Struct PrecClimber

pub struct PrecClimber<R: Clone + 'static> { /* private fields */ }

👎Deprecated since 2.4.0: Use pest::pratt_parser instead (it is an equivalent which also supports unary prefix/suffix operators). While prec_climber is going to be kept in 2.x minor and patch releases, it may be removed in a future major release.

List of operators and precedences, which can perform precedence climbing on infix expressions contained in a Pairs. The token pairs contained in the Pairs should start with a primary pair and then alternate between an operator and a primary.

Implementations

impl<R: RuleType> PrecClimber<R>

pub fn new(ops: Vec<Operator<R>>) -> PrecClimber<R>

👎Deprecated since 2.4.0: Use pest::pratt_parser instead (it is an equivalent which also supports unary prefix/suffix operators). While prec_climber is going to be kept in 2.x minor and patch releases, it may be removed in a future major release.

Creates a new PrecClimber from the Operators contained in ops. Every entry in the Vec has precedence index + 1. In order to have operators with same precedence, they need to be chained with | between them.

Examples

PrecClimber::new(vec![
    Operator::new(Rule::plus, Assoc::Left) | Operator::new(Rule::minus, Assoc::Left),
    Operator::new(Rule::times, Assoc::Left) | Operator::new(Rule::divide, Assoc::Left),
    Operator::new(Rule::power, Assoc::Right)
]);

pub fn climb<'i, P, F, G, T>(&self, pairs: P, primary: F, infix: G) -> T

where P: Iterator<Item = Pair<'i, R>>, F: FnMut(Pair<'i, R>) -> T, G: FnMut(T, Pair<'i, R>, T) -> T,

👎Deprecated since 2.4.0: Use pest::pratt_parser instead (it is an equivalent which also supports unary prefix/suffix operators). While prec_climber is going to be kept in 2.x minor and patch releases, it may be removed in a future major release.

Performs the precedence climbing algorithm on the pairs in a similar manner to map-reduce. Primary pairs are mapped with primary and then reduced to one single result with infix.

Panics

Panics will occur when pairs is empty or when the alternating primary, operator, primary order is not respected.

Examples

let primary = |pair| {
    consume(pair, climber)
};
let infix = |lhs: i32, op: Pair<Rule>, rhs: i32| {
    match op.rule() {
        Rule::plus => lhs + rhs,
        Rule::minus => lhs - rhs,
        Rule::times => lhs * rhs,
        Rule::divide => lhs / rhs,
        Rule::power => lhs.pow(rhs as u32),
        _ => unreachable!()
    }
};

let result = climber.climb(pairs, primary, infix);

Trait Implementations

impl<R: Debug + Clone + 'static> Debug for PrecClimber<R>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.