PrefixElement

PrefixElement is a node in a prefix tree (also known as a trie) used to represent a single label along a path that encodes a set of strings. It serves as the building block for data structures that support efficient prefix-based operations, such as searching, insertion, and autocomplete.

A PrefixElement typically stores several fields. The label identifies the edge or step from its parent to the node, and is often a single character in simple tries but can be a string segment in more compact implementations. The terminal flag (or isWord marker) indicates whether the path from the root to this node corresponds to a stored key, such as a word, identifier, or phrase. The children collection maps possible next labels to their respective PrefixElement nodes, enabling traversal to extend or complete keys.

Common operations involving PrefixElement include insertion, which traverses existing nodes for each symbol of a key and creates new nodes as needed; search, which checks for the existence of a complete key; and prefix-based queries, such as autocomplete or dictionary lookups, which explore the subtree under a given node to enumerate matching keys. Optional enhancements may store frequency counts, metadata, or pointers to parent nodes to support additional algorithms and optimizations. Deletion operations may mark a key as removed or physically prune nodes when they become unnecessary.

PrefixElement is also involved in variants of prefix trees, such as compact or radix tries, where a node may represent a string label spanning multiple characters to reduce node count. In practice, PrefixElement enables fast, scalable prefix matching and is widely used in text processing, spell checking, and autocomplete systems. See also Trie, Prefix tree, and Radix tree.