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use std::collections::VecDeque;
#[derive(Clone, Copy)]
enum TablePointer<R> where R: Clone + Copy {
Link(usize),
Route(R),
RouteWithLink(usize, R),
NotFound,
}
pub struct NoMatchingRoute;
pub type RouteMatch<'a, R> = Result<(R, &'a str), NoMatchingRoute>;
#[derive(Clone)]
pub struct RoutingTable<R> where R: Copy {
tables: Vec<[TablePointer<R>; 128]>,
}
impl<R> RoutingTable<R> where R: Copy {
pub fn new() -> RoutingTable<R> {
let zero_table = [TablePointer::NotFound; 128];
RoutingTable {
tables: vec![zero_table],
}
}
pub fn insert(&mut self, path: &str, route: R) {
assert!(!path.is_empty());
let mut index: usize = 0;
let p: Vec<usize> = path.as_bytes().iter().map(|i| usize::from(*i)).collect();
let mut path_queue = VecDeque::from(p);
while path_queue.len() > 1 {
let ch = path_queue.pop_front().unwrap() as usize % 128;
match self.tables[index][ch] {
TablePointer::NotFound => {
self.tables.push([TablePointer::NotFound; 128]);
let i_other_table = self.tables.len() - 1;
self.tables[index][ch] = TablePointer::Link(i_other_table);
path_queue.push_front(ch);
}
TablePointer::Link(i_other_table) => {
index = i_other_table as usize;
}
TablePointer::RouteWithLink(i_other_table, _) => {
index = i_other_table as usize;
path_queue.push_front(ch);
}
TablePointer::Route(route) => {
self.tables.push([TablePointer::NotFound; 128]);
let i_other_table = self.tables.len() - 1;
self.tables[index][ch] = TablePointer::RouteWithLink(i_other_table, route);
path_queue.push_front(ch);
}
}
}
// last character element in path
let ch = path_queue.pop_front().unwrap() % 128;
match self.tables[index][ch] {
TablePointer::NotFound => {
// slot is empty, just place the Route
self.tables[index][ch] = TablePointer::Route(route)
}
TablePointer::Link(i) => {
// slot is filled with link to longer path. Replace by RouteWithLink
self.tables[index][ch] = TablePointer::RouteWithLink(i, route);
}
_ => {
panic!("Not expected here, maybe duplicate")
}
}
}
pub fn match_path<'a>(&self, path: &'a str) -> RouteMatch<'a, R> {
let mut table: &[TablePointer<R>; 128] = &self.tables[0];
let path_bytes = path.as_bytes();
let path_max_i = path_bytes.len() - 1;
let mut i = 0;
while i <= path_max_i {
let ch = path_bytes[i] as usize % 128;
match table[ch] {
TablePointer::NotFound => {
return Err(NoMatchingRoute);
}
TablePointer::Link(i_other_table) => {
table = &self.tables[i_other_table];
i += 1;
}
TablePointer::RouteWithLink(i_other_table, route) => {
if i == path_max_i {
return Ok((route, Default::default()));
} else {
table = &self.tables[i_other_table];
}
}
TablePointer::Route(route) => {
return Ok((route, path.get(i + 1..=path_max_i).unwrap()));
}
}
}
Err(NoMatchingRoute)
}
}
#[cfg(test)]
mod test1 {
use super::*;
use test::Bencher;
#[derive(Clone, Copy)]
enum Route {
Login,
Logout,
Info,
Check
}
#[bench]
fn bench_1(b: &mut Bencher) {
let mut r = RoutingTable::new();
r.insert("/login", Route::Login);
r.insert("/info", Route::Info);
r.insert("/logout", Route::Logout);
r.insert("/logout2", Route::Info);
r.insert("/check", Route::Check);
match r.tables[0][47] {
TablePointer::Link(n) => assert!(n == 1),
_ => panic!("Wrong"),
}
b.iter(|| {
match r.match_path("/login") {
RouteMatch::Match(Route::Login, rest) => assert_eq!(rest, ""),
_ => panic!("Wrong")
}
match r.match_path("/logout") {
RouteMatch::Match(Route::Logout, rest) => assert_eq!(rest, ""),
_ => panic!("Wrong")
}
match r.match_path("/info") {
RouteMatch::Match(Route::Info, rest) => assert_eq!(rest, ""),
_ => panic!("Wrong")
}
match r.match_path("/logout2") {
RouteMatch::Match(Route::Info, rest) => assert_eq!(rest, ""),
_ => panic!("Wrong")
}
match r.match_path("/asdasdasd") {
RouteMatch::None => (),
_ => panic!("Wrong")
}
match r.match_path("/login/foo/bar") {
RouteMatch::Match(Route::Login, rest) => assert_eq!(rest, "/foo/bar"),
_ => panic!("Wrong")
}
})
}
}
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