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//! Reimplements core logic and types from `std::io` in an `alloc`-friendly
//! fashion.
use alloc::vec::Vec;
use core::fmt::{self, Display};
use core::result;
pub enum ErrorKind {
Other,
}
// I/O errors can never occur in no-std mode. All our no-std I/O implementations
// are infallible.
pub struct Error;
impl Display for Error {
fn fmt(&self, _formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
unreachable!()
}
}
impl Error {
pub(crate) fn new(_kind: ErrorKind, _error: &'static str) -> Error {
Error
}
}
pub type Result<T> = result::Result<T, Error>;
pub trait Write {
fn write(&mut self, buf: &[u8]) -> Result<usize>;
fn write_all(&mut self, buf: &[u8]) -> Result<()> {
// All our Write impls in no_std mode always write the whole buffer in
// one call infallibly.
let result = self.write(buf);
debug_assert!(result.is_ok());
debug_assert_eq!(result.unwrap_or(0), buf.len());
Ok(())
}
fn flush(&mut self) -> Result<()>;
}
impl<W: Write> Write for &mut W {
#[inline]
fn write(&mut self, buf: &[u8]) -> Result<usize> {
(*self).write(buf)
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> Result<()> {
(*self).write_all(buf)
}
#[inline]
fn flush(&mut self) -> Result<()> {
(*self).flush()
}
}
impl Write for Vec<u8> {
#[inline]
fn write(&mut self, buf: &[u8]) -> Result<usize> {
self.extend_from_slice(buf);
Ok(buf.len())
}
#[inline]
fn write_all(&mut self, buf: &[u8]) -> Result<()> {
self.extend_from_slice(buf);
Ok(())
}
#[inline]
fn flush(&mut self) -> Result<()> {
Ok(())
}
}