serde_cbor_2/
ser.rs

1//! Serialize a Rust data structure to CBOR data.
2
3#[cfg(feature = "alloc")]
4use alloc::vec::Vec;
5
6#[cfg(feature = "std")]
7pub use crate::write::IoWrite;
8pub use crate::write::{SliceWrite, Write};
9
10use crate::error::{Error, Result};
11use half::f16;
12use serde::ser::{self, Serialize};
13#[cfg(feature = "std")]
14use std::io;
15
16use crate::tags::{get_tag, CBOR_NEWTYPE_NAME};
17
18/// Serializes a value to a vector.
19#[cfg(any(feature = "std", feature = "alloc"))]
20pub fn to_vec<T>(value: &T) -> Result<Vec<u8>>
21where
22    T: ser::Serialize,
23{
24    let mut vec = Vec::new();
25    value.serialize(&mut Serializer::new(&mut vec))?;
26    Ok(vec)
27}
28
29/// Serializes a value to a vector in packed format.
30#[cfg(feature = "std")]
31pub fn to_vec_packed<T>(value: &T) -> Result<Vec<u8>>
32where
33    T: ser::Serialize,
34{
35    let mut vec = Vec::new();
36    value.serialize(&mut Serializer::new(&mut IoWrite::new(&mut vec)).packed_format())?;
37    Ok(vec)
38}
39
40/// Serializes a value to a writer.
41#[cfg(feature = "std")]
42pub fn to_writer<W, T>(writer: W, value: &T) -> Result<()>
43where
44    W: io::Write,
45    T: ser::Serialize,
46{
47    value.serialize(&mut Serializer::new(&mut IoWrite::new(writer)))
48}
49
50/// A structure for serializing Rust values to CBOR.
51#[derive(Debug)]
52pub struct Serializer<W> {
53    writer: W,
54    packed: bool,
55    enum_as_map: bool,
56}
57
58impl<W> Serializer<W>
59where
60    W: Write,
61{
62    /// Creates a new CBOR serializer.
63    ///
64    /// `to_vec` and `to_writer` should normally be used instead of this method.
65    #[inline]
66    pub fn new(writer: W) -> Self {
67        Serializer {
68            writer,
69            packed: false,
70            enum_as_map: true,
71        }
72    }
73
74    /// Choose concise/packed format for serializer.
75    ///
76    /// In the packed format enum variant names and field names
77    /// are replaced with numeric indizes to conserve space.
78    pub fn packed_format(mut self) -> Self {
79        self.packed = true;
80        self
81    }
82
83    /// Enable old enum format used by `serde_cbor` versions <= v0.9.
84    ///
85    /// The `legacy_enums` option determines how enums are encoded.
86    ///
87    /// This makes no difference when encoding and decoding enums using
88    /// this crate, but it shows up when decoding to a `Value` or decoding
89    /// in other languages.
90    ///
91    /// # Examples
92    ///
93    /// Given the following enum
94    ///
95    /// ```rust
96    /// enum Enum {
97    ///     Unit,
98    ///     NewType(i32),
99    ///     Tuple(String, bool),
100    ///     Struct{ x: i32, y: i32 },
101    /// }
102    /// ```
103    /// we will give the `Value` with the same encoding for each case using
104    /// JSON notation.
105    ///
106    /// ## Default encodings
107    ///
108    /// * `Enum::Unit` encodes as `"Unit"`
109    /// * `Enum::NewType(10)` encodes as `{"NewType": 10}`
110    /// * `Enum::Tuple("x", true)` encodes as `{"Tuple": ["x", true]}`
111    ///
112    /// ## Legacy encodings
113    ///
114    /// * `Enum::Unit` encodes as `"Unit"`
115    /// * `Enum::NewType(10)` encodes as `["NewType", 10]`
116    /// * `Enum::Tuple("x", true)` encodes as `["Tuple", "x", true]`
117    /// * `Enum::Struct{ x: 5, y: -5 }` encodes as `["Struct", {"x": 5, "y": -5}]`
118    pub fn legacy_enums(mut self) -> Self {
119        self.enum_as_map = false;
120        self
121    }
122
123    /// Writes a CBOR self-describe tag to the stream.
124    ///
125    /// Tagging allows a decoder to distinguish different file formats based on their content
126    /// without further information.
127    #[inline]
128    pub fn self_describe(&mut self) -> Result<()> {
129        let mut buf = [(6 << 5) | 25, 0, 0];
130        buf[1..].copy_from_slice(&55799u16.to_be_bytes());
131        self.writer.write_all(&buf).map_err(|e| e.into())
132    }
133
134    /// Unwrap the `Writer` from the `Serializer`.
135    #[inline]
136    pub fn into_inner(self) -> W {
137        self.writer
138    }
139
140    #[inline]
141    fn write_u8(&mut self, major: u8, value: u8) -> Result<()> {
142        if value <= 0x17 {
143            self.writer.write_all(&[(major << 5) | value])
144        } else {
145            let buf = [(major << 5) | 24, value];
146            self.writer.write_all(&buf)
147        }
148        .map_err(|e| e.into())
149    }
150
151    #[inline]
152    fn write_u16(&mut self, major: u8, value: u16) -> Result<()> {
153        if value <= u16::from(u8::MAX) {
154            self.write_u8(major, value as u8)
155        } else {
156            let mut buf = [(major << 5) | 25, 0, 0];
157            buf[1..].copy_from_slice(&value.to_be_bytes());
158            self.writer.write_all(&buf).map_err(|e| e.into())
159        }
160    }
161
162    #[inline]
163    fn write_u32(&mut self, major: u8, value: u32) -> Result<()> {
164        if value <= u32::from(u16::MAX) {
165            self.write_u16(major, value as u16)
166        } else {
167            let mut buf = [(major << 5) | 26, 0, 0, 0, 0];
168            buf[1..].copy_from_slice(&value.to_be_bytes());
169            self.writer.write_all(&buf).map_err(|e| e.into())
170        }
171    }
172
173    #[inline]
174    fn write_u64(&mut self, major: u8, value: u64) -> Result<()> {
175        if value <= u64::from(u32::MAX) {
176            self.write_u32(major, value as u32)
177        } else {
178            let mut buf = [(major << 5) | 27, 0, 0, 0, 0, 0, 0, 0, 0];
179            buf[1..].copy_from_slice(&value.to_be_bytes());
180            self.writer.write_all(&buf).map_err(|e| e.into())
181        }
182    }
183
184    #[inline]
185    fn serialize_collection(
186        &mut self,
187        major: u8,
188        len: Option<usize>,
189    ) -> Result<CollectionSerializer<'_, W>> {
190        let needs_eof = match len {
191            Some(len) => {
192                self.write_u64(major, len as u64)?;
193                false
194            }
195            None => {
196                self.writer
197                    .write_all(&[(major << 5) | 31])
198                    .map_err(|e| e.into())?;
199                true
200            }
201        };
202
203        Ok(CollectionSerializer {
204            ser: self,
205            needs_eof,
206        })
207    }
208}
209
210impl<'a, W> ser::Serializer for &'a mut Serializer<W>
211where
212    W: Write,
213{
214    type Ok = ();
215    type Error = Error;
216
217    type SerializeSeq = CollectionSerializer<'a, W>;
218    type SerializeTuple = &'a mut Serializer<W>;
219    type SerializeTupleStruct = &'a mut Serializer<W>;
220    type SerializeTupleVariant = &'a mut Serializer<W>;
221    type SerializeMap = CollectionSerializer<'a, W>;
222    type SerializeStruct = StructSerializer<'a, W>;
223    type SerializeStructVariant = StructSerializer<'a, W>;
224
225    #[inline]
226    fn serialize_bool(self, value: bool) -> Result<()> {
227        let value = if value { 0xf5 } else { 0xf4 };
228        self.writer.write_all(&[value]).map_err(|e| e.into())
229    }
230
231    #[inline]
232    fn serialize_i8(self, value: i8) -> Result<()> {
233        if value < 0 {
234            self.write_u8(1, -(value + 1) as u8)
235        } else {
236            self.write_u8(0, value as u8)
237        }
238    }
239
240    #[inline]
241    fn serialize_i16(self, value: i16) -> Result<()> {
242        if value < 0 {
243            self.write_u16(1, -(value + 1) as u16)
244        } else {
245            self.write_u16(0, value as u16)
246        }
247    }
248
249    #[inline]
250    fn serialize_i32(self, value: i32) -> Result<()> {
251        if value < 0 {
252            self.write_u32(1, -(value + 1) as u32)
253        } else {
254            self.write_u32(0, value as u32)
255        }
256    }
257
258    #[inline]
259    fn serialize_i64(self, value: i64) -> Result<()> {
260        if value < 0 {
261            self.write_u64(1, -(value + 1) as u64)
262        } else {
263            self.write_u64(0, value as u64)
264        }
265    }
266
267    #[inline]
268    fn serialize_i128(self, value: i128) -> Result<()> {
269        if value < 0 {
270            if -(value + 1) > i128::from(u64::MAX) {
271                return Err(Error::message("The number can't be stored in CBOR"));
272            }
273            self.write_u64(1, -(value + 1) as u64)
274        } else {
275            if value > i128::from(u64::MAX) {
276                return Err(Error::message("The number can't be stored in CBOR"));
277            }
278            self.write_u64(0, value as u64)
279        }
280    }
281
282    #[inline]
283    fn serialize_u8(self, value: u8) -> Result<()> {
284        self.write_u8(0, value)
285    }
286
287    #[inline]
288    fn serialize_u16(self, value: u16) -> Result<()> {
289        self.write_u16(0, value)
290    }
291
292    #[inline]
293    fn serialize_u32(self, value: u32) -> Result<()> {
294        self.write_u32(0, value)
295    }
296
297    #[inline]
298    fn serialize_u64(self, value: u64) -> Result<()> {
299        self.write_u64(0, value)
300    }
301
302    #[inline]
303    fn serialize_u128(self, value: u128) -> Result<()> {
304        if value > u128::from(u64::MAX) {
305            return Err(Error::message("The number can't be stored in CBOR"));
306        }
307        self.write_u64(0, value as u64)
308    }
309
310    #[inline]
311    #[allow(clippy::float_cmp)]
312    fn serialize_f32(self, value: f32) -> Result<()> {
313        if value.is_infinite() {
314            if value.is_sign_positive() {
315                self.writer.write_all(&[0xf9, 0x7c, 0x00])
316            } else {
317                self.writer.write_all(&[0xf9, 0xfc, 0x00])
318            }
319        } else if value.is_nan() {
320            self.writer.write_all(&[0xf9, 0x7e, 0x00])
321        } else if f32::from(f16::from_f32(value)) == value {
322            let mut buf = [0xf9, 0, 0];
323            buf[1..].copy_from_slice(&f16::from_f32(value).to_bits().to_be_bytes());
324            self.writer.write_all(&buf)
325        } else {
326            let mut buf = [0xfa, 0, 0, 0, 0];
327            buf[1..].copy_from_slice(&value.to_bits().to_be_bytes());
328            self.writer.write_all(&buf)
329        }
330        .map_err(|e| e.into())
331    }
332
333    #[inline]
334    #[allow(clippy::float_cmp)]
335    fn serialize_f64(self, value: f64) -> Result<()> {
336        if !value.is_finite() || f64::from(value as f32) == value {
337            self.serialize_f32(value as f32)
338        } else {
339            let mut buf = [0xfb, 0, 0, 0, 0, 0, 0, 0, 0];
340            buf[1..].copy_from_slice(&value.to_bits().to_be_bytes());
341            self.writer.write_all(&buf).map_err(|e| e.into())
342        }
343    }
344
345    #[inline]
346    fn serialize_char(self, value: char) -> Result<()> {
347        // A char encoded as UTF-8 takes 4 bytes at most.
348        let mut buf = [0; 4];
349        self.serialize_str(value.encode_utf8(&mut buf))
350    }
351
352    #[inline]
353    fn serialize_str(self, value: &str) -> Result<()> {
354        self.write_u64(3, value.len() as u64)?;
355        self.writer
356            .write_all(value.as_bytes())
357            .map_err(|e| e.into())
358    }
359
360    #[inline]
361    fn serialize_bytes(self, value: &[u8]) -> Result<()> {
362        self.write_u64(2, value.len() as u64)?;
363        self.writer.write_all(value).map_err(|e| e.into())
364    }
365
366    #[inline]
367    fn serialize_unit(self) -> Result<()> {
368        self.serialize_none()
369    }
370
371    #[inline]
372    fn serialize_some<T>(self, value: &T) -> Result<()>
373    where
374        T: ?Sized + ser::Serialize,
375    {
376        value.serialize(self)
377    }
378
379    #[inline]
380    fn serialize_none(self) -> Result<()> {
381        self.writer.write_all(&[0xf6]).map_err(|e| e.into())
382    }
383
384    #[inline]
385    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
386        self.serialize_unit()
387    }
388
389    #[inline]
390    fn serialize_unit_variant(
391        self,
392        _name: &'static str,
393        variant_index: u32,
394        variant: &'static str,
395    ) -> Result<()> {
396        if self.packed {
397            self.serialize_u32(variant_index)
398        } else {
399            self.serialize_str(variant)
400        }
401    }
402
403    #[inline]
404    fn serialize_newtype_struct<T>(self, name: &'static str, value: &T) -> Result<()>
405    where
406        T: ?Sized + ser::Serialize,
407    {
408        if name == CBOR_NEWTYPE_NAME {
409            if let Some(tag) = get_tag() {
410                self.write_u64(6, tag)?;
411            }
412        }
413        value.serialize(self)
414    }
415
416    #[inline]
417    fn serialize_newtype_variant<T>(
418        self,
419        name: &'static str,
420        variant_index: u32,
421        variant: &'static str,
422        value: &T,
423    ) -> Result<()>
424    where
425        T: ?Sized + ser::Serialize,
426    {
427        if self.enum_as_map {
428            self.write_u64(5, 1u64)?;
429            variant.serialize(&mut *self)?;
430        } else {
431            self.writer
432                .write_all(&[(4 << 5) | 2])
433                .map_err(|e| e.into())?;
434            self.serialize_unit_variant(name, variant_index, variant)?;
435        }
436        value.serialize(self)
437    }
438
439    #[inline]
440    fn serialize_seq(self, len: Option<usize>) -> Result<CollectionSerializer<'a, W>> {
441        self.serialize_collection(4, len)
442    }
443
444    #[inline]
445    fn serialize_tuple(self, len: usize) -> Result<&'a mut Serializer<W>> {
446        self.write_u64(4, len as u64)?;
447        Ok(self)
448    }
449
450    #[inline]
451    fn serialize_tuple_struct(
452        self,
453        _name: &'static str,
454        len: usize,
455    ) -> Result<&'a mut Serializer<W>> {
456        self.serialize_tuple(len)
457    }
458
459    #[inline]
460    fn serialize_tuple_variant(
461        self,
462        name: &'static str,
463        variant_index: u32,
464        variant: &'static str,
465        len: usize,
466    ) -> Result<&'a mut Serializer<W>> {
467        if self.enum_as_map {
468            self.write_u64(5, 1u64)?;
469            variant.serialize(&mut *self)?;
470            self.serialize_tuple(len)
471        } else {
472            self.write_u64(4, (len + 1) as u64)?;
473            self.serialize_unit_variant(name, variant_index, variant)?;
474            Ok(self)
475        }
476    }
477
478    #[inline]
479    fn serialize_map(self, len: Option<usize>) -> Result<CollectionSerializer<'a, W>> {
480        self.serialize_collection(5, len)
481    }
482
483    #[cfg(not(feature = "std"))]
484    fn collect_str<T: ?Sized>(self, value: &T) -> Result<()>
485    where
486        T: core::fmt::Display,
487    {
488        use crate::write::FmtWrite;
489        use core::fmt::Write;
490
491        let mut w = FmtWrite::new(&mut self.writer);
492        write!(w, "{}", value)?;
493        Ok(())
494    }
495
496    #[inline]
497    fn serialize_struct(self, _name: &'static str, len: usize) -> Result<StructSerializer<'a, W>> {
498        self.write_u64(5, len as u64)?;
499        Ok(StructSerializer { ser: self, idx: 0 })
500    }
501
502    #[inline]
503    fn serialize_struct_variant(
504        self,
505        name: &'static str,
506        variant_index: u32,
507        variant: &'static str,
508        len: usize,
509    ) -> Result<StructSerializer<'a, W>> {
510        if self.enum_as_map {
511            self.write_u64(5, 1u64)?;
512        } else {
513            self.writer
514                .write_all(&[(4 << 5) | 2])
515                .map_err(|e| e.into())?;
516        }
517        self.serialize_unit_variant(name, variant_index, variant)?;
518        self.serialize_struct(name, len)
519    }
520
521    #[inline]
522    fn is_human_readable(&self) -> bool {
523        false
524    }
525}
526
527impl<W> ser::SerializeTuple for &mut Serializer<W>
528where
529    W: Write,
530{
531    type Ok = ();
532    type Error = Error;
533
534    #[inline]
535    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
536    where
537        T: ?Sized + ser::Serialize,
538    {
539        value.serialize(&mut **self)
540    }
541
542    #[inline]
543    fn end(self) -> Result<()> {
544        Ok(())
545    }
546}
547
548impl<W> ser::SerializeTupleStruct for &mut Serializer<W>
549where
550    W: Write,
551{
552    type Ok = ();
553    type Error = Error;
554
555    #[inline]
556    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
557    where
558        T: ?Sized + ser::Serialize,
559    {
560        value.serialize(&mut **self)
561    }
562
563    #[inline]
564    fn end(self) -> Result<()> {
565        Ok(())
566    }
567}
568
569impl<W> ser::SerializeTupleVariant for &mut Serializer<W>
570where
571    W: Write,
572{
573    type Ok = ();
574    type Error = Error;
575
576    #[inline]
577    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
578    where
579        T: ?Sized + ser::Serialize,
580    {
581        value.serialize(&mut **self)
582    }
583
584    #[inline]
585    fn end(self) -> Result<()> {
586        Ok(())
587    }
588}
589
590#[doc(hidden)]
591pub struct StructSerializer<'a, W> {
592    ser: &'a mut Serializer<W>,
593    idx: u32,
594}
595
596impl<W> StructSerializer<'_, W>
597where
598    W: Write,
599{
600    #[inline]
601    fn serialize_field_inner<T>(&mut self, key: &'static str, value: &T) -> Result<()>
602    where
603        T: ?Sized + ser::Serialize,
604    {
605        if self.ser.packed {
606            self.idx.serialize(&mut *self.ser)?;
607        } else {
608            key.serialize(&mut *self.ser)?;
609        }
610        value.serialize(&mut *self.ser)?;
611        self.idx += 1;
612        Ok(())
613    }
614
615    #[inline]
616    fn skip_field_inner(&mut self, _: &'static str) -> Result<()> {
617        self.idx += 1;
618        Ok(())
619    }
620
621    #[inline]
622    fn end_inner(self) -> Result<()> {
623        Ok(())
624    }
625}
626
627impl<W> ser::SerializeStruct for StructSerializer<'_, W>
628where
629    W: Write,
630{
631    type Ok = ();
632    type Error = Error;
633
634    #[inline]
635    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
636    where
637        T: ?Sized + ser::Serialize,
638    {
639        self.serialize_field_inner(key, value)
640    }
641
642    #[inline]
643    fn skip_field(&mut self, key: &'static str) -> Result<()> {
644        self.skip_field_inner(key)
645    }
646
647    #[inline]
648    fn end(self) -> Result<()> {
649        self.end_inner()
650    }
651}
652
653impl<W> ser::SerializeStructVariant for StructSerializer<'_, W>
654where
655    W: Write,
656{
657    type Ok = ();
658    type Error = Error;
659
660    #[inline]
661    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
662    where
663        T: ?Sized + ser::Serialize,
664    {
665        self.serialize_field_inner(key, value)
666    }
667
668    #[inline]
669    fn skip_field(&mut self, key: &'static str) -> Result<()> {
670        self.skip_field_inner(key)
671    }
672
673    #[inline]
674    fn end(self) -> Result<()> {
675        self.end_inner()
676    }
677}
678
679#[doc(hidden)]
680pub struct CollectionSerializer<'a, W> {
681    ser: &'a mut Serializer<W>,
682    needs_eof: bool,
683}
684
685impl<W> CollectionSerializer<'_, W>
686where
687    W: Write,
688{
689    #[inline]
690    fn end_inner(self) -> Result<()> {
691        if self.needs_eof {
692            self.ser.writer.write_all(&[0xff]).map_err(|e| e.into())
693        } else {
694            Ok(())
695        }
696    }
697}
698
699impl<W> ser::SerializeSeq for CollectionSerializer<'_, W>
700where
701    W: Write,
702{
703    type Ok = ();
704    type Error = Error;
705
706    #[inline]
707    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
708    where
709        T: ?Sized + ser::Serialize,
710    {
711        value.serialize(&mut *self.ser)
712    }
713
714    #[inline]
715    fn end(self) -> Result<()> {
716        self.end_inner()
717    }
718}
719
720impl<W> ser::SerializeMap for CollectionSerializer<'_, W>
721where
722    W: Write,
723{
724    type Ok = ();
725    type Error = Error;
726
727    #[inline]
728    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
729    where
730        T: ?Sized + ser::Serialize,
731    {
732        key.serialize(&mut *self.ser)
733    }
734
735    #[inline]
736    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
737    where
738        T: ?Sized + ser::Serialize,
739    {
740        value.serialize(&mut *self.ser)
741    }
742
743    #[inline]
744    fn end(self) -> Result<()> {
745        self.end_inner()
746    }
747}
serde_cbor_2/ser.rs

serde_cbor_2/
ser.rs
