Struct wasmedge_sdk::ImportObjectBuilder

pub struct ImportObjectBuilder { /* private fields */ }

Creates a normal or wasi import object.

Example

This example shows how to create a normal import object that contains a host function, a global variable, a memory and a table. The import object is named “extern”.

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

use wasmedge_sdk::{
    types::Val,
    Global, ImportObjectBuilder, Memory, Table,
    error::HostFuncError, WasmValue, GlobalType,
    MemoryType, Mutability, RefType, TableType,
    ValType, Caller, host_function,
};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // a native function to be imported as host function
    #[host_function]
    fn real_add(_: Caller, inputs: Vec<WasmValue>) -> std::result::Result<Vec<WasmValue>, HostFuncError> {
        if inputs.len() != 2 {
            return Err(HostFuncError::User(1));
        }

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

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

        let c = a + b;

        Ok(vec![WasmValue::from_i32(c)])
    }

    // create a Const global instance to be imported
    let global_const = Global::new(
        GlobalType::new(ValType::F32, Mutability::Const),
        Val::F32(3.5),
    )?;

    // create a memory instance to be imported
    let memory = Memory::new(MemoryType::new(10, Some(20), false)?)?;

    // create a table instance to be imported
    let table = Table::new(TableType::new(RefType::FuncRef, 10, Some(20)))?;

    // create an import object
    let module_name = "extern";
    let _import = ImportObjectBuilder::new()
        // add a function
        .with_func::<(i32, i32), i32>("add", real_add)?
        // add a global
        .with_global("global", global_const)?
        // add a memory
        .with_memory("memory", memory)?
        // add a table
        .with_table("table", table)?
        .build(module_name)?;

    Ok(())
}

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Implementations

impl ImportObjectBuilder

pub fn new() -> Self

Creates a new ImportObjectBuilder.

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

Adds a host function to the ImportObject to create.

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

Arguments

• name - The exported name of the host function to add.

• real_func - The native function.

error

If fail to create or add the host function, then an error is returned.

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

Adds a host function to the ImportObject to create.

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

Arguments

• name - The exported name of the host function to add.

• ty - The function type.

• real_func - The native function.

error

If fail to create or add the host function, then an error is returned.

pub fn with_func_async<Args, Rets>(
    self,
    name: impl AsRef<str>,
    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,

Adds an async host function to the ImportObject to create.

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

Arguments

• name - The exported name of the host function to add.

• real_func - The native function.

error

If fail to create or add the host function, then an error is returned.

pub fn with_global(
    self,
    name: impl AsRef<str>,
    global: Global
) -> WasmEdgeResult<Self>

Adds a global to the ImportObject to create.

Arguments

• name - The exported name of the global to add.

• global - The wasm global instance to add.

Error

If fail to create or add the global, then an error is returned.

pub fn with_memory(
    self,
    name: impl AsRef<str>,
    memory: Memory
) -> WasmEdgeResult<Self>

Adds a memory to the ImportObject to create.

Arguments

• name - The exported name of the memory to add.

• memory - The wasm memory instance to add.

Error

If fail to create or add the memory, then an error is returned.

pub fn with_table(
    self,
    name: impl AsRef<str>,
    table: Table
) -> WasmEdgeResult<Self>

Adds a table to the ImportObject to create.

Arguments

• name - The exported name of the table to add.

• table - The wasm table instance to add.

Error

If fail to create or add the table, then an error is returned.

pub fn build(self, name: impl AsRef<str>) -> WasmEdgeResult<ImportObject>

Creates a new ImportObject.

Argument

• name - The name of the ImportObject to create.

Error

If fail to create the ImportObject, then an error is returned.

Trait Implementations

impl Debug for ImportObjectBuilder

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

Formats the value using the given formatter.

impl Default for ImportObjectBuilder

fn default() -> ImportObjectBuilder

Returns the “default value” for a type.