Enum DataReader 

pub enum DataReader<'b> {
    Slice(BufReader<&'b [u8]>),
    Vec(BufReader<Vec<u8>>),
    File(LazyCache<File>),
}

A generic reader for data backed by different sources.

Provides a uniform interface for reading from in-memory buffers or files.

Variants

Slice(BufReader<&'b [u8]>)

A reader backed by a borrowed byte slice.

Useful for zero-copy reads from existing in-memory data.

Vec(BufReader<Vec<u8>>)

A reader backed by an owned byte vector.

Useful when the data needs to be owned.

File(LazyCache<File>)

A reader backed by a file with lazy caching.

Uses LazyCache for efficient disk I/O.

Implementations

impl DataReader<'_>

pub fn from_file(r: File) -> Result<Self, Error>

Creates a new DataReader backed by a file with lazy caching.

The file is wrapped in a LazyCache with:

• A hot cache of 14 MiB (2 × FILE_BYTES_MAX)
• A warm cache of 100 MiB

This configuration is optimized for file-based magic number detection, balancing memory usage with I/O efficiency.

Errors

Returns an error if the file cannot be read or if cache initialization fails.

impl<'b> DataReader<'b>

pub fn from_slice(s: &'b [u8]) -> Self

Creates a new DataReader backed by a borrowed byte slice.

This is a zero-copy constructor that wraps the slice in a BufReader. The lifetime of the returned reader is tied to the input slice.

Examples

use pure_magic::readers::{DataReader, DataRead};

let data = b"hello world";
let reader = DataReader::from_slice(data);
assert_eq!(reader.data_size(), data.len() as u64);

impl DataReader<'_>

pub fn from_vec(v: Vec<u8>) -> Self

Creates a new DataReader backed by an owned byte vector.

The vector is wrapped in a BufReader, allowing the data to be owned independently of any borrow.

Examples

use pure_magic::readers::{DataReader, DataRead};

let data = vec![1u8, 2, 3, 4, 5];
let reader = DataReader::from_vec(data);
assert_eq!(reader.data_size(), 5);

Trait Implementations

impl DataRead for DataReader<'_>

fn stream_position(&self) -> u64

Returns the current position in the data stream.

fn offset_from_start(&self, pos: SeekFrom) -> u64

Computes the absolute byte offset from a SeekFrom position.

fn read_range(&mut self, range: Range<u64>) -> Result<&[u8], Error>

Reads a range of bytes from the data.

fn read_count(&mut self, count: u64) -> Result<&[u8], Error>

Reads up to count bytes from the current position.

fn read_exact_range(&mut self, range: Range<u64>) -> Result<&[u8], Error>

Reads exactly the specified byte range.

fn read_exact_count(&mut self, count: u64) -> Result<&[u8], Error>

Reads exactly count bytes from the current position.

fn read_exact_into(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads exactly enough bytes to fill buf.

fn read_until_any_delim_or_limit( &mut self, delims: &[u8], limit: u64, ) -> Result<&[u8], Error>

Reads bytes until any of the delimiters or limit bytes is reached.

fn read_until_or_limit(&mut self, byte: u8, limit: u64) -> Result<&[u8], Error>

Reads bytes until byte or limit bytes is reached.

fn read_while_or_limit<F>(&mut self, f: F, limit: u64) -> Result<&[u8], Error>

where F: Fn(u8) -> bool,

Reads bytes while f returns true or until limit bytes is reached.

fn read_until_utf16_or_limit( &mut self, utf16_char: &[u8; 2], limit: u64, ) -> Result<&[u8], Error>

Reads bytes until a UTF-16 character or limit bytes is reached.

fn data_size(&self) -> u64

Returns the total size of the data in bytes.

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Sets the position for future reads.