serde_json/
ser.rs

1//! Serialize a Rust data structure into JSON data.
2
3use crate::error::{Error, ErrorCode, Result};
4use crate::io;
5use alloc::string::String;
6#[cfg(feature = "raw_value")]
7use alloc::string::ToString;
8use alloc::vec::Vec;
9use core::fmt::{self, Display};
10use core::hint;
11use core::num::FpCategory;
12use core::str;
13use serde::ser::{self, Impossible, Serialize};
14
15/// A structure for serializing Rust values into JSON.
16#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
17pub struct Serializer<W, F = CompactFormatter> {
18    writer: W,
19    formatter: F,
20}
21
22impl<W> Serializer<W>
23where
24    W: io::Write,
25{
26    /// Creates a new JSON serializer.
27    #[inline]
28    pub fn new(writer: W) -> Self {
29        Serializer::with_formatter(writer, CompactFormatter)
30    }
31}
32
33impl<'a, W> Serializer<W, PrettyFormatter<'a>>
34where
35    W: io::Write,
36{
37    /// Creates a new JSON pretty print serializer.
38    #[inline]
39    pub fn pretty(writer: W) -> Self {
40        Serializer::with_formatter(writer, PrettyFormatter::new())
41    }
42}
43
44impl<W, F> Serializer<W, F>
45where
46    W: io::Write,
47    F: Formatter,
48{
49    /// Creates a new JSON visitor whose output will be written to the writer
50    /// specified.
51    #[inline]
52    pub fn with_formatter(writer: W, formatter: F) -> Self {
53        Serializer { writer, formatter }
54    }
55
56    /// Unwrap the `Writer` from the `Serializer`.
57    #[inline]
58    pub fn into_inner(self) -> W {
59        self.writer
60    }
61}
62
63impl<'a, W, F> ser::Serializer for &'a mut Serializer<W, F>
64where
65    W: io::Write,
66    F: Formatter,
67{
68    type Ok = ();
69    type Error = Error;
70
71    type SerializeSeq = Compound<'a, W, F>;
72    type SerializeTuple = Compound<'a, W, F>;
73    type SerializeTupleStruct = Compound<'a, W, F>;
74    type SerializeTupleVariant = Compound<'a, W, F>;
75    type SerializeMap = Compound<'a, W, F>;
76    type SerializeStruct = Compound<'a, W, F>;
77    type SerializeStructVariant = Compound<'a, W, F>;
78
79    #[inline]
80    fn serialize_bool(self, value: bool) -> Result<()> {
81        self.formatter
82            .write_bool(&mut self.writer, value)
83            .map_err(Error::io)
84    }
85
86    #[inline]
87    fn serialize_i8(self, value: i8) -> Result<()> {
88        self.formatter
89            .write_i8(&mut self.writer, value)
90            .map_err(Error::io)
91    }
92
93    #[inline]
94    fn serialize_i16(self, value: i16) -> Result<()> {
95        self.formatter
96            .write_i16(&mut self.writer, value)
97            .map_err(Error::io)
98    }
99
100    #[inline]
101    fn serialize_i32(self, value: i32) -> Result<()> {
102        self.formatter
103            .write_i32(&mut self.writer, value)
104            .map_err(Error::io)
105    }
106
107    #[inline]
108    fn serialize_i64(self, value: i64) -> Result<()> {
109        self.formatter
110            .write_i64(&mut self.writer, value)
111            .map_err(Error::io)
112    }
113
114    fn serialize_i128(self, value: i128) -> Result<()> {
115        self.formatter
116            .write_i128(&mut self.writer, value)
117            .map_err(Error::io)
118    }
119
120    #[inline]
121    fn serialize_u8(self, value: u8) -> Result<()> {
122        self.formatter
123            .write_u8(&mut self.writer, value)
124            .map_err(Error::io)
125    }
126
127    #[inline]
128    fn serialize_u16(self, value: u16) -> Result<()> {
129        self.formatter
130            .write_u16(&mut self.writer, value)
131            .map_err(Error::io)
132    }
133
134    #[inline]
135    fn serialize_u32(self, value: u32) -> Result<()> {
136        self.formatter
137            .write_u32(&mut self.writer, value)
138            .map_err(Error::io)
139    }
140
141    #[inline]
142    fn serialize_u64(self, value: u64) -> Result<()> {
143        self.formatter
144            .write_u64(&mut self.writer, value)
145            .map_err(Error::io)
146    }
147
148    fn serialize_u128(self, value: u128) -> Result<()> {
149        self.formatter
150            .write_u128(&mut self.writer, value)
151            .map_err(Error::io)
152    }
153
154    #[inline]
155    fn serialize_f32(self, value: f32) -> Result<()> {
156        match value.classify() {
157            FpCategory::Nan | FpCategory::Infinite => self
158                .formatter
159                .write_null(&mut self.writer)
160                .map_err(Error::io),
161            _ => self
162                .formatter
163                .write_f32(&mut self.writer, value)
164                .map_err(Error::io),
165        }
166    }
167
168    #[inline]
169    fn serialize_f64(self, value: f64) -> Result<()> {
170        match value.classify() {
171            FpCategory::Nan | FpCategory::Infinite => self
172                .formatter
173                .write_null(&mut self.writer)
174                .map_err(Error::io),
175            _ => self
176                .formatter
177                .write_f64(&mut self.writer, value)
178                .map_err(Error::io),
179        }
180    }
181
182    #[inline]
183    fn serialize_char(self, value: char) -> Result<()> {
184        // A char encoded as UTF-8 takes 4 bytes at most.
185        let mut buf = [0; 4];
186        self.serialize_str(value.encode_utf8(&mut buf))
187    }
188
189    #[inline]
190    fn serialize_str(self, value: &str) -> Result<()> {
191        format_escaped_str(&mut self.writer, &mut self.formatter, value).map_err(Error::io)
192    }
193
194    #[inline]
195    fn serialize_bytes(self, value: &[u8]) -> Result<()> {
196        self.formatter
197            .write_byte_array(&mut self.writer, value)
198            .map_err(Error::io)
199    }
200
201    #[inline]
202    fn serialize_unit(self) -> Result<()> {
203        self.formatter
204            .write_null(&mut self.writer)
205            .map_err(Error::io)
206    }
207
208    #[inline]
209    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
210        self.serialize_unit()
211    }
212
213    #[inline]
214    fn serialize_unit_variant(
215        self,
216        _name: &'static str,
217        _variant_index: u32,
218        variant: &'static str,
219    ) -> Result<()> {
220        self.serialize_str(variant)
221    }
222
223    /// Serialize newtypes without an object wrapper.
224    #[inline]
225    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<()>
226    where
227        T: ?Sized + Serialize,
228    {
229        value.serialize(self)
230    }
231
232    #[inline]
233    fn serialize_newtype_variant<T>(
234        self,
235        _name: &'static str,
236        _variant_index: u32,
237        variant: &'static str,
238        value: &T,
239    ) -> Result<()>
240    where
241        T: ?Sized + Serialize,
242    {
243        tri!(self
244            .formatter
245            .begin_object(&mut self.writer)
246            .map_err(Error::io));
247        tri!(self
248            .formatter
249            .begin_object_key(&mut self.writer, true)
250            .map_err(Error::io));
251        tri!(self.serialize_str(variant));
252        tri!(self
253            .formatter
254            .end_object_key(&mut self.writer)
255            .map_err(Error::io));
256        tri!(self
257            .formatter
258            .begin_object_value(&mut self.writer)
259            .map_err(Error::io));
260        tri!(value.serialize(&mut *self));
261        tri!(self
262            .formatter
263            .end_object_value(&mut self.writer)
264            .map_err(Error::io));
265        self.formatter
266            .end_object(&mut self.writer)
267            .map_err(Error::io)
268    }
269
270    #[inline]
271    fn serialize_none(self) -> Result<()> {
272        self.serialize_unit()
273    }
274
275    #[inline]
276    fn serialize_some<T>(self, value: &T) -> Result<()>
277    where
278        T: ?Sized + Serialize,
279    {
280        value.serialize(self)
281    }
282
283    #[inline]
284    fn serialize_seq(self, len: Option<usize>) -> Result<Self::SerializeSeq> {
285        tri!(self
286            .formatter
287            .begin_array(&mut self.writer)
288            .map_err(Error::io));
289        if len == Some(0) {
290            tri!(self
291                .formatter
292                .end_array(&mut self.writer)
293                .map_err(Error::io));
294            Ok(Compound::Map {
295                ser: self,
296                state: State::Empty,
297            })
298        } else {
299            Ok(Compound::Map {
300                ser: self,
301                state: State::First,
302            })
303        }
304    }
305
306    #[inline]
307    fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple> {
308        self.serialize_seq(Some(len))
309    }
310
311    #[inline]
312    fn serialize_tuple_struct(
313        self,
314        _name: &'static str,
315        len: usize,
316    ) -> Result<Self::SerializeTupleStruct> {
317        self.serialize_seq(Some(len))
318    }
319
320    #[inline]
321    fn serialize_tuple_variant(
322        self,
323        _name: &'static str,
324        _variant_index: u32,
325        variant: &'static str,
326        len: usize,
327    ) -> Result<Self::SerializeTupleVariant> {
328        tri!(self
329            .formatter
330            .begin_object(&mut self.writer)
331            .map_err(Error::io));
332        tri!(self
333            .formatter
334            .begin_object_key(&mut self.writer, true)
335            .map_err(Error::io));
336        tri!(self.serialize_str(variant));
337        tri!(self
338            .formatter
339            .end_object_key(&mut self.writer)
340            .map_err(Error::io));
341        tri!(self
342            .formatter
343            .begin_object_value(&mut self.writer)
344            .map_err(Error::io));
345        self.serialize_seq(Some(len))
346    }
347
348    #[inline]
349    fn serialize_map(self, len: Option<usize>) -> Result<Self::SerializeMap> {
350        tri!(self
351            .formatter
352            .begin_object(&mut self.writer)
353            .map_err(Error::io));
354        if len == Some(0) {
355            tri!(self
356                .formatter
357                .end_object(&mut self.writer)
358                .map_err(Error::io));
359            Ok(Compound::Map {
360                ser: self,
361                state: State::Empty,
362            })
363        } else {
364            Ok(Compound::Map {
365                ser: self,
366                state: State::First,
367            })
368        }
369    }
370
371    #[inline]
372    fn serialize_struct(self, name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
373        match name {
374            #[cfg(feature = "arbitrary_precision")]
375            crate::number::TOKEN => Ok(Compound::Number { ser: self }),
376            #[cfg(feature = "raw_value")]
377            crate::raw::TOKEN => Ok(Compound::RawValue { ser: self }),
378            _ => self.serialize_map(Some(len)),
379        }
380    }
381
382    #[inline]
383    fn serialize_struct_variant(
384        self,
385        _name: &'static str,
386        _variant_index: u32,
387        variant: &'static str,
388        len: usize,
389    ) -> Result<Self::SerializeStructVariant> {
390        tri!(self
391            .formatter
392            .begin_object(&mut self.writer)
393            .map_err(Error::io));
394        tri!(self
395            .formatter
396            .begin_object_key(&mut self.writer, true)
397            .map_err(Error::io));
398        tri!(self.serialize_str(variant));
399        tri!(self
400            .formatter
401            .end_object_key(&mut self.writer)
402            .map_err(Error::io));
403        tri!(self
404            .formatter
405            .begin_object_value(&mut self.writer)
406            .map_err(Error::io));
407        self.serialize_map(Some(len))
408    }
409
410    fn collect_str<T>(self, value: &T) -> Result<()>
411    where
412        T: ?Sized + Display,
413    {
414        use self::fmt::Write;
415
416        struct Adapter<'ser, W: 'ser, F: 'ser> {
417            writer: &'ser mut W,
418            formatter: &'ser mut F,
419            error: Option<io::Error>,
420        }
421
422        impl<'ser, W, F> Write for Adapter<'ser, W, F>
423        where
424            W: io::Write,
425            F: Formatter,
426        {
427            fn write_str(&mut self, s: &str) -> fmt::Result {
428                debug_assert!(self.error.is_none());
429                match format_escaped_str_contents(self.writer, self.formatter, s) {
430                    Ok(()) => Ok(()),
431                    Err(err) => {
432                        self.error = Some(err);
433                        Err(fmt::Error)
434                    }
435                }
436            }
437        }
438
439        tri!(self
440            .formatter
441            .begin_string(&mut self.writer)
442            .map_err(Error::io));
443        let mut adapter = Adapter {
444            writer: &mut self.writer,
445            formatter: &mut self.formatter,
446            error: None,
447        };
448        match write!(adapter, "{}", value) {
449            Ok(()) => debug_assert!(adapter.error.is_none()),
450            Err(fmt::Error) => {
451                return Err(Error::io(adapter.error.expect("there should be an error")));
452            }
453        }
454        self.formatter
455            .end_string(&mut self.writer)
456            .map_err(Error::io)
457    }
458}
459
460// Not public API. Should be pub(crate).
461#[doc(hidden)]
462#[derive(Eq, PartialEq)]
463pub enum State {
464    Empty,
465    First,
466    Rest,
467}
468
469// Not public API. Should be pub(crate).
470#[doc(hidden)]
471pub enum Compound<'a, W: 'a, F: 'a> {
472    Map {
473        ser: &'a mut Serializer<W, F>,
474        state: State,
475    },
476    #[cfg(feature = "arbitrary_precision")]
477    Number { ser: &'a mut Serializer<W, F> },
478    #[cfg(feature = "raw_value")]
479    RawValue { ser: &'a mut Serializer<W, F> },
480}
481
482impl<'a, W, F> ser::SerializeSeq for Compound<'a, W, F>
483where
484    W: io::Write,
485    F: Formatter,
486{
487    type Ok = ();
488    type Error = Error;
489
490    #[inline]
491    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
492    where
493        T: ?Sized + Serialize,
494    {
495        match self {
496            Compound::Map { ser, state } => {
497                tri!(ser
498                    .formatter
499                    .begin_array_value(&mut ser.writer, *state == State::First)
500                    .map_err(Error::io));
501                *state = State::Rest;
502                tri!(value.serialize(&mut **ser));
503                ser.formatter
504                    .end_array_value(&mut ser.writer)
505                    .map_err(Error::io)
506            }
507            #[cfg(feature = "arbitrary_precision")]
508            Compound::Number { .. } => unreachable!(),
509            #[cfg(feature = "raw_value")]
510            Compound::RawValue { .. } => unreachable!(),
511        }
512    }
513
514    #[inline]
515    fn end(self) -> Result<()> {
516        match self {
517            Compound::Map { ser, state } => match state {
518                State::Empty => Ok(()),
519                _ => ser.formatter.end_array(&mut ser.writer).map_err(Error::io),
520            },
521            #[cfg(feature = "arbitrary_precision")]
522            Compound::Number { .. } => unreachable!(),
523            #[cfg(feature = "raw_value")]
524            Compound::RawValue { .. } => unreachable!(),
525        }
526    }
527}
528
529impl<'a, W, F> ser::SerializeTuple for Compound<'a, W, F>
530where
531    W: io::Write,
532    F: Formatter,
533{
534    type Ok = ();
535    type Error = Error;
536
537    #[inline]
538    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
539    where
540        T: ?Sized + Serialize,
541    {
542        ser::SerializeSeq::serialize_element(self, value)
543    }
544
545    #[inline]
546    fn end(self) -> Result<()> {
547        ser::SerializeSeq::end(self)
548    }
549}
550
551impl<'a, W, F> ser::SerializeTupleStruct for Compound<'a, W, F>
552where
553    W: io::Write,
554    F: Formatter,
555{
556    type Ok = ();
557    type Error = Error;
558
559    #[inline]
560    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
561    where
562        T: ?Sized + Serialize,
563    {
564        ser::SerializeSeq::serialize_element(self, value)
565    }
566
567    #[inline]
568    fn end(self) -> Result<()> {
569        ser::SerializeSeq::end(self)
570    }
571}
572
573impl<'a, W, F> ser::SerializeTupleVariant for Compound<'a, W, F>
574where
575    W: io::Write,
576    F: Formatter,
577{
578    type Ok = ();
579    type Error = Error;
580
581    #[inline]
582    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
583    where
584        T: ?Sized + Serialize,
585    {
586        ser::SerializeSeq::serialize_element(self, value)
587    }
588
589    #[inline]
590    fn end(self) -> Result<()> {
591        match self {
592            Compound::Map { ser, state } => {
593                match state {
594                    State::Empty => {}
595                    _ => tri!(ser.formatter.end_array(&mut ser.writer).map_err(Error::io)),
596                }
597                tri!(ser
598                    .formatter
599                    .end_object_value(&mut ser.writer)
600                    .map_err(Error::io));
601                ser.formatter.end_object(&mut ser.writer).map_err(Error::io)
602            }
603            #[cfg(feature = "arbitrary_precision")]
604            Compound::Number { .. } => unreachable!(),
605            #[cfg(feature = "raw_value")]
606            Compound::RawValue { .. } => unreachable!(),
607        }
608    }
609}
610
611impl<'a, W, F> ser::SerializeMap for Compound<'a, W, F>
612where
613    W: io::Write,
614    F: Formatter,
615{
616    type Ok = ();
617    type Error = Error;
618
619    #[inline]
620    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
621    where
622        T: ?Sized + Serialize,
623    {
624        match self {
625            Compound::Map { ser, state } => {
626                tri!(ser
627                    .formatter
628                    .begin_object_key(&mut ser.writer, *state == State::First)
629                    .map_err(Error::io));
630                *state = State::Rest;
631
632                tri!(key.serialize(MapKeySerializer { ser: *ser }));
633
634                ser.formatter
635                    .end_object_key(&mut ser.writer)
636                    .map_err(Error::io)
637            }
638            #[cfg(feature = "arbitrary_precision")]
639            Compound::Number { .. } => unreachable!(),
640            #[cfg(feature = "raw_value")]
641            Compound::RawValue { .. } => unreachable!(),
642        }
643    }
644
645    #[inline]
646    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
647    where
648        T: ?Sized + Serialize,
649    {
650        match self {
651            Compound::Map { ser, .. } => {
652                tri!(ser
653                    .formatter
654                    .begin_object_value(&mut ser.writer)
655                    .map_err(Error::io));
656                tri!(value.serialize(&mut **ser));
657                ser.formatter
658                    .end_object_value(&mut ser.writer)
659                    .map_err(Error::io)
660            }
661            #[cfg(feature = "arbitrary_precision")]
662            Compound::Number { .. } => unreachable!(),
663            #[cfg(feature = "raw_value")]
664            Compound::RawValue { .. } => unreachable!(),
665        }
666    }
667
668    #[inline]
669    fn end(self) -> Result<()> {
670        match self {
671            Compound::Map { ser, state } => match state {
672                State::Empty => Ok(()),
673                _ => ser.formatter.end_object(&mut ser.writer).map_err(Error::io),
674            },
675            #[cfg(feature = "arbitrary_precision")]
676            Compound::Number { .. } => unreachable!(),
677            #[cfg(feature = "raw_value")]
678            Compound::RawValue { .. } => unreachable!(),
679        }
680    }
681}
682
683impl<'a, W, F> ser::SerializeStruct for Compound<'a, W, F>
684where
685    W: io::Write,
686    F: Formatter,
687{
688    type Ok = ();
689    type Error = Error;
690
691    #[inline]
692    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
693    where
694        T: ?Sized + Serialize,
695    {
696        match self {
697            Compound::Map { .. } => ser::SerializeMap::serialize_entry(self, key, value),
698            #[cfg(feature = "arbitrary_precision")]
699            Compound::Number { ser, .. } => {
700                if key == crate::number::TOKEN {
701                    value.serialize(NumberStrEmitter(ser))
702                } else {
703                    Err(invalid_number())
704                }
705            }
706            #[cfg(feature = "raw_value")]
707            Compound::RawValue { ser, .. } => {
708                if key == crate::raw::TOKEN {
709                    value.serialize(RawValueStrEmitter(ser))
710                } else {
711                    Err(invalid_raw_value())
712                }
713            }
714        }
715    }
716
717    #[inline]
718    fn end(self) -> Result<()> {
719        match self {
720            Compound::Map { .. } => ser::SerializeMap::end(self),
721            #[cfg(feature = "arbitrary_precision")]
722            Compound::Number { .. } => Ok(()),
723            #[cfg(feature = "raw_value")]
724            Compound::RawValue { .. } => Ok(()),
725        }
726    }
727}
728
729impl<'a, W, F> ser::SerializeStructVariant for Compound<'a, W, F>
730where
731    W: io::Write,
732    F: Formatter,
733{
734    type Ok = ();
735    type Error = Error;
736
737    #[inline]
738    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
739    where
740        T: ?Sized + Serialize,
741    {
742        match *self {
743            Compound::Map { .. } => ser::SerializeStruct::serialize_field(self, key, value),
744            #[cfg(feature = "arbitrary_precision")]
745            Compound::Number { .. } => unreachable!(),
746            #[cfg(feature = "raw_value")]
747            Compound::RawValue { .. } => unreachable!(),
748        }
749    }
750
751    #[inline]
752    fn end(self) -> Result<()> {
753        match self {
754            Compound::Map { ser, state } => {
755                match state {
756                    State::Empty => {}
757                    _ => tri!(ser.formatter.end_object(&mut ser.writer).map_err(Error::io)),
758                }
759                tri!(ser
760                    .formatter
761                    .end_object_value(&mut ser.writer)
762                    .map_err(Error::io));
763                ser.formatter.end_object(&mut ser.writer).map_err(Error::io)
764            }
765            #[cfg(feature = "arbitrary_precision")]
766            Compound::Number { .. } => unreachable!(),
767            #[cfg(feature = "raw_value")]
768            Compound::RawValue { .. } => unreachable!(),
769        }
770    }
771}
772
773struct MapKeySerializer<'a, W: 'a, F: 'a> {
774    ser: &'a mut Serializer<W, F>,
775}
776
777#[cfg(feature = "arbitrary_precision")]
778fn invalid_number() -> Error {
779    Error::syntax(ErrorCode::InvalidNumber, 0, 0)
780}
781
782#[cfg(feature = "raw_value")]
783fn invalid_raw_value() -> Error {
784    Error::syntax(ErrorCode::ExpectedSomeValue, 0, 0)
785}
786
787fn key_must_be_a_string() -> Error {
788    Error::syntax(ErrorCode::KeyMustBeAString, 0, 0)
789}
790
791fn float_key_must_be_finite() -> Error {
792    Error::syntax(ErrorCode::FloatKeyMustBeFinite, 0, 0)
793}
794
795impl<'a, W, F> ser::Serializer for MapKeySerializer<'a, W, F>
796where
797    W: io::Write,
798    F: Formatter,
799{
800    type Ok = ();
801    type Error = Error;
802
803    #[inline]
804    fn serialize_str(self, value: &str) -> Result<()> {
805        self.ser.serialize_str(value)
806    }
807
808    #[inline]
809    fn serialize_unit_variant(
810        self,
811        _name: &'static str,
812        _variant_index: u32,
813        variant: &'static str,
814    ) -> Result<()> {
815        self.ser.serialize_str(variant)
816    }
817
818    #[inline]
819    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<()>
820    where
821        T: ?Sized + Serialize,
822    {
823        value.serialize(self)
824    }
825
826    type SerializeSeq = Impossible<(), Error>;
827    type SerializeTuple = Impossible<(), Error>;
828    type SerializeTupleStruct = Impossible<(), Error>;
829    type SerializeTupleVariant = Impossible<(), Error>;
830    type SerializeMap = Impossible<(), Error>;
831    type SerializeStruct = Impossible<(), Error>;
832    type SerializeStructVariant = Impossible<(), Error>;
833
834    fn serialize_bool(self, value: bool) -> Result<()> {
835        tri!(self
836            .ser
837            .formatter
838            .begin_string(&mut self.ser.writer)
839            .map_err(Error::io));
840        tri!(self
841            .ser
842            .formatter
843            .write_bool(&mut self.ser.writer, value)
844            .map_err(Error::io));
845        self.ser
846            .formatter
847            .end_string(&mut self.ser.writer)
848            .map_err(Error::io)
849    }
850
851    fn serialize_i8(self, value: i8) -> Result<()> {
852        tri!(self
853            .ser
854            .formatter
855            .begin_string(&mut self.ser.writer)
856            .map_err(Error::io));
857        tri!(self
858            .ser
859            .formatter
860            .write_i8(&mut self.ser.writer, value)
861            .map_err(Error::io));
862        self.ser
863            .formatter
864            .end_string(&mut self.ser.writer)
865            .map_err(Error::io)
866    }
867
868    fn serialize_i16(self, value: i16) -> Result<()> {
869        tri!(self
870            .ser
871            .formatter
872            .begin_string(&mut self.ser.writer)
873            .map_err(Error::io));
874        tri!(self
875            .ser
876            .formatter
877            .write_i16(&mut self.ser.writer, value)
878            .map_err(Error::io));
879        self.ser
880            .formatter
881            .end_string(&mut self.ser.writer)
882            .map_err(Error::io)
883    }
884
885    fn serialize_i32(self, value: i32) -> Result<()> {
886        tri!(self
887            .ser
888            .formatter
889            .begin_string(&mut self.ser.writer)
890            .map_err(Error::io));
891        tri!(self
892            .ser
893            .formatter
894            .write_i32(&mut self.ser.writer, value)
895            .map_err(Error::io));
896        self.ser
897            .formatter
898            .end_string(&mut self.ser.writer)
899            .map_err(Error::io)
900    }
901
902    fn serialize_i64(self, value: i64) -> Result<()> {
903        tri!(self
904            .ser
905            .formatter
906            .begin_string(&mut self.ser.writer)
907            .map_err(Error::io));
908        tri!(self
909            .ser
910            .formatter
911            .write_i64(&mut self.ser.writer, value)
912            .map_err(Error::io));
913        self.ser
914            .formatter
915            .end_string(&mut self.ser.writer)
916            .map_err(Error::io)
917    }
918
919    fn serialize_i128(self, value: i128) -> Result<()> {
920        tri!(self
921            .ser
922            .formatter
923            .begin_string(&mut self.ser.writer)
924            .map_err(Error::io));
925        tri!(self
926            .ser
927            .formatter
928            .write_i128(&mut self.ser.writer, value)
929            .map_err(Error::io));
930        self.ser
931            .formatter
932            .end_string(&mut self.ser.writer)
933            .map_err(Error::io)
934    }
935
936    fn serialize_u8(self, value: u8) -> Result<()> {
937        tri!(self
938            .ser
939            .formatter
940            .begin_string(&mut self.ser.writer)
941            .map_err(Error::io));
942        tri!(self
943            .ser
944            .formatter
945            .write_u8(&mut self.ser.writer, value)
946            .map_err(Error::io));
947        self.ser
948            .formatter
949            .end_string(&mut self.ser.writer)
950            .map_err(Error::io)
951    }
952
953    fn serialize_u16(self, value: u16) -> Result<()> {
954        tri!(self
955            .ser
956            .formatter
957            .begin_string(&mut self.ser.writer)
958            .map_err(Error::io));
959        tri!(self
960            .ser
961            .formatter
962            .write_u16(&mut self.ser.writer, value)
963            .map_err(Error::io));
964        self.ser
965            .formatter
966            .end_string(&mut self.ser.writer)
967            .map_err(Error::io)
968    }
969
970    fn serialize_u32(self, value: u32) -> Result<()> {
971        tri!(self
972            .ser
973            .formatter
974            .begin_string(&mut self.ser.writer)
975            .map_err(Error::io));
976        tri!(self
977            .ser
978            .formatter
979            .write_u32(&mut self.ser.writer, value)
980            .map_err(Error::io));
981        self.ser
982            .formatter
983            .end_string(&mut self.ser.writer)
984            .map_err(Error::io)
985    }
986
987    fn serialize_u64(self, value: u64) -> Result<()> {
988        tri!(self
989            .ser
990            .formatter
991            .begin_string(&mut self.ser.writer)
992            .map_err(Error::io));
993        tri!(self
994            .ser
995            .formatter
996            .write_u64(&mut self.ser.writer, value)
997            .map_err(Error::io));
998        self.ser
999            .formatter
1000            .end_string(&mut self.ser.writer)
1001            .map_err(Error::io)
1002    }
1003
1004    fn serialize_u128(self, value: u128) -> Result<()> {
1005        tri!(self
1006            .ser
1007            .formatter
1008            .begin_string(&mut self.ser.writer)
1009            .map_err(Error::io));
1010        tri!(self
1011            .ser
1012            .formatter
1013            .write_u128(&mut self.ser.writer, value)
1014            .map_err(Error::io));
1015        self.ser
1016            .formatter
1017            .end_string(&mut self.ser.writer)
1018            .map_err(Error::io)
1019    }
1020
1021    fn serialize_f32(self, value: f32) -> Result<()> {
1022        if !value.is_finite() {
1023            return Err(float_key_must_be_finite());
1024        }
1025
1026        tri!(self
1027            .ser
1028            .formatter
1029            .begin_string(&mut self.ser.writer)
1030            .map_err(Error::io));
1031        tri!(self
1032            .ser
1033            .formatter
1034            .write_f32(&mut self.ser.writer, value)
1035            .map_err(Error::io));
1036        self.ser
1037            .formatter
1038            .end_string(&mut self.ser.writer)
1039            .map_err(Error::io)
1040    }
1041
1042    fn serialize_f64(self, value: f64) -> Result<()> {
1043        if !value.is_finite() {
1044            return Err(float_key_must_be_finite());
1045        }
1046
1047        tri!(self
1048            .ser
1049            .formatter
1050            .begin_string(&mut self.ser.writer)
1051            .map_err(Error::io));
1052        tri!(self
1053            .ser
1054            .formatter
1055            .write_f64(&mut self.ser.writer, value)
1056            .map_err(Error::io));
1057        self.ser
1058            .formatter
1059            .end_string(&mut self.ser.writer)
1060            .map_err(Error::io)
1061    }
1062
1063    fn serialize_char(self, value: char) -> Result<()> {
1064        self.ser.serialize_str(value.encode_utf8(&mut [0u8; 4]))
1065    }
1066
1067    fn serialize_bytes(self, _value: &[u8]) -> Result<()> {
1068        Err(key_must_be_a_string())
1069    }
1070
1071    fn serialize_unit(self) -> Result<()> {
1072        Err(key_must_be_a_string())
1073    }
1074
1075    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
1076        Err(key_must_be_a_string())
1077    }
1078
1079    fn serialize_newtype_variant<T>(
1080        self,
1081        _name: &'static str,
1082        _variant_index: u32,
1083        _variant: &'static str,
1084        _value: &T,
1085    ) -> Result<()>
1086    where
1087        T: ?Sized + Serialize,
1088    {
1089        Err(key_must_be_a_string())
1090    }
1091
1092    fn serialize_none(self) -> Result<()> {
1093        Err(key_must_be_a_string())
1094    }
1095
1096    fn serialize_some<T>(self, value: &T) -> Result<()>
1097    where
1098        T: ?Sized + Serialize,
1099    {
1100        value.serialize(self)
1101    }
1102
1103    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
1104        Err(key_must_be_a_string())
1105    }
1106
1107    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
1108        Err(key_must_be_a_string())
1109    }
1110
1111    fn serialize_tuple_struct(
1112        self,
1113        _name: &'static str,
1114        _len: usize,
1115    ) -> Result<Self::SerializeTupleStruct> {
1116        Err(key_must_be_a_string())
1117    }
1118
1119    fn serialize_tuple_variant(
1120        self,
1121        _name: &'static str,
1122        _variant_index: u32,
1123        _variant: &'static str,
1124        _len: usize,
1125    ) -> Result<Self::SerializeTupleVariant> {
1126        Err(key_must_be_a_string())
1127    }
1128
1129    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
1130        Err(key_must_be_a_string())
1131    }
1132
1133    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
1134        Err(key_must_be_a_string())
1135    }
1136
1137    fn serialize_struct_variant(
1138        self,
1139        _name: &'static str,
1140        _variant_index: u32,
1141        _variant: &'static str,
1142        _len: usize,
1143    ) -> Result<Self::SerializeStructVariant> {
1144        Err(key_must_be_a_string())
1145    }
1146
1147    fn collect_str<T>(self, value: &T) -> Result<()>
1148    where
1149        T: ?Sized + Display,
1150    {
1151        self.ser.collect_str(value)
1152    }
1153}
1154
1155#[cfg(feature = "arbitrary_precision")]
1156struct NumberStrEmitter<'a, W: 'a + io::Write, F: 'a + Formatter>(&'a mut Serializer<W, F>);
1157
1158#[cfg(feature = "arbitrary_precision")]
1159impl<'a, W: io::Write, F: Formatter> ser::Serializer for NumberStrEmitter<'a, W, F> {
1160    type Ok = ();
1161    type Error = Error;
1162
1163    type SerializeSeq = Impossible<(), Error>;
1164    type SerializeTuple = Impossible<(), Error>;
1165    type SerializeTupleStruct = Impossible<(), Error>;
1166    type SerializeTupleVariant = Impossible<(), Error>;
1167    type SerializeMap = Impossible<(), Error>;
1168    type SerializeStruct = Impossible<(), Error>;
1169    type SerializeStructVariant = Impossible<(), Error>;
1170
1171    fn serialize_bool(self, _v: bool) -> Result<()> {
1172        Err(invalid_number())
1173    }
1174
1175    fn serialize_i8(self, _v: i8) -> Result<()> {
1176        Err(invalid_number())
1177    }
1178
1179    fn serialize_i16(self, _v: i16) -> Result<()> {
1180        Err(invalid_number())
1181    }
1182
1183    fn serialize_i32(self, _v: i32) -> Result<()> {
1184        Err(invalid_number())
1185    }
1186
1187    fn serialize_i64(self, _v: i64) -> Result<()> {
1188        Err(invalid_number())
1189    }
1190
1191    fn serialize_i128(self, _v: i128) -> Result<()> {
1192        Err(invalid_number())
1193    }
1194
1195    fn serialize_u8(self, _v: u8) -> Result<()> {
1196        Err(invalid_number())
1197    }
1198
1199    fn serialize_u16(self, _v: u16) -> Result<()> {
1200        Err(invalid_number())
1201    }
1202
1203    fn serialize_u32(self, _v: u32) -> Result<()> {
1204        Err(invalid_number())
1205    }
1206
1207    fn serialize_u64(self, _v: u64) -> Result<()> {
1208        Err(invalid_number())
1209    }
1210
1211    fn serialize_u128(self, _v: u128) -> Result<()> {
1212        Err(invalid_number())
1213    }
1214
1215    fn serialize_f32(self, _v: f32) -> Result<()> {
1216        Err(invalid_number())
1217    }
1218
1219    fn serialize_f64(self, _v: f64) -> Result<()> {
1220        Err(invalid_number())
1221    }
1222
1223    fn serialize_char(self, _v: char) -> Result<()> {
1224        Err(invalid_number())
1225    }
1226
1227    fn serialize_str(self, value: &str) -> Result<()> {
1228        let NumberStrEmitter(serializer) = self;
1229        serializer
1230            .formatter
1231            .write_number_str(&mut serializer.writer, value)
1232            .map_err(Error::io)
1233    }
1234
1235    fn serialize_bytes(self, _value: &[u8]) -> Result<()> {
1236        Err(invalid_number())
1237    }
1238
1239    fn serialize_none(self) -> Result<()> {
1240        Err(invalid_number())
1241    }
1242
1243    fn serialize_some<T>(self, _value: &T) -> Result<()>
1244    where
1245        T: ?Sized + Serialize,
1246    {
1247        Err(invalid_number())
1248    }
1249
1250    fn serialize_unit(self) -> Result<()> {
1251        Err(invalid_number())
1252    }
1253
1254    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
1255        Err(invalid_number())
1256    }
1257
1258    fn serialize_unit_variant(
1259        self,
1260        _name: &'static str,
1261        _variant_index: u32,
1262        _variant: &'static str,
1263    ) -> Result<()> {
1264        Err(invalid_number())
1265    }
1266
1267    fn serialize_newtype_struct<T>(self, _name: &'static str, _value: &T) -> Result<()>
1268    where
1269        T: ?Sized + Serialize,
1270    {
1271        Err(invalid_number())
1272    }
1273
1274    fn serialize_newtype_variant<T>(
1275        self,
1276        _name: &'static str,
1277        _variant_index: u32,
1278        _variant: &'static str,
1279        _value: &T,
1280    ) -> Result<()>
1281    where
1282        T: ?Sized + Serialize,
1283    {
1284        Err(invalid_number())
1285    }
1286
1287    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
1288        Err(invalid_number())
1289    }
1290
1291    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
1292        Err(invalid_number())
1293    }
1294
1295    fn serialize_tuple_struct(
1296        self,
1297        _name: &'static str,
1298        _len: usize,
1299    ) -> Result<Self::SerializeTupleStruct> {
1300        Err(invalid_number())
1301    }
1302
1303    fn serialize_tuple_variant(
1304        self,
1305        _name: &'static str,
1306        _variant_index: u32,
1307        _variant: &'static str,
1308        _len: usize,
1309    ) -> Result<Self::SerializeTupleVariant> {
1310        Err(invalid_number())
1311    }
1312
1313    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
1314        Err(invalid_number())
1315    }
1316
1317    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
1318        Err(invalid_number())
1319    }
1320
1321    fn serialize_struct_variant(
1322        self,
1323        _name: &'static str,
1324        _variant_index: u32,
1325        _variant: &'static str,
1326        _len: usize,
1327    ) -> Result<Self::SerializeStructVariant> {
1328        Err(invalid_number())
1329    }
1330}
1331
1332#[cfg(feature = "raw_value")]
1333struct RawValueStrEmitter<'a, W: 'a + io::Write, F: 'a + Formatter>(&'a mut Serializer<W, F>);
1334
1335#[cfg(feature = "raw_value")]
1336impl<'a, W: io::Write, F: Formatter> ser::Serializer for RawValueStrEmitter<'a, W, F> {
1337    type Ok = ();
1338    type Error = Error;
1339
1340    type SerializeSeq = Impossible<(), Error>;
1341    type SerializeTuple = Impossible<(), Error>;
1342    type SerializeTupleStruct = Impossible<(), Error>;
1343    type SerializeTupleVariant = Impossible<(), Error>;
1344    type SerializeMap = Impossible<(), Error>;
1345    type SerializeStruct = Impossible<(), Error>;
1346    type SerializeStructVariant = Impossible<(), Error>;
1347
1348    fn serialize_bool(self, _v: bool) -> Result<()> {
1349        Err(ser::Error::custom("expected RawValue"))
1350    }
1351
1352    fn serialize_i8(self, _v: i8) -> Result<()> {
1353        Err(ser::Error::custom("expected RawValue"))
1354    }
1355
1356    fn serialize_i16(self, _v: i16) -> Result<()> {
1357        Err(ser::Error::custom("expected RawValue"))
1358    }
1359
1360    fn serialize_i32(self, _v: i32) -> Result<()> {
1361        Err(ser::Error::custom("expected RawValue"))
1362    }
1363
1364    fn serialize_i64(self, _v: i64) -> Result<()> {
1365        Err(ser::Error::custom("expected RawValue"))
1366    }
1367
1368    fn serialize_i128(self, _v: i128) -> Result<()> {
1369        Err(ser::Error::custom("expected RawValue"))
1370    }
1371
1372    fn serialize_u8(self, _v: u8) -> Result<()> {
1373        Err(ser::Error::custom("expected RawValue"))
1374    }
1375
1376    fn serialize_u16(self, _v: u16) -> Result<()> {
1377        Err(ser::Error::custom("expected RawValue"))
1378    }
1379
1380    fn serialize_u32(self, _v: u32) -> Result<()> {
1381        Err(ser::Error::custom("expected RawValue"))
1382    }
1383
1384    fn serialize_u64(self, _v: u64) -> Result<()> {
1385        Err(ser::Error::custom("expected RawValue"))
1386    }
1387
1388    fn serialize_u128(self, _v: u128) -> Result<()> {
1389        Err(ser::Error::custom("expected RawValue"))
1390    }
1391
1392    fn serialize_f32(self, _v: f32) -> Result<()> {
1393        Err(ser::Error::custom("expected RawValue"))
1394    }
1395
1396    fn serialize_f64(self, _v: f64) -> Result<()> {
1397        Err(ser::Error::custom("expected RawValue"))
1398    }
1399
1400    fn serialize_char(self, _v: char) -> Result<()> {
1401        Err(ser::Error::custom("expected RawValue"))
1402    }
1403
1404    fn serialize_str(self, value: &str) -> Result<()> {
1405        let RawValueStrEmitter(serializer) = self;
1406        serializer
1407            .formatter
1408            .write_raw_fragment(&mut serializer.writer, value)
1409            .map_err(Error::io)
1410    }
1411
1412    fn serialize_bytes(self, _value: &[u8]) -> Result<()> {
1413        Err(ser::Error::custom("expected RawValue"))
1414    }
1415
1416    fn serialize_none(self) -> Result<()> {
1417        Err(ser::Error::custom("expected RawValue"))
1418    }
1419
1420    fn serialize_some<T>(self, _value: &T) -> Result<()>
1421    where
1422        T: ?Sized + Serialize,
1423    {
1424        Err(ser::Error::custom("expected RawValue"))
1425    }
1426
1427    fn serialize_unit(self) -> Result<()> {
1428        Err(ser::Error::custom("expected RawValue"))
1429    }
1430
1431    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
1432        Err(ser::Error::custom("expected RawValue"))
1433    }
1434
1435    fn serialize_unit_variant(
1436        self,
1437        _name: &'static str,
1438        _variant_index: u32,
1439        _variant: &'static str,
1440    ) -> Result<()> {
1441        Err(ser::Error::custom("expected RawValue"))
1442    }
1443
1444    fn serialize_newtype_struct<T>(self, _name: &'static str, _value: &T) -> Result<()>
1445    where
1446        T: ?Sized + Serialize,
1447    {
1448        Err(ser::Error::custom("expected RawValue"))
1449    }
1450
1451    fn serialize_newtype_variant<T>(
1452        self,
1453        _name: &'static str,
1454        _variant_index: u32,
1455        _variant: &'static str,
1456        _value: &T,
1457    ) -> Result<()>
1458    where
1459        T: ?Sized + Serialize,
1460    {
1461        Err(ser::Error::custom("expected RawValue"))
1462    }
1463
1464    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
1465        Err(ser::Error::custom("expected RawValue"))
1466    }
1467
1468    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
1469        Err(ser::Error::custom("expected RawValue"))
1470    }
1471
1472    fn serialize_tuple_struct(
1473        self,
1474        _name: &'static str,
1475        _len: usize,
1476    ) -> Result<Self::SerializeTupleStruct> {
1477        Err(ser::Error::custom("expected RawValue"))
1478    }
1479
1480    fn serialize_tuple_variant(
1481        self,
1482        _name: &'static str,
1483        _variant_index: u32,
1484        _variant: &'static str,
1485        _len: usize,
1486    ) -> Result<Self::SerializeTupleVariant> {
1487        Err(ser::Error::custom("expected RawValue"))
1488    }
1489
1490    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
1491        Err(ser::Error::custom("expected RawValue"))
1492    }
1493
1494    fn serialize_struct(self, _name: &'static str, _len: usize) -> Result<Self::SerializeStruct> {
1495        Err(ser::Error::custom("expected RawValue"))
1496    }
1497
1498    fn serialize_struct_variant(
1499        self,
1500        _name: &'static str,
1501        _variant_index: u32,
1502        _variant: &'static str,
1503        _len: usize,
1504    ) -> Result<Self::SerializeStructVariant> {
1505        Err(ser::Error::custom("expected RawValue"))
1506    }
1507
1508    fn collect_str<T>(self, value: &T) -> Result<Self::Ok>
1509    where
1510        T: ?Sized + Display,
1511    {
1512        self.serialize_str(&value.to_string())
1513    }
1514}
1515
1516/// Represents a character escape code in a type-safe manner.
1517pub enum CharEscape {
1518    /// An escaped quote `"`
1519    Quote,
1520    /// An escaped reverse solidus `\`
1521    ReverseSolidus,
1522    /// An escaped solidus `/`
1523    Solidus,
1524    /// An escaped backspace character (usually escaped as `\b`)
1525    Backspace,
1526    /// An escaped form feed character (usually escaped as `\f`)
1527    FormFeed,
1528    /// An escaped line feed character (usually escaped as `\n`)
1529    LineFeed,
1530    /// An escaped carriage return character (usually escaped as `\r`)
1531    CarriageReturn,
1532    /// An escaped tab character (usually escaped as `\t`)
1533    Tab,
1534    /// An escaped ASCII plane control character (usually escaped as
1535    /// `\u00XX` where `XX` are two hex characters)
1536    AsciiControl(u8),
1537}
1538
1539/// This trait abstracts away serializing the JSON control characters, which allows the user to
1540/// optionally pretty print the JSON output.
1541pub trait Formatter {
1542    /// Writes a `null` value to the specified writer.
1543    #[inline]
1544    fn write_null<W>(&mut self, writer: &mut W) -> io::Result<()>
1545    where
1546        W: ?Sized + io::Write,
1547    {
1548        writer.write_all(b"null")
1549    }
1550
1551    /// Writes a `true` or `false` value to the specified writer.
1552    #[inline]
1553    fn write_bool<W>(&mut self, writer: &mut W, value: bool) -> io::Result<()>
1554    where
1555        W: ?Sized + io::Write,
1556    {
1557        let s = if value {
1558            b"true" as &[u8]
1559        } else {
1560            b"false" as &[u8]
1561        };
1562        writer.write_all(s)
1563    }
1564
1565    /// Writes an integer value like `-123` to the specified writer.
1566    #[inline]
1567    fn write_i8<W>(&mut self, writer: &mut W, value: i8) -> io::Result<()>
1568    where
1569        W: ?Sized + io::Write,
1570    {
1571        let mut buffer = itoa::Buffer::new();
1572        let s = buffer.format(value);
1573        writer.write_all(s.as_bytes())
1574    }
1575
1576    /// Writes an integer value like `-123` to the specified writer.
1577    #[inline]
1578    fn write_i16<W>(&mut self, writer: &mut W, value: i16) -> io::Result<()>
1579    where
1580        W: ?Sized + io::Write,
1581    {
1582        let mut buffer = itoa::Buffer::new();
1583        let s = buffer.format(value);
1584        writer.write_all(s.as_bytes())
1585    }
1586
1587    /// Writes an integer value like `-123` to the specified writer.
1588    #[inline]
1589    fn write_i32<W>(&mut self, writer: &mut W, value: i32) -> io::Result<()>
1590    where
1591        W: ?Sized + io::Write,
1592    {
1593        let mut buffer = itoa::Buffer::new();
1594        let s = buffer.format(value);
1595        writer.write_all(s.as_bytes())
1596    }
1597
1598    /// Writes an integer value like `-123` to the specified writer.
1599    #[inline]
1600    fn write_i64<W>(&mut self, writer: &mut W, value: i64) -> io::Result<()>
1601    where
1602        W: ?Sized + io::Write,
1603    {
1604        let mut buffer = itoa::Buffer::new();
1605        let s = buffer.format(value);
1606        writer.write_all(s.as_bytes())
1607    }
1608
1609    /// Writes an integer value like `-123` to the specified writer.
1610    #[inline]
1611    fn write_i128<W>(&mut self, writer: &mut W, value: i128) -> io::Result<()>
1612    where
1613        W: ?Sized + io::Write,
1614    {
1615        let mut buffer = itoa::Buffer::new();
1616        let s = buffer.format(value);
1617        writer.write_all(s.as_bytes())
1618    }
1619
1620    /// Writes an integer value like `123` to the specified writer.
1621    #[inline]
1622    fn write_u8<W>(&mut self, writer: &mut W, value: u8) -> io::Result<()>
1623    where
1624        W: ?Sized + io::Write,
1625    {
1626        let mut buffer = itoa::Buffer::new();
1627        let s = buffer.format(value);
1628        writer.write_all(s.as_bytes())
1629    }
1630
1631    /// Writes an integer value like `123` to the specified writer.
1632    #[inline]
1633    fn write_u16<W>(&mut self, writer: &mut W, value: u16) -> io::Result<()>
1634    where
1635        W: ?Sized + io::Write,
1636    {
1637        let mut buffer = itoa::Buffer::new();
1638        let s = buffer.format(value);
1639        writer.write_all(s.as_bytes())
1640    }
1641
1642    /// Writes an integer value like `123` to the specified writer.
1643    #[inline]
1644    fn write_u32<W>(&mut self, writer: &mut W, value: u32) -> io::Result<()>
1645    where
1646        W: ?Sized + io::Write,
1647    {
1648        let mut buffer = itoa::Buffer::new();
1649        let s = buffer.format(value);
1650        writer.write_all(s.as_bytes())
1651    }
1652
1653    /// Writes an integer value like `123` to the specified writer.
1654    #[inline]
1655    fn write_u64<W>(&mut self, writer: &mut W, value: u64) -> io::Result<()>
1656    where
1657        W: ?Sized + io::Write,
1658    {
1659        let mut buffer = itoa::Buffer::new();
1660        let s = buffer.format(value);
1661        writer.write_all(s.as_bytes())
1662    }
1663
1664    /// Writes an integer value like `123` to the specified writer.
1665    #[inline]
1666    fn write_u128<W>(&mut self, writer: &mut W, value: u128) -> io::Result<()>
1667    where
1668        W: ?Sized + io::Write,
1669    {
1670        let mut buffer = itoa::Buffer::new();
1671        let s = buffer.format(value);
1672        writer.write_all(s.as_bytes())
1673    }
1674
1675    /// Writes a floating point value like `-31.26e+12` to the specified writer.
1676    ///
1677    /// # Special cases
1678    ///
1679    /// This function **does not** check for NaN or infinity. If the input
1680    /// number is not a finite float, the printed representation will be some
1681    /// correctly formatted but unspecified numerical value.
1682    ///
1683    /// Please check [`is_finite`] yourself before calling this function, or
1684    /// check [`is_nan`] and [`is_infinite`] and handle those cases yourself
1685    /// with a different `Formatter` method.
1686    ///
1687    /// [`is_finite`]: f32::is_finite
1688    /// [`is_nan`]: f32::is_nan
1689    /// [`is_infinite`]: f32::is_infinite
1690    #[inline]
1691    fn write_f32<W>(&mut self, writer: &mut W, value: f32) -> io::Result<()>
1692    where
1693        W: ?Sized + io::Write,
1694    {
1695        let mut buffer = ryu::Buffer::new();
1696        let s = buffer.format_finite(value);
1697        writer.write_all(s.as_bytes())
1698    }
1699
1700    /// Writes a floating point value like `-31.26e+12` to the specified writer.
1701    ///
1702    /// # Special cases
1703    ///
1704    /// This function **does not** check for NaN or infinity. If the input
1705    /// number is not a finite float, the printed representation will be some
1706    /// correctly formatted but unspecified numerical value.
1707    ///
1708    /// Please check [`is_finite`] yourself before calling this function, or
1709    /// check [`is_nan`] and [`is_infinite`] and handle those cases yourself
1710    /// with a different `Formatter` method.
1711    ///
1712    /// [`is_finite`]: f64::is_finite
1713    /// [`is_nan`]: f64::is_nan
1714    /// [`is_infinite`]: f64::is_infinite
1715    #[inline]
1716    fn write_f64<W>(&mut self, writer: &mut W, value: f64) -> io::Result<()>
1717    where
1718        W: ?Sized + io::Write,
1719    {
1720        let mut buffer = ryu::Buffer::new();
1721        let s = buffer.format_finite(value);
1722        writer.write_all(s.as_bytes())
1723    }
1724
1725    /// Writes a number that has already been rendered to a string.
1726    #[inline]
1727    fn write_number_str<W>(&mut self, writer: &mut W, value: &str) -> io::Result<()>
1728    where
1729        W: ?Sized + io::Write,
1730    {
1731        writer.write_all(value.as_bytes())
1732    }
1733
1734    /// Called before each series of `write_string_fragment` and
1735    /// `write_char_escape`.  Writes a `"` to the specified writer.
1736    #[inline]
1737    fn begin_string<W>(&mut self, writer: &mut W) -> io::Result<()>
1738    where
1739        W: ?Sized + io::Write,
1740    {
1741        writer.write_all(b"\"")
1742    }
1743
1744    /// Called after each series of `write_string_fragment` and
1745    /// `write_char_escape`.  Writes a `"` to the specified writer.
1746    #[inline]
1747    fn end_string<W>(&mut self, writer: &mut W) -> io::Result<()>
1748    where
1749        W: ?Sized + io::Write,
1750    {
1751        writer.write_all(b"\"")
1752    }
1753
1754    /// Writes a string fragment that doesn't need any escaping to the
1755    /// specified writer.
1756    #[inline]
1757    fn write_string_fragment<W>(&mut self, writer: &mut W, fragment: &str) -> io::Result<()>
1758    where
1759        W: ?Sized + io::Write,
1760    {
1761        writer.write_all(fragment.as_bytes())
1762    }
1763
1764    /// Writes a character escape code to the specified writer.
1765    #[inline]
1766    fn write_char_escape<W>(&mut self, writer: &mut W, char_escape: CharEscape) -> io::Result<()>
1767    where
1768        W: ?Sized + io::Write,
1769    {
1770        use self::CharEscape::*;
1771
1772        let escape_char = match char_escape {
1773            Quote => b'"',
1774            ReverseSolidus => b'\\',
1775            Solidus => b'/',
1776            Backspace => b'b',
1777            FormFeed => b'f',
1778            LineFeed => b'n',
1779            CarriageReturn => b'r',
1780            Tab => b't',
1781            AsciiControl(_) => b'u',
1782        };
1783
1784        match char_escape {
1785            AsciiControl(byte) => {
1786                static HEX_DIGITS: [u8; 16] = *b"0123456789abcdef";
1787                let bytes = &[
1788                    b'\\',
1789                    escape_char,
1790                    b'0',
1791                    b'0',
1792                    HEX_DIGITS[(byte >> 4) as usize],
1793                    HEX_DIGITS[(byte & 0xF) as usize],
1794                ];
1795                writer.write_all(bytes)
1796            }
1797            _ => writer.write_all(&[b'\\', escape_char]),
1798        }
1799    }
1800
1801    /// Writes the representation of a byte array. Formatters can choose whether
1802    /// to represent bytes as a JSON array of integers (the default), or some
1803    /// JSON string encoding like hex or base64.
1804    fn write_byte_array<W>(&mut self, writer: &mut W, value: &[u8]) -> io::Result<()>
1805    where
1806        W: ?Sized + io::Write,
1807    {
1808        tri!(self.begin_array(writer));
1809        let mut first = true;
1810        for byte in value {
1811            tri!(self.begin_array_value(writer, first));
1812            tri!(self.write_u8(writer, *byte));
1813            tri!(self.end_array_value(writer));
1814            first = false;
1815        }
1816        self.end_array(writer)
1817    }
1818
1819    /// Called before every array.  Writes a `[` to the specified
1820    /// writer.
1821    #[inline]
1822    fn begin_array<W>(&mut self, writer: &mut W) -> io::Result<()>
1823    where
1824        W: ?Sized + io::Write,
1825    {
1826        writer.write_all(b"[")
1827    }
1828
1829    /// Called after every array.  Writes a `]` to the specified
1830    /// writer.
1831    #[inline]
1832    fn end_array<W>(&mut self, writer: &mut W) -> io::Result<()>
1833    where
1834        W: ?Sized + io::Write,
1835    {
1836        writer.write_all(b"]")
1837    }
1838
1839    /// Called before every array value.  Writes a `,` if needed to
1840    /// the specified writer.
1841    #[inline]
1842    fn begin_array_value<W>(&mut self, writer: &mut W, first: bool) -> io::Result<()>
1843    where
1844        W: ?Sized + io::Write,
1845    {
1846        if first {
1847            Ok(())
1848        } else {
1849            writer.write_all(b",")
1850        }
1851    }
1852
1853    /// Called after every array value.
1854    #[inline]
1855    fn end_array_value<W>(&mut self, _writer: &mut W) -> io::Result<()>
1856    where
1857        W: ?Sized + io::Write,
1858    {
1859        Ok(())
1860    }
1861
1862    /// Called before every object.  Writes a `{` to the specified
1863    /// writer.
1864    #[inline]
1865    fn begin_object<W>(&mut self, writer: &mut W) -> io::Result<()>
1866    where
1867        W: ?Sized + io::Write,
1868    {
1869        writer.write_all(b"{")
1870    }
1871
1872    /// Called after every object.  Writes a `}` to the specified
1873    /// writer.
1874    #[inline]
1875    fn end_object<W>(&mut self, writer: &mut W) -> io::Result<()>
1876    where
1877        W: ?Sized + io::Write,
1878    {
1879        writer.write_all(b"}")
1880    }
1881
1882    /// Called before every object key.
1883    #[inline]
1884    fn begin_object_key<W>(&mut self, writer: &mut W, first: bool) -> io::Result<()>
1885    where
1886        W: ?Sized + io::Write,
1887    {
1888        if first {
1889            Ok(())
1890        } else {
1891            writer.write_all(b",")
1892        }
1893    }
1894
1895    /// Called after every object key.  A `:` should be written to the
1896    /// specified writer by either this method or
1897    /// `begin_object_value`.
1898    #[inline]
1899    fn end_object_key<W>(&mut self, _writer: &mut W) -> io::Result<()>
1900    where
1901        W: ?Sized + io::Write,
1902    {
1903        Ok(())
1904    }
1905
1906    /// Called before every object value.  A `:` should be written to
1907    /// the specified writer by either this method or
1908    /// `end_object_key`.
1909    #[inline]
1910    fn begin_object_value<W>(&mut self, writer: &mut W) -> io::Result<()>
1911    where
1912        W: ?Sized + io::Write,
1913    {
1914        writer.write_all(b":")
1915    }
1916
1917    /// Called after every object value.
1918    #[inline]
1919    fn end_object_value<W>(&mut self, _writer: &mut W) -> io::Result<()>
1920    where
1921        W: ?Sized + io::Write,
1922    {
1923        Ok(())
1924    }
1925
1926    /// Writes a raw JSON fragment that doesn't need any escaping to the
1927    /// specified writer.
1928    #[inline]
1929    fn write_raw_fragment<W>(&mut self, writer: &mut W, fragment: &str) -> io::Result<()>
1930    where
1931        W: ?Sized + io::Write,
1932    {
1933        writer.write_all(fragment.as_bytes())
1934    }
1935}
1936
1937/// This structure compacts a JSON value with no extra whitespace.
1938#[derive(Clone, Debug, Default)]
1939pub struct CompactFormatter;
1940
1941impl Formatter for CompactFormatter {}
1942
1943/// This structure pretty prints a JSON value to make it human readable.
1944#[derive(Clone, Debug)]
1945pub struct PrettyFormatter<'a> {
1946    current_indent: usize,
1947    has_value: bool,
1948    indent: &'a [u8],
1949}
1950
1951impl<'a> PrettyFormatter<'a> {
1952    /// Construct a pretty printer formatter that defaults to using two spaces for indentation.
1953    pub fn new() -> Self {
1954        PrettyFormatter::with_indent(b"  ")
1955    }
1956
1957    /// Construct a pretty printer formatter that uses the `indent` string for indentation.
1958    pub fn with_indent(indent: &'a [u8]) -> Self {
1959        PrettyFormatter {
1960            current_indent: 0,
1961            has_value: false,
1962            indent,
1963        }
1964    }
1965}
1966
1967impl<'a> Default for PrettyFormatter<'a> {
1968    fn default() -> Self {
1969        PrettyFormatter::new()
1970    }
1971}
1972
1973impl<'a> Formatter for PrettyFormatter<'a> {
1974    #[inline]
1975    fn begin_array<W>(&mut self, writer: &mut W) -> io::Result<()>
1976    where
1977        W: ?Sized + io::Write,
1978    {
1979        self.current_indent += 1;
1980        self.has_value = false;
1981        writer.write_all(b"[")
1982    }
1983
1984    #[inline]
1985    fn end_array<W>(&mut self, writer: &mut W) -> io::Result<()>
1986    where
1987        W: ?Sized + io::Write,
1988    {
1989        self.current_indent -= 1;
1990
1991        if self.has_value {
1992            tri!(writer.write_all(b"\n"));
1993            tri!(indent(writer, self.current_indent, self.indent));
1994        }
1995
1996        writer.write_all(b"]")
1997    }
1998
1999    #[inline]
2000    fn begin_array_value<W>(&mut self, writer: &mut W, first: bool) -> io::Result<()>
2001    where
2002        W: ?Sized + io::Write,
2003    {
2004        tri!(writer.write_all(if first { b"\n" } else { b",\n" }));
2005        indent(writer, self.current_indent, self.indent)
2006    }
2007
2008    #[inline]
2009    fn end_array_value<W>(&mut self, _writer: &mut W) -> io::Result<()>
2010    where
2011        W: ?Sized + io::Write,
2012    {
2013        self.has_value = true;
2014        Ok(())
2015    }
2016
2017    #[inline]
2018    fn begin_object<W>(&mut self, writer: &mut W) -> io::Result<()>
2019    where
2020        W: ?Sized + io::Write,
2021    {
2022        self.current_indent += 1;
2023        self.has_value = false;
2024        writer.write_all(b"{")
2025    }
2026
2027    #[inline]
2028    fn end_object<W>(&mut self, writer: &mut W) -> io::Result<()>
2029    where
2030        W: ?Sized + io::Write,
2031    {
2032        self.current_indent -= 1;
2033
2034        if self.has_value {
2035            tri!(writer.write_all(b"\n"));
2036            tri!(indent(writer, self.current_indent, self.indent));
2037        }
2038
2039        writer.write_all(b"}")
2040    }
2041
2042    #[inline]
2043    fn begin_object_key<W>(&mut self, writer: &mut W, first: bool) -> io::Result<()>
2044    where
2045        W: ?Sized + io::Write,
2046    {
2047        tri!(writer.write_all(if first { b"\n" } else { b",\n" }));
2048        indent(writer, self.current_indent, self.indent)
2049    }
2050
2051    #[inline]
2052    fn begin_object_value<W>(&mut self, writer: &mut W) -> io::Result<()>
2053    where
2054        W: ?Sized + io::Write,
2055    {
2056        writer.write_all(b": ")
2057    }
2058
2059    #[inline]
2060    fn end_object_value<W>(&mut self, _writer: &mut W) -> io::Result<()>
2061    where
2062        W: ?Sized + io::Write,
2063    {
2064        self.has_value = true;
2065        Ok(())
2066    }
2067}
2068
2069fn format_escaped_str<W, F>(writer: &mut W, formatter: &mut F, value: &str) -> io::Result<()>
2070where
2071    W: ?Sized + io::Write,
2072    F: ?Sized + Formatter,
2073{
2074    tri!(formatter.begin_string(writer));
2075    tri!(format_escaped_str_contents(writer, formatter, value));
2076    formatter.end_string(writer)
2077}
2078
2079fn format_escaped_str_contents<W, F>(
2080    writer: &mut W,
2081    formatter: &mut F,
2082    value: &str,
2083) -> io::Result<()>
2084where
2085    W: ?Sized + io::Write,
2086    F: ?Sized + Formatter,
2087{
2088    let mut bytes = value.as_bytes();
2089
2090    let mut i = 0;
2091    while i < bytes.len() {
2092        let (string_run, rest) = bytes.split_at(i);
2093        let (&byte, rest) = rest.split_first().unwrap();
2094
2095        let escape = ESCAPE[byte as usize];
2096
2097        i += 1;
2098        if escape == 0 {
2099            continue;
2100        }
2101
2102        bytes = rest;
2103        i = 0;
2104
2105        // Safety: string_run is a valid utf8 string, since we only split on ascii sequences
2106        let string_run = unsafe { str::from_utf8_unchecked(string_run) };
2107        if !string_run.is_empty() {
2108            tri!(formatter.write_string_fragment(writer, string_run));
2109        }
2110
2111        let char_escape = match escape {
2112            self::BB => CharEscape::Backspace,
2113            self::TT => CharEscape::Tab,
2114            self::NN => CharEscape::LineFeed,
2115            self::FF => CharEscape::FormFeed,
2116            self::RR => CharEscape::CarriageReturn,
2117            self::QU => CharEscape::Quote,
2118            self::BS => CharEscape::ReverseSolidus,
2119            self::UU => CharEscape::AsciiControl(byte),
2120            // Safety: the escape table does not contain any other type of character.
2121            _ => unsafe { hint::unreachable_unchecked() },
2122        };
2123        tri!(formatter.write_char_escape(writer, char_escape));
2124    }
2125
2126    // Safety: bytes is a valid utf8 string, since we only split on ascii sequences
2127    let string_run = unsafe { str::from_utf8_unchecked(bytes) };
2128    if string_run.is_empty() {
2129        return Ok(());
2130    }
2131
2132    formatter.write_string_fragment(writer, string_run)
2133}
2134
2135const BB: u8 = b'b'; // \x08
2136const TT: u8 = b't'; // \x09
2137const NN: u8 = b'n'; // \x0A
2138const FF: u8 = b'f'; // \x0C
2139const RR: u8 = b'r'; // \x0D
2140const QU: u8 = b'"'; // \x22
2141const BS: u8 = b'\\'; // \x5C
2142const UU: u8 = b'u'; // \x00...\x1F except the ones above
2143const __: u8 = 0;
2144
2145// Lookup table of escape sequences. A value of b'x' at index i means that byte
2146// i is escaped as "\x" in JSON. A value of 0 means that byte i is not escaped.
2147static ESCAPE: [u8; 256] = [
2148    //   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
2149    UU, UU, UU, UU, UU, UU, UU, UU, BB, TT, NN, UU, FF, RR, UU, UU, // 0
2150    UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, UU, // 1
2151    __, __, QU, __, __, __, __, __, __, __, __, __, __, __, __, __, // 2
2152    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 3
2153    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 4
2154    __, __, __, __, __, __, __, __, __, __, __, __, BS, __, __, __, // 5
2155    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 6
2156    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 7
2157    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 8
2158    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // 9
2159    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // A
2160    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // B
2161    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // C
2162    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // D
2163    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // E
2164    __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, // F
2165];
2166
2167/// Serialize the given data structure as JSON into the I/O stream.
2168///
2169/// Serialization guarantees it only feeds valid UTF-8 sequences to the writer.
2170///
2171/// # Errors
2172///
2173/// Serialization can fail if `T`'s implementation of `Serialize` decides to
2174/// fail, or if `T` contains a map with non-string keys.
2175#[inline]
2176#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
2177pub fn to_writer<W, T>(writer: W, value: &T) -> Result<()>
2178where
2179    W: io::Write,
2180    T: ?Sized + Serialize,
2181{
2182    let mut ser = Serializer::new(writer);
2183    value.serialize(&mut ser)
2184}
2185
2186/// Serialize the given data structure as pretty-printed JSON into the I/O
2187/// stream.
2188///
2189/// Serialization guarantees it only feeds valid UTF-8 sequences to the writer.
2190///
2191/// # Errors
2192///
2193/// Serialization can fail if `T`'s implementation of `Serialize` decides to
2194/// fail, or if `T` contains a map with non-string keys.
2195#[inline]
2196#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
2197pub fn to_writer_pretty<W, T>(writer: W, value: &T) -> Result<()>
2198where
2199    W: io::Write,
2200    T: ?Sized + Serialize,
2201{
2202    let mut ser = Serializer::pretty(writer);
2203    value.serialize(&mut ser)
2204}
2205
2206/// Serialize the given data structure as a JSON byte vector.
2207///
2208/// # Errors
2209///
2210/// Serialization can fail if `T`'s implementation of `Serialize` decides to
2211/// fail, or if `T` contains a map with non-string keys.
2212#[inline]
2213pub fn to_vec<T>(value: &T) -> Result<Vec<u8>>
2214where
2215    T: ?Sized + Serialize,
2216{
2217    let mut writer = Vec::with_capacity(128);
2218    tri!(to_writer(&mut writer, value));
2219    Ok(writer)
2220}
2221
2222/// Serialize the given data structure as a pretty-printed JSON byte vector.
2223///
2224/// # Errors
2225///
2226/// Serialization can fail if `T`'s implementation of `Serialize` decides to
2227/// fail, or if `T` contains a map with non-string keys.
2228#[inline]
2229pub fn to_vec_pretty<T>(value: &T) -> Result<Vec<u8>>
2230where
2231    T: ?Sized + Serialize,
2232{
2233    let mut writer = Vec::with_capacity(128);
2234    tri!(to_writer_pretty(&mut writer, value));
2235    Ok(writer)
2236}
2237
2238/// Serialize the given data structure as a String of JSON.
2239///
2240/// # Errors
2241///
2242/// Serialization can fail if `T`'s implementation of `Serialize` decides to
2243/// fail, or if `T` contains a map with non-string keys.
2244#[inline]
2245pub fn to_string<T>(value: &T) -> Result<String>
2246where
2247    T: ?Sized + Serialize,
2248{
2249    let vec = tri!(to_vec(value));
2250    let string = unsafe {
2251        // We do not emit invalid UTF-8.
2252        String::from_utf8_unchecked(vec)
2253    };
2254    Ok(string)
2255}
2256
2257/// Serialize the given data structure as a pretty-printed String of JSON.
2258///
2259/// # Errors
2260///
2261/// Serialization can fail if `T`'s implementation of `Serialize` decides to
2262/// fail, or if `T` contains a map with non-string keys.
2263#[inline]
2264pub fn to_string_pretty<T>(value: &T) -> Result<String>
2265where
2266    T: ?Sized + Serialize,
2267{
2268    let vec = tri!(to_vec_pretty(value));
2269    let string = unsafe {
2270        // We do not emit invalid UTF-8.
2271        String::from_utf8_unchecked(vec)
2272    };
2273    Ok(string)
2274}
2275
2276fn indent<W>(wr: &mut W, n: usize, s: &[u8]) -> io::Result<()>
2277where
2278    W: ?Sized + io::Write,
2279{
2280    for _ in 0..n {
2281        tri!(wr.write_all(s));
2282    }
2283
2284    Ok(())
2285}
serde_json/ser.rs

serde_json/
ser.rs
