Trait CaseInsensitiveLookup

Source

pub trait CaseInsensitiveLookup<V> {
    // Required methods
    fn get_ci(&self, key: &str) -> Option<&V>;
    fn contains_key_ci(&self, key: &str) -> bool;
    fn get_mut_ci(&mut self, key: &str) -> Option<&mut V>;
}

Expand description

Helper trait for case-insensitive lookups on standard HashMap<String, V>

This trait provides extension methods for performing case-insensitive lookups on existing String-keyed HashMaps without requiring migration to CaseInsensitiveMap.

§Performance

Best case: O(1) when exact case matches (uses HashMap’s fast path)
Worst case: O(n) when case differs (iterates all keys to find match)

For hot paths (executed per-row or frequently), store normalized (lowercase) keys in the HashMap to guarantee O(1) lookups. This trait is most appropriate for:

Small HashMaps (< 100 entries)
Cold paths (planning phase, executed once per query)
Cases where preserving original case in keys is important

See SemanticAnalyzer::variables for an example of the optimized pattern where keys are normalized to lowercase on insertion, ensuring all lookups hit the O(1) fast path.

§Examples

use std::collections::HashMap;
use lance_graph::case_insensitive::CaseInsensitiveLookup;

let mut map = HashMap::new();
map.insert("Person".to_string(), 1);

assert_eq!(map.get_ci("person"), Some(&1));
assert_eq!(map.get_ci("PERSON"), Some(&1));
assert_eq!(map.get_ci("Person"), Some(&1));