index-db 0.4.0

//! # index-db
//!
//! A B+tree indexing primitive for storage engines: ordered keys mapped to
//! values, with fast point lookups, laid out as a tree of fixed-fan-out nodes
//! rather than on the heap one entry at a time.
//!
//! The one public type is [`BPlusTree`], an ordered map. Keys are kept sorted
//! across the tree, so a lookup is a binary search at each level and the height
//! grows only with the logarithm of the entry count. Beyond point operations it
//! supports ordered iteration and range scans, forward and in reverse. The node
//! layout — sorted keys packed into fixed-capacity arrays, internal nodes routing
//! to children — is the same structure a storage engine persists as an on-disk
//! index; this release keeps the tree in memory.
//!
//! ## Example
//!
//! ```
//! use index_db::BPlusTree;
//!
//! let mut index = BPlusTree::new();
//! index.insert(42_u32, "answer");
//! index.insert(7, "lucky");
//!
//! assert_eq!(index.get(&42), Some(&"answer"));
//! assert_eq!(index.get(&13), None);
//!
//! // Ordered range scan.
//! let keys: Vec<_> = index.range(0..50).map(|(&k, _)| k).collect();
//! assert_eq!(keys, vec![7, 42]);
//!
//! assert_eq!(index.remove(&7), Some("lucky"));
//! assert_eq!(index.len(), 1);
//! ```
//!
//! ## Scope
//!
//! As of `v0.4.0` the in-memory ordered-map surface is complete and
//! feature-frozen: search, insert, delete (with merge and redistribute), forward
//! and reverse range scans, and bulk construction from sorted input. Node access
//! runs through an internal storage seam so that a page-backed, concurrent
//! backend over `page-db` can be added without changing the tree algorithm; that
//! backend is the planned next step. See `dev/ROADMAP.md`.

#![cfg_attr(not(feature = "std"), no_std)]
#![cfg_attr(docsrs, feature(doc_cfg))]
#![deny(missing_docs)]
#![deny(unused_must_use)]
#![deny(unused_results)]
#![deny(clippy::unwrap_used)]
#![deny(clippy::expect_used)]
#![deny(clippy::todo)]
#![deny(clippy::unimplemented)]
#![deny(clippy::print_stdout)]
#![deny(clippy::print_stderr)]
#![deny(clippy::dbg_macro)]
#![forbid(unsafe_code)]

extern crate alloc;

mod iter;
mod node;
mod ops;
mod store;
mod tree;

pub use crate::iter::Iter;
pub use crate::tree::BPlusTree;