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cleanup(core/example/hello_world): use Deno.core.print instead of new op (#10645)

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Aaron O'Mullan 2021-05-15 15:24:01 +02:00 committed by GitHub
parent d059f9b06e
commit 9f9a50a3e8
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1 changed files with 9 additions and 57 deletions
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66
core/examples/hello_world.rs
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@ -4,54 +4,16 @@
use deno_core::op_sync;
use deno_core::JsRuntime;
use deno_core::ZeroCopyBuf;
use std::io::Write;
fn main() {
// Initialize a runtime instance
let mut runtime = JsRuntime::new(Default::default());
// The first thing we do is define two ops. They will be used to show how to
// pass data to Rust and back to JavaScript.
//
// The first one is used to print data to stdout, because by default the
// JavaScript console functions are just stubs (they don't do anything).
//
// The second one just transforms some input and returns it to JavaScript.
// Register the op for outputting a string to stdout.
// It can be invoked with Deno.core.opcall and the id this method returns
// or Deno.core.opSync and the name provided.
runtime.register_op(
"op_print",
// The op_fn callback takes a state object OpState,
// a structured arg of type `T` and an optional ZeroCopyBuf,
// a mutable reference to a JavaScript ArrayBuffer
op_sync(
|_state, msg: Option<String>, zero_copy: Option<ZeroCopyBuf>| {
let mut out = std::io::stdout();
// Write msg to stdout
if let Some(msg) = msg {
out.write_all(msg.as_bytes()).unwrap();
}
// Write the contents of every buffer to stdout
if let Some(buf) = zero_copy {
out.write_all(&buf).unwrap();
}
Ok(()) // No meaningful result
},
),
);
// Register the JSON op for summing a number array.
// Register an op for summing a number array.
runtime.register_op(
"op_sum",
// The op_sync function automatically deserializes
// the first ZeroCopyBuf and serializes the return value
// to reduce boilerplate
// The op-layer automatically deserializes inputs
// and serializes the returned Result & value
op_sync(|_state, nums: Vec<f64>, _: ()| {
// Sum inputs
let sum = nums.iter().fold(0.0, |a, v| a + v);
@ -61,28 +23,18 @@ fn main() {
);
runtime.sync_ops_cache();
// Now we see how to invoke the ops we just defined. The runtime automatically
// Now we see how to invoke the op we just defined. The runtime automatically
// contains a Deno.core object with several functions for interacting with it.
// You can find its definition in core.js.
runtime
.execute(
"<init>",
r#"
// Define a print function that uses
// our op_print op to display the stringified argument.
const _newline = new Uint8Array([10]);
function print(value) {
Deno.core.opSync('op_print', value.toString(), _newline);
}
"#,
)
.unwrap();
// Now we can finally use this in an example.
runtime
.execute(
"<usage>",
r#"
// Print helper function, calling Deno.core.print()
function print(value) {
Deno.core.print(value.toString()+"\n");
}
const arr = [1, 2, 3];
print("The sum of");
print(arr);