dequemap

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dequemap provides a double-ended queue with map features. It combines a VecDeque index with a BTreeMap or HashMap backend, allowing push/pop from both ends while maintaining key-value access.

Supports no_std environments with alloc.

Features

DequeBTreeMap — ordered map with double-ended queue operations
DequeHashMap — hash map with double-ended queue operations
Entry API (VacantEntry / OccupiedEntry) similar to std's map entries
no_std compatible
Optional serde support
Push front/back, pop front/back, remove, retain, clear

Cargo Feature Flags

Feature	Description	Default
`std`	Use Rust standard library (`std`)	yes
`btreemap`	Enable `DequeBTreeMap` (ordered backend)	yes
`hashmap`	Enable `DequeHashMap` (hash backend, pulls in `hashbrown`)	no
`serde`	Enable serialization/deserialization support	no

Basic Usage

use dequemap::DequeBTreeMap;

let mut map = DequeBTreeMap::new();
map.push_back("a", 1);
map.push_back("b", 2);
map.push_front("c", 3);

assert_eq!(map.front(), Some((&"c", &3)));
assert_eq!(map.back(), Some((&"b", &2)));
assert_eq!(map.pop_front(), Some(("c", 3)));
assert_eq!(map.len(), 2);

Tests

cargo test -p dequemap --features "btreemap,hashmap,serde"

30 tests covering both backends, Entry API, serde roundtrip, large entries, and edge cases.

License