6e55c543e2
* test-all: add wiggle & children, plus wasi-common, to cargo test * wiggle: add licenses, readmes, docs, cargo metadata
93 lines
3.7 KiB
Rust
93 lines
3.7 KiB
Rust
extern crate proc_macro;
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use proc_macro::TokenStream;
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use syn::parse_macro_input;
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/// This macro expands to a set of `pub` Rust modules:
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///
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/// * The `types` module contains definitions for each `typename` declared in
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/// the witx document. Type names are translated to the Rust-idiomatic
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/// CamelCase.
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///
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/// * For each `module` defined in the witx document, a Rust module is defined
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/// containing definitions for that module. Module names are teanslated to the
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/// Rust-idiomatic snake\_case.
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///
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/// * For each `@interface func` defined in a witx module, an abi-level
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/// function is generated which takes ABI-level arguments, along with a
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/// "context" struct (whose type is given by the `ctx` field in the
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/// macro invocation) and a `GuestMemory` implementation.
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///
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/// * A public "module trait" is defined (called the module name, in
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/// SnakeCase) which has a `&self` method for each function in the
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/// module. These methods takes idiomatic Rust types for each argument
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/// and return `Result<($return_types),$error_type>`
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///
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/// Arguments are provided using Rust struct value syntax.
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///
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/// * `witx` takes a list of string literal paths. Paths are relative to the
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/// CARGO_MANIFEST_DIR of the crate where the macro is invoked.
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/// * `ctx` takes a type name. This type must implement all of the module
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/// traits
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///
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/// ## Example
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///
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/// ```
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/// use wiggle_runtime::{GuestPtr, GuestErrorType};
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///
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/// /// The test witx file `arrays.witx` lives in the test directory. For a
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/// /// full-fledged example with runtime tests, see `tests/arrays.rs` and
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/// /// the rest of the files in that directory.
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/// wiggle::from_witx!({
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/// witx: ["tests/arrays.witx"],
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/// ctx: YourCtxType,
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/// });
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///
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/// /// The `ctx` type for this wiggle invocation.
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/// pub struct YourCtxType {}
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///
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/// /// `arrays.witx` contains one module called `arrays`. So, we must
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/// /// implement this one method trait for our ctx type:
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/// impl arrays::Arrays for YourCtxType {
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/// /// The arrays module has two methods, shown here.
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/// /// Note that the `GuestPtr` type comes from `wiggle_runtime`,
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/// /// whereas the witx-defined types like `Excuse` and `Errno` come
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/// /// from the `pub mod types` emitted by the `wiggle::from_witx!`
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/// /// invocation above.
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/// fn reduce_excuses(&self, _a: &GuestPtr<[GuestPtr<types::Excuse>]>)
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/// -> Result<types::Excuse, types::Errno> {
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/// unimplemented!()
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/// }
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/// fn populate_excuses(&self, _a: &GuestPtr<[GuestPtr<types::Excuse>]>)
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/// -> Result<(), types::Errno> {
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/// unimplemented!()
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/// }
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/// }
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///
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/// /// For all types used in the `Error` position of a `Result` in the module
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/// /// traits, you must implement `GuestErrorType` which tells wiggle-generated
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/// /// code how to determine if a method call has been successful, as well as
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/// /// how to translate a wiggle runtime error into an ABI-level error.
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/// impl<'a> GuestErrorType<'a> for types::Errno {
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/// type Context = YourCtxType;
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/// fn success() -> Self {
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/// unimplemented!()
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/// }
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/// fn from_error(_e: wiggle_runtime::GuestError, _c: &Self::Context) -> Self {
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/// unimplemented!()
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/// }
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/// }
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///
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/// # fn main() { println!("this fools doc tests into compiling the above outside a function body")
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/// # }
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/// ```
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#[proc_macro]
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pub fn from_witx(args: TokenStream) -> TokenStream {
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let mut config = parse_macro_input!(args as wiggle_generate::Config);
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config.witx.make_paths_relative_to(
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std::env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR env var"),
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);
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let doc = witx::load(&config.witx.paths).expect("loading witx");
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TokenStream::from(wiggle_generate::generate(&doc, &config))
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}
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