Struct PrefilterBuilder 

pub struct PrefilterBuilder { /* private fields */ }

A builder for prefilters.

Use when either:

• Simply extracting the possible prefilters from individual matchers, without building a router prefilter for many possible matchers
• When more control, additional logging, etc is required than simply calling RouterPrefilter::insert

Examples

use router_prefilter::PrefilterBuilder;
use router_prefilter::matchers::{Matcher, MatcherVisitor};

struct Route(&'static str);

impl Matcher for Route {
    fn visit(&self, visitor: &mut MatcherVisitor) {
        visitor.visit_match_starts_with(self.0);
    }
}

let mut builder = PrefilterBuilder::new();
let prefilter = builder.compute_prefilter(Route("/api"));
assert!(prefilter.is_some());

let no_prefilter = builder.compute_prefilter(Route(""));
assert!(no_prefilter.is_none());

Implementations

impl PrefilterBuilder

pub fn new() -> Self

Create a new prefilter builder

pub fn compute_prefilter<M: Matcher>( &mut self, matcher: M, ) -> Option<MatchPrefilter>

Compute a prefilter (if possible) for the given matcher.

Returns None if no literal prefixes can be extracted from the matcher.

Panics

Panics if the matcher’s Matcher::visit implementation leaves unbalanced nesting (more calls to MatcherVisitor::visit_nested_start than MatcherVisitor::visit_nested_finish, or vice versa).

use router_prefilter::PrefilterBuilder;
use router_prefilter::matchers::{Matcher, MatcherVisitor};

struct UnbalancedMatcher;

impl Matcher for UnbalancedMatcher {
    fn visit(&self, visitor: &mut MatcherVisitor) {
        visitor.visit_nested_start();
        visitor.visit_match_starts_with("/api");
        // missing visit_nested_finish
    }
}

let mut builder = PrefilterBuilder::new();
let _ = builder.compute_prefilter(UnbalancedMatcher); // panics

Examples

use router_prefilter::PrefilterBuilder;
use router_prefilter::matchers::{Matcher, MatcherVisitor};

struct Route(&'static str);

impl Matcher for Route {
    fn visit(&self, visitor: &mut MatcherVisitor) {
        visitor.visit_match_starts_with(self.0);
    }
}

let mut builder = PrefilterBuilder::new();

let prefilter = builder.compute_prefilter(Route("/api")).unwrap();
let prefixes: Vec<_> = prefilter.prefixes().collect();
assert_eq!(prefixes, vec![b"/api".as_slice()]);

Trait Implementations

impl Debug for PrefilterBuilder

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

Formats the value using the given formatter.

impl Default for PrefilterBuilder

fn default() -> Self

Returns the “default value” for a type.