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// SPDX-License-Identifier: MIT OR Apache-2.0
// Copyright (c) 2026 Noyalib. All rights reserved.
//! `tokio_async`: parse a YAML stream from a Tokio `AsyncRead`
//! source with bounded buffering or a backpressured framed stream.
//!
//! Run: `cargo run --example tokio_async_reader --features tokio`
#[cfg(feature = "tokio")]
#[tokio::main(flavor = "current_thread")]
async fn main() {
use bytes::BytesMut;
use noyalib::tokio_async::{YamlDecoder, async_yaml_stream, from_async_reader_multi};
use tokio::io::BufReader;
use tokio_util::codec::Decoder as _;
#[derive(Debug, serde::Deserialize)]
struct Pkg {
name: String,
version: String,
}
let stream = b"\
---
name: noyalib
version: 0.0.6
---
name: noya-cli
version: 0.0.6
---
name: noyalib-lsp
version: 0.0.6
";
// ── Pattern 1: drain-and-parse via from_async_reader_multi ──
let mut buf_reader = BufReader::new(&stream[..]);
let docs: Vec<Pkg> = from_async_reader_multi(&mut buf_reader)
.await
.expect("parse multi");
println!("from_async_reader_multi:");
for (i, pkg) in docs.iter().enumerate() {
println!(" [{i}] {} {}", pkg.name, pkg.version);
}
// ── Pattern 2: backpressured AsyncYamlStream ──
//
// A service can consume this with its preferred compatible
// `StreamExt::next`. Reading pauses until the next item is polled.
let document_stream = async_yaml_stream::<_, Pkg>(BufReader::new(&stream[..]));
drop(document_stream);
// ── Pattern 3: lower-level YamlDecoder control ──
//
// For brevity the example feeds the whole buffer in one shot
// and drives `decode` / `decode_eof` by hand. In a real
// server you'd wrap the codec in `tokio_util::codec::FramedRead`
// and pull items via `futures::StreamExt::next` — that pulls
// in `futures-util`, which is intentionally not a noyalib dep.
let mut decoder = YamlDecoder::<Pkg>::new();
let mut buf = BytesMut::from(&stream[..]);
println!("\nYamlDecoder (manual drive):");
let mut i = 0;
while let Some(pkg) = decoder.decode(&mut buf).expect("decode") {
println!(" [{i}] {} {}", pkg.name, pkg.version);
i += 1;
}
if let Some(pkg) = decoder.decode_eof(&mut buf).expect("decode_eof") {
println!(" [{i}] {} {}", pkg.name, pkg.version);
}
// ── Pattern 4: untrusted-network frame-size cap ──
//
// Constructors derive the cap from `max_document_length`.
// Services may tighten it with `max_frame_size(usize)`; when an
// incomplete frame exceeds it, `decode` returns `Error::Io`.
let mut guarded = YamlDecoder::<Pkg>::new().max_frame_size(64);
// Stream a single doc whose first line is longer than 64 bytes
// and no `---` boundary lands inside the cap.
let oversize =
b"name: a-very-long-package-name-that-definitely-exceeds-sixty-four-bytes\nversion: '1'\n";
let mut buf = BytesMut::from(&oversize[..]);
match guarded.decode(&mut buf) {
Err(e) => println!("\nmax_frame_size(64) rejected the oversize frame: {e}"),
Ok(_) => println!("\nunexpected: oversize frame should have been rejected"),
}
}
#[cfg(not(feature = "tokio"))]
fn main() {
eprintln!("This example requires the `tokio` feature.");
eprintln!("Run with: cargo run --example tokio_async_reader --features tokio");
}