Symbol Table

In the context of a lexical analyzer, a symbol table is a systematic data structure that maintains a record of all identifiers (such as variable names, function names, and constants) encountered during the scanning of source code. It maps each identifier to associated attributes, including its type, scope, memory address, and other metadata. This component is critical for ensuring that identifiers are consistently recognized and processed throughout the compilation or interpretation phases, supporting tasks like syntax analysis, semantic analysis, and code generation.

The symbol table operates by storing entries for each unique identifier as the lexical analyzer scans the source code. It typically uses hash tables, binary search trees, or arrays for efficient insertion, deletion, and lookup operations. During lexical analysis, when an identifier is tokenized, the symbol table is checked: if the identifier is new, an entry is created; if it exists, its attributes are retrieved or updated. This enables quick access to identifier information, reducing redundancy and ensuring accurate symbol resolution in subsequent compilation stages.