Rule-based programs 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 compiler frontend in processing. Analysis generally occurs in one pass. Lexers and parsers are most often used for compilers, but can be used for other computer language tools, such as prettyprinters or linters. Lexing can be divided into two stages: the scanning, which segments the input string into syntactic units called lexemes and categorizes these into token classes, and the evaluating, which converts lexemes into processed values.
Rule-based programs 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 compiler frontend in processing. Analysis generally occurs in one pass. Lexers and parsers are most often used for compilers, but can be used for other computer language tools, such as prettyprinters or linters. Lexing can be divided into two stages the scanning, which segments the input string into syntactic units called lexemes and categorizes these i:nto token classes, and the eva,luating which converts lexemes into processed values.