Crate microjson

Small JSON Parser in no_std

This library reads and parses JSON strings.

Its intended use case is to read a JSON payload once.

It does not serialise data.

Sample usage

Simply put this in your Cargo.toml:

[dependencies]
microjson = "0.1"

You can read strings and integers easily:

let integer = JSONValue::load("42");

let value : isize = integer.read_integer()?;

let string = JSONValue::load("\"hello there\"");

let value : &str = string.read_string()?;

You can read arrays like this:

let input = r#" [0, 1, 2, 3, 4, 5] "#;

let array = JSONValue::load(input);

for (n, item) in array.iter_array()?.enumerate() {
    let value = item.read_integer()?;
    assert_eq!(value, n as isize);
}

And, of course, any combination of the above:

let input = r#" { "arr": [3, "foo", 3.625, false] } "#;

let object = JSONValue::load(input);

assert_eq!(
    object.get_key_value("arr")?.iter_array()?.nth(2).unwrap().read_float()?,
    3.625
);

If you are unsure what kind of data you have, you can query the JSONValueType.

let input = r#" 3.1415 "#;

let object = JSONValue::load(input);

match object.value_type {
    JSONValueType::String => {},
    JSONValueType::Number => {},
    JSONValueType::Object => {},
    JSONValueType::Array => {},
    JSONValueType::Bool => {},
    JSONValueType::Null => {},
    JSONValueType::Error => {},
}

Verifying Data

To load some JSON, you need only call

let value = JSONValue::load(r#" [1,2,3,5"foo"] "#);

However, this data is malformed. [JSONValue::parse] will return an Ok result, as to determine that the data was corrupt would require scanning through the entire string. The error would only be reported when you attempted to iterate to the fourth item and parse it as a value.

If you need to know that the data is sound, use JSONValue::verify. Alternatively, you can parse and verify in one step.

let value = JSONValue::load_and_verify(r#" [1,2,3,5"foo"] "#);

Feature Flags

These flags can be enabled using features.

Flag	Description
small_number_parsing	Replaces the core float parsing with a less accurate version that has a smaller code footprint.
std	Includes a marker to implement std::error::Error for JSONParsingError and use the standard library.

Structs

EscapedStringIterator

Iterator over a JSON-escaped string

JSONArrayIterator

An iterator through a JSON array value

JSONObjectIterator

An iterator through a JSON object

JSONValue

Enums

JSONParsingError

Errors while parsing JSON

JSONValueType

Denotes the different types of values JSON objects can have