Struct HashIndex 

pub struct HashIndex { /* private fields */ }

Hash-based index for fast O(1) exact-match lookups.

This index uses a hash map for constant-time key lookups, making it ideal for:

• Primary key lookups
• Session/token lookups
• Any scenario where you only need exact matches

Performance

• Insert: O(1) average
• Lookup: O(1) average
• Delete: O(1) average

Limitations

• Does not support range queries (use BTreeIndex for that)
• Does not maintain order

Example

use rustlite_core::index::{HashIndex, Index};

let mut index = HashIndex::new();
index.insert(b"session:abc123", 42).unwrap();
index.insert(b"session:def456", 43).unwrap();

// Fast O(1) lookup
assert_eq!(index.find(b"session:abc123").unwrap(), vec![42]);
assert!(index.find(b"nonexistent").unwrap().is_empty());

Implementations

impl HashIndex

pub fn new() -> Self

Create a new empty Hash index.

pub fn with_capacity(capacity: usize) -> Self

Create a new Hash index with the specified capacity.

pub fn contains_key(&self, key: &[u8]) -> bool

Check if the index contains a key.

pub fn key_count(&self) -> usize

Get the number of unique keys in the index.

pub fn iter(&self) -> impl Iterator<Item = (&[u8], &[u64])>

Iterate over all entries (unordered).

Trait Implementations

impl Clone for HashIndex

fn clone(&self) -> HashIndex

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HashIndex

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

Formats the value using the given formatter.

impl Default for HashIndex

fn default() -> Self

Returns the “default value” for a type.

impl Index for HashIndex

fn insert(&mut self, key: &[u8], value: u64) -> Result<()>

Insert a key-value pair into the index. The value is typically a pointer/offset to the actual data.

fn find(&self, key: &[u8]) -> Result<Vec<u64>>

Find all values matching the exact key.

fn remove(&mut self, key: &[u8]) -> Result<bool>

Remove all entries for a key from the index. Returns true if any entries were removed.

fn len(&self) -> usize

Returns the number of entries in the index.

fn clear(&mut self)

Clear all entries from the index.

fn index_type(&self) -> IndexType

Returns the index type.

fn is_empty(&self) -> bool

Returns true if the index is empty.