Struct FastaStreamHasher 

pub struct FastaStreamHasher { /* private fields */ }

A streaming FASTA hasher that processes data chunk-by-chunk.

This is designed for WASM environments where files are fetched in chunks. Memory usage is constant (~100KB) regardless of file size:

• Internal state: ~200 bytes (hasher state, counters)
• Line buffer: ~8KB (handles long lines)
• Gzip decoder state: ~32KB if compressed
• Results: grows only with number of sequences (not sequence length)

Example

use gtars_refget::digest::stream::FastaStreamHasher;

let mut hasher = FastaStreamHasher::new();

// Process first chunk
hasher.update(b">chr1\nACGT").expect("update");

// Process second chunk
hasher.update(b"TGCA\n>chr2\nGGGG\n").expect("update");

// Finalize and get results
let collection = hasher.finish().expect("finish");
assert_eq!(collection.sequences.len(), 2);

Implementations

impl FastaStreamHasher

pub fn new() -> Self

Create a new streaming FASTA hasher.

pub fn update(&mut self, chunk: &[u8]) -> Result<()>

Process a chunk of FASTA data.

This method can be called multiple times with successive chunks of data. Handles both plain text and gzip-compressed FASTA with true streaming decompression (constant memory usage).

Arguments

• chunk - A slice of bytes from the FASTA file

Returns

Ok(()) on success, Err on parsing error

pub fn finish(self) -> Result<SequenceCollection>

Finalize processing and return the SequenceCollection.

This must be called after all chunks have been processed via update().

pub fn sequence_count(&self) -> usize

Get the current number of completed sequences.

pub fn in_sequence(&self) -> bool

Check if currently processing a sequence.

pub fn current_sequence_name(&self) -> Option<&str>

Get the name of the sequence currently being processed (if any).

pub fn current_sequence_length(&self) -> usize

Get the current length of the sequence being processed.

Trait Implementations

impl Default for FastaStreamHasher

fn default() -> Self

Returns the “default value” for a type.