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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
use std::collections::HashSet;
use crate::raw::*;
use crate::*;
/// ToHierarchyLister will convert a flat list to hierarchy by filter
/// not needed entries.
///
/// # Notes
///
/// ToHierarchyLister filter entries after fetch entries. So it's possible
/// to return an empty vec. It doesn't mean the all pages have been
/// returned.
///
/// Please keep calling next until we returned `Ok(None)`
pub struct HierarchyLister<P> {
lister: P,
path: String,
visited: HashSet<String>,
recursive: bool,
}
impl<P> HierarchyLister<P> {
/// Create a new hierarchy lister
pub fn new(lister: P, path: &str, recursive: bool) -> HierarchyLister<P> {
let path = if path == "/" {
"".to_string()
} else {
path.to_string()
};
HierarchyLister {
lister,
path,
visited: HashSet::default(),
recursive,
}
}
/// ## NOTES
///
/// We take `&mut Entry` here because we need to perform modification on entry in the case like
/// listing "a/" with existing key `a/b/c`.
///
/// In this case, we got a key `a/b/c`, but we should return `a/b/` instead to keep the hierarchy.
fn keep_entry(&mut self, e: &mut oio::Entry) -> bool {
// If path is not started with prefix, drop it.
//
// Ideally, it should never happen. But we just tolerate
// this state.
if !e.path().starts_with(&self.path) {
return false;
}
// Don't return already visited path.
if self.visited.contains(e.path()) {
return false;
}
let prefix_len = self.path.len();
let idx = if let Some(idx) = e.path()[prefix_len..].find('/') {
idx + prefix_len + 1
} else {
// If there is no `/` in path, it's a normal file, we
// can return it directly.
return true;
};
// idx == path.len() means it's contain only one `/` at the
// end of path.
if idx == e.path().len() {
if !self.visited.contains(e.path()) {
self.visited.insert(e.path().to_string());
}
return true;
}
// If idx < path.len() means that are more levels to come.
// We should check the first dir path.
let has = {
let path = &e.path()[..idx];
self.visited.contains(path)
};
if !has {
let path = {
let path = &e.path()[..idx];
path.to_string()
};
e.set_path(&path);
e.set_mode(EntryMode::DIR);
self.visited.insert(path);
return true;
}
false
}
}
impl<P: oio::List> oio::List for HierarchyLister<P> {
async fn next(&mut self) -> Result<Option<oio::Entry>> {
loop {
let mut entry = match self.lister.next().await? {
Some(entry) => entry,
None => return Ok(None),
};
if self.recursive {
return Ok(Some(entry));
}
if self.keep_entry(&mut entry) {
return Ok(Some(entry));
}
}
}
}
impl<P: oio::BlockingList> oio::BlockingList for HierarchyLister<P> {
fn next(&mut self) -> Result<Option<oio::Entry>> {
loop {
let mut entry = match self.lister.next()? {
Some(entry) => entry,
None => return Ok(None),
};
if self.recursive {
return Ok(Some(entry));
}
if self.keep_entry(&mut entry) {
return Ok(Some(entry));
}
}
}
}
#[cfg(test)]
mod tests {
use std::collections::HashSet;
use std::vec::IntoIter;
use log::debug;
use oio::BlockingList;
use super::*;
struct MockLister {
inner: IntoIter<&'static str>,
}
impl MockLister {
fn new(inner: Vec<&'static str>) -> Self {
Self {
inner: inner.into_iter(),
}
}
}
impl BlockingList for MockLister {
fn next(&mut self) -> Result<Option<oio::Entry>> {
let entry = self.inner.next().map(|path| {
if path.ends_with('/') {
oio::Entry::new(path, Metadata::new(EntryMode::DIR))
} else {
oio::Entry::new(path, Metadata::new(EntryMode::FILE))
}
});
Ok(entry)
}
}
#[test]
fn test_blocking_list() -> Result<()> {
let _ = tracing_subscriber::fmt().with_test_writer().try_init();
let lister = MockLister::new(vec![
"x/x/", "x/y/", "y/", "x/x/x", "y/y", "xy/", "z", "y/a",
]);
let mut lister = HierarchyLister::new(lister, "", false);
let mut entries = Vec::default();
let mut set = HashSet::new();
while let Some(e) = lister.next()? {
debug!("got path {}", e.path());
assert!(
set.insert(e.path().to_string()),
"duplicated value: {}",
e.path()
);
entries.push(e)
}
assert_eq!(
entries[0],
oio::Entry::new("x/", Metadata::new(EntryMode::DIR))
);
assert_eq!(
entries[1],
oio::Entry::new("y/", Metadata::new(EntryMode::DIR))
);
assert_eq!(
entries[2],
oio::Entry::new("xy/", Metadata::new(EntryMode::DIR))
);
assert_eq!(
entries[3],
oio::Entry::new("z", Metadata::new(EntryMode::FILE))
);
Ok(())
}
}