Trait TryNext

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pub trait TryNext<S = ()>where
    S: Default + Copy,{
    type Item;
    type Error;

    // Required method
    fn try_next(&mut self) -> Result<Option<Self::Item>, Self::Error>;

    // Provided methods
    fn try_collect(&mut self) -> Result<Vec<Self::Item>, Self::Error> { ... }
    fn stats(&self) -> S { ... }
}

Expand description

Context-free, fallible producer.

A trait for types that can produce items one at a time, where fetching the next item may fail.

This trait is synchronous — each call to try_next blocks until an item is produced or an error occurs. See the module-level documentation for details and examples.

S - Optional stats type.

Required Associated Types§

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type Item

The type of items yielded by this source.

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type Error

The error type that may be returned when producing the next item fails.

Required Methods§

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fn try_next(&mut self) -> Result<Option<Self::Item>, Self::Error>

Attempts to produce the next item from the source.

Returns:

Ok(Some(item)) — a new item was produced,
Ok(None) — the source is exhausted,
Err(e) — iteration failed with an error.

Provided Methods§

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fn try_collect(&mut self) -> Result<Vec<Self::Item>, Self::Error>

Collects all remaining items into a Vec.

The method repeatedly calls try_next until None or an error is returned, collecting all successful items into a vector.
If any call returns Err(e), iteration stops immediately and that error is returned.

§Feature

This method is only available when the alloc feature is enabled.

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fn stats(&self) -> S

Implementations on Foreign Types§

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impl<R> TryNext for BufReader<R>
where R: Read,

Implements TryNext for BufReader.

This version does not use a context, and simply reads the next byte sequentially from the buffer.

§Example

use std::io::BufReader;
use try_next::TryNext;

let data = b"hi";
let mut reader = BufReader::new(&data[..]);

assert_eq!(reader.try_next().unwrap(), Some(b'h'));
assert_eq!(reader.try_next().unwrap(), Some(b'i'));
assert_eq!(reader.try_next().unwrap(), None);