Struct postcard::accumulator::CobsAccumulator

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pub struct CobsAccumulator<const N: usize> { /* private fields */ }
Expand description

An accumulator used to collect chunked COBS data and deserialize it.

This is often useful when you receive “parts” of the message at a time, for example when draining a serial port buffer that may not contain an entire uninterrupted message.

§Examples

Deserialize a struct by reading chunks from a Reader.

use postcard::accumulator::{CobsAccumulator, FeedResult};
use serde::Deserialize;
use std::io::Read;

let input = /* Anything that implements the `Read` trait */

let mut raw_buf = [0u8; 32];
let mut cobs_buf: CobsAccumulator<256> = CobsAccumulator::new();

while let Ok(ct) = input.read(&mut raw_buf) {
    // Finished reading input
    if ct == 0 {
        break;
    }

    let buf = &raw_buf[..ct];
    let mut window = &buf[..];

    'cobs: while !window.is_empty() {
        window = match cobs_buf.feed::<MyData>(&window) {
            FeedResult::Consumed => break 'cobs,
            FeedResult::OverFull(new_wind) => new_wind,
            FeedResult::DeserError(new_wind) => new_wind,
            FeedResult::Success { data, remaining } => {
                // Do something with `data: MyData` here.

                dbg!(data);

                remaining
            }
        };
    }
}

Implementations§

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impl<const N: usize> CobsAccumulator<N>

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pub const fn new() -> Self

Create a new accumulator.

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pub fn feed<'a, T>(&mut self, input: &'a [u8]) -> FeedResult<'a, T>
where T: for<'de> Deserialize<'de>,

Appends data to the internal buffer and attempts to deserialize the accumulated data into T.

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pub fn feed_ref<'de, 'a, T>(&'de mut self, input: &'a [u8]) -> FeedResult<'a, T>
where T: Deserialize<'de>,

Appends data to the internal buffer and attempts to deserialize the accumulated data into T.

This differs from feed, as it allows the T to reference data within the internal buffer, but mutably borrows the accumulator for the lifetime of the deserialization. If T does not require the reference, the borrow of self ends at the end of the function.

Trait Implementations§

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impl<const N: usize> Default for CobsAccumulator<N>

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fn default() -> Self

Returns the “default value” for a type. Read more

Auto Trait Implementations§

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impl<const N: usize> Freeze for CobsAccumulator<N>

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impl<const N: usize> RefUnwindSafe for CobsAccumulator<N>

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impl<const N: usize> Send for CobsAccumulator<N>

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impl<const N: usize> Sync for CobsAccumulator<N>

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impl<const N: usize> Unpin for CobsAccumulator<N>

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impl<const N: usize> UnwindSafe for CobsAccumulator<N>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.