Skip to content
WABT bindings for Rust
Rust C++
Branch: master
Clone or download

Latest commit

Fetching latest commit…
Cannot retrieve the latest commit at this time.

Files

Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
src
wabt-sys
.gitignore
.gitmodules
.travis.yml
Cargo.toml
LICENSE
README.md Update README (#63) Feb 4, 2020
appveyor.yml

README.md

WABT bindings for Rust

crates.io docs.rs

Rust bindings for WABT.

Usage

Add this to your Cargo.toml:

[dependencies]
wabt = "0.9.0"

Use cases

Assemble a given program in WebAssembly text format (aka wat) and translate it into binary.

extern crate wabt;
use wabt::wat2wasm;

fn main() {
    assert_eq!(
        wat2wasm("(module)").unwrap(),
        &[
            0, 97, 115, 109, // \0ASM - magic
            1, 0, 0, 0       //  0x01 - version
        ]
    );
}

or disassemble a wasm binary into the text format.

extern crate wabt;
use wabt::wasm2wat;
fn main() {
    assert_eq!(
        wasm2wat(&[
            0, 97, 115, 109, // \0ASM - magic
            1, 0, 0, 0       //    01 - version
        ]),
        Ok("(module)\n".to_owned()),
    );
}

wabt can be also used for parsing the official testsuite scripts.

use wabt::script::{ScriptParser, Command, CommandKind, Action, Value};

let wast = r#"
;; Define anonymous module with function export named `sub`.
(module
  (func (export "sub") (param $x i32) (param $y i32) (result i32)
    ;; return x - y;
    (i32.sub
      (get_local $x) (get_local $y)
    )
  )
)

;; Assert that invoking export `sub` with parameters (8, 3)
;; should return 5.
(assert_return
  (invoke "sub"
    (i32.const 8) (i32.const 3)
  )
  (i32.const 5)
)
"#;

let mut parser = ScriptParser::from_str(wast)?;
while let Some(Command { kind, .. }) = parser.next()? {
    match kind {
        CommandKind::Module { module, name } => {
            // The module is declared as annonymous.
            assert_eq!(name, None);

            // Convert the module into the binary representation and check the magic number.
            let module_binary = module.into_vec()?;
            assert_eq!(&module_binary[0..4], &[0, 97, 115, 109]);
        }
        CommandKind::AssertReturn { action, expected } => {
            assert_eq!(action, Action::Invoke {
                module: None,
                field: "sub".to_string(),
                args: vec![
                    Value::I32(8),
                    Value::I32(3)
                ],
            });
            assert_eq!(expected, vec![Value::I32(5)]);
        },
        _ => panic!("there are no other commands apart from that defined above"),
    }
}

Alternatives

You might find wat or wast crate useful if you only want to parse .wat or .wast source. The advantage of using them is that they are implemented completely in Rust. Moreover, wast among other things allows you to add your own extensions to WebAssembly text format.

For print the text representation of a wasm binary, wasmprinter can work better for you, since it is implemented completely in Rust.

You can’t perform that action at this time.