Standard library

std/json

JSON: parse text into a json.Value tree and encode it back.

let v = try json.parse(`{"name": "gojo", "tags": ["fast", "safe"]}`)
if let name = v.get("name") {
    println(name.str() ?? "not a string")
}
var out = json.object()
out.set("ok", json.boolean(true))
println(out.encode())          // {"ok":true}

Objects keep their keys in insertion order. Integers that fit in int stay exact (Int); other numbers are Num (f64).

Constants: maxDepth

Types: enum Value, struct Error

Functions: null, boolean, integer, number, string, array, object, quoted, parse

Constants

maxDepth

pub const maxDepth = 500

Deeper nesting is refused: parsing is recursive, and goroutine stacks are small.

Types

enum Value

pub enum Value {
    Null
    Bool(b: bool)
    Int(i: int)
    Num(f: f64)
    Str(s: String)
    Arr(items: Vec[Value])
    Obj(fields: Map[String, Value])
}

A JSON value. Build one with the functions below (json.object(), json.string(s)...) or with the variants, and read one with the methods.

Value.isNull

pub fn isNull(self) -> bool

Whether this is null.

Value.isObject

pub fn isObject(self) -> bool

Whether this is an object.

Value.isArray

pub fn isArray(self) -> bool

Whether this is an array.

Value.boolean

pub fn boolean(self) -> ?bool

The value of true or false.

Value.int

pub fn int(self) -> ?int

An integer (also a float with no fractional part that fits).

Value.num

pub fn num(self) -> ?f64

A number, integer or not.

Value.str

pub fn str(self) -> ?str

The text of a string.

Value.get

pub fn get(self, key: str) yield ?&Value

The value at key of an object.

Value.at

pub fn at(self, i: int) yield ?&Value

Element i of an array.

Value.len

pub fn len(self) -> int

Elements of an array, members of an object, or 0.

Value.keys

pub fn keys(self) -> Vec[String]

The keys of an object, in order.

Value.set

pub fn set(inout self, key: str, v: sink Value)

Sets a member of an object (does nothing to other values).

Value.push

pub fn push(inout self, v: sink Value)

Appends to an array (does nothing to other values).

Value.encode

pub fn encode(self) -> String

Compact JSON text.

Value.pretty

pub fn pretty(self) -> String

JSON text indented by two spaces.

struct Error

pub struct Error {
    pub msg: String
    // where, from 1
    pub line: int
    pub column: int
}

Why parse failed, and where.

Error.message

pub fn message(self) -> String

The message, with the line and column.

Functions

null, boolean, integer, number, string, array, object

pub fn null() -> Value
pub fn boolean(b: bool) -> Value
pub fn integer(i: int) -> Value
pub fn number(f: f64) -> Value
pub fn string(s: str) -> Value
pub fn array() -> Value
pub fn object() -> Value

Values to build documents with; array() and object() are empty (add to them with push and set).

quoted

pub fn quoted(s: str) -> String

Quotes a string as JSON.

parse

pub fn parse(text: str) -> Value ! Error

Parses one JSON value (with nothing but white space after it).