mirror of
https://github.com/fluencelabs/wasm-bindgen
synced 2025-05-14 14:51:20 +00:00
3efe51eb8b
This commit is a large-ish scale reorganization of our examples. The main goal here is to have a dedicated section of the guide for example, and all examples will be listed there. Each example's `README` is now just boilerplate pointing at the guide along with a blurb about how to run it. Some examples like `math` and `smorgasboard` have been deleted as they didn't really serve much purpose, and others like `closures` have been rewritten with `web-sys` instead of hand-bound bindings. Overall it's hoped that this puts us in a good and consistent state for our examples, with all of them being described in the guide, excerpts are in the guide, and they're all relatively idiomatically using `web-sys`.
58 lines
1.9 KiB
Rust
58 lines
1.9 KiB
Rust
extern crate wasm_bindgen;
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extern crate js_sys;
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use wasm_bindgen::prelude::*;
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use wasm_bindgen::JsCast;
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use js_sys::{WebAssembly, Object, Reflect, Function, Uint8Array};
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// lifted from the `console_log` example
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#[wasm_bindgen]
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extern "C" {
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#[wasm_bindgen(js_namespace = console)]
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fn log(a: &str);
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}
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macro_rules! console_log {
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($($t:tt)*) => (log(&format_args!($($t)*).to_string()))
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}
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const WASM: &[u8] = include_bytes!("add.wasm");
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#[wasm_bindgen]
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pub fn run() -> Result<(), JsValue> {
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console_log!("instantiating a new wasm module directly");
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let my_memory = wasm_bindgen::memory()
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.dyn_into::<WebAssembly::Memory>()
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.unwrap();
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// Note that this is somewhat dangerous, once we look at our
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// `WebAssembly.Memory` buffer then if we allocate more pages for ourself
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// (aka do a memory allocation in Rust) it'll cause the buffer to change.
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// That means we can't actually do any memory allocations after we do this
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// until we pass it back to JS.
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let my_memory = Uint8Array::new(&my_memory.buffer())
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.subarray(
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WASM.as_ptr() as u32,
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WASM.as_ptr() as u32 + WASM.len() as u32,
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);
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let a = WebAssembly::Module::new(my_memory.as_ref())?;
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let b = WebAssembly::Instance::new(&a, &Object::new())?;
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let c = b.exports();
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let add = Reflect::get(c.as_ref(), &"add".into())
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.dyn_into::<Function>()
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.expect("add export wasn't a function");
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let three = add.call2(&JsValue::undefined(), &1.into(), &2.into())?;
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console_log!("1 + 2 = {:?}", three);
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let mem = Reflect::get(c.as_ref(), &"memory".into())
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.dyn_into::<WebAssembly::Memory>()
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.expect("memory export wasn't a `WebAssembly.Memory`");
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console_log!("created module has {} pages of memory", mem.grow(0));
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console_log!("giving the module 4 more pages of memory");
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mem.grow(4);
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console_log!("now the module has {} pages of memory", mem.grow(0));
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Ok(())
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}
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