Struct UnknownFieldsView 

pub struct UnknownFieldsView<'a> { /* private fields */ }

A borrowed view of unknown fields.

Stores unknown fields as wire records rather than decoded values, enabling zero-copy round-tripping for borrowable input spans. Borrowed spans may hold one or more consecutive complete (tag, value) records: adjacent unknown fields are coalesced into a single span, so a long run of unknown fields costs one Vec slot rather than one per field. Synthetic records cover cases where the view decoder must preserve a value that has no borrowable source span. Coalescing bounds the view’s memory only — the decode-time unknown-field allowance is still charged per field (see push_record).

Implementations

impl<'a> UnknownFieldsView<'a>

pub fn new() -> Self

Creates an empty view.

pub fn is_empty(&self) -> bool

Returns true if no unknown fields were recorded.

pub fn encoded_len(&self) -> usize

Total byte length of all unknown field data.

pub fn write_to(&self, buf: &mut impl EncodeSink)

Write all unknown-field bytes in decode order. Each record holds one or more complete (tag, value) records, so concatenating them produces a valid encoding.

pub fn to_owned(&self) -> Result<UnknownFields, DecodeError>

Convert to an owned UnknownFields by parsing all stored wire records.

Each record holds one or more consecutive (tag + value) records as they should be re-emitted. Parsing uses crate::encoding::decode_unknown_field under exactly the budget push_record and push_varint charged at decode time — the same field count and group-nesting depth — so replay cannot exhaust either. Views holding manually pushed spans (via push_raw) additionally get DEFAULT_UNKNOWN_FIELD_LIMIT slots and the full RECURSION_LIMIT, since those spans were never charged. A coalesced borrowed span re-materializes one owned UnknownField per wire record, so this conversion is where a long run of unknown fields actually allocates.

Errors

Returns Err if a stored record is malformed or exceeds the replay budget. Neither can occur when the view was produced by wire decoding — every borrowed record was parsed off the wire, and the budget equals what decoding charged — so any such view converts successfully. Only views holding push_raw spans can fail here.

Trait Implementations

impl<'a> Clone for UnknownFieldsView<'a>

fn clone(&self) -> UnknownFieldsView<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UnknownFieldsView<'_>

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

Formats the value using the given formatter.

impl<'a> Default for UnknownFieldsView<'a>

fn default() -> UnknownFieldsView<'a>

Returns the “default value” for a type.