

Run benchmarks: cargo bench

Credits

• Rust Port & Optimization: Dao Trong Nguyen (@nguyen10t2)
• Original Author (Go): Lam (@lamtq)
• Technical Consultant: Mai Tan Phat (@phatMT97) - Author of VKey

License

MIT. See LICENSE.