Endidentifier

Endidentifier is a term used in discussions of lexical analysis to denote the boundary that terminates an identifier token in a stream of source code or data. It is not a formal keyword in most languages, but a concept describing how tokenizers determine where an identifier ends and the next token begins.

In typical language grammars, an identifier is a sequence of characters allowed by the language’s lexical rules. The endidentifier marks the point at which the scanner stops treating the preceding characters as part of the identifier, either when a character not permitted inside identifiers is encountered or when a higher-priority token is recognized. Endidentifier can be implicit, defined by character classes, or explicit, in languages that require a specific terminator character or delimiter to end tokens.

In practice, the endidentifier is important for correct tokenization because it interacts with keyword recognition and punctuation handling. A lexer often reads characters to form a candidate identifier, then checks whether the result matches a reserved keyword; if so, the token type may be a keyword rather than an identifier. If not, the endidentifier has determined the final token.

Implementation typically uses a finite automaton that accepts identifier characters and halts on the first character that cannot belong to an identifier. Examples include languages where identifiers follow a pattern such as letter, followed by letters or digits or underscores, with whitespace or operators serving as endidentifiers.

See also: lexical analysis, tokenization, identifiers, keywords.