| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/serde_json-1.0.96/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../serde_json/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../serde_json/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! # 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 |
| |
| </span><span class="attribute">#![doc(html_root_url = <span class="string">"https://docs.rs/serde_json/1.0.96"</span>)] |
| </span><span class="comment">// Ignored clippy lints |
| </span><span class="attribute">#![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, |
| <span class="comment">// clippy bug: https://github.com/rust-lang/rust-clippy/issues/8366 |
| </span>clippy::ptr_arg, |
| clippy::return_self_not_must_use, |
| clippy::transmute_ptr_to_ptr, |
| clippy::unnecessary_wraps, |
| <span class="comment">// clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704 |
| </span>clippy::unnested_or_patterns, |
| )] |
| </span><span class="comment">// Ignored clippy_pedantic lints |
| </span><span class="attribute">#![allow( |
| <span class="comment">// buggy |
| </span>clippy::iter_not_returning_iterator, <span class="comment">// https://github.com/rust-lang/rust-clippy/issues/8285 |
| // Deserializer::from_str, into_iter |
| </span>clippy::should_implement_trait, |
| <span class="comment">// integer and float ser/de requires these sorts of casts |
| </span>clippy::cast_possible_truncation, |
| clippy::cast_possible_wrap, |
| clippy::cast_precision_loss, |
| clippy::cast_sign_loss, |
| <span class="comment">// correctly used |
| </span>clippy::enum_glob_use, |
| clippy::if_not_else, |
| clippy::integer_division, |
| clippy::let_underscore_untyped, |
| clippy::map_err_ignore, |
| clippy::match_same_arms, |
| clippy::similar_names, |
| clippy::unused_self, |
| clippy::wildcard_imports, |
| <span class="comment">// things are often more readable this way |
| </span>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, |
| <span class="comment">// we support older compilers |
| </span>clippy::checked_conversions, |
| clippy::mem_replace_with_default, |
| <span class="comment">// noisy |
| </span>clippy::missing_errors_doc, |
| clippy::must_use_candidate, |
| )] |
| #![allow(non_upper_case_globals)] |
| #![deny(missing_docs)] |
| #![cfg_attr(not(feature = <span class="string">"std"</span>), no_std)] |
| #![cfg_attr(docsrs, feature(doc_cfg))] |
| |
| </span><span class="kw">extern crate </span>alloc; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[doc(inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::de::from_reader; |
| <span class="attribute">#[doc(inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::de::{from_slice, from_str, Deserializer, StreamDeserializer}; |
| <span class="attribute">#[doc(inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::error::{Error, <span class="prelude-ty">Result</span>}; |
| <span class="attribute">#[doc(inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::ser::{to_string, to_string_pretty, to_vec, to_vec_pretty}; |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[doc(inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::ser::{to_writer, to_writer_pretty, Serializer}; |
| <span class="attribute">#[doc(inline)] |
| </span><span class="kw">pub use </span><span class="kw">crate</span>::value::{from_value, to_value, Map, Number, Value}; |
| |
| <span class="comment">// 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%. |
| </span><span class="macro">macro_rules! </span>tri { |
| (<span class="macro-nonterminal">$e</span>:expr $(,)<span class="question-mark">?</span>) => { |
| <span class="kw">match </span><span class="macro-nonterminal">$e </span>{ |
| core::result::Result::Ok(val) => val, |
| core::result::Result::Err(err) => <span class="kw">return </span>core::result::Result::Err(err), |
| } |
| }; |
| } |
| |
| <span class="attribute">#[macro_use] |
| </span><span class="kw">mod </span>macros; |
| |
| <span class="kw">pub mod </span>de; |
| <span class="kw">pub mod </span>error; |
| <span class="kw">pub mod </span>map; |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"std"</span>)))] |
| </span><span class="kw">pub mod </span>ser; |
| <span class="attribute">#[cfg(not(feature = <span class="string">"std"</span>))] |
| </span><span class="kw">mod </span>ser; |
| <span class="kw">pub mod </span>value; |
| |
| <span class="kw">mod </span>features_check; |
| |
| <span class="kw">mod </span>io; |
| <span class="attribute">#[cfg(feature = <span class="string">"std"</span>)] |
| </span><span class="kw">mod </span>iter; |
| <span class="attribute">#[cfg(feature = <span class="string">"float_roundtrip"</span>)] |
| </span><span class="kw">mod </span>lexical; |
| <span class="kw">mod </span>number; |
| <span class="kw">mod </span>read; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"raw_value"</span>)] |
| </span><span class="kw">mod </span>raw; |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="serde_json" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
