69 lines
1.9 KiB
Rust
69 lines
1.9 KiB
Rust
//! Translation of hello example
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extern crate alloc;
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use alloc::rc::Rc;
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use anyhow::{ensure, format_err, Context as _, Result};
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use core::cell::Ref;
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use std::fs::read;
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use wasmtime_api::*;
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struct HelloCallback;
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impl Callable for HelloCallback {
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fn call(&self, _params: &[Val], _results: &mut [Val]) -> Result<(), HostRef<Trap>> {
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println!("Calling back...");
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println!("> Hello World!");
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Ok(())
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}
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}
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fn main() -> Result<()> {
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// Initialize.
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println!("Initializing...");
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let engine = HostRef::new(Engine::default());
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let store = HostRef::new(Store::new(&engine));
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// Load binary.
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println!("Loading binary...");
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let binary = read("examples/hello.wasm")?;
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// Compile.
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println!("Compiling module...");
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let module = HostRef::new(Module::new(&store, &binary).context("> Error compiling module!")?);
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// Create external print functions.
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println!("Creating callback...");
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let hello_type = FuncType::new(Box::new([]), Box::new([]));
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let hello_func = HostRef::new(Func::new(&store, hello_type, Rc::new(HelloCallback)));
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// Instantiate.
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println!("Instantiating module...");
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let imports = vec![hello_func.into()];
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let instance = HostRef::new(
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Instance::new(&store, &module, imports.as_slice())
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.context("> Error instantiating module!")?,
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);
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// Extract export.
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println!("Extracting export...");
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let exports = Ref::map(instance.borrow(), |instance| instance.exports());
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ensure!(!exports.is_empty(), "> Error accessing exports!");
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let run_func = exports[0].func().context("> Error accessing exports!")?;
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// Call.
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println!("Calling export...");
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run_func
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.borrow()
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.call(&[])
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.map_err(|e| format_err!("> Error calling function: {:?}", e))?;
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// Shut down.
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println!("Shutting down...");
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drop(store);
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// All done.
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println!("Done.");
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Ok(())
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}
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