wasmi 1.0.9

WebAssembly interpreter
Documentation 
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//! This submodule tests the unusual use case of calling host functions through the engine from the host side.

use wasmi::{Caller, Config, Engine, Error, Func, Linker, Module, Store};

/// Setup a new `Store` for testing with initial value of 5.
fn setup_store() -> Store<i32> {
    let config = Config::default();
    let engine = Engine::new(&config);
    Store::new(&engine, 5_i32)
}

#[test]
fn host_call_from_host_params_0_results_0() {
    let mut store = setup_store();
    let err_if_zero = Func::wrap(&mut store, |caller: Caller<i32>| {
        if *caller.data() == 0 {
            return Err(Error::new("test trap"));
        }
        Ok(())
    });
    let err_if_zero = err_if_zero.typed::<(), ()>(&mut store).unwrap();
    assert!(err_if_zero.call(&mut store, ()).is_ok());
    *store.data_mut() = 0;
    assert!(err_if_zero.call(&mut store, ()).is_err());
}

#[test]
fn host_call_from_host_params_0_results_1() {
    let mut store = setup_store();
    let data_plus_42 = Func::wrap(&mut store, |caller: Caller<i32>| caller.data() + 42_i32);
    let data_plus_42 = data_plus_42.typed::<(), i32>(&mut store).unwrap();
    assert_eq!(data_plus_42.call(&mut store, ()).unwrap(), 47_i32);
    *store.data_mut() = 10;
    assert_eq!(data_plus_42.call(&mut store, ()).unwrap(), 52_i32);
}

#[test]
fn host_call_from_host_params_2_results_1() {
    let mut store = setup_store();
    let sum_with_data = Func::wrap(&mut store, |caller: Caller<i32>, a: i32, b: i32| {
        caller.data() + a + b
    });
    let sum_with_data = sum_with_data.typed::<(i32, i32), i32>(&mut store).unwrap();
    assert_eq!(sum_with_data.call(&mut store, (1, 2)).unwrap(), 8_i32);
    *store.data_mut() = 10;
    assert_eq!(sum_with_data.call(&mut store, (10, 15)).unwrap(), 35_i32);
}

#[test]
fn host_call_from_host_params_0_results_2() {
    let mut store = setup_store();
    let get_data = Func::wrap(&mut store, |caller: Caller<i32>| {
        let data = *caller.data();
        (data + data, data * data)
    });
    let get_data = get_data.typed::<(), (i32, i32)>(&mut store).unwrap();
    assert_eq!(get_data.call(&mut store, ()).unwrap(), (10, 25));
    *store.data_mut() = 10;
    assert_eq!(get_data.call(&mut store, ()).unwrap(), (20, 100));
}

#[test]
fn host_call_from_host_params_4_results_4() {
    let mut store = setup_store();
    // Function f(D, a,b,c,d) that outputs (d+D, c+D, b+D, a+D)
    let reverse_and_add = Func::wrap(
        &mut store,
        |caller: Caller<i32>, a: i32, b: i32, c: i32, d: i32| {
            let offset = caller.data();
            (d + offset, c + offset, b + offset, a + offset)
        },
    );
    let reverse_and_add = reverse_and_add
        .typed::<(i32, i32, i32, i32), (i32, i32, i32, i32)>(&mut store)
        .unwrap();
    assert_eq!(
        reverse_and_add.call(&mut store, (1, 2, 3, 4)).unwrap(),
        (9, 8, 7, 6)
    );
    *store.data_mut() = 10;
    assert_eq!(
        reverse_and_add.call(&mut store, (40, 30, 20, 10)).unwrap(),
        (20, 30, 40, 50)
    );
}

#[test]
fn host_tail_calls_0() {
    let wasm = r#"
        (module
            (import "host" "sum_with_data" (func $sum_with_data (param i32) (result i32)))
            (func (export "test") (param i32) (result i32)
                (local.get 0)
                (return_call $sum_with_data)
            )
        )
    "#;
    let engine = Engine::default();
    let module = Module::new(&engine, wasm).unwrap();
    let mut store = Store::new(&engine, 5_i32);
    let mut linker = Linker::new(&engine);
    linker
        .func_wrap("host", "sum_with_data", |caller: Caller<i32>, a: i32| {
            caller.data() + a
        })
        .unwrap();
    let instance = linker.instantiate_and_start(&mut store, &module).unwrap();
    let test = instance
        .get_typed_func::<i32, i32>(&mut store, "test")
        .unwrap();

    assert_eq!(*store.data(), 5);
    assert_eq!(test.call(&mut store, 1).unwrap(), 1 + 5);
    *store.data_mut() = 10;
    assert_eq!(*store.data(), 10);
    assert_eq!(test.call(&mut store, 5).unwrap(), 5 + 10);
}

#[test]
fn host_tail_calls_1() {
    let wasm = r#"
        (module
            (import "host" "sum_with_data" (func $sum_with_data (param i32) (result i32)))
            (func $f (param i32) (result i32)
                (local.get 0)
                (return_call $sum_with_data)
            )
            (func (export "test") (param i32) (result i32)
                (local.get 0)
                (call $f)
            )
        )
    "#;
    let engine = Engine::default();
    let module = Module::new(&engine, wasm).unwrap();
    let mut store = Store::new(&engine, 5_i32);
    let mut linker = Linker::new(&engine);
    linker
        .func_wrap("host", "sum_with_data", |caller: Caller<i32>, a: i32| {
            caller.data() + a
        })
        .unwrap();
    let instance = linker.instantiate_and_start(&mut store, &module).unwrap();
    let test = instance
        .get_typed_func::<i32, i32>(&mut store, "test")
        .unwrap();

    assert_eq!(*store.data(), 5);
    assert_eq!(test.call(&mut store, 1).unwrap(), 1 + 5);
    *store.data_mut() = 10;
    assert_eq!(*store.data(), 10);
    assert_eq!(test.call(&mut store, 5).unwrap(), 5 + 10);
}