Struct EncoderDictionary 

pub struct EncoderDictionary { /* private fields */ }

A dictionary prepared for the ENCODER side, analogous to zstd’s CDict (vs the decoder’s Dictionary / DDict).

It carries the entropy tables, content, and repeat-offset history the compressor needs, but is a distinct type with no decode path: there is no way to turn it into a DictionaryHandle or feed it to a FrameDecoder. That keeps the compress-only state (which may have been parsed without building the decode lookup tables, see set_dictionary_from_bytes) from ever reaching the decode side — the encoder/decoder dictionary split mirrors C zstd’s CDict / DDict. Cloning one is a handle, not a copy: it is attached to a compressor by value, so a dictionary serving many frames would otherwise have its parsed tables and content duplicated for each of them — on exactly the path where one dictionary is prepared once precisely to be used again and again.

Implementations

impl EncoderDictionary

pub fn from_dictionary(dictionary: Dictionary) -> Self

Wrap an already-parsed Dictionary for encoder use. A fully-decoded dictionary is valid here; only the encoder entropy tables, content, and offset history are read. The CDict cParams tier is keyed by the content length here; prefer Self::from_bytes when the serialized blob is at hand — it keys the tier by the exact serialized size as upstream ZSTD_createCDict does.

pub fn from_bytes(raw_dictionary: &[u8]) -> Result<Self, DictionaryDecodeError>

Parse a serialized dictionary blob for encoder use, skipping the decode lookup-table build the encoder never reads (see Dictionary::decode_dict_for_encoding). The encoder entropy tables — and thus the emitted frame — are identical to a full parse.

pub fn from_serialized_or_raw_content( raw_dictionary: &[u8], ) -> Result<Self, DictionaryDecodeError>

Load whichever kind of dictionary raw_dictionary holds, the way zstd -D does: a serialized blob is parsed, anything else is taken as raw content (see Dictionary::from_serialized_or_raw_content).

Either way the blob’s own length is what the compression-parameter tier is chosen by, which is why this exists rather than parsing and calling Self::from_dictionary: that keys the tier on the content length, and for a serialized dictionary the entropy tables in between can put the two on opposite sides of a boundary.

pub fn id(&self) -> u32

The dictionary id.

Zero is a raw-content dictionary, which has no header to carry an id. Such a dictionary attaches like any other; what changes is the frame, which omits the Dictionary_ID field rather than storing a zero, so a decoder has to be handed the same bytes explicitly.

Trait Implementations

impl Clone for EncoderDictionary

fn clone(&self) -> EncoderDictionary

Returns a duplicate of the value.

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

Performs copy-assignment from source.