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94 lines
2.8 KiB
94 lines
2.8 KiB
//! This is an example of working with mulit-value modules and dealing with
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//! multi-value functions.
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//!
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//! Note that the `Func::wrap*` interfaces cannot be used to return multiple
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//! values just yet, so we need to use the more dynamic `Func::new` and
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//! `Func::call` methods.
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// You can execute this example with `cargo run --example multi`
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use anyhow::{format_err, Result};
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use wasmtime::*;
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fn main() -> Result<()> {
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// Configure our `Store`, but be sure to use a `Config` that enables the
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// wasm multi-value feature since it's not stable yet.
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println!("Initializing...");
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let engine = Engine::new(Config::new().wasm_multi_value(true));
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let store = Store::new(&engine);
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// Compile.
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println!("Compiling module...");
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let module = Module::from_file(&store, "examples/multi.wat")?;
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// Create external print functions.
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println!("Creating callback...");
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let callback_type = FuncType::new(
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Box::new([ValType::I32, ValType::I64]),
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Box::new([ValType::I64, ValType::I32]),
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);
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let callback_func = Func::new(&store, callback_type, |_, args, results| {
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println!("Calling back...");
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println!("> {} {}", args[0].unwrap_i32(), args[1].unwrap_i64());
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results[0] = Val::I64(args[1].unwrap_i64() + 1);
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results[1] = Val::I32(args[0].unwrap_i32() + 1);
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Ok(())
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});
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// Instantiate.
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println!("Instantiating module...");
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let instance = Instance::new(&module, &[callback_func.into()])?;
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// Extract exports.
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println!("Extracting export...");
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let g = instance
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.get_export("g")
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.and_then(|e| e.func())
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.ok_or(format_err!("failed to find export `g`"))?;
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// Call `$g`.
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println!("Calling export \"g\"...");
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let results = g.call(&[Val::I32(1), Val::I64(3)])?;
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println!("Printing result...");
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println!("> {} {}", results[0].unwrap_i64(), results[1].unwrap_i32());
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assert_eq!(results[0].unwrap_i64(), 4);
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assert_eq!(results[1].unwrap_i32(), 2);
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// Call `$round_trip_many`.
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println!("Calling export \"round_trip_many\"...");
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let round_trip_many = instance
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.get_export("round_trip_many")
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.and_then(|e| e.func())
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.ok_or(format_err!("failed to find export `round_trip_many`"))?;
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let args = vec![
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Val::I64(0),
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Val::I64(1),
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Val::I64(2),
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Val::I64(3),
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Val::I64(4),
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Val::I64(5),
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Val::I64(6),
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Val::I64(7),
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Val::I64(8),
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Val::I64(9),
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];
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let results = round_trip_many.call(&args)?;
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println!("Printing result...");
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print!(">");
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for r in results.iter() {
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print!(" {}", r.unwrap_i64());
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}
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println!();
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assert_eq!(results.len(), 10);
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assert!(args
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.iter()
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.zip(results.iter())
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.all(|(a, r)| a.i64() == r.i64()));
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Ok(())
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}
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