#![doc(
html_logo_url = "https://github.com/wasmerio.png?size=200",
html_favicon_url = "https://wasmer.io/images/icons/favicon-32x32.png"
)]
#![deny(
missing_docs,
trivial_numeric_casts,
unused_extern_crates,
broken_intra_doc_links
)]
#![warn(unused_import_braces)]
#![cfg_attr(
feature = "cargo-clippy",
allow(clippy::new_without_default, vtable_address_comparisons)
)]
#![cfg_attr(
feature = "cargo-clippy",
warn(
clippy::float_arithmetic,
clippy::mut_mut,
clippy::nonminimal_bool,
clippy::option_map_unwrap_or,
clippy::option_map_unwrap_or_else,
clippy::print_stdout,
clippy::unicode_not_nfc,
clippy::use_self
)
)]
//! This crate contains the `wasmer` API. The `wasmer` API facilitates the efficient,
//! sandboxed execution of [WebAssembly (Wasm)][wasm] modules.
//!
//! Here's an example of the `wasmer` API in action:
//! ```
//! use wasmer::{Store, Module, Instance, Value, imports};
//!
//! fn main() -> anyhow::Result<()> {
//! let module_wat = r#"
//! (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))
//! "#;
//!
//! let store = Store::default();
//! let module = Module::new(&store, &module_wat)?;
//! // The module doesn't import anything, so we create an empty import object.
//! let import_object = imports! {};
//! let instance = Instance::new(&module, &import_object)?;
//!
//! let add_one = instance.exports.get_function("add_one")?;
//! let result = add_one.call(&[Value::I32(42)])?;
//! assert_eq!(result[0], Value::I32(43));
//!
//! Ok(())
//! }
//! ```
//!
//! For more examples of using the `wasmer` API, check out the
//! [wasmer examples][wasmer-examples].
//!
//! ---------
//!
//! # Table of Contents
//!
//! - [Wasm Primitives](#wasm-primitives)
//! - [Externs](#externs)
//! - [Functions](#functions)
//! - [Memories](#memories)
//! - [Globals](#globals)
//! - [Tables](#tables)
//! - [Project Layout](#project-layout)
//! - [Engines](#engines)
//! - [Compilers](#compilers)
//! - [Features](#features)
//!
//!
//! # Wasm Primitives
//! In order to make use of the power of the `wasmer` API, it's important
//! to understand the primitives around which the API is built.
//!
//! Wasm only deals with a small number of core data types, these data
//! types can be found in the [`Value`] type.
//!
//! In addition to the core Wasm types, the core types of the API are
//! referred to as "externs".
//!
//! ## Externs
//! An [`Extern`] is a type that can be imported or exported from a Wasm
//! module.
//!
//! To import an extern, simply give it a namespace and a name with the
//! [`imports`] macro:
//!
//! ```
//! # use wasmer::{imports, Function, Memory, MemoryType, Store, ImportObject};
//! # fn imports_example(store: &Store) -> ImportObject {
//! let memory = Memory::new(&store, MemoryType::new(1, None, false)).unwrap();
//! imports! {
//! "env" => {
//! "my_function" => Function::new_native(store, || println!("Hello")),
//! "memory" => memory,
//! }
//! }
//! # }
//! ```
//!
//! And to access an exported extern, see the [`Exports`] API, accessible
//! from any instance via `instance.exports`:
//!
//! ```
//! # use wasmer::{imports, Instance, Function, Memory, NativeFunc};
//! # fn exports_example(instance: &Instance) -> anyhow::Result<()> {
//! let memory = instance.exports.get_memory("memory")?;
//! let memory: &Memory = instance.exports.get("some_other_memory")?;
//! let add: NativeFunc<(i32, i32), i32> = instance.exports.get_native_function("add")?;
//! let result = add.call(5, 37)?;
//! assert_eq!(result, 42);
//! # Ok(())
//! # }
//! ```
//!
//! These are the primary types that the `wasmer` API uses.
//!
//! ### Functions
//! There are 2 types of functions in `wasmer`:
//! 1. Wasm functions
//! 2. Host functions
//!
//! A Wasm function is a function defined in a WebAssembly module that can
//! only perform computation without side effects and call other functions.
//!
//! Wasm functions take 0 or more arguments and return 0 or more results.
//! Wasm functions can only deal with the primitive types defined in
//! [`Value`].
//!
//! A Host function is any function implemented on the host, in this case in
//! Rust.
//!
//! Host functions can optionally be created with an environment that
//! implements [`WasmerEnv`]. This environment is useful for maintaining
//! host state (for example the filesystem in WASI).
//!
//! Thus WebAssembly modules by themselves cannot do anything but computation
//! on the core types in [`Value`]. In order to make them more useful we
//! give them access to the outside world with [`imports`].
//!
//! If you're looking for a sandboxed, POSIX-like environment to execute Wasm
//! in, check out the [`wasmer-wasi`][wasmer-wasi] crate for our implementation of WASI,
//! the WebAssembly System Interface.
//!
//! In the `wasmer` API we support functions which take their arguments and
//! return their results dynamically, [`Function`], and functions which
//! take their arguments and return their results statically, [`NativeFunc`].
//!
//! ### Memories
//! Memories store data.
//!
//! In most Wasm programs, nearly all data will live in a [`Memory`].
//!
//! This data can be shared between the host and guest to allow for more
//! interesting programs.
//!
//! ### Globals
//! A [`Global`] is a type that may be either mutable or immutable, and
//! contains one of the core Wasm types defined in [`Value`].
//!
//! ### Tables
//! A [`Table`] is an indexed list of items.
//!
//!
//! ## Project Layout
//!
//! The Wasmer project is divided into a number of crates, below is a dependency
//! graph with transitive dependencies removed.
//!
//!
//!
//!