Fprefix

Fprefix is a prefix-aware data structure designed to efficiently store and query large sets of strings by focusing on their shared prefixes. It is commonly described as a variant of a trie or radix tree that can support fast prefix matching, autocomplete, and prefix-based grouping. In many descriptions, Fprefix emphasizes functional properties such as immutability or persistent versions to enable safe concurrent access and versioning.

Architecture and variants: In a typical implementation, Fprefix uses a compressed trie (radix tree) where common prefixes are shared and nodes may be merged. Some variants incorporate functional persistence, allowing previous versions to remain accessible after updates. Other variants use a DAG representation to reduce node duplication while preserving fast prefix queries.

Operations and performance: Core operations include insert(word), hasPrefix(prefix), and enumerateWithPrefix(prefix, limit). Time complexity generally scales with the length of the queried prefix and the number of results; practical implementations aim for near-linear behavior with respect to the prefix length and efficient memory usage through path compression.

Applications: Fprefix is used in code editors and IDEs for code completion, search engines for query suggestions, spell-checkers for prefix-based corrections, and natural language processing tasks that require fast access to lexicon entries sharing common prefixes.

History and terminology: The term Fprefix is not widely standardized, and references to it typically appear in library documentation or research notes rather than formal specifications. The concept is related to established prefix-tree data structures, with the Fprefix label serving as a name used by certain projects.

See also: Trie, Radix tree, Prefix tree, Autocomplete, Prefix function, Persistent data structure.