Struct Usefulness 

pub struct Usefulness { /* private fields */ }

Contains the information about usefulness of the grammar’s rules. Useful rules are both reachable and productive.

Implementations

impl Usefulness

pub fn new(grammar: &Cfg) -> Self

Analyzes usefulness of the grammar’s rules. In particular, it checks for reachable and productive symbols.

pub fn productivity(&self, sym: Symbol) -> bool

Checks whether a symbol is productive. Can be used to determine the precise reason of a rule’s unproductiveness.

pub fn reachable(&mut self, syms: impl AsRef<[Symbol]>)

Sets symbol reachability. Takes an array of reachable symbols.

pub fn all_useful(&self) -> bool

Checks whether all rules in the grammar are useful.

pub fn all_productive(&self) -> bool

Checks whether all rules in the grammar are productive.

pub fn all_reachable(&self) -> bool

Checks whether all rules in the grammar are reachable.

pub fn usefulness<'r>(&self, rule: &'r CfgRule) -> UsefulnessForRule<'r>

Get the usefulness of the given rule.

pub fn useless_rules<'a, 'g>( &'a self, grammar: &'g Cfg, ) -> impl Iterator<Item = UsefulnessForRule<'g>> + 'a

where 'g: 'a,

Returns an iterator over the grammar’s useless rules.

pub fn remove_useless_rules(&self, grammar: &mut Cfg)

Removes useless rules. The language represented by the grammar doesn’t change.