qubit_io/std_io/impls/
output.rs

1// =============================================================================
2//    Copyright (c) 2026 Haixing Hu.
3//
4//    SPDX-License-Identifier: Apache-2.0
5//
6//    Licensed under the Apache License, Version 2.0.
7// =============================================================================
8
9//! Standard [`Write`](std::io::Write) implementations of item output traits.
10
11use std::io::Result;
12use std::io::Write;
13
14use crate::Output;
15use crate::traits::validate_write_count;
16use crate::util::UncheckedSlice;
17
18/// Bridges byte-oriented standard writers to item-oriented output.
19impl<W> Output for W
20where
21    W: Write + ?Sized,
22{
23    /// Bytes written by the standard Write implementation.
24    type Item = u8;
25
26    /// Writes bytes from a caller-validated indexed input range.
27    ///
28    /// # Parameters
29    ///
30    /// - `input`: Source byte slice.
31    /// - `index`: Start offset inside `input`.
32    /// - `count`: Maximum number of bytes to write.
33    ///
34    /// # Returns
35    ///
36    /// The number of bytes reported by the standard writer.
37    ///
38    /// # Errors
39    ///
40    /// Returns the error reported by the standard writer.
41    ///
42    /// # Panics
43    ///
44    /// Panics in debug builds if the requested source range does not fit.
45    ///
46    /// # Safety
47    ///
48    /// The caller must ensure that index through index plus count is a valid
49    /// range inside input without overflowing.
50    #[inline(always)]
51    unsafe fn write_unchecked(&mut self, input: &[u8], index: usize, count: usize) -> Result<usize> {
52        // SAFETY: The caller guarantees that the range is valid inside input.
53        let source = unsafe { UncheckedSlice::subslice(input, index, count) };
54        Write::write(self, source)
55    }
56
57    /// Writes bytes from the complete input slice.
58    ///
59    /// # Parameters
60    ///
61    /// - `input`: Source byte slice.
62    ///
63    /// # Returns
64    ///
65    /// The number of bytes written from `input`.
66    ///
67    /// # Errors
68    ///
69    /// Returns [`std::io::ErrorKind::InvalidData`] if the writer reports more
70    /// bytes than `input` contains, or the error reported by the standard
71    /// writer.
72    #[inline(always)]
73    fn write(&mut self, input: &[Self::Item]) -> Result<usize> {
74        let written = Write::write(self, input)?;
75        validate_write_count(written, input.len())?;
76        Ok(written)
77    }
78
79    /// Flushes the standard writer.
80    ///
81    /// # Returns
82    ///
83    /// Returns `Ok(())` after the standard writer is flushed.
84    ///
85    /// # Errors
86    ///
87    /// Returns the error reported by the standard writer.
88    #[inline(always)]
89    fn flush(&mut self) -> Result<()> {
90        Write::flush(self)
91    }
92}
qubit_io/std_io/impls/output.rs

qubit_io/std_io/impls/
output.rs
