Struct GrammarAnalysis

pub struct GrammarAnalysis<'g> { /* private fields */ }

A structure for calculating the set of nullable nonterminals as well as the FIRST and FOLLOW sets for each nonterminal.

Implementations

impl<'g> GrammarAnalysis<'g>

pub fn build(grammar: &'g Grammar) -> GrammarAnalysis<'g>

The constructor for GrammarAnalysis. This builds the nullable set and the FIRST and FOLLOW sets for grammar.

pub fn nullables(&self) -> HashSet<Symbol<'g>>

Returns the set of nullable symbols.

The result is a set of nonterminals. A Symbol is nullable if it can expand into an empty string of terminals through the application of some sequence of production rules.

pub fn is_nullable(&self, symbol: Symbol<'g>) -> bool

Returns whether the given symbol is nullable.

pub fn first_seq(&self, seq: &[Symbol<'g>]) -> HashSet<Symbol<'g>>

pub fn is_nullable_seq(&self, seq: &[Symbol<'g>]) -> bool

pub fn first(&self, symbol: Symbol<'g>) -> HashSet<Symbol<'g>>

Returns the FIRST set for a nonterminal Symbol.

The result is a set of terminals. A terminal is in the FIRST set of a nonterminal if some sequence of production rules starting with that nonterminal expands to a string of terminals starting with that terminal.

pub fn follow(&self, symbol: Symbol<'g>) -> HashSet<Symbol<'g>>

Returns the FOLLOW set for a nonterminal Symbol.

The result is a set of terminals. A terminal is in the FOLLOW set of a nonterminal that terminal could legally follow the nonterminal during parsing.

pub fn can_end_with(&self, start_symbol: Symbol<'g>, symbol: Symbol<'g>) -> bool