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/*
* Example from
* https://docs.rs/wasmtime/latest/wasmtime/component/macro.bindgen.html
*/
use wasmtime::component::*;
use wasmtime::{Config, Engine, Store};
bindgen!();
struct MyState {
name: String,
}
// Imports into the world, like the `name` import for this world, are satisfied
// through traits.
impl HelloWorldImports for MyState {
// Note the `Result` return value here where `Ok` is returned back to
// the component and `Err` will raise a trap.
fn name(&mut self) -> wasmtime::Result<String> {
Ok(self.name.clone())
}
}
fn main() -> wasmtime::Result<()> {
// Configure an `Engine` and compile the `Component` that is being run for
// the application.
let mut config = Config::new();
config.wasm_component_model(true);
let engine = Engine::new(&config)?;
let component = Component::from_file(&engine,
"component/hello_world-component.wasm")?;
// Instantiation of bindings always happens through a `Linker`.
// Configuration of the linker is done through a generated `add_to_linker`
// method on the bindings structure.
//
// Note that the closure provided here is a projection from `T` in
// `Store<T>` to `&mut U` where `U` implements the `HelloWorldImports`
// trait. In this case the `T`, `MyState`, is stored directly in the
// structure so no projection is necessary here.
let mut linker = Linker::new(&engine);
HelloWorld::add_to_linker(&mut linker, |state: &mut MyState| state)?;
// As with the core wasm API of Wasmtime instantiation occurs within a
// `Store`. The bindings structure contains an `instantiate` method which
// takes the store, component, and linker. This returns the `bindings`
// structure which is an instance of `HelloWorld` and supports typed access
// to the exports of the component.
let mut store = Store::new(
&engine,
MyState {
name: "me".to_string(),
},
);
let (bindings, _) = HelloWorld::instantiate(&mut store, &component, &linker)?;
// Here our `greet` function doesn't take any parameters for the component,
// but in the Wasmtime embedding API the first argument is always a `Store`.
bindings.call_greet(&mut store)?;
Ok(())
}
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