Trait JsonRef 

pub trait JsonRef<'a>: Sized + Copy {
    type Item: JsonRef<'a>;

    // Required methods
    fn is_array(self) -> bool;
    fn is_object(self) -> bool;
    fn as_null(self) -> Option<()>;
    fn as_bool(self) -> Option<bool>;
    fn as_number_str(self) -> Option<&'a str>;
    fn as_str(self) -> Option<&'a str>;
    fn get(self, key: &str) -> Option<Self::Item>;
    fn index_at(self, i: usize) -> Option<Self::Item>;
    fn len(self) -> Option<usize>;

    // Provided methods
    fn is_null(self) -> bool { ... }
    fn is_bool(self) -> bool { ... }
    fn is_number(self) -> bool { ... }
    fn is_string(self) -> bool { ... }
    fn as_i64(self) -> Option<i64> { ... }
    fn as_u64(self) -> Option<u64> { ... }
    fn as_f64(self) -> Option<f64> { ... }
}

Read-only, tree-like access to a parsed JSON value.

Modelled on serde_json::Value’s accessor methods. The lifetime 'a is the string-access lifetime: returned &'a str slices are valid for at least 'a.

Implemented by:

• TapeRef<'a, _> — lightweight cursor into a flat crate::tape::Tape.
• Option<J> where J: JsonRef<'a> — transparent wrapper enabling chaining without intermediate ? or .and_then: root.get("a").get("b").as_str().

Required Associated Types

type Item: JsonRef<'a>

The concrete node type returned by get and index_at.

For concrete node types (TapeRef) this is Self. For Option<J> it is J::Item, keeping chains flat: opt.get("a") returns Option<J::Item>, not Option<Option<J>>.

Required Methods

fn is_array(self) -> bool

Returns true if this value is a JSON array.

fn is_object(self) -> bool

Returns true if this value is a JSON object.

fn as_null(self) -> Option<()>

Returns Some(()) if this value is null, otherwise None.

fn as_bool(self) -> Option<bool>

Returns the boolean if this value is a boolean, otherwise None.

fn as_number_str(self) -> Option<&'a str>

Returns the raw number token if this value is a number, otherwise None.

The slice always contains valid JSON number syntax.

fn as_str(self) -> Option<&'a str>

Returns the string content if this value is a JSON string, otherwise None.

fn get(self, key: &str) -> Option<Self::Item>

Look up an object member by key.

Returns None if this value is not an object or the key is absent.

fn index_at(self, i: usize) -> Option<Self::Item>

Index into an array by zero-based position.

Returns None if this value is not an array or i is out of bounds.

fn len(self) -> Option<usize>

Returns the number of elements (array) or key-value pairs (object).

Returns None if this value is neither an array nor an object.

Provided Methods

fn is_null(self) -> bool

Returns true if this value is JSON null.

fn is_bool(self) -> bool

Returns true if this value is a JSON boolean.

fn is_number(self) -> bool

Returns true if this value is a JSON number.

fn is_string(self) -> bool

Returns true if this value is a JSON string.

fn as_i64(self) -> Option<i64>

Parse the number as i64.

Returns None for non-numbers or when the value is out of range.

fn as_u64(self) -> Option<u64>

Parse the number as u64.

Returns None for non-numbers or when the value is out of range.

fn as_f64(self) -> Option<f64>

Parse the number as f64.

Returns None for non-numbers.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<'a, J: JsonRef<'a>> JsonRef<'a> for Option<J>

Blanket implementation of JsonRef for Option<J> where J: JsonRef.

Every accessor returns the same result as calling it on the inner value, or the appropriate “absent” answer when self is None:

• Boolean tests (is_*) return false.
• as_* accessors return None.
• get, index_at, len return None.

This allows chaining without intermediate ? or .and_then:

let city = root.get("address").get("city").as_str();
let first = root.get("items").index_at(0).as_i64();

type Item = <J as JsonRef<'a>>::Item

Chaining stays flat: Option<J> produces the same item type as J.

fn is_array(self) -> bool

fn is_object(self) -> bool

fn as_null(self) -> Option<()>

fn as_bool(self) -> Option<bool>

fn as_number_str(self) -> Option<&'a str>

fn as_str(self) -> Option<&'a str>

fn get(self, key: &str) -> Option<J::Item>

fn index_at(self, i: usize) -> Option<J::Item>

fn len(self) -> Option<usize>

Implementors

impl<'t, 'src: 't> JsonRef<'t> for TapeRef<'t, 'src>

type Item = TapeRef<'t, 'src>