What Does a Lexer Do
The Lexer Just Turns the Meaningless String into a Flat List of Things Like “Number Literal”, “String Literal”, “Identifier”, or “Operator”, and Can Do Things...
The lexer just turns the meaningless string into a flat list of things like “number literal”, “string literal”, “identifier”, or “operator”, and can do things like recognizing reserved identifiers (“keywords”) and discarding whitespace. Formally, a lexer recognizes some set of Regular languages.
What is the purpose of a lexer?
A lexer will take an input character stream and convert it into tokens. This can be used for a variety of purposes. You could apply transformations to the lexemes for simple text processing and manipulation. Or the stream of lexemes can be fed to a parser which will convert it into a parser tree.
What are lexer rules?
Rules defined within a lexer grammar must have a name beginning with an uppercase letter. These rules implicitly match characters on the input stream instead of tokens on the token stream. Referenced grammar elements include token references (implicit lexer rule references), characters, and strings.
David Miller brings 15 years of experience in global economics, personal finance strategy, and market dynamics. He specializes in turning complex economic trends into actionable insights for everyday readers.
