qubit_io/wrappers/
counting_reader.rs

1/*******************************************************************************
2 *
3 *    Copyright (c) 2026 Haixing Hu.
4 *
5 *    SPDX-License-Identifier: Apache-2.0
6 *
7 *    Licensed under the Apache License, Version 2.0.
8 *
9 ******************************************************************************/
10use std::io::{
11    BufRead,
12    Read,
13    Result,
14    Seek,
15    SeekFrom,
16};
17
18/// Reader wrapper that counts successfully read bytes.
19///
20/// The count is increased only after the wrapped reader reports a successful
21/// byte count. Failed reads do not change the counter.
22///
23/// # Examples
24/// ```
25/// use std::io::{
26///     Cursor,
27///     Read,
28/// };
29///
30/// use qubit_io::CountingReader;
31///
32/// let mut reader = CountingReader::new(Cursor::new(b"abc"));
33/// let mut data = Vec::new();
34/// reader.read_to_end(&mut data)?;
35///
36/// assert_eq!(b"abc", data.as_slice());
37/// assert_eq!(3, reader.bytes_read());
38/// # Ok::<(), std::io::Error>(())
39/// ```
40pub struct CountingReader<R> {
41    inner: R,
42    bytes_read: u64,
43}
44
45impl<R> CountingReader<R> {
46    /// Creates a counting reader.
47    ///
48    /// # Parameters
49    /// - `inner`: Reader to wrap.
50    ///
51    /// # Returns
52    /// A new counting reader with a zero byte count.
53    #[inline]
54    pub fn new(inner: R) -> Self {
55        Self {
56            inner,
57            bytes_read: 0,
58        }
59    }
60
61    /// Returns the number of bytes successfully read through this wrapper.
62    ///
63    /// # Returns
64    /// Total byte count. The value saturates at [`u64::MAX`].
65    #[inline]
66    pub fn bytes_read(&self) -> u64 {
67        self.bytes_read
68    }
69
70    /// Returns an immutable reference to the wrapped reader.
71    ///
72    /// # Returns
73    /// The wrapped reader reference.
74    #[inline]
75    pub fn get_ref(&self) -> &R {
76        &self.inner
77    }
78
79    /// Returns a mutable reference to the wrapped reader.
80    ///
81    /// # Returns
82    /// The wrapped reader reference.
83    #[inline]
84    pub fn get_mut(&mut self) -> &mut R {
85        &mut self.inner
86    }
87
88    /// Consumes this wrapper and returns the wrapped reader.
89    ///
90    /// # Returns
91    /// The wrapped reader.
92    #[inline]
93    pub fn into_inner(self) -> R {
94        self.inner
95    }
96}
97
98impl<R> Read for CountingReader<R>
99where
100    R: Read,
101{
102    fn read(&mut self, buffer: &mut [u8]) -> Result<usize> {
103        let count = self.inner.read(buffer)?;
104        self.bytes_read = self.bytes_read.saturating_add(count as u64);
105        Ok(count)
106    }
107}
108
109impl<R> BufRead for CountingReader<R>
110where
111    R: BufRead,
112{
113    #[inline]
114    fn fill_buf(&mut self) -> Result<&[u8]> {
115        self.inner.fill_buf()
116    }
117
118    #[inline]
119    fn consume(&mut self, amount: usize) {
120        self.bytes_read = self.bytes_read.saturating_add(amount as u64);
121        self.inner.consume(amount);
122    }
123}
124
125impl<R> Seek for CountingReader<R>
126where
127    R: Seek,
128{
129    #[inline]
130    fn seek(&mut self, position: SeekFrom) -> Result<u64> {
131        self.inner.seek(position)
132    }
133}
qubit_io/wrappers/counting_reader.rs

qubit_io/wrappers/
counting_reader.rs
