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use std::{
collections::HashMap,
iter::{Peekable, Rev},
str::Split,
};
use crate::error::RouteError;
#[derive(Debug, Eq, PartialEq)]
struct Node<T> {
plus_child: Option<Box<Node<T>>>,
star_child: Option<T>,
named_children: HashMap<String, Node<T>>,
data: Option<T>,
}
impl<T> Default for Node<T> {
fn default() -> Self {
Self {
plus_child: None,
star_child: None,
named_children: HashMap::new(),
data: None,
}
}
}
#[derive(Debug, Eq, PartialEq)]
pub(crate) struct Trie<T> {
root: Node<T>,
}
impl<T> Default for Trie<T> {
fn default() -> Self {
Self {
root: Node::default(),
}
}
}
impl<T> Trie<T> {
pub(crate) fn add(&mut self, pattern: &str, data: T) -> Result<(), RouteError> {
let segments = pattern.split('.').rev().peekable();
if Self::internal_add(segments, &mut self.root, data) {
Ok(())
} else {
Err(RouteError::Duplicate(pattern.to_string()))
}
}
fn internal_add(
mut segments: Peekable<Rev<Split<char>>>,
parent_node: &mut Node<T>,
data: T,
) -> bool {
let segment = segments.next().unwrap();
let is_last = segments.peek().is_none();
let node = match segment {
"+" => parent_node.plus_child.get_or_insert_with(Box::default),
"*" => return parent_node.star_child.replace(data).is_none(),
_ => parent_node
.named_children
.entry(segment.to_string())
.or_default(),
};
if is_last {
if node.data.is_some() {
return false;
}
node.data = Some(data);
true
} else {
Self::internal_add(segments, node, data)
}
}
pub(crate) fn matches(&self, domain: &str) -> Option<&T> {
if domain.is_empty() {
return self.root.star_child.as_ref();
}
let segments = domain.split('.').rev().collect::<Vec<_>>();
Self::internal_matches(&segments, &self.root)
}
fn internal_matches<'a>(segments: &[&str], parent_node: &'a Node<T>) -> Option<&'a T> {
let (segment, tail) = match segments.split_first() {
Some((segment, tail)) => (*segment, tail),
None => return parent_node.data.as_ref(),
};
if let Some(node) = parent_node.named_children.get(segment) {
if let Some(data) = Self::internal_matches(tail, node) {
return Some(data);
}
}
if let Some(plus_child) = &parent_node.plus_child {
if let Some(data) = Self::internal_matches(tail, plus_child) {
return Some(data);
}
}
if let Some(data) = &parent_node.star_child {
return Some(data);
}
None
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_add() {
let mut tree = Trie::default();
tree.add("www.example.com", 1).unwrap();
tree.add("example.com", 2).unwrap();
tree.add("+.example.com", 3).unwrap();
tree.add("+.a.example.com", 4).unwrap();
tree.add("b.a.+.com", 5).unwrap();
tree.add("+.+.com", 6).unwrap();
tree.add("*.com", 7).unwrap();
tree.add("*", 8).unwrap();
assert_eq!(
tree,
Trie {
root: Node {
plus_child: None,
star_child: Some(8),
named_children: vec![(
"com".to_string(),
Node {
plus_child: Some(Box::new(Node {
plus_child: Some(Box::new(Node {
plus_child: None,
star_child: None,
named_children: Default::default(),
data: Some(6),
})),
star_child: None,
named_children: vec![(
"a".to_string(),
Node {
plus_child: None,
star_child: None,
named_children: vec![(
"b".to_string(),
Node {
plus_child: None,
star_child: None,
named_children: Default::default(),
data: Some(5)
}
)]
.into_iter()
.collect(),
data: None
}
)]
.into_iter()
.collect(),
data: None
})),
star_child: Some(7),
named_children: vec![(
"example".to_string(),
Node {
plus_child: Some(Box::new(Node {
plus_child: None,
star_child: None,
named_children: Default::default(),
data: Some(3)
})),
star_child: None,
named_children: vec![
(
"www".to_string(),
Node {
plus_child: None,
star_child: None,
named_children: Default::default(),
data: Some(1)
}
),
(
"a".to_string(),
Node {
plus_child: Some(Box::new(Node {
plus_child: None,
star_child: None,
named_children: Default::default(),
data: Some(4)
})),
star_child: None,
named_children: Default::default(),
data: None
}
)
]
.into_iter()
.collect(),
data: Some(2)
}
)]
.into_iter()
.collect(),
data: None
}
)]
.into_iter()
.collect(),
data: None
}
}
)
}
#[test]
fn test_matches() {
let mut tree = Trie::default();
let domains = vec![
("www.example.com", 1),
("example.com", 2),
("+.example.com", 3),
("+.a.example.com", 4),
("b.a.+.com", 5),
("+.+.com", 6),
("*.com", 7),
("*", 8),
];
for (domain, id) in domains {
tree.add(domain, id).unwrap();
}
let matches = vec![
("www.example.com", Some(&1)),
("example.com", Some(&2)),
("c.example.com", Some(&3)),
("c.a.example.com", Some(&4)),
("c.b.example.com", Some(&7)),
("b.a.sd.com", Some(&5)),
("k.c.com", Some(&6)),
("asd.com", Some(&7)),
("localhost", Some(&8)),
("", Some(&8)),
];
for (domain, id) in matches {
assert_eq!(tree.matches(domain), id);
}
}
}