1 //! # Embedding API for the Component Model 2 //! 3 //! This module contains the embedding API for the [Component Model] in 4 //! Wasmtime. This module requires the `component-model` feature to be enabled, 5 //! which is enabled by default. The embedding API here is mirrored after the 6 //! core wasm embedding API at the crate root and is intended to have the same 7 //! look-and-feel while handling concepts of the component model. 8 //! 9 //! [Component Model]: https://component-model.bytecodealliance.org 10 //! 11 //! The component model is a broad topic which can't be explained here fully, so 12 //! it's recommended to read over individual items' documentation to see more 13 //! about the capabilities of the embedding API. At a high-level, however, 14 //! perhaps the most interesting items in this module are: 15 //! 16 //! * [`Component`] - a compiled component ready to be instantiated. Similar to 17 //! a [`Module`](crate::Module) for core wasm. 18 //! 19 //! * [`Linker`] - a component-style location for defining host functions. This 20 //! is not the same as [`wasmtime::Linker`](crate::Linker) for core wasm 21 //! modules. 22 //! 23 //! * [`bindgen!`] - a macro to generate Rust bindings for a [WIT] [world]. This 24 //! maps all WIT types into Rust automatically and generates traits for 25 //! embedders to implement. 26 //! 27 //! [WIT]: https://component-model.bytecodealliance.org/design/wit.html 28 //! [world]: https://component-model.bytecodealliance.org/design/worlds.html 29 //! 30 //! Embedders of the component model will typically start by defining their API 31 //! in [WIT]. This describes what will be available to guests and what needs to 32 //! be provided to the embedder by the guest. This [`world`][world] that was 33 //! created is then fed into [`bindgen!`] to generate types and traits for the 34 //! embedder to use. The embedder then implements these traits, adds 35 //! functionality via the generated `add_to_linker` method (see [`bindgen!`] for 36 //! more info), and then instantiates/executes a component. 37 //! 38 //! It's recommended to read over the [documentation for the Component 39 //! Model][Component Model] to get an overview about how to build components 40 //! from various languages. 41 //! 42 //! ## Example Usage 43 //! 44 //! Imagine you have the following WIT package definition in a file called world.wit 45 //! along with a component (my_component.wasm) that targets `my-world`: 46 //! 47 //! ```text,ignore 48 //! package component:my-package; 49 //! 50 //! world my-world { 51 //! import name: func() -> string; 52 //! export greet: func() -> string; 53 //! } 54 //! ``` 55 //! 56 //! You can instantiate and call the component like so: 57 //! 58 //! ``` 59 //! fn main() -> wasmtime::Result<()> { 60 //! # if true { return Ok(()) } 61 //! // Instantiate the engine and store 62 //! let engine = wasmtime::Engine::default(); 63 //! let mut store = wasmtime::Store::new(&engine, ()); 64 //! 65 //! // Load the component from disk 66 //! let bytes = std::fs::read("my_component.wasm")?; 67 //! let component = wasmtime::component::Component::new(&engine, bytes)?; 68 //! 69 //! // Configure the linker 70 //! let mut linker = wasmtime::component::Linker::new(&engine); 71 //! // The component expects one import `name` that 72 //! // takes no params and returns a string 73 //! linker 74 //! .root() 75 //! .func_wrap("name", |_store, _params: ()| { 76 //! Ok((String::from("Alice"),)) 77 //! })?; 78 //! 79 //! // Instantiate the component 80 //! let instance = linker.instantiate(&mut store, &component)?; 81 //! 82 //! // Call the `greet` function 83 //! let func = instance.get_func(&mut store, "greet").expect("greet export not found"); 84 //! let mut result = [wasmtime::component::Val::String("".into())]; 85 //! func.call(&mut store, &[], &mut result)?; 86 //! 87 //! // This should print out `Greeting: [String("Hello, Alice!")]` 88 //! println!("Greeting: {:?}", result); 89 //! 90 //! Ok(()) 91 //! } 92 //! ``` 93 //! 94 //! Manually configuring the linker and calling untyped component exports is 95 //! a bit tedious and error prone. The [`bindgen!`] macro can be used to 96 //! generate bindings eliminating much of this boilerplate. 97 //! 98 //! See the docs for [`bindgen!`] for more information on how to use it. 99 100 // rustdoc appears to lie about a warning above, so squelch it for now. 101 #![allow(rustdoc::redundant_explicit_links)] 102 103 mod component; 104 mod func; 105 mod instance; 106 mod linker; 107 mod matching; 108 mod resource_table; 109 mod resources; 110 mod storage; 111 mod store; 112 pub mod types; 113 mod values; 114 pub use self::component::Component; 115 pub use self::func::{ 116 ComponentNamedList, ComponentType, Func, Lift, Lower, TypedFunc, WasmList, WasmStr, 117 }; 118 pub use self::instance::{ExportInstance, Exports, Instance, InstancePre}; 119 pub use self::linker::{Linker, LinkerInstance}; 120 pub use self::resource_table::{ResourceTable, ResourceTableError}; 121 pub use self::resources::{Resource, ResourceAny}; 122 pub use self::types::{ResourceType, Type}; 123 pub use self::values::Val; 124 125 pub(crate) use self::resources::HostResourceData; 126 127 // These items are expected to be used by an eventual 128 // `#[derive(ComponentType)]`, they are not part of Wasmtime's API stability 129 // guarantees 130 #[doc(hidden)] 131 pub mod __internal { 132 pub use super::func::{ 133 bad_type_info, format_flags, lower_payload, typecheck_enum, typecheck_flags, 134 typecheck_record, typecheck_variant, ComponentVariant, LiftContext, LowerContext, 135 MaybeUninitExt, Options, 136 }; 137 pub use super::matching::InstanceType; 138 pub use crate::map_maybe_uninit; 139 pub use crate::store::StoreOpaque; 140 pub use alloc::boxed::Box; 141 pub use alloc::string::String; 142 pub use alloc::vec::Vec; 143 pub use anyhow; 144 #[cfg(feature = "async")] 145 pub use async_trait::async_trait; 146 pub use wasmtime_environ; 147 pub use wasmtime_environ::component::{CanonicalAbiInfo, ComponentTypes, InterfaceType}; 148 } 149 150 pub(crate) use self::store::ComponentStoreData; 151 152 /// Generate bindings for a [WIT world]. 153 /// 154 /// [WIT world]: https://component-model.bytecodealliance.org/design/worlds.html 155 /// [WIT package]: https://component-model.bytecodealliance.org/design/packages.html 156 /// 157 /// This macro ingests a [WIT world] and will generate all the necessary 158 /// bindings for instantiating components that ascribe to the `world`. This 159 /// provides a higher-level representation of working with a component than the 160 /// raw [`Instance`] type which must be manually-type-checked and manually have 161 /// its imports provided via the [`Linker`] type. 162 /// 163 /// The most basic usage of this macro is: 164 /// 165 /// ```rust,ignore 166 /// wasmtime::component::bindgen!(); 167 /// ``` 168 /// 169 /// This will parse your projects [WIT package] in a `wit` directory adjacent to 170 /// your crate's `Cargo.toml`. All of the `*.wit` files in that directory are 171 /// parsed and then the single `world` found will be used for bindings. 172 /// 173 /// For example if your project contained: 174 /// 175 /// ```text,ignore 176 /// // wit/my-component.wit 177 /// 178 /// package my:project; 179 /// 180 /// world hello-world { 181 /// import name: func() -> string; 182 /// export greet: func(); 183 /// } 184 /// ``` 185 /// 186 /// Then you can interact with the generated bindings like so: 187 /// 188 /// ```rust 189 /// use wasmtime::component::*; 190 /// use wasmtime::{Config, Engine, Store}; 191 /// 192 /// # const _: () = { macro_rules! bindgen { () => () } 193 /// bindgen!(); 194 /// # }; 195 /// # bindgen!({ 196 /// # inline: r#" 197 /// # package my:project; 198 /// # world hello-world { 199 /// # import name: func() -> string; 200 /// # export greet: func(); 201 /// # } 202 /// # "#, 203 /// # }); 204 /// 205 /// struct MyState { 206 /// name: String, 207 /// } 208 /// 209 /// // Imports into the world, like the `name` import for this world, are 210 /// // satisfied through traits. 211 /// impl HelloWorldImports for MyState { 212 /// // Note the `Result` return value here where `Ok` is returned back to 213 /// // the component and `Err` will raise a trap. 214 /// fn name(&mut self) -> String { 215 /// self.name.clone() 216 /// } 217 /// } 218 /// 219 /// fn main() -> wasmtime::Result<()> { 220 /// # if true { return Ok(()) } 221 /// // Configure an `Engine` and compile the `Component` that is being run for 222 /// // the application. 223 /// let mut config = Config::new(); 224 /// config.wasm_component_model(true); 225 /// let engine = Engine::new(&config)?; 226 /// let component = Component::from_file(&engine, "./your-component.wasm")?; 227 /// 228 /// // Instantiation of bindings always happens through a `Linker`. 229 /// // Configuration of the linker is done through a generated `add_to_linker` 230 /// // method on the bindings structure. 231 /// // 232 /// // Note that the closure provided here is a projection from `T` in 233 /// // `Store<T>` to `&mut U` where `U` implements the `HelloWorldImports` 234 /// // trait. In this case the `T`, `MyState`, is stored directly in the 235 /// // structure so no projection is necessary here. 236 /// let mut linker = Linker::new(&engine); 237 /// HelloWorld::add_to_linker(&mut linker, |state: &mut MyState| state)?; 238 /// 239 /// // As with the core wasm API of Wasmtime instantiation occurs within a 240 /// // `Store`. The bindings structure contains an `instantiate` method which 241 /// // takes the store, component, and linker. This returns the `bindings` 242 /// // structure which is an instance of `HelloWorld` and supports typed access 243 /// // to the exports of the component. 244 /// let mut store = Store::new( 245 /// &engine, 246 /// MyState { 247 /// name: "me".to_string(), 248 /// }, 249 /// ); 250 /// let (bindings, _) = HelloWorld::instantiate(&mut store, &component, &linker)?; 251 /// 252 /// // Here our `greet` function doesn't take any parameters for the component, 253 /// // but in the Wasmtime embedding API the first argument is always a `Store`. 254 /// bindings.call_greet(&mut store)?; 255 /// Ok(()) 256 /// } 257 /// ``` 258 /// 259 /// The function signatures within generated traits and on generated exports 260 /// match the component-model signatures as specified in the WIT `world` item. 261 /// Note that WIT also has support for importing and exports interfaces within 262 /// worlds, which can be bound here as well: 263 /// 264 /// For example this WIT input 265 /// 266 /// ```text,ignore 267 /// // wit/my-component.wit 268 /// 269 /// package my:project; 270 /// 271 /// interface host { 272 /// gen-random-integer: func() -> u32; 273 /// sha256: func(bytes: list<u8>) -> string; 274 /// } 275 /// 276 /// world hello-world { 277 /// import host; 278 /// 279 /// export demo: interface { 280 /// run: func(); 281 /// } 282 /// } 283 /// ``` 284 /// 285 /// Then you can interact with the generated bindings like so: 286 /// 287 /// ```rust 288 /// use wasmtime::component::*; 289 /// use wasmtime::{Config, Engine, Store}; 290 /// use my::project::host::Host; 291 /// 292 /// # const _: () = { macro_rules! bindgen { () => () } 293 /// bindgen!(); 294 /// # }; 295 /// # bindgen!({ 296 /// # inline: r#" 297 /// # package my:project; 298 /// # 299 /// # interface host { 300 /// # gen-random-integer: func() -> u32; 301 /// # sha256: func(bytes: list<u8>) -> string; 302 /// # } 303 /// # 304 /// # world hello-world { 305 /// # import host; 306 /// # 307 /// # export demo: interface { 308 /// # run: func(); 309 /// # } 310 /// # } 311 /// # "#, 312 /// # }); 313 /// 314 /// struct MyState { 315 /// // ... 316 /// } 317 /// 318 /// // Note that the trait here is per-interface and within a submodule now. 319 /// impl Host for MyState { 320 /// fn gen_random_integer(&mut self) -> u32 { 321 /// # panic!(); 322 /// # #[cfg(FALSE)] 323 /// rand::thread_rng().gen() 324 /// } 325 /// 326 /// fn sha256(&mut self, bytes: Vec<u8>) -> String { 327 /// // ... 328 /// # panic!() 329 /// } 330 /// } 331 /// 332 /// fn main() -> wasmtime::Result<()> { 333 /// # if true { return Ok(()) } 334 /// let mut config = Config::new(); 335 /// config.wasm_component_model(true); 336 /// let engine = Engine::new(&config)?; 337 /// let component = Component::from_file(&engine, "./your-component.wasm")?; 338 /// 339 /// let mut linker = Linker::new(&engine); 340 /// HelloWorld::add_to_linker(&mut linker, |state: &mut MyState| state)?; 341 /// 342 /// let mut store = Store::new( 343 /// &engine, 344 /// MyState { /* ... */ }, 345 /// ); 346 /// let (bindings, _) = HelloWorld::instantiate(&mut store, &component, &linker)?; 347 /// 348 /// // Note that the `demo` method returns a `&Demo` through which we can 349 /// // run the methods on that interface. 350 /// bindings.demo().call_run(&mut store)?; 351 /// Ok(()) 352 /// } 353 /// ``` 354 /// 355 /// The generated bindings can additionally be explored more fully with `cargo 356 /// doc` to see what types and traits and such are generated. 357 /// 358 /// # Syntax 359 /// 360 /// This procedural macro accepts a few different syntaxes. The primary purpose 361 /// of this macro is to locate a WIT package, parse it, and then extract a 362 /// `world` from the parsed package. There are then codegen-specific options to 363 /// the bindings themselves which can additionally be specified. 364 /// 365 /// Usage of this macro looks like: 366 /// 367 /// ```rust,ignore 368 /// // Parse the `wit/` folder adjacent to this crate's `Cargo.toml` and look 369 /// // for a single `world` in it. There must be exactly one for this to 370 /// // succeed. 371 /// bindgen!(); 372 /// 373 /// // Parse the `wit/` folder adjacent to this crate's `Cargo.toml` and look 374 /// // for the world `foo` contained in it. 375 /// bindgen!("foo"); 376 /// 377 /// // Parse the folder `other/wit/folder` adjacent to `Cargo.toml`. 378 /// bindgen!(in "other/wit/folder"); 379 /// bindgen!("foo" in "other/wit/folder"); 380 /// 381 /// // Parse the file `foo.wit` as a single-file WIT package with no 382 /// // dependencies. 383 /// bindgen!("foo" in "foo.wit"); 384 /// ``` 385 /// 386 /// A more configured version of invoking this macro looks like: 387 /// 388 /// ```rust,ignore 389 /// bindgen!({ 390 /// world: "foo", // not needed if `path` has one `world` 391 /// 392 /// // same as in `bindgen!(in "other/wit/folder") 393 /// path: "other/wit/folder", 394 /// 395 /// // Instead of `path` the WIT document can be provided inline if 396 /// // desired. 397 /// inline: " 398 /// package my:inline; 399 /// 400 /// world foo { 401 /// // ... 402 /// } 403 /// ", 404 /// 405 /// // Add calls to `tracing::span!` before each import or export is called 406 /// // to log arguments and return values. 407 /// // 408 /// // This option defaults to `false`. 409 /// tracing: true, 410 /// 411 /// // Imports will be async functions through #[async_trait] and exports 412 /// // are also invoked as async functions. Requires `Config::async_support` 413 /// // to be `true`. 414 /// // 415 /// // Note that this is only async for the host as the guest will still 416 /// // appear as if it's invoking blocking functions. 417 /// // 418 /// // This option defaults to `false`. 419 /// async: true, 420 /// 421 /// // Alternative mode of async configuration where this still implies 422 /// // async instantiation happens, for example, but more control is 423 /// // provided over which imports are async and which aren't. 424 /// // 425 /// // Note that in this mode all exports are still async. 426 /// async: { 427 /// // All imports are async except for functions with these names 428 /// except_imports: ["foo", "bar"], 429 /// 430 /// // All imports are synchronous except for functions with these names 431 /// // 432 /// // Note that this key cannot be specified with `except_imports`, 433 /// // only one or the other is accepted. 434 /// only_imports: ["foo", "bar"], 435 /// }, 436 /// 437 /// // This option is used to indicate whether imports can trap. 438 /// // 439 /// // Imports that may trap have their return types wrapped in 440 /// // `wasmtime::Result<T>` where the `Err` variant indicates that a 441 /// // trap will be raised in the guest. 442 /// // 443 /// // By default imports cannot trap and the return value is the return 444 /// // value from the WIT bindings itself. This value can be set to `true` 445 /// // to indicate that any import can trap. This value can also be set to 446 /// // an array-of-strings to indicate that only a set list of imports 447 /// // can trap. 448 /// trappable_imports: false, // no imports can trap (default) 449 /// // trappable_imports: true, // all imports can trap 450 /// // trappable_imports: ["foo", "bar"], // only these can trap 451 /// 452 /// // This can be used to translate WIT return values of the form 453 /// // `result<T, error-type>` into `Result<T, RustErrorType>` in Rust. 454 /// // Users must define `RustErrorType` and the `Host` trait for the 455 /// // interface which defines `error-type` will have a method 456 /// // called `convert_error_type` which converts `RustErrorType` 457 /// // into `wasmtime::Result<ErrorType>`. This conversion can either 458 /// // return the raw WIT error (`ErrorType` here) or a trap. 459 /// // 460 /// // By default this option is not specified. This option only takes 461 /// // effect when `trappable_imports` is set for some imports. 462 /// trappable_error_type: { 463 /// "wasi:io/streams/stream-error" => RustErrorType, 464 /// }, 465 /// 466 /// // All generated bindgen types are "owned" meaning types like `String` 467 /// // are used instead of `&str`, for example. This is the default and 468 /// // ensures that the same type used in both imports and exports uses the 469 /// // same generated type. 470 /// ownership: Owning, 471 /// 472 /// // Alternative to `Owning` above where borrowed types attempt to be used 473 /// // instead. The `duplicate_if_necessary` configures whether duplicate 474 /// // Rust types will be generated for the same WIT type if necessary, for 475 /// // example when a type is used both as an import and an export. 476 /// ownership: Borrowing { 477 /// duplicate_if_necessary: true 478 /// }, 479 /// 480 /// // Restrict the code generated to what's needed for the interface 481 /// // imports in the inlined WIT document fragment. 482 /// interfaces: " 483 /// import wasi:cli/command; 484 /// ", 485 /// 486 /// // Remap imported interfaces or resources to types defined in Rust 487 /// // elsewhere. Using this option will prevent any code from being 488 /// // generated for interfaces mentioned here. Resources named here will 489 /// // not have a type generated to represent the resource. 490 /// // 491 /// // Interfaces mapped with this option should be previously generated 492 /// // with an invocation of this macro. Resources need to be mapped to a 493 /// // Rust type name. 494 /// with: { 495 /// // This can be used to indicate that entire interfaces have 496 /// // bindings generated elsewhere with a path pointing to the 497 /// // bindinges-generated module. 498 /// "wasi:random/random": wasmtime_wasi::bindings::random::random, 499 /// 500 /// // Similarly entire packages can also be specified. 501 /// "wasi:cli": wasmtime_wasi::bindings::cli, 502 /// 503 /// // Or, if applicable, entire namespaces can additionally be mapped. 504 /// "wasi": wasmtime_wasi::bindings, 505 /// 506 /// // Versions are supported if multiple versions are in play: 507 /// "wasi:http/types@0.2.0": wasmtime_wasi_http::bindings::http::types, 508 /// "wasi:[email protected]": wasmtime_wasi_http::bindings::http, 509 /// 510 /// // The `with` key can also be used to specify the `T` used in 511 /// // import bindings of `Resource<T>`. This can be done to configure 512 /// // which typed resource shows up in generated bindings and can be 513 /// // useful when working with the typed methods of `ResourceTable`. 514 /// "wasi:filesystem/types/descriptor": MyDescriptorType, 515 /// }, 516 /// 517 /// // Addtional derive attributes to include on generated types (structs or enums). 518 /// // 519 /// // These are deduplicated and attached in a deterministic order. 520 /// additional_derives: [ 521 /// Hash, 522 /// serde::Deserialize, 523 /// serde::Serialize, 524 /// ] 525 /// }); 526 /// ``` 527 pub use wasmtime_component_macro::bindgen; 528 529 /// Derive macro to generate implementations of the [`ComponentType`] trait. 530 /// 531 /// This derive macro can be applied to `struct` and `enum` definitions and is 532 /// used to bind either a `record`, `enum`, or `variant` in the component model. 533 /// 534 /// Note you might be looking for [`bindgen!`] rather than this macro as that 535 /// will generate the entire type for you rather than just a trait 536 /// implementation. 537 /// 538 /// This macro supports a `#[component]` attribute which is used to customize 539 /// how the type is bound to the component model. A top-level `#[component]` 540 /// attribute is required to specify either `record`, `enum`, or `variant`. 541 /// 542 /// ## Records 543 /// 544 /// `record`s in the component model correspond to `struct`s in Rust. An example 545 /// is: 546 /// 547 /// ```rust 548 /// use wasmtime::component::ComponentType; 549 /// 550 /// #[derive(ComponentType)] 551 /// #[component(record)] 552 /// struct Color { 553 /// r: u8, 554 /// g: u8, 555 /// b: u8, 556 /// } 557 /// ``` 558 /// 559 /// which corresponds to the WIT type: 560 /// 561 /// ```wit 562 /// record color { 563 /// r: u8, 564 /// g: u8, 565 /// b: u8, 566 /// } 567 /// ``` 568 /// 569 /// Note that the name `Color` here does not need to match the name in WIT. 570 /// That's purely used as a name in Rust of what to refer to. The field names 571 /// must match that in WIT, however. Field names can be customized with the 572 /// `#[component]` attribute though. 573 /// 574 /// ```rust 575 /// use wasmtime::component::ComponentType; 576 /// 577 /// #[derive(ComponentType)] 578 /// #[component(record)] 579 /// struct VerboseColor { 580 /// #[component(name = "r")] 581 /// red: u8, 582 /// #[component(name = "g")] 583 /// green: u8, 584 /// #[component(name = "b")] 585 /// blue: u8, 586 /// } 587 /// ``` 588 /// 589 /// Also note that field ordering is significant at this time and must match 590 /// WIT. 591 /// 592 /// ## Variants 593 /// 594 /// `variant`s in the component model correspond to a subset of shapes of a Rust 595 /// `enum`. Variants in the component model have a single optional payload type 596 /// which means that not all Rust `enum`s correspond to component model 597 /// `variant`s. An example variant is: 598 /// 599 /// ```rust 600 /// use wasmtime::component::ComponentType; 601 /// 602 /// #[derive(ComponentType)] 603 /// #[component(variant)] 604 /// enum Filter { 605 /// #[component(name = "none")] 606 /// None, 607 /// #[component(name = "all")] 608 /// All, 609 /// #[component(name = "some")] 610 /// Some(Vec<String>), 611 /// } 612 /// ``` 613 /// 614 /// which corresponds to the WIT type: 615 /// 616 /// ```wit 617 /// variant filter { 618 /// none, 619 /// all, 620 /// some(list<string>), 621 /// } 622 /// ``` 623 /// 624 /// The `variant` style of derive allows an optional payload on Rust `enum` 625 /// variants but it must be a single unnamed field. Variants of the form `Foo(T, 626 /// U)` or `Foo { name: T }` are not supported at this time. 627 /// 628 /// Note that the order of variants in Rust must match the order of variants in 629 /// WIT. Additionally it's likely that `#[component(name = "...")]` is required 630 /// on all Rust `enum` variants because the name currently defaults to the Rust 631 /// name which is typically UpperCamelCase whereas WIT uses kebab-case. 632 /// 633 /// ## Enums 634 /// 635 /// `enum`s in the component model correspond to C-like `enum`s in Rust. Note 636 /// that a component model `enum` does not allow any payloads so the Rust `enum` 637 /// must additionally have no payloads. 638 /// 639 /// ```rust 640 /// use wasmtime::component::ComponentType; 641 /// 642 /// #[derive(ComponentType)] 643 /// #[component(enum)] 644 /// enum Setting { 645 /// #[component(name = "yes")] 646 /// Yes, 647 /// #[component(name = "no")] 648 /// No, 649 /// #[component(name = "auto")] 650 /// Auto, 651 /// } 652 /// ``` 653 /// 654 /// which corresponds to the WIT type: 655 /// 656 /// ```wit 657 /// enum setting { 658 /// yes, 659 /// no, 660 /// auto, 661 /// } 662 /// ``` 663 /// 664 /// Note that the order of variants in Rust must match the order of variants in 665 /// WIT. Additionally it's likely that `#[component(name = "...")]` is required 666 /// on all Rust `enum` variants because the name currently defaults to the Rust 667 /// name which is typically UpperCamelCase whereas WIT uses kebab-case. 668 pub use wasmtime_component_macro::ComponentType; 669 670 /// A derive macro for generating implementations of the [`Lift`] trait. 671 /// 672 /// This macro will likely be applied in conjunction with the 673 /// [`#[derive(ComponentType)]`](macro@ComponentType) macro along the lines 674 /// of `#[derive(ComponentType, Lift)]`. This trait enables reading values from 675 /// WebAssembly. 676 /// 677 /// Note you might be looking for [`bindgen!`] rather than this macro as that 678 /// will generate the entire type for you rather than just a trait 679 /// implementation. 680 /// 681 /// At this time this derive macro has no configuration. 682 /// 683 /// ## Examples 684 /// 685 /// ```rust 686 /// use wasmtime::component::{ComponentType, Lift}; 687 /// 688 /// #[derive(ComponentType, Lift)] 689 /// #[component(record)] 690 /// struct Color { 691 /// r: u8, 692 /// g: u8, 693 /// b: u8, 694 /// } 695 /// ``` 696 pub use wasmtime_component_macro::Lift; 697 698 /// A derive macro for generating implementations of the [`Lower`] trait. 699 /// 700 /// This macro will likely be applied in conjunction with the 701 /// [`#[derive(ComponentType)]`](macro@ComponentType) macro along the lines 702 /// of `#[derive(ComponentType, Lower)]`. This trait enables passing values to 703 /// WebAssembly. 704 /// 705 /// Note you might be looking for [`bindgen!`] rather than this macro as that 706 /// will generate the entire type for you rather than just a trait 707 /// implementation. 708 /// 709 /// At this time this derive macro has no configuration. 710 /// 711 /// ## Examples 712 /// 713 /// ```rust 714 /// use wasmtime::component::{ComponentType, Lower}; 715 /// 716 /// #[derive(ComponentType, Lower)] 717 /// #[component(record)] 718 /// struct Color { 719 /// r: u8, 720 /// g: u8, 721 /// b: u8, 722 /// } 723 /// ``` 724 pub use wasmtime_component_macro::Lower; 725 726 /// A macro to generate a Rust type corresponding to WIT `flags` 727 /// 728 /// This macro generates a type that implements the [`ComponentType`], [`Lift`], 729 /// and [`Lower`] traits. The generated Rust type corresponds to the `flags` 730 /// type in WIT. 731 /// 732 /// Example usage of this looks like: 733 /// 734 /// ```rust 735 /// use wasmtime::component::flags; 736 /// 737 /// flags! { 738 /// Permissions { 739 /// #[component(name = "read")] 740 /// const READ; 741 /// #[component(name = "write")] 742 /// const WRITE; 743 /// #[component(name = "execute")] 744 /// const EXECUTE; 745 /// } 746 /// } 747 /// 748 /// fn validate_permissions(permissions: &mut Permissions) { 749 /// if permissions.contains(Permissions::EXECUTE | Permissions::WRITE) { 750 /// panic!("cannot enable both writable and executable at the same time"); 751 /// } 752 /// 753 /// if permissions.contains(Permissions::READ) { 754 /// panic!("permissions must at least contain read"); 755 /// } 756 /// } 757 /// ``` 758 /// 759 /// which corresponds to the WIT type: 760 /// 761 /// ```wit 762 /// flags permissions { 763 /// read, 764 /// write, 765 /// execute, 766 /// } 767 /// ``` 768 /// 769 /// This generates a structure which is similar to/inspired by the [`bitflags` 770 /// crate](https://crates.io/crates/bitflags). The `Permissions` structure 771 /// generated implements the [`PartialEq`], [`Eq`], [`Debug`], [`BitOr`], 772 /// [`BitOrAssign`], [`BitAnd`], [`BitAndAssign`], [`BitXor`], [`BitXorAssign`], 773 /// and [`Not`] traits - in addition to the Wasmtime-specific component ones 774 /// [`ComponentType`], [`Lift`], and [`Lower`]. 775 /// 776 /// [`BitOr`]: std::ops::BitOr 777 /// [`BitOrAssign`]: std::ops::BitOrAssign 778 /// [`BitAnd`]: std::ops::BitAnd 779 /// [`BitAndAssign`]: std::ops::BitAndAssign 780 /// [`BitXor`]: std::ops::BitXor 781 /// [`BitXorAssign`]: std::ops::BitXorAssign 782 /// [`Not`]: std::ops::Not 783 pub use wasmtime_component_macro::flags; 784