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// =============================================================================
// Copyright (c) 2026 Haixing Hu.
//
// SPDX-License-Identifier: Apache-2.0
//
// Licensed under the Apache License, Version 2.0.
// =============================================================================
use crateByteInput;
use crateSeekableInput;
/// A synchronous input that transfers and seeks in bytes.
///
/// This trait adds no methods. Every [`SeekableInput`] with both
/// `Item = u8` and `Unit = u8`, including unsized streams, implements it
/// automatically. Implement the underlying input and seek traits instead.
///
/// # Examples
/// A byte cursor supports seeking through the trait object interface:
///
/// ```
/// use std::io::{Cursor, Result, SeekFrom};
/// use qubit_io::SeekableByteInput;
/// fn rewind(stream: &mut dyn SeekableByteInput) -> Result<u64> { stream.seek_to(SeekFrom::Start(0)) }
/// let mut cursor = Cursor::new(b"QBIT");
/// let stream: &mut dyn SeekableByteInput = &mut cursor;
/// assert_eq!(stream.seek_to(SeekFrom::Start(3))?, 3);
/// assert_eq!(rewind(stream)?, 0);
/// let mut byte = [0];
/// assert_eq!(stream.read(&mut byte)?, 1);
/// assert_eq!(&byte, b"Q");
/// assert_eq!(stream.seek_to(SeekFrom::Start(1))?, 1);
/// assert_eq!(stream.read(&mut byte)?, 1);
/// assert_eq!(&byte, b"B");
/// # Ok::<(), std::io::Error>(())
/// ```
/// Streams with a different item type do not satisfy this bound:
///
/// ```compile_fail
/// use qubit_io::{SeekableByteInput, SeekableInput};
///
/// fn accept(stream: impl SeekableByteInput) {}
///
/// fn reject(stream: impl SeekableInput<Item = char, Unit = char>) {
/// accept(stream);
/// }
/// ```
///
/// The seek unit must also match the transferred items:
///
/// ```compile_fail
/// use qubit_io::{Input, Seekable, SeekableByteInput};
///
/// fn accept(stream: impl SeekableByteInput) {}
///
/// fn reject(stream: impl Input<Item = u8> + Seekable<Unit = char>) {
/// accept(stream);
/// }
/// ```