Enum justjson::Value

source ·

pub enum Value<'a> {
    Number(JsonNumber<'a>),
    String(JsonString<'a>),
    Boolean(bool),
    Object(Object<'a>),
    Array(Vec<Value<'a>>),
    Null,
}

Available on crate feature alloc only.

Expand description

A JSON value.

The Backing generic is the storage mechanism used by JsonNumber and JsonString. This is generally &str or Cow<str>.

Variants§

§

Number(JsonNumber<'a>)

A JSON number.

§

String(JsonString<'a>)

A JSON string.

§

Boolean(bool)

A boolean value.

§

Object(Object<'a>)

A JSON object (key/value pairs).

§

Array(Vec<Value<'a>>)

A JSON array (list of values).

§

Null

A null value.

Implementations§

source §

impl<'a> Value<'a>

source

pub fn from_json(json: &'a str) -> Result<Self, Error>

Parses a JSON value from json, returning a Value<&str> that borrows data from json.

Because the str type guarantees that json is valid UTF-8, no additional unicode checks are performed on unescaped unicode sequences.

Examples found in repository ?

examples/borrowed-value.rs (line 4)

fn main() {
    let value = Value::from_json(r#"{"hello":"world"}"#).expect("error parsing json");
    let obj = value.as_object().expect("json contains an object");
    assert_eq!(obj[0].key, "hello");
    let value = obj[0].value.as_string().expect("value is a string");
    assert_eq!(value, "world");
}

source

pub fn from_json_with_config( json: &'a str, config: ParseConfig ) -> Result<Self, Error>

Parses a JSON value from json using the settings fromconfig, returning a Value<&str> that borrows data from json.

Because the str type guarantees that json is valid UTF-8, no additional unicode checks are performed on unescaped unicode sequences.

source

pub fn from_json_bytes(json: &'a [u8]) -> Result<Self, Error>

Parses a JSON value from json, returning a Value<&str> that borrows data from json.

This function verifies that json is valid UTF-8 while parsing the JSON.

source

pub fn from_json_bytes_with_config( json: &'a [u8], config: ParseConfig ) -> Result<Self, Error>

Parses a JSON value from json using the settings fromconfig, returning a Value<&str> that borrows data from json.

This function verifies that json is valid UTF-8 while parsing the JSON.

source

pub const fn as_object(&self) -> Option<&Object<'a>>

Returns the Object inside of this value, if this is a Value::Object.

Examples found in repository ?

examples/borrowed-value.rs (line 5)

fn main() {
    let value = Value::from_json(r#"{"hello":"world"}"#).expect("error parsing json");
    let obj = value.as_object().expect("json contains an object");
    assert_eq!(obj[0].key, "hello");
    let value = obj[0].value.as_string().expect("value is a string");
    assert_eq!(value, "world");
}

source

pub fn as_object_mut(&mut self) -> Option<&mut Object<'a>>

Returns a mutable reference to the Object inside of this value, if this is a Value::Object.

source

pub fn get(&self, key: &str) -> Option<&Value<'a>>

Returns the contained value associated with key, if this is a Value::Object. Returns None if the value is not an object or if the key is not found.

Performance

Object uses a Vec of Entry types to store its entries. If the operation being performed can be done with a single iteration over the value’s contents instead of multiple random accesses, the iteration should be preferred. Additional options to make random access faster in environments that can support it are being considered for future releases.

source

pub fn get_mut(&mut self, key: &str) -> Option<&mut Value<'a>>

Returns a mutable reference to the contained value associated with key, if this is a Value::Object. Returns None if the value is not an object or if the key is not found.

Performance

Object uses a Vec of Entry types to store its entries. If the operation being performed can be done with a single iteration over the value’s contents instead of multiple random accesses, the iteration should be preferred. Additional options to make random access faster in environments that can support it are being considered for future releases.

source

pub const fn as_string(&self) -> Option<&JsonString<'a>>

Returns the JsonString inside of this value, if this is a Value::String.

Examples found in repository ?

examples/borrowed-value.rs (line 7)

fn main() {
    let value = Value::from_json(r#"{"hello":"world"}"#).expect("error parsing json");
    let obj = value.as_object().expect("json contains an object");
    assert_eq!(obj[0].key, "hello");
    let value = obj[0].value.as_string().expect("value is a string");
    assert_eq!(value, "world");
}

source

pub fn as_str(&self) -> Option<&str>

Returns a reference to the contents of this value if it is a Value::String, and it does not have any escape sequences that need to be decoded.

source

pub const fn as_number(&self) -> Option<&JsonNumber<'a>>

Returns the JsonNumber inside of this value, if this is a Value::Number.

source

pub fn as_f32(&self) -> Option<f32>

Parses the contained value as an f32, if it is a number.

The JSON parser only validates that the number takes a correct form. If a number cannot be parsed by the underlying routine due to having too many digits, it this function can return None.

source

pub fn as_f64(&self) -> Option<f64>

Parses the contained value as an f64, if it is a number.

The JSON parser only validates that the number takes a correct form. If a number cannot be parsed by the underlying routine due to having too many digits, it this function can return None.

source

pub const fn as_bool(&self) -> Option<bool>

Returns the bool inside of this value, if this is a Value::Boolean.

source

pub fn as_array(&self) -> Option<&[Self]>

Returns the slice of values inside of this value, if this is a Value::Array.

source

pub fn as_array_mut(&mut self) -> Option<&mut Vec<Self>>

Returns a mutable reference to the Vec of values inside of this value, if this is a Value::Array.

source

pub fn get_index(&self, index: usize) -> Option<&Value<'a>>

Returns the contained value at index, if this is a Value::Array. Returns None if the value is not an array or if index is beyond the bounds of the array.

source

pub fn get_index_mut(&mut self, index: usize) -> Option<&mut Value<'a>>

Returns a mutable reference to the contained value at index, if this is a Value::Array. Returns None if the value is not an array or if index is beyond the bounds of the array.

source

pub const fn is_null(&self) -> bool

Returns true if this value is null/Value::Null.

source

pub fn to_json_pretty(&self) -> String

Converts this value to its JSON representation, with extra whitespace to make it easier for a human to read.

This uses two spaces for indentation, and \n for end of lines. Use to_json_pretty_custom() to customize the formatting behavior.

Panics

This function will panic if there is not enough memory to format the JSON.

source

pub fn to_json_pretty_custom( &self, indentation: &str, line_ending: &str ) -> String

Converts this value to its JSON representation, with extra whitespace to make it easier for a human to read.

Panics

This function will panic if there is not enough memory to format the JSON.

source

pub fn to_json(&self) -> String

Converts this value to its JSON representation, with no extraneous whitespace.

Panics

This function will panic if there is not enough memory to format the JSON.

source

pub fn write_json_to<W: Write>(&self, destination: W) -> Result

Writes this value’s JSON representation to destination, with no extraneous whitespace.

source

pub fn pretty_write_json_to<W: Write>(&self, destination: W) -> Result

Writes this value’s JSON representation to destination, with extra whitespace to make it easier for a human to read.

This uses two spaces for indentation, and \n for end of lines. Use to_json_pretty_custom() to customize the formatting behavior.

source

pub fn pretty_write_json_to_custom<W: Write>( &self, indentation: &str, line_ending: &str, destination: W ) -> Result

Writes this value’s JSON representation to destination, with extra whitespace to make it easier for a human to read.

source §