A rule-based program, performing lexical tokenization, is called tokenizer, or scanner, although scanner is also a term for the first stage of a lexer. A lexer forms the first phase of a 展开

What is called "lexeme" in rule-based natural language processing is not equal to what is called lexeme in linguistics. What is called "lexeme" in rule-based natural language processing can be equal to the linguistic equivalent only in analytic languages, … 展开

The specification of a programming language often includes a set of rules, the lexical grammar, which defines the lexical syntax. The lexical syntax … 展开

Typically, lexical tokenization occurs at the word level. However, it is sometimes difficult to define what is meant by a "word". Often, a tokenizer … 展开

A lexical token is a string with an assigned and thus identified meaning, in contrast to the probabilistic token used in large language models. A lexical token consists of a token name and an optional token value. The token name is a category of a rule-based lexical unit. 展开

Scanner
The first stage, the scanner, is usually based on a finite-state machine (FSM). It has encoded within it information on the possible sequences of … 展开

Lexers are often generated by a lexer generator, analogous to parser generators, and such tools often come together. The most established is 展开