minicbor 2.2.1

A small CBOR codec suitable for no_std environments.
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
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317

use crate::{SIGNED, BYTES, TEXT, ARRAY, MAP, TAGGED, SIMPLE};
use crate::data::{Int, Tag};
use crate::encode::{Encode, Error, Write};

/// A non-allocating CBOR encoder writing encoded bytes to the given [`Write`] sink.
#[derive(Debug, Clone)]
pub struct Encoder<W> { writer: W }

impl<W: Write> Encoder<W> {
    /// Construct an `Encoder` that writes to the given [`Write`] sink.
    pub fn new(writer: W) -> Encoder<W> {
        Encoder { writer }
    }

    /// Access the inner writer.
    pub fn writer(&self) -> &W {
        &self.writer
    }

    /// Get mutable access to the inner writer.
    pub fn writer_mut(&mut self) -> &mut W {
        &mut self.writer
    }

    /// Get back the [`Write`] impl.
    pub fn into_writer(self) -> W {
        self.writer
    }

    /// Encode any type that implements [`Encode`].
    pub fn encode<T: Encode<()>>(&mut self, x: T) -> Result<&mut Self, Error<W::Error>> {
        x.encode(self, &mut ())?;
        Ok(self)
    }

    /// Encode any type that implements [`Encode`].
    pub fn encode_with<C, T: Encode<C>>(&mut self, x: T, ctx: &mut C) -> Result<&mut Self, Error<W::Error>> {
        x.encode(self, ctx)?;
        Ok(self)
    }

    /// Encode a `u8` value.
    pub fn u8(&mut self, x: u8) -> Result<&mut Self, Error<W::Error>> {
        if let 0 ..= 0x17 = x {
            self.put(&[x])
        } else {
            self.put(&[24, x])
        }
    }

    /// Encode an `i8` value.
    pub fn i8(&mut self, x: i8) -> Result<&mut Self, Error<W::Error>> {
        if x >= 0 {
            return self.u8(x as u8)
        }
        match (-1 - x) as u8 {
            n @ 0 ..= 0x17 => self.put(&[SIGNED | n]),
            n              => self.put(&[SIGNED | 24, n])
        }
    }

    /// Encode a `u16` value.
    pub fn u16(&mut self, x: u16) -> Result<&mut Self, Error<W::Error>> {
        match x {
            0    ..= 0x17 => self.put(&[x as u8]),
            0x18 ..= 0xff => self.put(&[24, x as u8]),
            _             => self.put(&[25])?.put(&x.to_be_bytes()[..])
        }
    }

    /// Encode an `i16` value.
    pub fn i16(&mut self, x: i16) -> Result<&mut Self, Error<W::Error>> {
        if x >= 0 {
            return self.u16(x as u16)
        }
        match (-1 - x) as u16 {
            n @ 0    ..= 0x17 => self.put(&[SIGNED | n as u8]),
            n @ 0x18 ..= 0xff => self.put(&[SIGNED | 24, n as u8]),
            n                 => self.put(&[SIGNED | 25])?.put(&n.to_be_bytes()[..])
        }
    }

    /// Encode a `u32` value.
    pub fn u32(&mut self, x: u32) -> Result<&mut Self, Error<W::Error>> {
        match x {
            0     ..= 0x17   => self.put(&[x as u8]),
            0x18  ..= 0xff   => self.put(&[24, x as u8]),
            0x100 ..= 0xffff => self.put(&[25])?.put(&(x as u16).to_be_bytes()[..]),
            _                => self.put(&[26])?.put(&x.to_be_bytes()[..])
        }
    }

    /// Encode an `i32` value.
    pub fn i32(&mut self, x: i32) -> Result<&mut Self, Error<W::Error>> {
        if x >= 0 {
            return self.u32(x as u32)
        }
        match (-1 - x) as u32 {
            n @ 0     ..= 0x17   => self.put(&[SIGNED | n as u8]),
            n @ 0x18  ..= 0xff   => self.put(&[SIGNED | 24, n as u8]),
            n @ 0x100 ..= 0xffff => self.put(&[SIGNED | 25])?.put(&(n as u16).to_be_bytes()[..]),
            n                    => self.put(&[SIGNED | 26])?.put(&n.to_be_bytes()[..])
        }
    }

    /// Encode a `u64` value.
    pub fn u64(&mut self, x: u64) -> Result<&mut Self, Error<W::Error>> {
        match x {
            0        ..= 0x17        => self.put(&[x as u8]),
            0x18     ..= 0xff        => self.put(&[24, x as u8]),
            0x100    ..= 0xffff      => self.put(&[25])?.put(&(x as u16).to_be_bytes()[..]),
            0x1_0000 ..= 0xffff_ffff => self.put(&[26])?.put(&(x as u32).to_be_bytes()[..]),
            _                        => self.put(&[27])?.put(&x.to_be_bytes()[..])
        }
    }

    /// Encode an `i64` value.
    pub fn i64(&mut self, x: i64) -> Result<&mut Self, Error<W::Error>> {
        if x >= 0 {
            return self.u64(x as u64)
        }
        match (-1 - x) as u64 {
            n @ 0        ..= 0x17        => self.put(&[SIGNED | n as u8]),
            n @ 0x18     ..= 0xff        => self.put(&[SIGNED | 24, n as u8]),
            n @ 0x100    ..= 0xffff      => self.put(&[SIGNED | 25])?.put(&(n as u16).to_be_bytes()[..]),
            n @ 0x1_0000 ..= 0xffff_ffff => self.put(&[SIGNED | 26])?.put(&(n as u32).to_be_bytes()[..]),
            n                            => self.put(&[SIGNED | 27])?.put(&n.to_be_bytes()[..])
        }
    }

    /// Encode a CBOR integer.
    ///
    /// See [`Int`] for details regarding the value range of CBOR integers.
    pub fn int(&mut self, x: Int) -> Result<&mut Self, Error<W::Error>> {
        if !x.is_negative() {
            return self.u64(x.value())
        }
        match x.value() {
            n @ 0        ..= 0x17        => self.put(&[SIGNED | n as u8]),
            n @ 0x18     ..= 0xff        => self.put(&[SIGNED | 24, n as u8]),
            n @ 0x100    ..= 0xffff      => self.put(&[SIGNED | 25])?.put(&(n as u16).to_be_bytes()[..]),
            n @ 0x1_0000 ..= 0xffff_ffff => self.put(&[SIGNED | 26])?.put(&(n as u32).to_be_bytes()[..]),
            n                            => self.put(&[SIGNED | 27])?.put(&n.to_be_bytes()[..])
        }
    }

    /// Encode a CBOR `null` value.
    pub fn null(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[SIMPLE | 22])
    }

    /// Encode a CBOR `undefined` value.
    pub fn undefined(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[SIMPLE | 23])
    }

    /// Encode a CBOR simple value.
    pub fn simple(&mut self, x: u8) -> Result<&mut Self, Error<W::Error>> {
        if x < 0x14 {
            self.put(&[SIMPLE | x])
        } else {
            self.put(&[SIMPLE | 24, x])
        }
    }

    /// Encode an `f32` value as a half float (`f16)`.
    ///
    /// *Requires feature* `"half"`.
    ///
    /// **NB**: The conversion from `f32` to `f16` is potentially lossy.
    /// Generally values are truncated and rounded to the nearest 16-bit
    /// value, except:
    ///
    ///   - 32-bit values which do not fit into 16 bit become ±∞.
    ///   - 32-bit subnormal values become ±0.
    ///   - Exponents smaller than the min. 16-bit exponent become
    ///     16-bit subnormals or ±0.
    ///
    /// For further details please consult the [half][1] crate which is
    /// used internally for `f16` support.
    ///
    /// [1]: https://crates.io/crates/half
    #[cfg(feature = "half")]
    pub fn f16(&mut self, x: f32) -> Result<&mut Self, Error<W::Error>> {
        let n = half::f16::from_f32(x).to_bits();
        self.put(&[SIMPLE | 25])?.put(&n.to_be_bytes()[..])
    }

    /// Encode an `f32` value.
    pub fn f32(&mut self, x: f32) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[SIMPLE | 26])?.put(&x.to_be_bytes()[..])
    }

    /// Encode an `f64` value.
    pub fn f64(&mut self, x: f64) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[SIMPLE | 27])?.put(&x.to_be_bytes()[..])
    }

    /// Encode a `bool` value.
    pub fn bool(&mut self, x: bool) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[SIMPLE | if x { 0x15 } else { 0x14 }])
    }

    /// Encode a `char` value.
    pub fn char(&mut self, x: char) -> Result<&mut Self, Error<W::Error>> {
        self.u32(u32::from(x))
    }

    /// Encode a CBOR tag.
    pub fn tag<T: Into<Tag>>(&mut self, x: T) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(TAGGED, x.into().into())
    }

    /// Encode a byte slice.
    pub fn bytes(&mut self, x: &[u8]) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(BYTES, x.len() as u64)?.put(x)
    }

    /// Begin encoding `len` bytes.
    ///
    /// In contrast to [`Encoder::bytes`] which also encodes a byte string, this
    /// method writes only the CBOR item head.
    pub fn bytes_len(&mut self, len: u64) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(BYTES, len)
    }

    /// Encode a string slice.
    pub fn str(&mut self, x: &str) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(TEXT, x.len() as u64)?.put(x.as_bytes())
    }

    /// Begin encoding a string of `len` bytes.
    ///
    /// In contrast to [`Encoder::str`] which also encodes a string, this
    /// method writes only the CBOR item head.
    pub fn str_len(&mut self, len: u64) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(TEXT, len)
    }

    /// Begin encoding an array with `len` elements.
    pub fn array(&mut self, len: u64) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(ARRAY, len)
    }

    /// Begin encoding a map with `len` entries.
    pub fn map(&mut self, len: u64) -> Result<&mut Self, Error<W::Error>> {
        self.type_len(MAP, len)
    }

    /// Begin encoding an array of unknown size.
    ///
    /// Use [`Encoder::end`] to terminate the array.
    pub fn begin_array(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[0x9f])
    }

    /// Begin encoding an indefinite number of byte slices.
    ///
    /// Use [`Encoder::end`] to terminate.
    pub fn begin_bytes(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[0x5f])
    }

    /// Begin encoding a map of unknown size.
    ///
    /// Use [`Encoder::end`] to terminate the map.
    pub fn begin_map(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[0xbf])
    }

    /// Begin encoding an indefinite number of string slices.
    ///
    /// Use [`Encoder::end`] to terminate.
    pub fn begin_str(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[0x7f])
    }

    /// Terminate an indefinite collection.
    pub fn end(&mut self) -> Result<&mut Self, Error<W::Error>> {
        self.put(&[0xff])
    }

    /// Syntactic sugar for `Ok(())`.
    pub fn ok(&mut self) -> Result<(), Error<W::Error>> {
        Ok(())
    }

    /// Encode a sequence of CBOR tokens.
    #[cfg(feature = "half")]
    pub fn tokens<'a, 'b: 'a, I>(&mut self, tokens: I) -> Result<(), Error<W::Error>>
    where
        I: IntoIterator<Item = &'a crate::data::Token<'b>>
    {
        for t in tokens {
            self.encode(t)?;
        }
        Ok(())
    }

    /// Write the encoded byte slice.
    pub(crate) fn put(&mut self, b: &[u8]) -> Result<&mut Self, Error<W::Error>> {
        self.writer.write_all(b).map_err(Error::write)?;
        Ok(self)
    }

    /// Write type and length information.
    fn type_len(&mut self, t: u8, x: u64) -> Result<&mut Self, Error<W::Error>> {
        match x {
            0        ..= 0x17        => self.put(&[t | x as u8]),
            0x18     ..= 0xff        => self.put(&[t | 24, x as u8]),
            0x100    ..= 0xffff      => self.put(&[t | 25])?.put(&(x as u16).to_be_bytes()[..]),
            0x1_0000 ..= 0xffff_ffff => self.put(&[t | 26])?.put(&(x as u32).to_be_bytes()),
            _                        => self.put(&[t | 27])?.put(&x.to_be_bytes()[..])
        }
    }
}