epserde 0.13.1

ε-serde is an ε-copy (i.e., almost zero-copy) serialization/deserialization framework
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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245

/*
 * SPDX-FileCopyrightText: 2023 Inria
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 */

use epserde::prelude::*;

#[cfg(not(feature = "std"))]
extern crate alloc;

#[cfg(not(feature = "std"))]
use alloc::rc::Rc;
use core::ops::ControlFlow;
#[cfg(feature = "std")]
use std::{
    hash::{BuildHasherDefault, DefaultHasher},
    ops::{Bound, RangeBounds, RangeInclusive},
    rc::Rc,
};

const TEST_STRS: &[&str] = &["abc\0\x0a🔥\u{0d2bdf}", ""];

#[test]
fn test_box_str() -> anyhow::Result<()> {
    for &test_str in TEST_STRS {
        let s = test_str;
        {
            let mut cursor = <AlignedCursor>::new();

            let mut schema = unsafe { s.serialize_with_schema(&mut cursor)? };
            schema.0.sort_by_key(|a| a.offset);

            cursor.set_position(0);
            let full_copy = unsafe { <Box<str>>::deserialize_full(&mut cursor)? };
            assert_eq!(&*full_copy, s);

            let eps_copy = unsafe { <Box<str>>::deserialize_eps(cursor.as_bytes())? };
            assert_eq!(eps_copy, s);
            let eps_copy = unsafe { String::deserialize_eps(cursor.as_bytes())? };
            assert_eq!(eps_copy, s);
        }
        let s = test_str.to_string();
        {
            let mut cursor = <AlignedCursor>::new();

            let mut schema = unsafe { s.serialize_with_schema(&mut cursor)? };
            schema.0.sort_by_key(|a| a.offset);

            cursor.set_position(0);
            let full_copy = unsafe { String::deserialize_full(&mut cursor)? };
            assert_eq!(full_copy, s);

            let eps_copy = unsafe { <Box<str>>::deserialize_eps(cursor.as_bytes())? };
            assert_eq!(eps_copy, s);
            let eps_copy = unsafe { String::deserialize_eps(cursor.as_bytes())? };
            assert_eq!(eps_copy, s);
        }
        let s = test_str.to_string().into_boxed_str();
        {
            let mut cursor = <AlignedCursor>::new();
            unsafe { s.serialize(&mut cursor)? };

            cursor.set_position(0);
            let full_copy = unsafe { <Box<str>>::deserialize_full(&mut cursor)? };
            assert_eq!(full_copy, s);

            let eps_copy = unsafe { <Box<str>>::deserialize_eps(cursor.as_bytes())? };
            assert_eq!(eps_copy, s.as_ref());
            let eps_copy = unsafe { String::deserialize_eps(cursor.as_bytes())? };
            assert_eq!(eps_copy, s.as_ref());
        }
    }
    Ok(())
}

fn test_generic<T>(s: T) -> anyhow::Result<()>
where
    T: Serialize + Deserialize + PartialEq + core::fmt::Debug,
    for<'a> DeserType<'a, T>: PartialEq<T> + core::fmt::Debug,
{
    {
        let mut cursor = <AlignedCursor<Aligned16>>::new();

        let mut schema = unsafe { s.serialize_with_schema(&mut cursor)? };
        schema.0.sort_by_key(|a| a.offset);

        cursor.set_position(0);
        let full_copy = unsafe { <T>::deserialize_full(&mut cursor)? };
        assert_eq!(full_copy, s);

        let bytes = cursor.as_bytes();
        let eps_copy = unsafe { <T>::deserialize_eps(bytes)? };
        assert_eq!(eps_copy, s);

        let _ = schema.to_csv();
        let _ = schema.to_csv_with_data(bytes);
    }
    {
        let mut cursor = <AlignedCursor<Aligned16>>::new();
        unsafe { s.serialize(&mut cursor)? };

        cursor.set_position(0);
        let full_copy = unsafe { <T>::deserialize_full(&mut cursor)? };
        assert_eq!(full_copy, s);

        let eps_copy = unsafe { <T>::deserialize_eps(cursor.as_bytes())? };
        assert_eq!(eps_copy, s);
    }
    Ok(())
}

#[test]
fn test_range() -> anyhow::Result<()> {
    test_generic::<core::ops::Range<i32>>(0..10)?;

    #[derive(Epserde, PartialEq, Debug)]
    struct Data(core::ops::Range<i32>);
    test_generic(Data(0..10))?;
    Ok(())
}

#[test]
fn test_option() -> anyhow::Result<()> {
    test_generic::<Option<i32>>(Some(42))?;
    test_generic::<Option<i32>>(None)?;

    // The ε-copy deserialization type of Option<Vec<usize>> is
    // Option<&[usize]>.
    let a: Option<Vec<usize>> = Some(vec![1, 2, 3]);
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    unsafe { a.serialize(&mut cursor)? };
    cursor.set_position(0);
    let full = unsafe { <Option<Vec<usize>>>::deserialize_full(&mut cursor)? };
    assert_eq!(full, a);
    let eps = unsafe { <Option<Vec<usize>>>::deserialize_eps(cursor.as_bytes())? };
    assert_eq!(eps, Some(&[1_usize, 2, 3][..]));

    let a: Option<Vec<usize>> = None;
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    unsafe { a.serialize(&mut cursor)? };
    cursor.set_position(0);
    let full = unsafe { <Option<Vec<usize>>>::deserialize_full(&mut cursor)? };
    assert_eq!(full, a);
    let eps = unsafe { <Option<Vec<usize>>>::deserialize_eps(cursor.as_bytes())? };
    assert_eq!(eps, None);
    Ok(())
}

#[test]
fn test_ser_rc_ref() -> anyhow::Result<()> {
    let v = vec![0, 1, 2, 3];
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    unsafe { Serialize::serialize(&Rc::new(v.as_slice()), &mut cursor)? };
    cursor.set_position(0);
    let s = unsafe { <Rc<Box<[i32]>>>::deserialize_eps(cursor.as_bytes())? };
    assert_eq!(&*s, &v);
    Ok(())
}

#[test]
fn test_ref_field() -> anyhow::Result<()> {
    let v = vec![0, 1, 2, 3];
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    #[derive(Epserde, Debug)]
    struct Data<A>(A);
    unsafe { Serialize::serialize(&Rc::new(Data(v.as_slice())), &mut cursor)? };
    cursor.set_position(0);
    let s = unsafe { <Rc<Data<Box<[i32]>>>>::deserialize_eps(cursor.as_bytes())? };
    assert_eq!(s.0, &v);
    Ok(())
}

#[cfg(feature = "std")]
#[test]
fn test_range_bound_deep_copy_idx() -> anyhow::Result<()> {
    let r = RangeInclusive::new("a".to_string(), "b".to_string());
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    unsafe { r.serialize(&mut cursor)? };
    cursor.set_position(0);
    let full = unsafe { RangeInclusive::<String>::deserialize_full(&mut cursor)? };
    assert_eq!(full, r);
    let eps = unsafe { RangeInclusive::<String>::deserialize_eps(cursor.as_bytes())? };
    assert_eq!(eps.start_bound(), Bound::Included(&"a"));
    assert_eq!(eps.end_bound(), Bound::Included(&"b"));
    Ok(())
}

#[test]
fn test_control_flow() -> anyhow::Result<()> {
    test_generic::<ControlFlow<i32, f64>>(ControlFlow::Break(42))?;
    test_generic::<ControlFlow<i32, f64>>(ControlFlow::Continue(1.618))?;
    Ok(())
}

#[test]
fn test_result() -> anyhow::Result<()> {
    test_generic::<Result<i32, f64>>(Ok(42))?;
    test_generic::<Result<i32, f64>>(Err(1.618))?;
    Ok(())
}

#[test]
fn test_bound() -> anyhow::Result<()> {
    test_generic::<core::ops::Bound<i32>>(core::ops::Bound::Unbounded)?;
    test_generic::<core::ops::Bound<i32>>(core::ops::Bound::Included(42))?;
    test_generic::<core::ops::Bound<i32>>(core::ops::Bound::Excluded(42))?;
    Ok(())
}

#[cfg(feature = "std")]
#[test]
fn test_builder_hasher_default() -> anyhow::Result<()> {
    let bhd = BuildHasherDefault::<DefaultHasher>::default();
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    unsafe { bhd.serialize(&mut cursor)? };
    cursor.set_position(0);
    let full = unsafe { BuildHasherDefault::<DefaultHasher>::deserialize_full(&mut cursor)? };
    assert_eq!(&full, &bhd);
    let eps = unsafe { BuildHasherDefault::<DefaultHasher>::deserialize_eps(cursor.as_bytes())? };
    assert_eq!(&eps, &bhd);
    Ok(())
}

#[cfg(feature = "std")]
#[test]
fn test_range_inclusive_exhausted() {
    // An exhausted RangeInclusive whose start cannot advance past its end
    // (here because doing so would overflow) keeps its exhausted flag, which
    // the standard library reports as an excluded end bound. Only start and
    // end are serialized, so reconstructing such a range would yield a
    // non-empty range; serializing it must therefore fail.
    //
    // Note that a range exhausted below the maximum value is represented by a
    // start advanced past the end (e.g., 1..=2 becomes 3..=2), which is a
    // genuinely empty range that serializes and reconstructs faithfully, so it
    // is not a useful case here.
    let mut r = (i32::MAX - 1)..=i32::MAX;
    r.next();
    r.next();
    assert!(r.is_empty());
    assert!(matches!(r.end_bound(), Bound::Excluded(_)));
    let mut cursor = <AlignedCursor<Aligned16>>::new();
    assert!(unsafe { r.serialize(&mut cursor) }.is_err());
}