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//! Maps paths to compact integer ids. We don't care about clearings paths which
//! no longer exist -- the assumption is total size of paths we ever look at is
//! not too big.
use rustc_hash::FxHashMap;
use crate::{FileId, VfsPath};
/// Structure to map between [`VfsPath`] and [`FileId`].
#[derive(Default)]
pub(crate) struct PathInterner {
map: FxHashMap<VfsPath, FileId>,
vec: Vec<VfsPath>,
}
impl PathInterner {
/// Get the id corresponding to `path`.
///
/// If `path` does not exists in `self`, returns [`None`].
pub(crate) fn get(&self, path: &VfsPath) -> Option<FileId> {
self.map.get(path).copied()
}
/// Insert `path` in `self`.
///
/// - If `path` already exists in `self`, returns its associated id;
/// - Else, returns a newly allocated id.
pub(crate) fn intern(&mut self, path: VfsPath) -> FileId {
if let Some(id) = self.get(&path) {
return id;
}
let id = FileId(self.vec.len() as u32);
self.map.insert(path.clone(), id);
self.vec.push(path);
id
}
/// Returns the path corresponding to `id`.
///
/// # Panics
///
/// Panics if `id` does not exists in `self`.
pub(crate) fn lookup(&self, id: FileId) -> &VfsPath {
&self.vec[id.0 as usize]
}
}
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