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//! JSON and serialization //! //! # What is JSON? //! //! JSON (JavaScript Object Notation) is a way to write data in JavaScript. Like XML, it allows to //! encode structured data in a text format that can be easily read by humans. Its simple syntax //! and native compatibility with JavaScript have made it a widely used format. //! //! Data types that can be encoded are JavaScript types (see the `serde_json:Value` enum for more //! details): //! //! * `Bool`: equivalent to rust's `bool` //! * `I64`: equivalent to rust's `i64` //! * `U64`: equivalent to rust's `u64` //! * `F64`: equivalent to rust's `f64` //! * `String`: equivalent to rust's `String` //! * `Array`: equivalent to rust's `Vec<T>`, but also allowing objects of different types in the //! same array //! * `Object`: equivalent to rust's `BTreeMap<String, serde_json::Value>`; set the //! `preserve_order` feature to use `LinkedHashMap<String, serde_json::Value>` instead //! * `Null` //! //! An object is a series of string keys mapping to values, in `"key": value` format. Arrays are //! enclosed in square brackets ([ ... ]) and objects in curly brackets ({ ... }). A simple JSON //! document encoding a person, his/her age, address and phone numbers could look like //! //! ```ignore //! { //! "FirstName": "John", //! "LastName": "Doe", //! "Age": 43, //! "Address": { //! "Street": "Downing Street 10", //! "City": "London", //! "Country": "Great Britain" //! }, //! "PhoneNumbers": [ //! "+44 1234567", //! "+44 2345678" //! ] //! } //! ``` //! //! If we assume that `FirstName` is optional and all other fields are mandatory, the above JSON could //! correspond to the following Rust structs: //! //! ```ignore //! #[derive(Serialize, Deserialize)] //! struct Data { //! #[serde(rename="FirstName")] // to comply with Rust coding standards //! first_name: Option<String>, //! LastName: String, //! Age: u32, //! Address: Address, //! PhoneNumbers: Vec<String>, //! } //! //! #[derive(Serialize, Deserialize)] //! struct Address { //! Street: String, //! City: String, //! Country: String, //! } //! ``` //! //! # Type-based Serialization and Deserialization //! //! Serde provides a mechanism for low boilerplate serialization & deserialization of values to and //! from JSON via the serialization API. To be able to serialize a piece of data, it must implement //! the `serde::Serialize` trait. To be able to deserialize a piece of data, it must implement the //! `serde::Deserialize` trait. Serde provides provides an annotation to automatically generate //! the code for these traits: `#[derive(Serialize, Deserialize)]`. //! //! The JSON API also provides an enum `serde_json::Value` and a method `to_value` to serialize //! objects. A `serde_json::Value` value can be serialized as a string or buffer using the //! functions described above. You can also use the `json::Serializer` object, which implements the //! `Serializer` trait. //! //! # Examples of use //! //! ## Parsing a `str` to `Value` and reading the result //! //! ```rust //! extern crate serde_json; //! //! use serde_json::Value; //! //! fn main() { //! let data: Value = serde_json::from_str("{\"foo\": 13, \"bar\": \"baz\"}").unwrap(); //! println!("data: {:?}", data); //! // data: {"bar":"baz","foo":13} //! println!("object? {}", data.is_object()); //! // object? true //! //! let obj = data.as_object().unwrap(); //! let foo = obj.get("foo").unwrap(); //! //! println!("array? {:?}", foo.as_array()); //! // array? None //! println!("u64? {:?}", foo.as_u64()); //! // u64? Some(13u64) //! //! for (key, value) in obj.iter() { //! println!("{}: {}", key, match *value { //! Value::U64(v) => format!("{} (u64)", v), //! Value::String(ref v) => format!("{} (string)", v), //! _ => format!("other") //! }); //! } //! // bar: baz (string) //! // foo: 13 (u64) //! } //! ``` #![cfg_attr(feature = "clippy", feature(plugin))] #![cfg_attr(feature = "clippy", plugin(clippy))] #![cfg_attr(feature = "clippy", deny(clippy, clippy_pedantic))] // Because of "JavaScript"... fixed in Manishearth/rust-clippy#1071 #![cfg_attr(feature = "clippy", allow(doc_markdown))] // Whitelisted clippy_pedantic lints #![cfg_attr(feature = "clippy", allow( // integer and float ser/de requires these sorts of casts cast_possible_truncation, cast_possible_wrap, cast_precision_loss, cast_sign_loss, // string ser/de uses indexing and slicing indexing_slicing, // things are often more readable this way shadow_reuse, shadow_unrelated, single_match_else, stutter, // not practical missing_docs_in_private_items, ))] #![deny(missing_docs)] extern crate num_traits; extern crate core; #[macro_use] extern crate serde; extern crate itoa; extern crate dtoa; #[cfg(feature = "preserve_order")] extern crate linked_hash_map; pub use self::de::{Deserializer, StreamDeserializer, from_iter, from_reader, from_slice, from_str}; pub use self::error::{Error, ErrorCode, Result}; pub use self::ser::{Serializer, escape_str, to_string, to_string_pretty, to_vec, to_vec_pretty, to_writer, to_writer_pretty}; pub use self::value::{Map, Value, from_value, to_value}; pub mod builder; pub mod de; pub mod error; pub mod ser; pub mod value; mod read;