config/
ser.rs

1use std::fmt::Display;
2use std::fmt::Write as _;
3
4use serde_core::ser;
5
6use crate::error::{ConfigError, Result};
7use crate::value::{Value, ValueKind};
8use crate::Config;
9
10#[derive(Default, Debug)]
11pub(crate) struct ConfigSerializer {
12    keys: Vec<SerKey>,
13    pub output: Config,
14}
15
16#[derive(Debug)]
17enum SerKey {
18    Named(String),
19    Seq(usize),
20}
21
22/// An uninhabited type: no values like this can ever exist!
23pub(crate) enum Unreachable {}
24
25/// Serializer for numbered sequences
26///
27/// This wrapper is present when we are outputting a sequence (numbered indices).
28/// Making this a separate type centralises the handling of sequences
29/// and ensures we don't have any call sites for `ser::SerializeSeq::serialize_element`
30/// that don't do the necessary work of `SeqSerializer::new`.
31///
32/// Existence of this wrapper implies that `.0.keys.last()` is
33/// `Some(SerKey::Seq(next_index))`.
34pub(crate) struct SeqSerializer<'a>(&'a mut ConfigSerializer);
35
36impl ConfigSerializer {
37    fn serialize_primitive<T>(&mut self, value: T) -> Result<()>
38    where
39        T: Into<Value> + Display,
40    {
41        // At some future point we could perhaps retain a cursor into the output `Config`,
42        // rather than reifying the whole thing into a single string with `make_full_key`
43        // and passing that whole path to the `set` method.
44        //
45        // That would be marginally more performant, but more fiddly.
46        let key = self.make_full_key()?;
47
48        self.output.set(&key, value.into())?;
49        Ok(())
50    }
51
52    fn make_full_key(&self) -> Result<String> {
53        let mut keys = self.keys.iter();
54
55        let mut whole = match keys.next() {
56            Some(SerKey::Named(s)) => s.clone(),
57            _ => return Err(ConfigError::Message("top level is not a struct".to_owned())),
58        };
59
60        for k in keys {
61            match k {
62                SerKey::Named(s) => write!(whole, ".{s}"),
63                SerKey::Seq(i) => write!(whole, "[{i}]"),
64            }
65            .expect("write! to a string failed");
66        }
67
68        Ok(whole)
69    }
70
71    fn push_key(&mut self, key: &str) {
72        self.keys.push(SerKey::Named(key.to_owned()));
73    }
74
75    fn pop_key(&mut self) {
76        self.keys.pop();
77    }
78}
79
80impl<'a> ser::Serializer for &'a mut ConfigSerializer {
81    type Ok = ();
82    type Error = ConfigError;
83    type SerializeSeq = SeqSerializer<'a>;
84    type SerializeTuple = SeqSerializer<'a>;
85    type SerializeTupleStruct = SeqSerializer<'a>;
86    type SerializeTupleVariant = SeqSerializer<'a>;
87    type SerializeMap = Self;
88    type SerializeStruct = Self;
89    type SerializeStructVariant = Self;
90
91    fn serialize_bool(self, v: bool) -> Result<Self::Ok> {
92        self.serialize_primitive(v)
93    }
94
95    fn serialize_i8(self, v: i8) -> Result<Self::Ok> {
96        self.serialize_i64(v.into())
97    }
98
99    fn serialize_i16(self, v: i16) -> Result<Self::Ok> {
100        self.serialize_i64(v.into())
101    }
102
103    fn serialize_i32(self, v: i32) -> Result<Self::Ok> {
104        self.serialize_i64(v.into())
105    }
106
107    fn serialize_i64(self, v: i64) -> Result<Self::Ok> {
108        self.serialize_primitive(v)
109    }
110
111    fn serialize_u8(self, v: u8) -> Result<Self::Ok> {
112        self.serialize_u64(v.into())
113    }
114
115    fn serialize_u16(self, v: u16) -> Result<Self::Ok> {
116        self.serialize_u64(v.into())
117    }
118
119    fn serialize_u32(self, v: u32) -> Result<Self::Ok> {
120        self.serialize_u64(v.into())
121    }
122
123    fn serialize_u64(self, v: u64) -> Result<Self::Ok> {
124        if v > (i64::MAX as u64) {
125            Err(ConfigError::Message(format!(
126                "value {} is greater than the max {}",
127                v,
128                i64::MAX
129            )))
130        } else {
131            self.serialize_i64(v as i64)
132        }
133    }
134
135    fn serialize_f32(self, v: f32) -> Result<Self::Ok> {
136        self.serialize_f64(v.into())
137    }
138
139    fn serialize_f64(self, v: f64) -> Result<Self::Ok> {
140        self.serialize_primitive(v)
141    }
142
143    fn serialize_char(self, v: char) -> Result<Self::Ok> {
144        self.serialize_primitive(v.to_string())
145    }
146
147    fn serialize_str(self, v: &str) -> Result<Self::Ok> {
148        self.serialize_primitive(v.to_owned())
149    }
150
151    fn serialize_bytes(self, v: &[u8]) -> Result<Self::Ok> {
152        use serde_core::ser::SerializeSeq;
153        let mut seq = self.serialize_seq(Some(v.len()))?;
154        for byte in v {
155            seq.serialize_element(byte)?;
156        }
157        seq.end();
158        Ok(())
159    }
160
161    fn serialize_none(self) -> Result<Self::Ok> {
162        self.serialize_unit()
163    }
164
165    fn serialize_some<T>(self, value: &T) -> Result<Self::Ok>
166    where
167        T: ?Sized + ser::Serialize,
168    {
169        value.serialize(self)
170    }
171
172    fn serialize_unit(self) -> Result<Self::Ok> {
173        self.serialize_primitive(Value::from(ValueKind::Nil))
174    }
175
176    fn serialize_unit_struct(self, _name: &'static str) -> Result<Self::Ok> {
177        self.serialize_unit()
178    }
179
180    fn serialize_unit_variant(
181        self,
182        _name: &'static str,
183        _variant_index: u32,
184        variant: &'static str,
185    ) -> Result<Self::Ok> {
186        self.serialize_str(variant)
187    }
188
189    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<Self::Ok>
190    where
191        T: ?Sized + ser::Serialize,
192    {
193        value.serialize(self)
194    }
195
196    fn serialize_newtype_variant<T>(
197        self,
198        _name: &'static str,
199        _variant_index: u32,
200        variant: &'static str,
201        value: &T,
202    ) -> Result<Self::Ok>
203    where
204        T: ?Sized + ser::Serialize,
205    {
206        self.push_key(variant);
207        value.serialize(&mut *self)?;
208        self.pop_key();
209        Ok(())
210    }
211
212    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
213        SeqSerializer::new(self)
214    }
215
216    fn serialize_tuple(self, len: usize) -> Result<Self::SerializeTuple> {
217        self.serialize_seq(Some(len))
218    }
219
220    fn serialize_tuple_struct(
221        self,
222        _name: &'static str,
223        len: usize,
224    ) -> Result<Self::SerializeTupleStruct> {
225        self.serialize_seq(Some(len))
226    }
227
228    fn serialize_tuple_variant(
229        self,
230        _name: &'static str,
231        _variant_index: u32,
232        variant: &'static str,
233        len: usize,
234    ) -> Result<Self::SerializeTupleVariant> {
235        self.push_key(variant);
236        self.serialize_seq(Some(len))
237    }
238
239    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
240        Ok(self)
241    }
242
243    fn serialize_struct(self, _name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
244        self.serialize_map(Some(len))
245    }
246
247    fn serialize_struct_variant(
248        self,
249        _name: &'static str,
250        _variant_index: u32,
251        variant: &'static str,
252        _len: usize,
253    ) -> Result<Self::SerializeStructVariant> {
254        self.push_key(variant);
255        Ok(self)
256    }
257}
258
259impl<'a> SeqSerializer<'a> {
260    fn new(inner: &'a mut ConfigSerializer) -> Result<Self> {
261        inner.keys.push(SerKey::Seq(0));
262
263        Ok(SeqSerializer(inner))
264    }
265
266    fn end(self) -> &'a mut ConfigSerializer {
267        // This ought to be Some(SerKey::Seq(..)) but we don't want to panic if we are buggy
268        let _: Option<SerKey> = self.0.keys.pop();
269        self.0
270    }
271}
272
273impl ser::SerializeSeq for SeqSerializer<'_> {
274    type Ok = ();
275    type Error = ConfigError;
276
277    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
278    where
279        T: ?Sized + ser::Serialize,
280    {
281        value.serialize(&mut *(self.0))?;
282        match self.0.keys.last_mut() {
283            Some(SerKey::Seq(i)) => *i += 1,
284            _ => {
285                return Err(ConfigError::Message(
286                    "config-rs internal error (ser._element but last not Seq!".to_owned(),
287                ))
288            }
289        };
290        Ok(())
291    }
292
293    fn end(self) -> Result<Self::Ok> {
294        self.end();
295        Ok(())
296    }
297}
298
299impl ser::SerializeTuple for SeqSerializer<'_> {
300    type Ok = ();
301    type Error = ConfigError;
302
303    fn serialize_element<T>(&mut self, value: &T) -> Result<()>
304    where
305        T: ?Sized + ser::Serialize,
306    {
307        ser::SerializeSeq::serialize_element(self, value)
308    }
309
310    fn end(self) -> Result<Self::Ok> {
311        ser::SerializeSeq::end(self)
312    }
313}
314
315impl ser::SerializeTupleStruct for SeqSerializer<'_> {
316    type Ok = ();
317    type Error = ConfigError;
318
319    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
320    where
321        T: ?Sized + ser::Serialize,
322    {
323        ser::SerializeSeq::serialize_element(self, value)
324    }
325
326    fn end(self) -> Result<Self::Ok> {
327        ser::SerializeSeq::end(self)
328    }
329}
330
331impl ser::SerializeTupleVariant for SeqSerializer<'_> {
332    type Ok = ();
333    type Error = ConfigError;
334
335    fn serialize_field<T>(&mut self, value: &T) -> Result<()>
336    where
337        T: ?Sized + ser::Serialize,
338    {
339        ser::SerializeSeq::serialize_element(self, value)
340    }
341
342    fn end(self) -> Result<Self::Ok> {
343        let inner = self.end();
344        inner.pop_key();
345        Ok(())
346    }
347}
348
349impl ser::SerializeMap for &mut ConfigSerializer {
350    type Ok = ();
351    type Error = ConfigError;
352
353    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
354    where
355        T: ?Sized + ser::Serialize,
356    {
357        let key_serializer = StringKeySerializer;
358        let key = key.serialize(key_serializer)?;
359        self.push_key(&key);
360        Ok(())
361    }
362
363    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
364    where
365        T: ?Sized + ser::Serialize,
366    {
367        value.serialize(&mut **self)?;
368        self.pop_key();
369        Ok(())
370    }
371
372    fn end(self) -> Result<Self::Ok> {
373        Ok(())
374    }
375}
376
377impl ser::SerializeStruct for &mut ConfigSerializer {
378    type Ok = ();
379    type Error = ConfigError;
380
381    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
382    where
383        T: ?Sized + ser::Serialize,
384    {
385        self.push_key(key);
386        value.serialize(&mut **self)?;
387        self.pop_key();
388        Ok(())
389    }
390
391    fn end(self) -> Result<Self::Ok> {
392        Ok(())
393    }
394}
395
396impl ser::SerializeStructVariant for &mut ConfigSerializer {
397    type Ok = ();
398    type Error = ConfigError;
399
400    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
401    where
402        T: ?Sized + ser::Serialize,
403    {
404        self.push_key(key);
405        value.serialize(&mut **self)?;
406        self.pop_key();
407        Ok(())
408    }
409
410    fn end(self) -> Result<Self::Ok> {
411        self.pop_key();
412        Ok(())
413    }
414}
415
416pub(crate) struct StringKeySerializer;
417
418/// Define `$emthod`, `serialize_foo`, taking `$type` and serialising it via [`Display`]
419macro_rules! string_serialize_via_display { { $method:ident, $type:ty } => {
420    fn $method(self, v: $type) -> Result<Self::Ok> {
421        #[allow(clippy::str_to_string)]
422        Ok(v.to_string())
423    }
424} }
425
426impl ser::Serializer for StringKeySerializer {
427    type Ok = String;
428    type Error = ConfigError;
429    type SerializeSeq = Unreachable;
430    type SerializeTuple = Unreachable;
431    type SerializeTupleStruct = Unreachable;
432    type SerializeTupleVariant = Unreachable;
433    type SerializeMap = Unreachable;
434    type SerializeStruct = Unreachable;
435    type SerializeStructVariant = Unreachable;
436
437    string_serialize_via_display!(serialize_bool, bool);
438    string_serialize_via_display!(serialize_i8, i8);
439    string_serialize_via_display!(serialize_i16, i16);
440    string_serialize_via_display!(serialize_i32, i32);
441    string_serialize_via_display!(serialize_i64, i64);
442    string_serialize_via_display!(serialize_u8, u8);
443    string_serialize_via_display!(serialize_u16, u16);
444    string_serialize_via_display!(serialize_u32, u32);
445    string_serialize_via_display!(serialize_u64, u64);
446    string_serialize_via_display!(serialize_f32, f32);
447    string_serialize_via_display!(serialize_f64, f64);
448    string_serialize_via_display!(serialize_char, char);
449    string_serialize_via_display!(serialize_str, &str);
450
451    fn serialize_bytes(self, v: &[u8]) -> Result<Self::Ok> {
452        Ok(String::from_utf8_lossy(v).to_string())
453    }
454
455    fn serialize_none(self) -> Result<Self::Ok> {
456        self.serialize_unit()
457    }
458
459    fn serialize_some<T>(self, value: &T) -> Result<Self::Ok>
460    where
461        T: ?Sized + ser::Serialize,
462    {
463        value.serialize(self)
464    }
465
466    fn serialize_unit(self) -> Result<Self::Ok> {
467        Ok(String::new())
468    }
469
470    fn serialize_unit_struct(self, _name: &str) -> Result<Self::Ok> {
471        self.serialize_unit()
472    }
473
474    fn serialize_unit_variant(
475        self,
476        _name: &str,
477        _variant_index: u32,
478        variant: &str,
479    ) -> Result<Self::Ok> {
480        Ok(variant.to_owned())
481    }
482
483    fn serialize_newtype_struct<T>(self, _name: &str, value: &T) -> Result<Self::Ok>
484    where
485        T: ?Sized + ser::Serialize,
486    {
487        value.serialize(self)
488    }
489
490    fn serialize_newtype_variant<T>(
491        self,
492        _name: &str,
493        _variant_index: u32,
494        _variant: &str,
495        value: &T,
496    ) -> Result<Self::Ok>
497    where
498        T: ?Sized + ser::Serialize,
499    {
500        value.serialize(self)
501    }
502
503    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
504        Err(ConfigError::Message(
505            "seq can't serialize to string key".to_owned(),
506        ))
507    }
508
509    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
510        Err(ConfigError::Message(
511            "tuple can't serialize to string key".to_owned(),
512        ))
513    }
514
515    fn serialize_tuple_struct(self, name: &str, _len: usize) -> Result<Self::SerializeTupleStruct> {
516        Err(ConfigError::Message(format!(
517            "tuple struct {name} can't serialize to string key"
518        )))
519    }
520
521    fn serialize_tuple_variant(
522        self,
523        name: &str,
524        _variant_index: u32,
525        variant: &str,
526        _len: usize,
527    ) -> Result<Self::SerializeTupleVariant> {
528        Err(ConfigError::Message(format!(
529            "tuple variant {name}::{variant} can't serialize to string key"
530        )))
531    }
532
533    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
534        Err(ConfigError::Message(
535            "map can't serialize to string key".to_owned(),
536        ))
537    }
538
539    fn serialize_struct(self, name: &str, _len: usize) -> Result<Self::SerializeStruct> {
540        Err(ConfigError::Message(format!(
541            "struct {name} can't serialize to string key"
542        )))
543    }
544
545    fn serialize_struct_variant(
546        self,
547        name: &str,
548        _variant_index: u32,
549        variant: &str,
550        _len: usize,
551    ) -> Result<Self::SerializeStructVariant> {
552        Err(ConfigError::Message(format!(
553            "struct variant {name}::{variant} can't serialize to string key"
554        )))
555    }
556}
557
558impl ser::SerializeSeq for Unreachable {
559    type Ok = String;
560    type Error = ConfigError;
561
562    fn serialize_element<T>(&mut self, _value: &T) -> Result<()>
563    where
564        T: ?Sized + ser::Serialize,
565    {
566        match *self {}
567    }
568
569    fn end(self) -> Result<Self::Ok> {
570        match self {}
571    }
572}
573
574impl ser::SerializeTuple for Unreachable {
575    type Ok = String;
576    type Error = ConfigError;
577
578    fn serialize_element<T>(&mut self, _value: &T) -> Result<()>
579    where
580        T: ?Sized + ser::Serialize,
581    {
582        match *self {}
583    }
584
585    fn end(self) -> Result<Self::Ok> {
586        match self {}
587    }
588}
589
590impl ser::SerializeTupleStruct for Unreachable {
591    type Ok = String;
592    type Error = ConfigError;
593
594    fn serialize_field<T>(&mut self, _value: &T) -> Result<()>
595    where
596        T: ?Sized + ser::Serialize,
597    {
598        match *self {}
599    }
600
601    fn end(self) -> Result<Self::Ok> {
602        match self {}
603    }
604}
605
606impl ser::SerializeTupleVariant for Unreachable {
607    type Ok = String;
608    type Error = ConfigError;
609
610    fn serialize_field<T>(&mut self, _value: &T) -> Result<()>
611    where
612        T: ?Sized + ser::Serialize,
613    {
614        match *self {}
615    }
616
617    fn end(self) -> Result<Self::Ok> {
618        match self {}
619    }
620}
621
622impl ser::SerializeMap for Unreachable {
623    type Ok = String;
624    type Error = ConfigError;
625
626    fn serialize_key<T>(&mut self, _key: &T) -> Result<()>
627    where
628        T: ?Sized + ser::Serialize,
629    {
630        match *self {}
631    }
632
633    fn serialize_value<T>(&mut self, _value: &T) -> Result<()>
634    where
635        T: ?Sized + ser::Serialize,
636    {
637        match *self {}
638    }
639
640    fn end(self) -> Result<Self::Ok> {
641        match self {}
642    }
643}
644
645impl ser::SerializeStruct for Unreachable {
646    type Ok = String;
647    type Error = ConfigError;
648
649    fn serialize_field<T>(&mut self, _key: &'static str, _value: &T) -> Result<()>
650    where
651        T: ?Sized + ser::Serialize,
652    {
653        match *self {}
654    }
655
656    fn end(self) -> Result<Self::Ok> {
657        match self {}
658    }
659}
660
661impl ser::SerializeStructVariant for Unreachable {
662    type Ok = String;
663    type Error = ConfigError;
664
665    fn serialize_field<T>(&mut self, _key: &'static str, _value: &T) -> Result<()>
666    where
667        T: ?Sized + ser::Serialize,
668    {
669        match *self {}
670    }
671
672    fn end(self) -> Result<Self::Ok> {
673        match self {}
674    }
675}
676
677#[cfg(test)]
678mod test {
679    use serde::{Deserialize, Serialize};
680
681    use super::*;
682
683    #[test]
684    fn test_struct() {
685        #[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
686        struct Test {
687            int: u32,
688            seq: Vec<String>,
689        }
690
691        let test = Test {
692            int: 1,
693            seq: vec!["a".to_owned(), "b".to_owned()],
694        };
695        let config = Config::try_from(&test).unwrap();
696
697        let actual: Test = config.try_deserialize().unwrap();
698        assert_eq!(test, actual);
699    }
700
701    #[test]
702    #[cfg(feature = "json")]
703    fn test_nest() {
704        let val = serde_json::json! { {
705            "top": {
706                "num": 1,
707                "array": [2],
708                "nested": [[3,4]],
709                "deep": [{
710                    "yes": true,
711                }],
712                "mixed": [
713                    { "boolish": false, },
714                    42,
715                    ["hi"],
716                    { "inner": 66 },
717                    23,
718                ],
719            }
720        } };
721        let config = Config::try_from(&val).unwrap();
722        let output: serde_json::Value = config.try_deserialize().unwrap();
723        assert_eq!(val, output);
724    }
725}
config/ser.rs

config/
ser.rs
