d1b1500d19
This commit adds a `wasmtime-rust` crate to the `misc` folder next to the previously added Python extension. The intention is that this showcases loading a WebAssembly file natively in Rust and how with an attribute macro it can feel lightweight in terms of boilerplate. The macro itself is pretty non-featureful today beyond the bare bones to get anything working, but there's all sorts of possibilities like JIT-compiled entry stubs we could eventually do with all the type information!
48 lines
1.3 KiB
Rust
48 lines
1.3 KiB
Rust
pub use wasmtime_rust_macro::wasmtime;
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// modules used by the macro
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#[doc(hidden)]
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pub mod __rt {
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pub use cranelift_codegen;
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pub use cranelift_native;
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pub use failure;
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pub use wasmtime_interface_types;
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pub use wasmtime_jit;
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use std::convert::{TryFrom, TryInto};
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use wasmtime_interface_types::Value;
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pub trait FromVecValue: Sized {
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fn from(list: Vec<Value>) -> Result<Self, failure::Error>;
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}
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macro_rules! tuple {
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($(($($a:ident),*),)*) => ($(
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impl<$($a: TryFrom<Value>),*> FromVecValue for ($($a,)*)
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where $(failure::Error: From<$a::Error>,)*
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{
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#[allow(non_snake_case)]
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fn from(list: Vec<Value>) -> Result<Self, failure::Error> {
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let mut iter = list.into_iter();
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$(
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let $a = iter.next()
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.ok_or_else(|| failure::format_err!("not enough values"))?
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.try_into()?;
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)*
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if iter.next().is_some() {
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failure::format_err!("too many return values");
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}
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Ok(($($a,)*))
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}
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}
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)*)
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}
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tuple! {
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(),
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(A),
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(A, B),
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(A, B, C),
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}
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}
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