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::{
12    Result,
13    Write,
14};
15
16use crate::{
17    Output,
18    UncheckedSlice,
19    traits::validate_write_count,
20};
21
22/// Bridges byte-oriented standard writers to item-oriented output.
23impl<W> Output for W
24where
25    W: Write + ?Sized,
26{
27    /// Bytes written by the standard Write implementation.
28    type Item = u8;
29
30    /// Writes bytes from a caller-validated indexed input range.
31    ///
32    /// # Parameters
33    ///
34    /// - `input`: Source byte slice.
35    /// - `index`: Start offset inside `input`.
36    /// - `count`: Maximum number of bytes to write.
37    ///
38    /// # Returns
39    ///
40    /// The number of bytes reported by the standard writer.
41    ///
42    /// # Errors
43    ///
44    /// Returns the error reported by the standard writer.
45    ///
46    /// # Panics
47    ///
48    /// Panics in debug builds if the requested source range does not fit.
49    ///
50    /// # Safety
51    ///
52    /// The caller must ensure that index through index plus count is a valid
53    /// range inside input without overflowing.
54    #[inline(always)]
55    unsafe fn write_unchecked(
56        &mut self,
57        input: &[u8],
58        index: usize,
59        count: usize,
60    ) -> Result<usize> {
61        // SAFETY: The caller guarantees that the range is valid inside input.
62        let source = unsafe { UncheckedSlice::subslice(input, index, count) };
63        Write::write(self, source)
64    }
65
66    /// Writes bytes from the complete input slice.
67    ///
68    /// # Parameters
69    ///
70    /// - `input`: Source byte slice.
71    ///
72    /// # Returns
73    ///
74    /// The number of bytes written from `input`.
75    ///
76    /// # Errors
77    ///
78    /// Returns [`std::io::ErrorKind::InvalidData`] if the writer reports more
79    /// bytes than `input` contains, or the error reported by the standard
80    /// writer.
81    #[inline(always)]
82    fn write(&mut self, input: &[Self::Item]) -> Result<usize> {
83        let written = Write::write(self, input)?;
84        validate_write_count(written, input.len())?;
85        Ok(written)
86    }
87
88    /// Flushes the standard writer.
89    ///
90    /// # Returns
91    ///
92    /// Returns `Ok(())` after the standard writer is flushed.
93    ///
94    /// # Errors
95    ///
96    /// Returns the error reported by the standard writer.
97    #[inline(always)]
98    fn flush(&mut self) -> Result<()> {
99        Write::flush(self)
100    }
101}
qubit_io/std_io/impls/output.rs

qubit_io/std_io/impls/
output.rs
