045d6a7310
* Remove the need for `HostRef<Store>` This commit goes through the public API of the `wasmtime` crate and removes the need for `HostRef<Store>`, as discussed in #708. This commit is accompanied with a few changes: * The `Store` type now also implements `Default`, creating a new `Engine` with default settings and returning that. * The `Store` type now implements `Clone`, and is documented as being a "cheap clone" aka being reference counted. As before there is no supported way to create a deep clone of a `Store`. * All APIs take/return `&Store` or `Store` instead of `HostRef<Store>`, and `HostRef<T>` is left as purely a detail of the C API. * The `global_exports` function is tagged as `#[doc(hidden)]` for now while we await its removal. * The `Store` type is not yet `Send` nor `Sync` due to the usage of `global_exports`, but it is intended to become so eventually. * Touch up comments on some examples * Run rustfmt
63 lines
1.4 KiB
Rust
63 lines
1.4 KiB
Rust
//! Example of instantiating of the WebAssembly module and
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//! invoking its exported function.
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use wasmtime::*;
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const WAT: &str = r#"
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(module
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(func $gcd (param i32 i32) (result i32)
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(local i32)
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block ;; label = @1
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block ;; label = @2
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local.get 0
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br_if 0 (;@2;)
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local.get 1
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local.set 2
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br 1 (;@1;)
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end
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loop ;; label = @2
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local.get 1
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local.get 0
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local.tee 2
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i32.rem_u
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local.set 0
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local.get 2
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local.set 1
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local.get 0
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br_if 0 (;@2;)
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end
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end
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local.get 2
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)
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(export "gcd" (func $gcd))
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)
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"#;
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fn main() -> anyhow::Result<()> {
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// Load our WebAssembly (parsed WAT in our case), and then load it into a
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// `Module` which is attached to a `Store` cache.
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let wasm = wat::parse_str(WAT)?;
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let store = Store::default();
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let module = HostRef::new(Module::new(&store, &wasm)?);
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// Find index of the `gcd` export.
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let gcd_index = module
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.borrow()
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.exports()
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.iter()
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.enumerate()
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.find(|(_, export)| export.name().to_string() == "gcd")
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.unwrap()
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.0;
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// Instantiate the module.
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let instance = Instance::new(&store, &module, &[])?;
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// Invoke `gcd` export
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let gcd = instance.exports()[gcd_index].func().expect("gcd");
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let result = gcd.borrow().call(&[Val::from(6i32), Val::from(27i32)])?;
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println!("{:?}", result);
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Ok(())
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}
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