Files
rojo/server/src/path_map.rs
2019-01-15 12:44:49 -08:00

108 lines
3.3 KiB
Rust

use std::{
path::{self, Path, PathBuf},
collections::{HashMap, HashSet},
};
use serde_derive::Serialize;
use log::warn;
#[derive(Debug, Serialize)]
struct PathMapNode<T> {
value: T,
children: HashSet<PathBuf>,
}
/// A map from paths to another type, like instance IDs, with a bit of
/// additional data that enables removing a path and all of its child paths from
/// the tree more quickly.
#[derive(Debug, Serialize)]
pub struct PathMap<T> {
nodes: HashMap<PathBuf, PathMapNode<T>>,
}
impl<T> PathMap<T> {
pub fn new() -> PathMap<T> {
PathMap {
nodes: HashMap::new(),
}
}
pub fn get(&self, path: &Path) -> Option<&T> {
self.nodes.get(path).map(|v| &v.value)
}
pub fn insert(&mut self, path: PathBuf, value: T) {
if let Some(parent_path) = path.parent() {
if let Some(parent) = self.nodes.get_mut(parent_path) {
parent.children.insert(path.to_path_buf());
}
}
self.nodes.insert(path, PathMapNode {
value,
children: HashSet::new(),
});
}
pub fn remove(&mut self, root_path: &Path) -> Option<T> {
if let Some(parent_path) = root_path.parent() {
if let Some(parent) = self.nodes.get_mut(parent_path) {
parent.children.remove(root_path);
}
}
let mut root_node = match self.nodes.remove(root_path) {
Some(node) => node,
None => return None,
};
let root_value = root_node.value;
let mut to_visit: Vec<PathBuf> = root_node.children.drain().collect();
while let Some(path) = to_visit.pop() {
match self.nodes.remove(&path) {
Some(mut node) => {
for child in node.children.drain() {
to_visit.push(child);
}
},
None => {
warn!("Consistency issue; tried to remove {} but it was already removed", path.display());
},
}
}
Some(root_value)
}
/// Traverses the route between `start_path` and `target_path` and returns
/// the path closest to `target_path` in the tree.
///
/// This is useful when trying to determine what paths need to be marked as
/// altered when a change to a path is registered. Depending on the order of
/// FS events, a file remove event could be followed by that file's
/// directory being removed, in which case we should process that
/// directory's parent.
pub fn descend(&self, start_path: &Path, target_path: &Path) -> PathBuf {
let relative_path = target_path.strip_prefix(start_path)
.expect("target_path did not begin with start_path");
let mut current_path = start_path.to_path_buf();
for component in relative_path.components() {
match component {
path::Component::Normal(name) => {
let next_path = current_path.join(name);
if self.nodes.contains_key(&next_path) {
current_path = next_path;
} else {
return current_path;
}
},
_ => unreachable!(),
}
}
current_path
}
}