In the context of formal language theory and compiler construction, FIRST and FOLLOW are functions associated with context-free grammars (CFGs):
FIRST Function:
- Definition: The FIRST function provides the set of terminal symbols that can appear as the first symbol(s) of a string derived from a given non-terminal in a CFG.
- Use Cases: Useful in parsing and predictive parsing table construction.
FOLLOW Function:
- Definition: The FOLLOW function provides the set of terminal symbols that can appear immediately to the right of a given non-terminal in some derivation.
- Use Cases: Important for constructing predictive parsing tables, which are used in top-down parsing.
These functions play a crucial role in the analysis and construction of parsers for context-free grammars, aiding in understanding the possible sequences of symbols in the language defined by the grammar.