wasm: add an example for wasm operator

examples/Cargo.toml

@@ -9,18 +9,24 @@ repository.workspace = true
 keywords.workspace = true
 rust-version.workspace = true
 
+[lib]
+crate-type = ["cdylib", "rlib"]
+
 [features]
 context = ["indicator/context"]
+wasm = ["wasm-bindgen", "context"]
 
 [dependencies]
 indicator = { path = "../crates/indicator", default-features = false }
+wasm-bindgen = { version = "0.2.87", optional = true }
+
+derive_more = { version = "0.99.11", features = ["as_ref", "from"] }
+num = "0.4.1"
 
 [dev-dependencies]
 anyhow = "1.0.75"
 rust_decimal.workspace = true
 rust_decimal_macros.workspace = true
-num = "0.4.1"
-derive_more = { version = "0.99.11", features = ["as_ref", "from"] }
 
 [[example]]
 name = "context"

examples/src/lib.rs

@@ -1 +1,2 @@
-
+#[cfg(feature = "wasm")]
+mod wasm;

examples/src/wasm.rs

@@ -0,0 +1,45 @@
+use indicator::prelude::*;
+use num::Num;
+use wasm_bindgen::prelude::*;
+
+#[operator(input = I, generate_out_with_data)]
+fn ma<T>(
+    #[input] x: &T,
+    #[data(as_ref?)] prev: Option<&T>,
+    #[data(as_ref)] alpha: &T,
+) -> (T, Option<T>)
+where
+    T: Num + Clone,
+{
+    let prev = prev.cloned().unwrap_or_else(|| x.clone());
+    let out = x.clone() * alpha.clone() + prev.clone() * (T::one() - alpha.clone());
+    (out.clone(), Some(out))
+}
+
+/// Wasm Ma Operator.
+#[wasm_bindgen]
+pub struct Ma(BoxOperator<'static, f64, f64>);
+
+#[wasm_bindgen]
+impl Ma {
+    pub fn new(alpha: f64) -> Self {
+        use derive_more::{AsRef, From};
+
+        #[derive(AsRef, Clone)]
+        struct Alpha(f64);
+
+        #[derive(AsRef, From)]
+        struct State(f64);
+
+        let op = insert_and_output(ma::<f64, _, State, Alpha, f64, State>)
+            .provide(Alpha(alpha))
+            .finish()
+            .boxed();
+
+        Ma(op)
+    }
+
+    pub fn next(&mut self, x: f64) -> f64 {
+        self.0.next(x)
+    }
+}

examples/wasm/README.md

@@ -0,0 +1,25 @@
+# Example: WASM Operator
+
+`indicator` supports `WebAssembly`, and here is an example for building an
+operator with `indicator` and
+[`wasm_bindgen`](https://crates.io/crates/wasm-bindgen) and compiling it to
+WebAssembly.
+
+The source code of the operator can be found [here](../src/wasm.rs).
+
+## Requirements
+
+To run this example, make sure that you have installed
+[`wasm-pack`](https://rustwasm.github.io/wasm-pack/installer/) and
+[`deno`](https://deno.com/).
+
+## Running
+
+Run the following code under the `examples/wasm` dir:
+
+```bash
+deno task run
+```
+
+It will start compiling the operator to a wasm with `wasm-pack` and run a
+`TypeScript` script that import and use it after the compilation.

examples/wasm/deno.json

@@ -0,0 +1,6 @@
+{
+    "tasks": {
+        "build": "wasm-pack build -d ./wasm/pkg -t deno ../ --features wasm",
+        "run": "deno task build && deno run -A main.ts"
+    }
+}

examples/wasm/main.ts

@@ -0,0 +1,7 @@
+import { Ma } from "./pkg/examples.js";
+
+const ma = Ma.new(0.1);
+
+for (let i = 0; i < 10; i++) {
+    console.log(ma.next(i));
+}