Macro json_object

macro_rules! json_object {
    () => { ... };
    ($key:ident : null, $($rest:tt)*) => { ... };
    ($key:ident : true, $($rest:tt)*) => { ... };
    ($key:ident : false, $($rest:tt)*) => { ... };
    ($key:ident : $value:expr, $($rest:tt)*) => { ... };
    ([$key:expr] : $value:expr, $($rest:tt)*) => { ... };
    ($key:ident, $($rest:tt)*) => { ... };
    ($key:ident : $value:ident) => { ... };
    ($key:ident : $value:expr) => { ... };
    ([$key:expr] : $value:expr) => { ... };
    ($key:ident) => { ... };
}

Creates a static json object that can be serialized very fast. Returns a struct implementing JSONValue.

The macro takes a comma-separated list of key-value pairs. Keys can be written literally, or surrounded by brackets ([key]) to reference external variables. A value can be omitted, in which case the the key name must be the name of a variable currently in scope, from which the value will be taken.

Values must be expressions of a type implementing JSONValue.

Examples

Create a simple json object.

use json_in_type::*;

let my_obj = json_object!{
    hello: "world"
};

assert_eq!(r#"{"hello":"world"}"#, my_obj.to_json_string());

Shorthand property names

It is common to create a json object from a set of variables, using the variable names as keys and the contents of the variables as values.

use json_in_type::*;

let x = "hello";
let y = 42;
let z = true;
let my_obj = json_object!{ x, y, z };

assert_eq!(r#"{"x":"hello","y":42,"z":true}"#, my_obj.to_json_string());

Reference external variables

use json_in_type::*;

let x = "hello";
let my_obj = json_object!{
    [x]: "world", // The trailing comma is ok
};

assert_eq!(r#"{"hello":"world"}"#, my_obj.to_json_string());

Compute keys dynamically

use json_in_type::*;

let x = "hello";
let my_obj = json_object!{
    [x]: "world",
    [[x, "_suffix"].concat()]: 42
};

assert_eq!(r#"{"hello":"world","hello_suffix":42}"#, my_obj.to_json_string());