Struct CompressionParametersBuilder 

pub struct CompressionParametersBuilder { /* private fields */ }

Builder for CompressionParameters. Each setter records one knob; Self::build validates them against CParameter::bounds.

Implementations

impl CompressionParametersBuilder

pub fn row_match_finder(self, mode: RowMatchFinderMode) -> Self

Choose the finder the greedy, lazy and lazy2 strategies search instead of leaving it to the window size. C ZSTD_c_useRowMatchFinder.

use structured_zstd::encoding::{
    compress_with_parameters, CompressionLevel, CompressionParameters,
    RowMatchFinderMode,
};
use structured_zstd::decoding::FrameDecoder;

let data = b"a row or a chain, the frame decodes the same ".repeat(2000);
let chain = CompressionParameters::builder(CompressionLevel::Level(7))
    .row_match_finder(RowMatchFinderMode::Disable)
    .build()
    .unwrap();
let frame = compress_with_parameters(&data[..], &chain);
let mut decoded = Vec::with_capacity(data.len());
FrameDecoder::new()
    .decode_all_to_vec(&frame, &mut decoded)
    .unwrap();
assert_eq!(decoded, data);

pub fn literal_compression(self, mode: LiteralCompressionMode) -> Self

Decide whether literals are entropy-coded, overriding the level’s own choice. C ZSTD_c_literalCompressionMode.

use structured_zstd::encoding::{
    compress_with_parameters, CompressionLevel, CompressionParameters,
    LiteralCompressionMode,
};

// Literal-heavy input: 32 distinct symbols and nothing for the match
// finder to repeat, so only entropy-coding the literals shrinks it.
let text: Vec<u8> = (0..8192u32)
    .map(|i| b'a' + (i.wrapping_mul(2_654_435_761) >> 27) as u8)
    .collect();
// Level -3 stores literals raw by default; asking for compression
// makes the frame smaller on input like this.
let compressed_literals = CompressionParameters::builder(CompressionLevel::Level(-3))
    .literal_compression(LiteralCompressionMode::Enable)
    .build()
    .unwrap();
let plain = compress_with_parameters(
    &text[..],
    &CompressionParameters::builder(CompressionLevel::Level(-3)).build().unwrap(),
);
let coded = compress_with_parameters(&text[..], &compressed_literals);
assert!(coded.len() < plain.len());

pub fn window_log(self, value: u32) -> Self

Override the maximum back-reference distance (log2). C ZSTD_c_windowLog.

pub fn hash_log(self, value: u32) -> Self

Override the match-finder hash table size (log2). C ZSTD_c_hashLog.

pub fn chain_log(self, value: u32) -> Self

Override the match-finder chain table size (log2). C ZSTD_c_chainLog.

pub fn search_log(self, value: u32) -> Self

Override the search-attempts count (log2). C ZSTD_c_searchLog.

pub fn min_match(self, value: u32) -> Self

Override the minimum match length in bytes. C ZSTD_c_minMatch.

pub fn target_length(self, value: u32) -> Self

Override the “good enough” target match length. C ZSTD_c_targetLength.

pub fn strategy(self, value: Strategy) -> Self

Override the match-finder Strategy. C ZSTD_c_strategy.

pub fn enable_long_distance_matching(self, enable: bool) -> Self

Enable or disable long-distance matching. C ZSTD_c_enableLongDistanceMatching. Off at every level preset. This is the explicit activation toggle; the ldm_* knob setters also enable LDM implicitly. The flag is plain last-write-wins, so a trailing enable_long_distance_matching(false) disables LDM even if an earlier ldm_* call set a knob (the knob is then ignored at build).

pub fn ldm_hash_log(self, value: u32) -> Self

Override the LDM hash table size (log2). C ZSTD_c_ldmHashLog. Implies Self::enable_long_distance_matching(true).

pub fn ldm_min_match(self, value: u32) -> Self

Override the LDM minimum match length. C ZSTD_c_ldmMinMatch. Implies Self::enable_long_distance_matching(true).

pub fn ldm_bucket_size_log(self, value: u32) -> Self

Override the LDM bucket size (log2). C ZSTD_c_ldmBucketSizeLog. Implies Self::enable_long_distance_matching(true).

pub fn ldm_hash_rate_log(self, value: u32) -> Self

Override the LDM hash-insertion rate (log2). C ZSTD_c_ldmHashRateLog. Implies Self::enable_long_distance_matching(true).

pub fn build(self) -> Result<CompressionParameters, ParameterError>

Validate every set knob against CParameter::bounds and produce the resolved CompressionParameters.

Errors

Returns ParameterError::OutOfBounds for the first knob whose value falls outside its inclusive range.

Trait Implementations

impl Clone for CompressionParametersBuilder

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for CompressionParametersBuilder

impl Debug for CompressionParametersBuilder

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

Formats the value using the given formatter.