Struct IntVecReader

pub struct IntVecReader<'a, E: Endianness>
where
    for<'b> BufBitReader<E, MemWordReader<u64, &'b Vec<u64>>, DefaultReadParams>: BitRead<E, Error = Infallible> + CodesRead<E> + BitSeek<Error = Infallible>,
{ /* private fields */ }

A stateful reader for an IntVec that provides fast random access.

This reader is created by the IntVec::reader method. It maintains an internal, reusable bitstream reader, which makes it highly efficient for performing multiple random lookups, especially when the access pattern is not known in advance (e.g., indices are generated on-the-fly in a loop).

By reusing the same underlying reader, it amortizes the setup cost across many get operations.

When to use IntVecReader

• When you need to perform multiple lookups and the indices are determined dynamically.
• When the next lookup index might depend on the result of the previous one.

For batch lookups where all indices are known beforehand, using IntVec::get_many is still preferable as it can perform global optimizations like sorting the indices. There is a parallel version of this method, IntVec::par_get_many.

Example

use compressed_intvec::prelude::*;

let data: &[u64] = &[10, 20, 30, 40, 50];
let intvec = LEIntVec::builder(data).build().unwrap();

// Create a reusable reader from the IntVec.
let mut reader = intvec.reader();

// Perform multiple lookups. The reader efficiently handles seeks.
assert_eq!(reader.get(3).unwrap(), Some(40));
assert_eq!(reader.get(1).unwrap(), Some(20));
assert_eq!(reader.get(0).unwrap(), Some(10));

Implementations

impl<'a, E: Endianness> IntVecReader<'a, E>

where for<'b> BufBitReader<E, MemWordReader<u64, &'b Vec<u64>>, DefaultReadParams>: BitRead<E, Error = Infallible> + CodesRead<E> + BitSeek<Error = Infallible>,

pub fn get(&mut self, index: usize) -> Result<Option<u64>, IntVecError>

Retrieves the element at the specified index using the reusable reader.

This method leverages the stateful nature of the reader to perform efficient random access.

Implementation Notes

The access strategy is identical to that of IntVec::get, but because this method operates on a long-lived reader instance, it avoids the setup overhead associated with calling IntVec::get repeatedly.

• For fixed-width integer encoding: Access is O(1). The bit position is calculated and the reader seeks directly to it.
• For variable-length, bit-level codes: The reader seeks to the nearest preceding sample point and decodes sequentially from there.

Example

use compressed_intvec::prelude::*;

let data: &[u64] = &[10, 20, 30, 40, 50];
let intvec = LEIntVec::builder(data).build().unwrap();
let mut reader = intvec.reader();

assert_eq!(reader.get(2).unwrap(), Some(30));
assert_eq!(reader.get(10).unwrap(), None); // Out of bounds