420dcd76fd
* Don't require `Store` in `Instance` constructor This can be inferred from the `Module` argument. Additionally add a `store` accessor to an `Instance` in case it's needed to instantiate another `Module`. cc #708 * Update more constructors * Fix a doctest * Don't ignore store in `wasm_instance_new` * Run rustfmt
62 lines
1.4 KiB
Rust
62 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 = 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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.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(&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.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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