Hashtablelike

Hashtablelike describes data structures that provide fast key-value access through hashing, mirroring the behavior of a classical hashtable while allowing variations in implementation and features. These structures implement a map or dictionary interface, offering operations such as insert (put), lookup (get), delete, and containment checks, typically with average-case constant time performance.

Core characteristics of hashtablelike structures include a hash function that maps keys to bucket indices, a collision resolution strategy (such as chaining or open addressing), and a mechanism to resize or rehash when the load factor grows. They may support iteration over key-value pairs, and some preserve additional ordering semantics or provide immutable or persistent variants.

Variants and implementations vary by language and design goals. Common implementations include mutable hash maps that allow in-place updates, and immutable or persistent versions that share structure between versions. Some platforms offer specialized forms with concurrency controls, such as thread-safe hash maps. Differences can also arise in memory layout, insertion and deletion performance, and support for key types or custom hash functions.

Differences from a pure hash table include features like guaranteed iteration order, persistence, immutability, or strong concurrency guarantees. In practice, hashtablelike structures are chosen for fast lookups, moderate memory usage, and predictable average performance. They are widely used for caches, symbol tables, configuration stores, and general-purpose associative arrays in many programming environments.