Trait scroll::Pwrite

pub trait Pwrite<Ctx, E>: Index<usize> + IndexMut<RangeFrom<usize>> + MeasureWith<Ctx> where
    Ctx: Copy,
    E: From<Error>, {
    fn pwrite<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
        &mut self, 
        n: N, 
        offset: usize
    ) -> Result<usize, E>
    where
        Ctx: Default,
    { ... }
    fn pwrite_with<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
        &mut self, 
        n: N, 
        offset: usize, 
        ctx: Ctx
    ) -> Result<usize, E> { ... }
    fn gwrite<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
        &mut self, 
        n: N, 
        offset: &mut usize
    ) -> Result<usize, E>
    where
        Ctx: Default,
    { ... }
    fn gwrite_with<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
        &mut self, 
        n: N, 
        offset: &mut usize, 
        ctx: Ctx
    ) -> Result<usize, E> { ... }
}

A very generic, contextual pwrite interface in Rust.

Like Pread — but for writing!

Implementing Pwrite on a data store allows you to then write almost arbitrarily complex types efficiently.

To this end the Pwrite trait works in conjuction with the TryIntoCtx; The TryIntoCtx trait implemented on a type defines how to convert said type into data that an implementation of Pwrite can … well … write.

As with Pread ‘data’ does not necessarily mean &[u8] but can be any indexable type. In fact much of the documentation of Pread applies to Pwrite as well just with ‘read’ switched for ‘write’ and ‘From’ switched with ‘Into’ so if you haven’t yet you should read the documentation of Pread first.

Unless you need to implement your own data store — that is either can’t convert to &[u8] or have a data that is not &[u8] — you will probably want to implement TryIntoCtx on your Rust types to be written.

Provided methods

fn pwrite<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
    &mut self,
    n: N,
    offset: usize
) -> Result<usize, E> where
    Ctx: Default, 

fn pwrite_with<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
    &mut self,
    n: N,
    offset: usize,
    ctx: Ctx
) -> Result<usize, E>

Write N at offset I with context Ctx

Example

use scroll::{Pwrite, Pread, LE};
let mut bytes: [u8; 8] = [0, 0, 0, 0, 0, 0, 0, 0];
bytes.pwrite_with::<u32>(0xbeefbeef, 0, LE).unwrap();
assert_eq!(bytes.pread_with::<u32>(0, LE).unwrap(), 0xbeefbeef);

fn gwrite<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
    &mut self,
    n: N,
    offset: &mut usize
) -> Result<usize, E> where
    Ctx: Default, 

Write n into self at offset, with a default Ctx. Updates the offset.

fn gwrite_with<N: TryIntoCtx<Ctx, Self::Output, Error = E>>(
    &mut self,
    n: N,
    offset: &mut usize,
    ctx: Ctx
) -> Result<usize, E>

Write n into self at offset, with the ctx. Updates the offset.

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Implementors

impl<Ctx: Copy, E: From<Error>, R: ?Sized + Index<usize> + IndexMut<RangeFrom<usize>> + MeasureWith<Ctx>> Pwrite<Ctx, E> for R

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