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Diffstat (limited to 'third_party/rust/serde_json/src/lib.rs')
| -rw-r--r-- | third_party/rust/serde_json/src/lib.rs | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/third_party/rust/serde_json/src/lib.rs b/third_party/rust/serde_json/src/lib.rs new file mode 100644 index 0000000000..48d0fe2191 --- /dev/null +++ b/third_party/rust/serde_json/src/lib.rs @@ -0,0 +1,421 @@ +//! # Serde JSON +//! +//! JSON is a ubiquitous open-standard format that uses human-readable text to +//! transmit data objects consisting of key-value pairs. +//! +//! ```json +//! { +//! "name": "John Doe", +//! "age": 43, +//! "address": { +//! "street": "10 Downing Street", +//! "city": "London" +//! }, +//! "phones": [ +//! "+44 1234567", +//! "+44 2345678" +//! ] +//! } +//! ``` +//! +//! There are three common ways that you might find yourself needing to work +//! with JSON data in Rust. +//! +//! - **As text data.** An unprocessed string of JSON data that you receive on +//! an HTTP endpoint, read from a file, or prepare to send to a remote +//! server. +//! - **As an untyped or loosely typed representation.** Maybe you want to +//! check that some JSON data is valid before passing it on, but without +//! knowing the structure of what it contains. Or you want to do very basic +//! manipulations like insert a key in a particular spot. +//! - **As a strongly typed Rust data structure.** When you expect all or most +//! of your data to conform to a particular structure and want to get real +//! work done without JSON's loosey-goosey nature tripping you up. +//! +//! Serde JSON provides efficient, flexible, safe ways of converting data +//! between each of these representations. +//! +//! # Operating on untyped JSON values +//! +//! Any valid JSON data can be manipulated in the following recursive enum +//! representation. This data structure is [`serde_json::Value`][value]. +//! +//! ``` +//! # use serde_json::{Number, Map}; +//! # +//! # #[allow(dead_code)] +//! enum Value { +//! Null, +//! Bool(bool), +//! Number(Number), +//! String(String), +//! Array(Vec<Value>), +//! Object(Map<String, Value>), +//! } +//! ``` +//! +//! A string of JSON data can be parsed into a `serde_json::Value` by the +//! [`serde_json::from_str`][from_str] function. There is also +//! [`from_slice`][from_slice] for parsing from a byte slice &[u8] and +//! [`from_reader`][from_reader] for parsing from any `io::Read` like a File or +//! a TCP stream. +//! +//! ``` +//! use serde_json::{Result, Value}; +//! +//! fn untyped_example() -> Result<()> { +//! // Some JSON input data as a &str. Maybe this comes from the user. +//! let data = r#" +//! { +//! "name": "John Doe", +//! "age": 43, +//! "phones": [ +//! "+44 1234567", +//! "+44 2345678" +//! ] +//! }"#; +//! +//! // Parse the string of data into serde_json::Value. +//! let v: Value = serde_json::from_str(data)?; +//! +//! // Access parts of the data by indexing with square brackets. +//! println!("Please call {} at the number {}", v["name"], v["phones"][0]); +//! +//! Ok(()) +//! } +//! # +//! # fn main() { +//! # untyped_example().unwrap(); +//! # } +//! ``` +//! +//! The result of square bracket indexing like `v["name"]` is a borrow of the +//! data at that index, so the type is `&Value`. A JSON map can be indexed with +//! string keys, while a JSON array can be indexed with integer keys. If the +//! type of the data is not right for the type with which it is being indexed, +//! or if a map does not contain the key being indexed, or if the index into a +//! vector is out of bounds, the returned element is `Value::Null`. +//! +//! When a `Value` is printed, it is printed as a JSON string. So in the code +//! above, the output looks like `Please call "John Doe" at the number "+44 +//! 1234567"`. The quotation marks appear because `v["name"]` is a `&Value` +//! containing a JSON string and its JSON representation is `"John Doe"`. +//! Printing as a plain string without quotation marks involves converting from +//! a JSON string to a Rust string with [`as_str()`] or avoiding the use of +//! `Value` as described in the following section. +//! +//! [`as_str()`]: crate::Value::as_str +//! +//! The `Value` representation is sufficient for very basic tasks but can be +//! tedious to work with for anything more significant. Error handling is +//! verbose to implement correctly, for example imagine trying to detect the +//! presence of unrecognized fields in the input data. The compiler is powerless +//! to help you when you make a mistake, for example imagine typoing `v["name"]` +//! as `v["nmae"]` in one of the dozens of places it is used in your code. +//! +//! # Parsing JSON as strongly typed data structures +//! +//! Serde provides a powerful way of mapping JSON data into Rust data structures +//! largely automatically. +//! +//! ``` +//! use serde::{Deserialize, Serialize}; +//! use serde_json::Result; +//! +//! #[derive(Serialize, Deserialize)] +//! struct Person { +//! name: String, +//! age: u8, +//! phones: Vec<String>, +//! } +//! +//! fn typed_example() -> Result<()> { +//! // Some JSON input data as a &str. Maybe this comes from the user. +//! let data = r#" +//! { +//! "name": "John Doe", +//! "age": 43, +//! "phones": [ +//! "+44 1234567", +//! "+44 2345678" +//! ] +//! }"#; +//! +//! // Parse the string of data into a Person object. This is exactly the +//! // same function as the one that produced serde_json::Value above, but +//! // now we are asking it for a Person as output. +//! let p: Person = serde_json::from_str(data)?; +//! +//! // Do things just like with any other Rust data structure. +//! println!("Please call {} at the number {}", p.name, p.phones[0]); +//! +//! Ok(()) +//! } +//! # +//! # fn main() { +//! # typed_example().unwrap(); +//! # } +//! ``` +//! +//! This is the same `serde_json::from_str` function as before, but this time we +//! assign the return value to a variable of type `Person` so Serde will +//! automatically interpret the input data as a `Person` and produce informative +//! error messages if the layout does not conform to what a `Person` is expected +//! to look like. +//! +//! Any type that implements Serde's `Deserialize` trait can be deserialized +//! this way. This includes built-in Rust standard library types like `Vec<T>` +//! and `HashMap<K, V>`, as well as any structs or enums annotated with +//! `#[derive(Deserialize)]`. +//! +//! Once we have `p` of type `Person`, our IDE and the Rust compiler can help us +//! use it correctly like they do for any other Rust code. The IDE can +//! autocomplete field names to prevent typos, which was impossible in the +//! `serde_json::Value` representation. And the Rust compiler can check that +//! when we write `p.phones[0]`, then `p.phones` is guaranteed to be a +//! `Vec<String>` so indexing into it makes sense and produces a `String`. +//! +//! # Constructing JSON values +//! +//! Serde JSON provides a [`json!` macro][macro] to build `serde_json::Value` +//! objects with very natural JSON syntax. +//! +//! ``` +//! use serde_json::json; +//! +//! fn main() { +//! // The type of `john` is `serde_json::Value` +//! let john = json!({ +//! "name": "John Doe", +//! "age": 43, +//! "phones": [ +//! "+44 1234567", +//! "+44 2345678" +//! ] +//! }); +//! +//! println!("first phone number: {}", john["phones"][0]); +//! +//! // Convert to a string of JSON and print it out +//! println!("{}", john.to_string()); +//! } +//! ``` +//! +//! The `Value::to_string()` function converts a `serde_json::Value` into a +//! `String` of JSON text. +//! +//! One neat thing about the `json!` macro is that variables and expressions can +//! be interpolated directly into the JSON value as you are building it. Serde +//! will check at compile time that the value you are interpolating is able to +//! be represented as JSON. +//! +//! ``` +//! # use serde_json::json; +//! # +//! # fn random_phone() -> u16 { 0 } +//! # +//! let full_name = "John Doe"; +//! let age_last_year = 42; +//! +//! // The type of `john` is `serde_json::Value` +//! let john = json!({ +//! "name": full_name, +//! "age": age_last_year + 1, +//! "phones": [ +//! format!("+44 {}", random_phone()) +//! ] +//! }); +//! ``` +//! +//! This is amazingly convenient, but we have the problem we had before with +//! `Value`: the IDE and Rust compiler cannot help us if we get it wrong. Serde +//! JSON provides a better way of serializing strongly-typed data structures +//! into JSON text. +//! +//! # Creating JSON by serializing data structures +//! +//! A data structure can be converted to a JSON string by +//! [`serde_json::to_string`][to_string]. There is also +//! [`serde_json::to_vec`][to_vec] which serializes to a `Vec<u8>` and +//! [`serde_json::to_writer`][to_writer] which serializes to any `io::Write` +//! such as a File or a TCP stream. +//! +//! ``` +//! use serde::{Deserialize, Serialize}; +//! use serde_json::Result; +//! +//! #[derive(Serialize, Deserialize)] +//! struct Address { +//! street: String, +//! city: String, +//! } +//! +//! fn print_an_address() -> Result<()> { +//! // Some data structure. +//! let address = Address { +//! street: "10 Downing Street".to_owned(), +//! city: "London".to_owned(), +//! }; +//! +//! // Serialize it to a JSON string. +//! let j = serde_json::to_string(&address)?; +//! +//! // Print, write to a file, or send to an HTTP server. +//! println!("{}", j); +//! +//! Ok(()) +//! } +//! # +//! # fn main() { +//! # print_an_address().unwrap(); +//! # } +//! ``` +//! +//! Any type that implements Serde's `Serialize` trait can be serialized this +//! way. This includes built-in Rust standard library types like `Vec<T>` and +//! `HashMap<K, V>`, as well as any structs or enums annotated with +//! `#[derive(Serialize)]`. +//! +//! # No-std support +//! +//! As long as there is a memory allocator, it is possible to use serde_json +//! without the rest of the Rust standard library. Disable the default "std" +//! feature and enable the "alloc" feature: +//! +//! ```toml +//! [dependencies] +//! serde_json = { version = "1.0", default-features = false, features = ["alloc"] } +//! ``` +//! +//! For JSON support in Serde without a memory allocator, please see the +//! [`serde-json-core`] crate. +//! +//! [value]: crate::value::Value +//! [from_str]: crate::de::from_str +//! [from_slice]: crate::de::from_slice +//! [from_reader]: crate::de::from_reader +//! [to_string]: crate::ser::to_string +//! [to_vec]: crate::ser::to_vec +//! [to_writer]: crate::ser::to_writer +//! [macro]: crate::json +//! [`serde-json-core`]: https://github.com/rust-embedded-community/serde-json-core + +#![doc(html_root_url = "https://docs.rs/serde_json/1.0.93")] +// Ignored clippy lints +#![allow( + clippy::collapsible_else_if, + clippy::comparison_chain, + clippy::deprecated_cfg_attr, + clippy::doc_markdown, + clippy::excessive_precision, + clippy::explicit_auto_deref, + clippy::float_cmp, + clippy::manual_range_contains, + clippy::match_like_matches_macro, + clippy::match_single_binding, + clippy::needless_doctest_main, + clippy::needless_late_init, + // clippy bug: https://github.com/rust-lang/rust-clippy/issues/8366 + clippy::ptr_arg, + clippy::return_self_not_must_use, + clippy::transmute_ptr_to_ptr, + clippy::unnecessary_wraps, + // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704 + clippy::unnested_or_patterns, +)] +// Ignored clippy_pedantic lints +#![allow( + // buggy + clippy::iter_not_returning_iterator, // https://github.com/rust-lang/rust-clippy/issues/8285 + // Deserializer::from_str, into_iter + clippy::should_implement_trait, + // integer and float ser/de requires these sorts of casts + clippy::cast_possible_truncation, + clippy::cast_possible_wrap, + clippy::cast_precision_loss, + clippy::cast_sign_loss, + // correctly used + clippy::enum_glob_use, + clippy::if_not_else, + clippy::integer_division, + clippy::map_err_ignore, + clippy::match_same_arms, + clippy::similar_names, + clippy::unused_self, + clippy::wildcard_imports, + // things are often more readable this way + clippy::cast_lossless, + clippy::module_name_repetitions, + clippy::redundant_else, + clippy::shadow_unrelated, + clippy::single_match_else, + clippy::too_many_lines, + clippy::unreadable_literal, + clippy::unseparated_literal_suffix, + clippy::use_self, + clippy::zero_prefixed_literal, + // we support older compilers + clippy::checked_conversions, + clippy::mem_replace_with_default, + // noisy + clippy::missing_errors_doc, + clippy::must_use_candidate, +)] +#![allow(non_upper_case_globals)] +#![deny(missing_docs)] +#![cfg_attr(not(feature = "std"), no_std)] +#![cfg_attr(docsrs, feature(doc_cfg))] + +extern crate alloc; + +#[cfg(feature = "std")] +#[doc(inline)] +pub use crate::de::from_reader; +#[doc(inline)] +pub use crate::de::{from_slice, from_str, Deserializer, StreamDeserializer}; +#[doc(inline)] +pub use crate::error::{Error, Result}; +#[doc(inline)] +pub use crate::ser::{to_string, to_string_pretty, to_vec, to_vec_pretty}; +#[cfg(feature = "std")] +#[doc(inline)] +pub use crate::ser::{to_writer, to_writer_pretty, Serializer}; +#[doc(inline)] +pub use crate::value::{from_value, to_value, Map, Number, Value}; + +// We only use our own error type; no need for From conversions provided by the +// standard library's try! macro. This reduces lines of LLVM IR by 4%. +macro_rules! tri { + ($e:expr $(,)?) => { + match $e { + core::result::Result::Ok(val) => val, + core::result::Result::Err(err) => return core::result::Result::Err(err), + } + }; +} + +#[macro_use] +mod macros; + +pub mod de; +pub mod error; +pub mod map; +#[cfg(feature = "std")] +#[cfg_attr(docsrs, doc(cfg(feature = "std")))] +pub mod ser; +#[cfg(not(feature = "std"))] +mod ser; +pub mod value; + +mod features_check; + +mod io; +#[cfg(feature = "std")] +mod iter; +#[cfg(feature = "float_roundtrip")] +mod lexical; +mod number; +mod read; + +#[cfg(feature = "raw_value")] +mod raw; |