9364eb1d98
* Compute instance exports on demand. Instead having instances eagerly compute a Vec of Externs, and bumping the refcount for each Extern, compute Externs on demand. This also enables `Instance::get_export` to avoid doing a linear search. This also means that the closure returned by `get0` and friends now holds an `InstanceHandle` to dynamically hold the instance live rather than being scoped to a lifetime. * Compute module imports and exports on demand too. And compute Extern::ty on demand too. * Add a utility function for computing an ExternType. * Add a utility function for looking up a function's signature. * Add a utility function for computing the ValType of a Global. * Rename wasmtime_environ::Export to EntityIndex. This helps differentiate it from other Export types in the tree, and describes what it is. * Fix a typo in a comment. * Simplify module imports and exports. * Make `Instance::exports` return the export names. This significantly simplifies the public API, as it's relatively common to need the names, and this avoids the need to do a zip with `Module::exports`. This also changes `ImportType` and `ExportType` to have public members instead of private members and accessors, as I find that simplifies the usage particularly in cases where there are temporary instances. * Remove `Instance::module`. This doesn't quite remove `Instance`'s `module` member, it gets a step closer. * Use a InstanceHandle utility function. * Don't consume self in the `Func::get*` methods. Instead, just create a closure containing the instance handle and the export for them to call. * Use `ExactSizeIterator` to avoid needing separate `num_*` methods. * Rename `Extern::func()` etc. to `into_func()` etc. * Revise examples to avoid using `nth`. * Add convenience methods to instance for getting specific extern types. * Use the convenience functions in more tests and examples. * Avoid cloning strings for `ImportType` and `ExportType`. * Remove more obviated clone() calls. * Simplify `Func`'s closure state. * Make wasmtime::Export's fields private. This makes them more consistent with ExportType. * Fix compilation error. * Make a lifetime parameter explicit, and use better lifetime names. Instead of 'me, use 'instance and 'module to make it clear what the lifetime is. * More lifetime cleanups.
1.4 KiB
1.4 KiB
WebAssembly Text Format (*.wat)
While not necessarily a full-blown language you might be curious how Wasmtime
interacts with the *.wat text format! The wasmtime CLI and Rust
embedding API both support the *.wat text format by default.
"Hello, World!" is pretty nontrivial in the *.wat format since it's
assembly-like and not really intended to be a primary programming language. That
being said we can create a simple add function to call it!
For example if you have a file add.wat like so:
(module
(func (export "add") (param i32 i32) (result i32)
local.get 0
local.get 1
i32.add))
Then you can execute this on the CLI with:
$ wasmtime add.wat --invoke add 1 2
warning: ...
warning: ...
3
And we can see that we're already adding numbers!
You can also see how this works in the Rust API like so:
# extern crate wasmtime;
# extern crate anyhow;
use wasmtime::*;
# fn main() -> anyhow::Result<()> {
let store = Store::default();
let wat = r#"
(module
(func (export "add") (param i32 i32) (result i32)
local.get 0
local.get 1
i32.add))
"#;
let module = Module::new(&store, wat)?;
let instance = Instance::new(&module, &[])?;
let add = instance.get_func("add").unwrap();
let add = add.get2::<i32, i32, i32>()?;
println!("1 + 2 = {}", add(1, 2)?);
# Ok(())
# }