Struct PortableExtensions 

pub struct PortableExtensions(/* private fields */);

The forward-compatibility bag: top-level keys this build does not interpret.

A newtype over a JSON value map, rather than a bare Map, so the write path goes through PortableExtensions::insert and a key that would collide with a document field is refused by name instead of producing a document that cannot be read back. A JSON map (not toml::Table) because TOML has no null: a newer build writing "future": null must survive a round trip through this one, and a TOML value cannot hold a null at all.

The map is sorted (the preserve_order feature is off), so key order is normalised — the values are what the round trip preserves.

Implementations

impl PortableExtensions

pub fn new() -> Self

An empty bag.

pub fn is_empty(&self) -> bool

Whether no unknown metadata is present.

pub fn len(&self) -> usize

The number of preserved keys.

pub fn contains_key(&self, key: &str) -> bool

Whether a preserved key is present.

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

Look up a preserved key.

pub fn insert(&mut self, key: impl Into<String>, value: Value) -> Result<()>

Preserve one (key, value) pair.

Refuses a key that names a document field rather than letting it shadow the real one: this guard is what keeps “a document this build writes is one it can read back” true.

Trait Implementations

impl Clone for PortableExtensions

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PortableExtensions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PortableExtensions

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for PortableExtensions

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for PortableExtensions

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for PortableExtensions

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for PortableExtensions