1//! # Serde
2//!
3//! Serde is a framework for ***ser***ializing and ***de***serializing Rust data
4//! structures efficiently and generically.
5//!
6//! The Serde ecosystem consists of data structures that know how to serialize
7//! and deserialize themselves along with data formats that know how to
8//! serialize and deserialize other things. Serde provides the layer by which
9//! these two groups interact with each other, allowing any supported data
10//! structure to be serialized and deserialized using any supported data format.
11//!
12//! See the Serde website <https://serde.rs/> for additional documentation and
13//! usage examples.
14//!
15//! ## Design
16//!
17//! Where many other languages rely on runtime reflection for serializing data,
18//! Serde is instead built on Rust's powerful trait system. A data structure
19//! that knows how to serialize and deserialize itself is one that implements
20//! Serde's `Serialize` and `Deserialize` traits (or uses Serde's derive
21//! attribute to automatically generate implementations at compile time). This
22//! avoids any overhead of reflection or runtime type information. In fact in
23//! many situations the interaction between data structure and data format can
24//! be completely optimized away by the Rust compiler, leaving Serde
25//! serialization to perform the same speed as a handwritten serializer for the
26//! specific selection of data structure and data format.
27//!
28//! ## Data formats
29//!
30//! The following is a partial list of data formats that have been implemented
31//! for Serde by the community.
32//!
33//! - [JSON], the ubiquitous JavaScript Object Notation used by many HTTP APIs.
34//! - [Postcard], a no\_std and embedded-systems friendly compact binary format.
35//! - [CBOR], a Concise Binary Object Representation designed for small message
36//! size without the need for version negotiation.
37//! - [YAML], a self-proclaimed human-friendly configuration language that ain't
38//! markup language.
39//! - [MessagePack], an efficient binary format that resembles a compact JSON.
40//! - [TOML], a minimal configuration format used by [Cargo].
41//! - [Pickle], a format common in the Python world.
42//! - [RON], a Rusty Object Notation.
43//! - [BSON], the data storage and network transfer format used by MongoDB.
44//! - [Avro], a binary format used within Apache Hadoop, with support for schema
45//! definition.
46//! - [JSON5], a superset of JSON including some productions from ES5.
47//! - [URL] query strings, in the x-www-form-urlencoded format.
48//! - [Starlark], the format used for describing build targets by the Bazel and
49//! Buck build systems. *(serialization only)*
50//! - [Envy], a way to deserialize environment variables into Rust structs.
51//! *(deserialization only)*
52//! - [Envy Store], a way to deserialize [AWS Parameter Store] parameters into
53//! Rust structs. *(deserialization only)*
54//! - [S-expressions], the textual representation of code and data used by the
55//! Lisp language family.
56//! - [D-Bus]'s binary wire format.
57//! - [FlexBuffers], the schemaless cousin of Google's FlatBuffers zero-copy
58//! serialization format.
59//! - [Bencode], a simple binary format used in the BitTorrent protocol.
60//! - [Token streams], for processing Rust procedural macro input.
61//! *(deserialization only)*
62//! - [DynamoDB Items], the format used by [rusoto_dynamodb] to transfer data to
63//! and from DynamoDB.
64//! - [Hjson], a syntax extension to JSON designed around human reading and
65//! editing. *(deserialization only)*
66//!
67//! [JSON]: https://github.com/serde-rs/json
68//! [Postcard]: https://github.com/jamesmunns/postcard
69//! [CBOR]: https://github.com/enarx/ciborium
70//! [YAML]: https://github.com/dtolnay/serde-yaml
71//! [MessagePack]: https://github.com/3Hren/msgpack-rust
72//! [TOML]: https://docs.rs/toml
73//! [Pickle]: https://github.com/birkenfeld/serde-pickle
74//! [RON]: https://github.com/ron-rs/ron
75//! [BSON]: https://github.com/mongodb/bson-rust
76//! [Avro]: https://docs.rs/apache-avro
77//! [JSON5]: https://github.com/callum-oakley/json5-rs
78//! [URL]: https://docs.rs/serde_qs
79//! [Starlark]: https://github.com/dtolnay/serde-starlark
80//! [Envy]: https://github.com/softprops/envy
81//! [Envy Store]: https://github.com/softprops/envy-store
82//! [Cargo]: https://doc.rust-lang.org/cargo/reference/manifest.html
83//! [AWS Parameter Store]: https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-parameter-store.html
84//! [S-expressions]: https://github.com/rotty/lexpr-rs
85//! [D-Bus]: https://docs.rs/zvariant
86//! [FlexBuffers]: https://github.com/google/flatbuffers/tree/master/rust/flexbuffers
87//! [Bencode]: https://github.com/P3KI/bendy
88//! [Token streams]: https://github.com/oxidecomputer/serde_tokenstream
89//! [DynamoDB Items]: https://docs.rs/serde_dynamo
90//! [rusoto_dynamodb]: https://docs.rs/rusoto_dynamodb
91//! [Hjson]: https://github.com/Canop/deser-hjson
92
93////////////////////////////////////////////////////////////////////////////////
94
95// Serde types in rustdoc of other crates get linked to here.
96#![doc(html_root_url = "https://docs.rs/serde/1.0.185")]
97// Support using Serde without the standard library!
98#![cfg_attr(not(feature = "std"), no_std)]
99// Unstable functionality only if the user asks for it. For tracking and
100// discussion of these features please refer to this issue:
101//
102// https://github.com/serde-rs/serde/issues/812
103#![cfg_attr(feature = "unstable", feature(error_in_core, never_type))]
104#![allow(unknown_lints, bare_trait_objects, deprecated)]
105// Ignored clippy and clippy_pedantic lints
106#![allow(
107 // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
108 clippy::unnested_or_patterns,
109 // clippy bug: https://github.com/rust-lang/rust-clippy/issues/7768
110 clippy::semicolon_if_nothing_returned,
111 // not available in our oldest supported compiler
112 clippy::empty_enum,
113 clippy::type_repetition_in_bounds, // https://github.com/rust-lang/rust-clippy/issues/8772
114 // integer and float ser/de requires these sorts of casts
115 clippy::cast_possible_truncation,
116 clippy::cast_possible_wrap,
117 clippy::cast_sign_loss,
118 // things are often more readable this way
119 clippy::cast_lossless,
120 clippy::module_name_repetitions,
121 clippy::option_if_let_else,
122 clippy::single_match_else,
123 clippy::type_complexity,
124 clippy::use_self,
125 clippy::zero_prefixed_literal,
126 // correctly used
127 clippy::derive_partial_eq_without_eq,
128 clippy::enum_glob_use,
129 clippy::explicit_auto_deref,
130 clippy::let_underscore_untyped,
131 clippy::map_err_ignore,
132 clippy::new_without_default,
133 clippy::result_unit_err,
134 clippy::wildcard_imports,
135 // not practical
136 clippy::needless_pass_by_value,
137 clippy::similar_names,
138 clippy::too_many_lines,
139 // preference
140 clippy::doc_markdown,
141 clippy::unseparated_literal_suffix,
142 // false positive
143 clippy::needless_doctest_main,
144 // noisy
145 clippy::missing_errors_doc,
146 clippy::must_use_candidate,
147)]
148// Restrictions
149#![deny(clippy::question_mark_used)]
150// Rustc lints.
151#![deny(missing_docs, unused_imports)]
152
153////////////////////////////////////////////////////////////////////////////////
154
155#[cfg(feature = "alloc")]
156extern crate alloc;
157
158/// A facade around all the types we need from the `std`, `core`, and `alloc`
159/// crates. This avoids elaborate import wrangling having to happen in every
160/// module.
161mod lib {
162 mod core {
163 #[cfg(not(feature = "std"))]
164 pub use core::*;
165 #[cfg(feature = "std")]
166 pub use std::*;
167 }
168
169 pub use self::core::{cmp, iter, mem, num, ptr, slice, str};
170 pub use self::core::{f32, f64};
171 pub use self::core::{i16, i32, i64, i8, isize};
172 pub use self::core::{u16, u32, u64, u8, usize};
173
174 pub use self::core::cell::{Cell, RefCell};
175 pub use self::core::clone::{self, Clone};
176 pub use self::core::cmp::Reverse;
177 pub use self::core::convert::{self, From, Into};
178 pub use self::core::default::{self, Default};
179 pub use self::core::fmt::{self, Debug, Display};
180 pub use self::core::marker::{self, PhantomData};
181 pub use self::core::num::Wrapping;
182 pub use self::core::ops::{Bound, Range, RangeFrom, RangeInclusive, RangeTo};
183 pub use self::core::option::{self, Option};
184 pub use self::core::result::{self, Result};
185 pub use self::core::time::Duration;
186
187 #[cfg(all(feature = "alloc", not(feature = "std")))]
188 pub use alloc::borrow::{Cow, ToOwned};
189 #[cfg(feature = "std")]
190 pub use std::borrow::{Cow, ToOwned};
191
192 #[cfg(all(feature = "alloc", not(feature = "std")))]
193 pub use alloc::string::{String, ToString};
194 #[cfg(feature = "std")]
195 pub use std::string::{String, ToString};
196
197 #[cfg(all(feature = "alloc", not(feature = "std")))]
198 pub use alloc::vec::Vec;
199 #[cfg(feature = "std")]
200 pub use std::vec::Vec;
201
202 #[cfg(all(feature = "alloc", not(feature = "std")))]
203 pub use alloc::boxed::Box;
204 #[cfg(feature = "std")]
205 pub use std::boxed::Box;
206
207 #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
208 pub use alloc::rc::{Rc, Weak as RcWeak};
209 #[cfg(all(feature = "rc", feature = "std"))]
210 pub use std::rc::{Rc, Weak as RcWeak};
211
212 #[cfg(all(feature = "rc", feature = "alloc", not(feature = "std")))]
213 pub use alloc::sync::{Arc, Weak as ArcWeak};
214 #[cfg(all(feature = "rc", feature = "std"))]
215 pub use std::sync::{Arc, Weak as ArcWeak};
216
217 #[cfg(all(feature = "alloc", not(feature = "std")))]
218 pub use alloc::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
219 #[cfg(feature = "std")]
220 pub use std::collections::{BTreeMap, BTreeSet, BinaryHeap, LinkedList, VecDeque};
221
222 #[cfg(all(not(no_core_cstr), not(feature = "std")))]
223 pub use self::core::ffi::CStr;
224 #[cfg(feature = "std")]
225 pub use std::ffi::CStr;
226
227 #[cfg(all(not(no_core_cstr), feature = "alloc", not(feature = "std")))]
228 pub use alloc::ffi::CString;
229 #[cfg(feature = "std")]
230 pub use std::ffi::CString;
231
232 #[cfg(feature = "std")]
233 pub use std::{error, net};
234
235 #[cfg(feature = "std")]
236 pub use std::collections::{HashMap, HashSet};
237 #[cfg(feature = "std")]
238 pub use std::ffi::{OsStr, OsString};
239 #[cfg(feature = "std")]
240 pub use std::hash::{BuildHasher, Hash};
241 #[cfg(feature = "std")]
242 pub use std::io::Write;
243 #[cfg(feature = "std")]
244 pub use std::path::{Path, PathBuf};
245 #[cfg(feature = "std")]
246 pub use std::sync::{Mutex, RwLock};
247 #[cfg(feature = "std")]
248 pub use std::time::{SystemTime, UNIX_EPOCH};
249
250 #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic)))]
251 pub use std::sync::atomic::{
252 AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU8,
253 AtomicUsize, Ordering,
254 };
255 #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic64)))]
256 pub use std::sync::atomic::{AtomicI64, AtomicU64};
257
258 #[cfg(all(feature = "std", not(no_target_has_atomic)))]
259 pub use std::sync::atomic::Ordering;
260 #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "8"))]
261 pub use std::sync::atomic::{AtomicBool, AtomicI8, AtomicU8};
262 #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "16"))]
263 pub use std::sync::atomic::{AtomicI16, AtomicU16};
264 #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "32"))]
265 pub use std::sync::atomic::{AtomicI32, AtomicU32};
266 #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "64"))]
267 pub use std::sync::atomic::{AtomicI64, AtomicU64};
268 #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "ptr"))]
269 pub use std::sync::atomic::{AtomicIsize, AtomicUsize};
270}
271
272// None of this crate's error handling needs the `From::from` error conversion
273// performed implicitly by the `?` operator or the standard library's `try!`
274// macro. This simplified macro gives a 5.5% improvement in compile time
275// compared to standard `try!`, and 9% improvement compared to `?`.
276macro_rules! tri {
277 ($expr:expr) => {
278 match $expr {
279 Ok(val) => val,
280 Err(err) => return Err(err),
281 }
282 };
283}
284
285////////////////////////////////////////////////////////////////////////////////
286
287#[macro_use]
288mod macros;
289
290#[macro_use]
291mod integer128;
292
293pub mod de;
294pub mod ser;
295
296#[doc(inline)]
297pub use crate::de::{Deserialize, Deserializer};
298#[doc(inline)]
299pub use crate::ser::{Serialize, Serializer};
300
301// Used by generated code and doc tests. Not public API.
302#[doc(hidden)]
303#[path = "private/mod.rs"]
304pub mod __private;
305
306#[path = "de/seed.rs"]
307mod seed;
308
309#[cfg(not(any(feature = "std", feature = "unstable")))]
310mod std_error;
311
312// Re-export #[derive(Serialize, Deserialize)].
313//
314// The reason re-exporting is not enabled by default is that disabling it would
315// be annoying for crates that provide handwritten impls or data formats. They
316// would need to disable default features and then explicitly re-enable std.
317#[cfg(feature = "serde_derive")]
318extern crate serde_derive;
319
320/// Derive macro available if serde is built with `features = ["derive"]`.
321#[cfg(feature = "serde_derive")]
322pub use serde_derive::{Deserialize, Serialize};
323
324#[cfg(all(not(no_serde_derive), any(feature = "std", feature = "alloc")))]
325mod actually_private {
326 pub struct T;
327}
328