Struct Flattrs 

pub struct Flattrs { /* private fields */ }

Flat attribute storage for message headers.

Uses a single contiguous buffer with inline entry lengths. Each entry is [key_hash: u64][len: u32][value: bytes]. Linear scan is used for lookup, which is optimal for small N.

Implementations

impl Flattrs

pub fn new() -> Self

Create a new empty Flattrs.

pub fn from_part(part: Part) -> Self

Create from a Part.

pub fn to_part(&self) -> Part

Convert to wire format for transmission.

Returns a Part for zero-copy serialization through the multipart codec.

pub fn set<T: Serialize>(&mut self, key: Key<T>, value: T)

Serialize a value and store it.

If the key already exists:

• Same size value: overwrite in place (no shifting)
• Different size: remove old entry and append new one

pub fn set_serialized(&mut self, key_hash: u64, serialized: &[u8])

Set an entry by its (key_hash, serialized_value) pair, replacing any existing entry under the same key_hash. Collision semantics match [set]: in-place overwrite when the new value is the same size, otherwise compact-and-append. A later write under the same key hash is the value returned by [get].

This is the lower-level companion to the typed [set] API, intended for callers that already have a key hash and pre-serialized bytes in hand — for example, copying entries across Flattrs buffers without re-deserializing, or stamping typed Attrs entries through a crate boundary where the concrete Key<T> is out of scope. Most callers should prefer [set].

pub fn get<T: AttrValue + DeserializeOwned>(&self, key: Key<T>) -> Option<T>

Get a value, deserializing from the buffer.

Uses linear search which is optimal for the typical small number of headers (2-5 entries).

pub fn contains_key<T>(&self, key: Key<T>) -> bool

Check if a key exists.

pub fn is_empty(&self) -> bool

Returns true if empty.

pub fn len(&self) -> usize

Returns the number of entries.

pub fn from_attrs(attrs: &Attrs) -> Self

Convert from an existing Attrs by serializing all values.

pub fn iter(&self) -> FlattrsIter<'_>

Iterate over all entries as (key_hash, value_bytes) pairs.

The byte slice is borrowed from the buffer — the caller must not hold the returned slice across a mutation of this Flattrs. Intended for generic copy paths that need to transfer entries without knowing their typed schema (e.g. filter-and-copy helpers keyed by meta marker). Callers that need typed access should use the typed [get] API.

Trait Implementations

impl Clone for Flattrs

fn clone(&self) -> Flattrs

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Flattrs

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

Formats the value using the given formatter.

impl Default for Flattrs

fn default() -> Flattrs

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Flattrs

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Flattrs

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

Formats the value using the given formatter.

impl From<&Attrs> for Flattrs

fn from(attrs: &Attrs) -> Self

Converts to this type from the input type.

impl From<Attrs> for Flattrs

fn from(attrs: Attrs) -> Self

Converts to this type from the input type.

impl Serialize for Flattrs

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.