Struct cfg::classification::useful::Usefulness

pub struct Usefulness<G> { /* private fields */ }

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

Implementations

impl<'a, G> Usefulness<&'a mut G>where G: RuleContainer + Default, for<'b> &'b G: RuleContainerRef<'b, Target = G>, for<'b> &'b mut G: RuleContainerMut<'b, Target = G>,

pub fn new(grammar: &'a mut G) -> Usefulness<&'a mut G>

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<Sr>(self, syms: Sr) -> Selfwhere Sr: 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.

impl<'a, G> Usefulness<&'a mut G>where G: RuleContainer + Default, &'a G: RuleContainerRef<'a, Target = G>, &'a mut G: RuleContainerMut<'a, Target = G>,

pub fn useless_rules( &'a self ) -> UselessRules<'a, G, <&'a G as RuleContainerRef<'a>>::Rules>

Returns an iterator over the grammar’s useless rules.

pub fn remove_useless_rules(&mut self)

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