Lexical Analysis Theory

Lexical analysis is the process of converting a sequence of characters (such as source code) into a sequence of tokens. Each token is a string with an assigned meaning, which can be identified by the lexical analyzer (lexer). The primary role of a lexical analyzer is to split the input into manageable chunks, such as operators, keywords, variables, and literals.

Key Concepts in Lexical Analysis:

• Token: A sequence of characters that collectively represent a basic unit of meaning (e.g., an identifier, a number, or an operator).
• Lexeme: The actual sequence of characters that matches a token pattern.
• Regular Expressions: Used to define patterns that tokens must match.
• Finite Automata: A mathematical model used to implement token recognition algorithms.

Lexical analysis is often the first phase in a compiler or interpreter pipeline. It is followed by syntax analysis, which checks the structure of the tokenized input against the grammar of the language.