b9dc38f4e1
This commit removes the need to use `HostRef<Engine>` in the Rust API. Usage is retained in the C API in one location, but otherwise `Engine` can always be used directly. This is the first step of progress on #708 for the `Engine` type. Changes here include: * `Engine` is now `Clone`, and is documented as being cheap. It's not intended that cloning an engine creates a deep copy. * `Engine` is now both `Send` and `Sync`, and asserted to be so. * Usage of `Engine` in APIs no longer requires or uses `HostRef`.
70 lines
1.5 KiB
Rust
70 lines
1.5 KiB
Rust
//! Example of instantiating of the WebAssembly module and
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//! invoking its exported function.
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use anyhow::{format_err, Result};
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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() -> Result<()> {
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let wasm = wat::parse_str(WAT)?;
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// Instantiate engine and store.
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let engine = Engine::default();
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let store = HostRef::new(Store::new(&engine));
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// Load a module.
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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
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.borrow()
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.call(&[Val::from(6i32), Val::from(27i32)])
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.map_err(|e| format_err!("call error: {:?}", e))?;
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println!("{:?}", result);
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Ok(())
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}
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