894b479213
This commit moves `wasm-bindgen` the CLI tool from internally using `parity-wasm` for wasm parsing/serialization to instead use `walrus`. The `walrus` crate is something we've been working on recently with an aim to replace the usage of `parity-wasm` in `wasm-bindgen` to make the current CLI tool more maintainable as well as more future-proof. The `walrus` crate provides a much nicer AST to work with as well as a structured `Module`, whereas `parity-wasm` provides a very raw interface to the wasm module which isn't really appropriate for our use case. The many transformations and tweaks that wasm-bindgen does have a huge amount of ad-hoc index management to carefully craft a final wasm binary, but this is all entirely taken care for us with the `walrus` crate. Additionally, `wasm-bindgen` will ingest and rewrite the wasm file, often changing the binary offsets of functions. Eventually with DWARF debug information we'll need to be sure to preserve the debug information throughout the transformations that `wasm-bindgen` does today. This is practically impossible to do with the `parity-wasm` architecture, but `walrus` was designed from the get-go to solve this problem transparently in the `walrus` crate itself. (it doesn't today, but this is planned work) It is the intention that this does not end up regressing any `wasm-bindgen` use cases, neither in functionality or in speed. As a large change and refactoring, however, it's likely that at least something will arise! We'll want to continue to remain vigilant to any issues that come up with this commit. Note that the `gc` crate has been deleted as part of this change, as the `gc` crate is no longer necessary since `walrus` does it automatically. Additionally the `gc` crate was one of the main problems with preserving debug information as it often deletes wasm items! Finally, this also starts moving crates to the 2018 edition where necessary since `walrus` requires the 2018 edition, and in general it's more pleasant to work within the 2018 edition!
wasm-bindgen
Facilitating high-level interactions between wasm modules and JavaScript.
Import JavaScript things into Rust and export Rust things to JavaScript.
extern crate wasm_bindgen;
use wasm_bindgen::prelude::*;
// Import the `window.alert` function from the Web.
#[wasm_bindgen]
extern "C" {
fn alert(s: &str);
}
// Export a `greet` function from Rust to JavaScript, that alerts a
// hello message.
#[wasm_bindgen]
pub fn greet(name: &str) {
alert(&format!("Hello, {}!", name));
}
Use exported Rust things from JavaScript with ECMAScript modules!
import { greet } from "./hello_world";
greet("World!");
Features
-
Lightweight. Only pay for what you use.
wasm-bindgenonly generates bindings and glue for the JavaScript imports you actually use and Rust functionality that you export. For example, importing and using thedocument.querySelectormethod doesn't causeNode.prototype.appendChildorwindow.alertto be included in the bindings as well. -
ECMAScript modules. Just import WebAssembly modules the same way you would import JavaScript modules. Future compatible with WebAssembly modules and ECMAScript modules integration.
-
Designed with the "host bindings" proposal in mind. Eventually, there won't be any JavaScript shims between Rust-generated wasm functions and native DOM methods. Because the wasm functions are statically type checked, some of those native methods' dynamic type checks should become unnecessary, promising to unlock even-faster-than-JavaScript DOM access.
Guide
📚 Read the wasm-bindgen guide here! 📚
API Docs
License
This project is licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Contribution
See the "Contributing" section of the guide for information on
hacking on wasm-bindgen!
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.