Struct wasmedge_sdk::Func

pub struct Func { /* private fields */ }

Defines a host function instance.

A WasmEdge Func is a wasm function instance, which is a “wrapper” of the original function (defined in either the host or the WebAssembly module) over the runtime module instance of its originating module.

Example

The following example shows how to create a host function, and invoke it with a given executor.

// If the version of rust used is less than v1.63,
// #![feature(explicit_generic_args_with_impl_trait)]

use wasmedge_sdk::{Func, Executor, params, WasmVal, error::HostFuncError, WasmValue, ValType, Caller, host_function};

// A native function to be wrapped as a host function
#[host_function]
fn real_add(_: Caller, input: Vec<WasmValue>) -> Result<Vec<WasmValue>, HostFuncError> {
    if input.len() != 2 {
        return Err(HostFuncError::User(1));
    }

    let a = if input[0].ty() == ValType::I32 {
        input[0].to_i32()
    } else {
        return Err(HostFuncError::User(2));
    };

    let b = if input[1].ty() == ValType::I32 {
        input[1].to_i32()
    } else {
        return Err(HostFuncError::User(3));
    };

    let c = a + b;
    Ok(vec![WasmValue::from_i32(c)])
}

// create a host function
let result = Func::wrap::<(i32, i32), i32>(real_add);
assert!(result.is_ok());
let func = result.unwrap();

// create an executor
let mut executor = Executor::new(None, None).unwrap();

// call the host function
let result = func.run(&mut executor, params!(2, 3));
assert!(result.is_ok());
let returns = result.unwrap();
assert_eq!(returns[0].to_i32(), 5);

[Click for more examples]

Implementations

impl Func

pub fn new(
    ty: FuncType,
    real_func: impl Fn(CallingFrame, Vec<WasmValue>) -> Result<Vec<WasmValue>, HostFuncError> + Send + Sync + 'static
) -> WasmEdgeResult<Self>

Creates a host function of the given func type.

N.B. that this function can be used in thread-safe scenarios.

Arguments

• ty - The function type.

• real_func - The native function that will be wrapped as a host function.

Error

• If fail to create a Func instance, then WasmEdgeError::Func(FuncError::Create) is returned.

pub fn wrap<Args, Rets>(
    real_func: impl Fn(CallingFrame, Vec<WasmValue>) -> Result<Vec<WasmValue>, HostFuncError> + Send + Sync + 'static
) -> WasmEdgeResult<Self>where
    Args: WasmValTypeList,
    Rets: WasmValTypeList,

Creates a host function by wrapping a native function.

N.B. that this function can be used in thread-safe scenarios.

Arguments

• real_func - The native function to be wrapped.

Error

• If fail to create a Func instance, then WasmEdgeError::Func(FuncError::Create) is returned.

pub fn wrap_async<Args, Rets>(
    real_func: impl Fn(CallingFrame, Vec<WasmValue>) -> Box<dyn Future<Output = Result<Vec<WasmValue>, HostFuncError>> + Send> + Send + Sync + 'static
) -> WasmEdgeResult<Self>where
    Args: WasmValTypeList,
    Rets: WasmValTypeList,

Creates an asynchronous host function by wrapping a native function.

N.B. that this function can be used in thread-safe scenarios.

Arguments

• real_func - The native function to be wrapped.

Error

• If fail to create a Func instance, then WasmEdgeError::Func(FuncError::Create) is returned.

pub fn name(&self) -> Option<&str>

Returns the exported name of this function.

Notice that this field is meaningful only if this host function is used as an exported instance.

pub fn mod_name(&self) -> Option<&str>

Returns the name of the module instance from which this function exports.

Notice that this field is meaningful only if this host function is used as an exported instance.

pub fn ty(&self) -> &FuncType

Returns a reference to the type of the host function.

pub fn as_ref(&self) -> FuncRef

Returns a reference to this function instance.

pub fn run(
    &self,
    executor: &Executor,
    args: impl IntoIterator<Item = WasmValue>
) -> WasmEdgeResult<Vec<WasmValue>>

Runs this host function and returns the result.

Arguments

• executor - The Executor instance.

• args - The arguments passed to the host function.

Error

If fail to run the host function, then an error is returned.

pub async fn run_async(
    &self,
    executor: &Executor,
    args: impl IntoIterator<Item = WasmValue> + Send
) -> WasmEdgeResult<Vec<WasmValue>>

Asynchronously runs this host function and returns the result.

Arguments

• executor - The Executor instance.

• args - The arguments passed to the host function.

Error

If fail to run the host function, then an error is returned.

Trait Implementations

impl Clone for Func

fn clone(&self) -> Func

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Func

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.