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//
// This file defines trait `EncastIO`
//
use crate::{
Cast, Endian, Flip, include_doc,
experimental::{AsifBytes, PushBulk},
};
use core::mem::{self, MaybeUninit};
use std::io;
#[cfg(doc)]
use crate::BE;
#[doc = include_doc!("trait_encast_io.md")]
pub trait EncastIO {
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`.
///
/// If successful, the resulting value is returned in [`Ok`]`(T)`.
/// On failure, an error value of struct [`std::io::Error`] is
/// returned in [`Err`].
///
/// The endianness of the resulting value is the same as the
/// endianness of the source bytes. In typical cases, both are
/// the native endianness.
///
fn encast<T: Cast>(&mut self) -> io::Result<T>;
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`.
///
/// If successful, the resulting value is returned in [`Ok`]`(T)`.
/// On failure, an error value of struct [`std::io::Error`] is
/// returned in [`Err`].
///
/// The resulting value is in native-endian. The endianness of
/// the source bytes is specified by `endian`.
///
fn encastf<T: Cast + Flip>(&mut self, endian: Endian) -> io::Result<T>;
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`.
///
/// If successful, the resulting values are saved in `slice` and
/// the number of the source bytes is returned in [`Ok`]`(usize)`.
/// On failure, an error value of struct [`std::io::Error`] is
/// returned in [`Err`].
///
/// The endianness of each resulting value is the same as the
/// endianness of the corresponding source bytes. In typical
/// cases, all are the native endiannesses.
///
fn encasts<T: Cast>(&mut self, slice: &mut [T]) -> io::Result<usize>;
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`.
///
/// If successful, the resulting values are saved in `slice` and
/// the number of the source bytes is returned in [`Ok`]`(usize)`.
/// On failure, an error value of struct [`std::io::Error`] is
/// returned in [`Err`].
///
/// The resulting values are in native-endian. The endianness of
/// the source bytes is specified by `endian`.
///
fn encastsf<T: Cast + Flip>(
&mut self,
slice: &mut [T],
endian: Endian,
) -> io::Result<usize>;
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`. The
/// number of values in the source bytes is specified by `len`.
///
/// If successful, the resulting values are returned in
/// [`Ok`]`(Vec<T>)`. On failure, an error value of struct
/// [`std::io::Error`] is returned in [`Err`].
///
/// The endianness of each resulting value is the same as the
/// endianness of the corresponding source bytes. In typical
/// cases, all are the native endiannesses.
///
fn encastv<T: Cast>(&mut self, len: usize) -> io::Result<Vec<T>>;
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`. The
/// number of values in the source bytes is specified by `len`.
///
/// If successful, the resulting values are returned in
/// [`Ok`]`(Vec<T>)`. On failure, an error value of struct
/// [`std::io::Error`] is returned in [`Err`].
///
/// The resulting value is in native-endian. The endianness of
/// the source bytes is specified by `endian`.
///
fn encastvf<T: Cast + Flip>(
&mut self,
len: usize,
endian: Endian,
) -> io::Result<Vec<T>>;
}
impl<R: ?Sized + io::Read> EncastIO for R {
#[inline]
fn encast<T: Cast>(&mut self) -> io::Result<T> {
let mut value = MaybeUninit::<T>::uninit();
unsafe {
// SAFETY: The following function call to `io::Read::read_exact`
// is safe because those types that implement trait Cast can be
// duplicated simply by copying bits by the definition of trait
// Cast.
self.read_exact(value.asif_bytes_mut())?;
// SAFETY: The following method call to `MaybeUninit::assume_init`
// is safe because `value` has been initialized.
Ok(value.assume_init())
}
}
#[inline]
fn encastf<T: Cast + Flip>(&mut self, endian: Endian) -> io::Result<T> {
let mut value = self.encast::<T>()?;
// Flips the endianness of the value in `value` if `endian` is
// not equivalent to the endianness of the target system.
value.flip_var(endian);
Ok(value)
}
#[inline]
fn encasts<T: Cast>(&mut self, slice: &mut [T]) -> io::Result<usize> {
unsafe {
// SAFETY: The following function call to `io::Read::read_exact`
// is safe because those types that implement trait Cast can be
// duplicated simply by copying bits by the definition of trait
// Cast.
self.read_exact(slice.asif_bytes_mut())?;
}
Ok(mem::size_of_val(slice))
}
#[inline]
fn encastsf<T: Cast + Flip>(
&mut self,
slice: &mut [T],
endian: Endian,
) -> io::Result<usize> {
if !endian.need_swap() {
// The endianness must not be reversed.
self.encasts::<T>(slice)
} else {
// The endianness must be reversed.
self.encastsf_swapped(slice)
}
}
fn encastv<T: Cast>(&mut self, len: usize) -> io::Result<Vec<T>> {
let mut vec: Vec<T> = Vec::new();
unsafe {
// SAFETY: The following method call to `PushBulk::push_bulk` is
// safe because the closure fills whole elements in `new_slice`.
vec.push_bulk(len, |new_slice| {
self.encasts(new_slice)
})?;
}
Ok(vec)
}
#[inline]
fn encastvf<T: Cast + Flip>(
&mut self,
len: usize,
endian: Endian,
) -> io::Result<Vec<T>> {
if !endian.need_swap() {
// The endianness must not be reversed.
self.encastv::<T>(len)
} else {
// The endianness must be reversed.
self.encastvf_swapped(len)
}
}
}
///
/// Provides internal methods for trait `EncastIO`.
///
trait EncastIOInternal {
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`.
///
/// If successful, the resulting values are saved in `slice` and
/// the number of the source bytes is returned in [`Ok`]`(usize)`.
/// On failure, an error value of struct [`std::io::Error`] is
/// returned in [`Err`].
///
/// The endianness of each resulting value is the swapped
/// endianness of the corresponding source bytes.
///
fn encastsf_swapped<T: Cast + Flip>(
&mut self,
slice: &mut [T],
) -> io::Result<usize>;
///
/// Encasts a byte representation of type `T` read from `self`
/// using trait [`std::io::Read`] as a value of type `T`. The
/// number of values in the source bytes is specified by `len`.
///
/// If successful, the resulting values are returned in
/// [`Ok`]`(Vec<T>)`. On failure, an error value of struct
/// [`std::io::Error`] is returned in [`Err`].
///
/// The endianness of each resulting value is the swapped
/// endianness of the corresponding source bytes.
///
fn encastvf_swapped<T: Cast + Flip>(
&mut self,
len: usize,
) -> io::Result<Vec<T>>;
}
impl<R: ?Sized + io::Read> EncastIOInternal for R {
fn encastsf_swapped<T: Cast + Flip>(
&mut self,
slice: &mut [T],
) -> io::Result<usize> {
let nbytes = mem::size_of_val(slice);
// Read values from `self`, reverse their endiannesses, then
// save the resulting values to `elem` in `slice`.
for elem in slice {
*elem = self.encast::<T>()?.flip_val_swapped();
}
Ok(nbytes)
}
fn encastvf_swapped<T: Cast + Flip>(
&mut self,
len: usize,
) -> io::Result<Vec<T>> {
let mut vec: Vec<T> = Vec::new();
unsafe {
// SAFETY: The following method call to `PushBulk::push_bulk` is
// safe because the closure fills whole elements in `new_slice`.
vec.push_bulk(len, |new_slice| {
self.encastsf_swapped(new_slice)
})?;
}
Ok(vec)
}
}