qubit-codec 0.9.0

Core codec traits and buffer conversion primitives for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146

// =============================================================================
//    Copyright (c) 2026 Haixing Hu.
//
//    SPDX-License-Identifier: Apache-2.0
//
//    Licensed under the Apache License, Version 2.0.
// =============================================================================

use qubit_codec::{
    Codec,
    CodecEncodeError,
    CodecTranscodeEncoder,
    TranscodeError,
    Transcoder,
};

#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
struct ResetFailCodec;

#[derive(Clone, Copy, Debug, Eq, PartialEq, thiserror::Error)]
#[error("reset failed")]
struct ResetFailError;

impl Codec for ResetFailCodec {
    type Value = u8;
    type Unit = u8;
    type DecodeError = core::convert::Infallible;
    type EncodeError = ResetFailError;

    const MIN_UNITS_PER_VALUE: core::num::NonZeroUsize =
        core::num::NonZeroUsize::MIN;

    const MAX_UNITS_PER_VALUE: core::num::NonZeroUsize =
        core::num::NonZeroUsize::MIN;

    fn can_encode_value(&self, value: &u8) -> bool {
        value.is_multiple_of(2)
    }

    const MAX_ENCODE_RESET_UNITS: usize = 1;

    unsafe fn decode(
        &mut self,
        input: &[u8],
        input_index: usize,
    ) -> Result<
        (u8, core::num::NonZeroUsize),
        qubit_codec::DecodeFailure<Self::DecodeError>,
    > {
        Ok((input[input_index], core::num::NonZeroUsize::MIN))
    }

    unsafe fn encode(
        &mut self,
        value: &u8,
        output: &mut [u8],
        output_index: usize,
    ) -> Result<core::num::NonZeroUsize, Self::EncodeError> {
        output[output_index] = *value;
        Ok(qubit_io::nz!(1))
    }

    unsafe fn encode_reset(
        &mut self,
        _output: &mut [u8],
        _output_index: usize,
    ) -> Result<usize, Self::EncodeError> {
        Err(ResetFailError)
    }
}

#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
struct RejectOddCodec;

impl Codec for RejectOddCodec {
    type Value = u8;
    type Unit = u8;
    type DecodeError = core::convert::Infallible;
    type EncodeError = &'static str;

    const MIN_UNITS_PER_VALUE: core::num::NonZeroUsize =
        core::num::NonZeroUsize::MIN;

    const MAX_UNITS_PER_VALUE: core::num::NonZeroUsize =
        core::num::NonZeroUsize::MIN;

    fn can_encode_value(&self, value: &u8) -> bool {
        value.is_multiple_of(2)
    }

    unsafe fn decode(
        &mut self,
        input: &[u8],
        input_index: usize,
    ) -> Result<
        (u8, core::num::NonZeroUsize),
        qubit_codec::DecodeFailure<Self::DecodeError>,
    > {
        Ok((input[input_index], core::num::NonZeroUsize::MIN))
    }

    unsafe fn encode(
        &mut self,
        value: &u8,
        output: &mut [u8],
        output_index: usize,
    ) -> Result<core::num::NonZeroUsize, Self::EncodeError> {
        debug_assert!(self.can_encode_value(value));
        output[output_index] = *value;
        Ok(qubit_io::nz!(1))
    }
}

#[test]
fn test_codec_transcode_encode_hooks_wraps_encode_errors() {
    let mut encoder = CodecTranscodeEncoder::new(RejectOddCodec);
    let mut output = [0_u8; 1];

    let error = encoder
        .transcode(&[7], 0, &mut output, 0)
        .expect_err("strict encode hooks should reject unencodable values");

    assert_eq!(
        TranscodeError::Domain(CodecEncodeError::UnencodableValue {
            input_index: 0
        }),
        error,
    );
}

#[test]
fn test_codec_transcode_encode_hooks_wraps_encode_reset_errors() {
    let mut encoder = CodecTranscodeEncoder::new(ResetFailCodec);
    let mut output = [0_u8; 1];

    let error = encoder
        .reset(&mut output, 0)
        .expect_err("reset errors should be wrapped");

    assert_eq!(
        TranscodeError::Domain(CodecEncodeError::EncodeReset {
            source: ResetFailError,
        }),
        error,
    );
}