Crate composable_indexes

A library for in-memory collections with flexible and composable indexes.

This crate provides a framework for building collections with multiple indexes that can be combined and composed. Key features include:

• Built-in indexes for common use cases (BTree, HashTable)
• Composable index combinators (grouping, filtering, mapping)
• Aggregation indexes for statistical operations
• Safe and efficient index maintenance as collection changes

Example

use composable_indexes::{Collection, index};

// A struct representing a person
struct Person { name: String, age: u32, occupation: String }

// Create a collection indexed by age using premap
let mut collection = Collection::<Person, _>::new(
  index::zip!(
    index::premap(|p: &Person| p.age, index::btree()),
    index::premap(|p: &Person| p.occupation.clone(), index::hashtable()),
  )
);

// insert & update collection
let alice = collection.insert(Person { name: "Alice".to_string(), age: 30, occupation: "Engineer".to_string() });
collection.insert(Person { name: "Bob".to_string(), age: 25, occupation: "Designer".to_string() });
collection.adjust_mut(alice, |p| { p.age = 31; });
// ...

let q = collection.query();

// Query oldest person
let _youngest = q.0.max_one();

// Query the number of unique occupations
let _occupation_count = q.1.count_distinct();

Modules

aggregation

Module providing aggregation indexes for computing aggregate values over collections. Includes common aggregations like count, sum, and mean.

index

Module providing various index implementations and combinators. Includes basic indexes like BTree and HashTable, as well as combinators for transforming, grouping, and filtering indexes.

Structs

Collection

A collection of items, with an index that is automatically kept up-to-date.

Key