Crate wasmer_runtime

Wasmer-runtime is a library that makes embedding WebAssembly in your application easy, efficient, and safe.

How to use Wasmer-Runtime

The easiest way is to use the instantiate function to create an Instance. Then you can use call or func and then call to call an exported function safely.

Here's an example:

Given this WebAssembly:

(module
  (type $t0 (func (param i32) (result i32)))
  (func $add_one (export "add_one") (type $t0) (param $p0 i32) (result i32)
    get_local $p0
    i32.const 1
    i32.add))

compiled into wasm bytecode, we can call the exported "add_one" function:

static WASM: &'static [u8] = &[
    // The module above compiled to bytecode goes here.
    // ...
];

use wasmer_runtime::{
    instantiate,
    Value,
    imports,
    error,
    Func,
};

fn main() -> error::Result<()> {
    // We're not importing anything, so make an empty import object.
    let import_object = imports! {};

    let mut instance = instantiate(WASM, &import_object)?;

    let add_one: Func<i32, i32> = instance.func("add_one")?;

    let value = add_one.call(42)?;

    assert_eq!(value, 43);

    Ok(())
}

Additional Notes:

wasmer-runtime is built to support multiple compiler backends. Currently, we support the Singlepass, Cranelift, and LLVM compilers with the wasmer-singlepass-backend, wasmer-clif-backend, and wasmer-llvm-backend crates, respectively.

You can specify the compiler you wish to use with the [compile_with] function or use the default with the [compile] function.

Modules

cache	The cache module provides the common data structures used by compiler backends to allow serializing compiled wasm code to a binary format. The binary format can be persisted, and loaded to allow skipping compilation and fast startup.
error	The error module contains the data structures and helper functions used to implement errors that are produced and returned from the wasmer runtime.
memory	The memory module contains the implementation data structures and helper functions used to manipulate and access wasm memory.
types	Types used in the Wasm runtime and conversion functions.
units	Various unit types.
wasm	Various types exposed by the Wasmer Runtime.

Macros

func	Helper macro to create a new Func object using the provided function pointer.
imports	Generate an ImportObject safely.

Structs

Array	Array.
CodeVersion	A CodeVersion is a container for a unit of generated code for a module.
CompilerConfig	Configuration data for the compiler
Ctx	The context of the currently running WebAssembly instance.
DynFunc	A representation of an exported WebAssembly function.
Features	Controls which experimental features will be enabled. Features usually have a corresponding WebAssembly proposal.
Func	Represents a function that can be used by WebAssembly.
Global	A handle to a Wasm Global
ImportObject	All of the import data used when instantiating.
Instance	An instantiated WebAssembly module.
Item	Item.
Memory	A shared or unshared wasm linear memory.
MiddlewareChain	A container for a chain of middlewares.
Module	A compiled WebAssembly module.
StreamingCompiler	A streaming compiler which is designed to generated code for a module based on a stream of wasm parser events.
Table	Container with a descriptor and a reference to a table storage.
WasmPtr	A pointer to a Wasm item.

Enums

Backend	Enum used to select which compiler should be used to generate code.
ExceptionCode	The code of an exception.
Export	Kind of WebAssembly export.
Value	Represents a WebAssembly value.

Constants

VERSION

The current version of this crate.

Traits

Compiler
LikeNamespace	This trait represents objects that act as a namespace for imports. For example, an Instance or ImportObject could be considered namespaces that could provide imports to an instance.

Functions

compile	Compile WebAssembly binary code into a Module. This function is useful if it is necessary to compile a module before it can be instantiated (otherwise, the instantiate function should be used).
compile_with	Compile a [Module] using the provided compiler from WebAssembly binary code. This function is useful if it is necessary to a compile a module before it can be instantiated and must be used if you wish to use a different backend from the default.
compile_with_config	The same as compile but takes a CompilerConfig for the purpose of changing the compiler's behavior
compile_with_config_with	The same as compile_with_config but takes a Compiler for the purpose of changing the backend.
compiler_for_backend	Get the Compiler as a trait object for the given Backend. Returns Option because support for the requested Compiler may not be enabled by feature flags.
default_compiler	Get a single instance of the default compiler to use.
instantiate	Compile and instantiate WebAssembly code without creating a Module.
pop_code_version	Pops a CodeVersion from the current code versions.
push_code_version	Pushes a new CodeVersion to the current code versions.
validate	Perform validation as defined by the WebAssembly specification. Returns true if validation succeeded, false if validation failed.