Rename vfs -> memofs across the codebase

memofs/src/in_memory_fs.rs

@@ -0,0 +1,249 @@
+use std::collections::{BTreeSet, HashMap, VecDeque};
+use std::io;
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, Mutex};
+
+use crossbeam_channel::{Receiver, Sender};
+
+use crate::{DirEntry, Metadata, ReadDir, VfsBackend, VfsEvent, VfsSnapshot};
+
+/// In-memory filesystem that can be used as a VFS backend.
+///
+/// Internally reference counted to enable giving a copy to
+/// [`Vfs`](struct.Vfs.html) and keeping the original to mutate the filesystem's
+/// state with.
+#[derive(Debug, Clone)]
+pub struct InMemoryFs {
+    inner: Arc<Mutex<InMemoryFsInner>>,
+}
+
+impl InMemoryFs {
+    /// Create a new empty `InMemoryFs`.
+    pub fn new() -> Self {
+        Self {
+            inner: Arc::new(Mutex::new(InMemoryFsInner::new())),
+        }
+    }
+
+    /// Load a [`VfsSnapshot`](enum.VfsSnapshot.html) into a subtree of the
+    /// in-memory filesystem.
+    ///
+    /// This function will return an error if the operations required to apply
+    /// the snapshot result in errors, like trying to create a file inside a
+    /// file.
+    pub fn load_snapshot<P: Into<PathBuf>>(
+        &mut self,
+        path: P,
+        snapshot: VfsSnapshot,
+    ) -> io::Result<()> {
+        let mut inner = self.inner.lock().unwrap();
+        inner.load_snapshot(path.into(), snapshot)
+    }
+
+    /// Raises a filesystem change event.
+    ///
+    /// If this `InMemoryFs` is being used as the backend of a
+    /// [`Vfs`](struct.Vfs.html), then any listeners be notified of this event.
+    pub fn raise_event(&mut self, event: VfsEvent) {
+        let inner = self.inner.lock().unwrap();
+        inner.event_sender.send(event).unwrap();
+    }
+}
+
+#[derive(Debug)]
+struct InMemoryFsInner {
+    entries: HashMap<PathBuf, Entry>,
+    orphans: BTreeSet<PathBuf>,
+
+    event_receiver: Receiver<VfsEvent>,
+    event_sender: Sender<VfsEvent>,
+}
+
+impl InMemoryFsInner {
+    fn new() -> Self {
+        let (event_sender, event_receiver) = crossbeam_channel::unbounded();
+
+        Self {
+            entries: HashMap::new(),
+            orphans: BTreeSet::new(),
+            event_receiver,
+            event_sender,
+        }
+    }
+
+    fn load_snapshot(&mut self, path: PathBuf, snapshot: VfsSnapshot) -> io::Result<()> {
+        if let Some(parent_path) = path.parent() {
+            if let Some(parent_entry) = self.entries.get_mut(parent_path) {
+                if let Entry::Dir { children } = parent_entry {
+                    children.insert(path.clone());
+                } else {
+                    return must_be_dir(parent_path);
+                }
+            } else {
+                self.orphans.insert(path.clone());
+            }
+        } else {
+            self.orphans.insert(path.clone());
+        }
+
+        match snapshot {
+            VfsSnapshot::File { contents } => {
+                self.entries.insert(path, Entry::File { contents });
+            }
+            VfsSnapshot::Dir { children } => {
+                self.entries.insert(
+                    path.clone(),
+                    Entry::Dir {
+                        children: BTreeSet::new(),
+                    },
+                );
+
+                for (child_name, child) in children {
+                    let full_path = path.join(child_name);
+                    self.load_snapshot(full_path, child)?;
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    fn remove(&mut self, root_path: PathBuf) {
+        self.orphans.remove(&root_path);
+
+        let mut to_remove = VecDeque::new();
+        to_remove.push_back(root_path);
+
+        while let Some(path) = to_remove.pop_front() {
+            if let Some(Entry::Dir { children }) = self.entries.remove(&path) {
+                to_remove.extend(children);
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+enum Entry {
+    File { contents: Vec<u8> },
+
+    Dir { children: BTreeSet<PathBuf> },
+}
+
+impl VfsBackend for InMemoryFs {
+    fn read(&mut self, path: &Path) -> io::Result<Vec<u8>> {
+        let inner = self.inner.lock().unwrap();
+
+        match inner.entries.get(path) {
+            Some(Entry::File { contents }) => Ok(contents.clone()),
+            Some(Entry::Dir { .. }) => must_be_file(path),
+            None => not_found(path),
+        }
+    }
+
+    fn write(&mut self, path: &Path, data: &[u8]) -> io::Result<()> {
+        let mut inner = self.inner.lock().unwrap();
+
+        inner.load_snapshot(
+            path.to_path_buf(),
+            VfsSnapshot::File {
+                contents: data.to_owned(),
+            },
+        )
+    }
+
+    fn read_dir(&mut self, path: &Path) -> io::Result<ReadDir> {
+        let inner = self.inner.lock().unwrap();
+
+        match inner.entries.get(path) {
+            Some(Entry::Dir { children }) => {
+                let iter = children
+                    .clone()
+                    .into_iter()
+                    .map(|path| Ok(DirEntry { path }));
+
+                Ok(ReadDir {
+                    inner: Box::new(iter),
+                })
+            }
+            Some(Entry::File { .. }) => must_be_dir(path),
+            None => not_found(path),
+        }
+    }
+
+    fn remove_file(&mut self, path: &Path) -> io::Result<()> {
+        let mut inner = self.inner.lock().unwrap();
+
+        match inner.entries.get(path) {
+            Some(Entry::File { .. }) => {
+                inner.remove(path.to_owned());
+                Ok(())
+            }
+            Some(Entry::Dir { .. }) => must_be_file(path),
+            None => not_found(path),
+        }
+    }
+
+    fn remove_dir_all(&mut self, path: &Path) -> io::Result<()> {
+        let mut inner = self.inner.lock().unwrap();
+
+        match inner.entries.get(path) {
+            Some(Entry::Dir { .. }) => {
+                inner.remove(path.to_owned());
+                Ok(())
+            }
+            Some(Entry::File { .. }) => must_be_dir(path),
+            None => not_found(path),
+        }
+    }
+
+    fn metadata(&mut self, path: &Path) -> io::Result<Metadata> {
+        let inner = self.inner.lock().unwrap();
+
+        match inner.entries.get(path) {
+            Some(Entry::File { .. }) => Ok(Metadata { is_file: true }),
+            Some(Entry::Dir { .. }) => Ok(Metadata { is_file: false }),
+            None => not_found(path),
+        }
+    }
+
+    fn event_receiver(&self) -> crossbeam_channel::Receiver<VfsEvent> {
+        let inner = self.inner.lock().unwrap();
+
+        inner.event_receiver.clone()
+    }
+
+    fn watch(&mut self, _path: &Path) -> io::Result<()> {
+        Ok(())
+    }
+
+    fn unwatch(&mut self, _path: &Path) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+fn must_be_file<T>(path: &Path) -> io::Result<T> {
+    Err(io::Error::new(
+        io::ErrorKind::Other,
+        format!(
+            "path {} was a directory, but must be a file",
+            path.display()
+        ),
+    ))
+}
+
+fn must_be_dir<T>(path: &Path) -> io::Result<T> {
+    Err(io::Error::new(
+        io::ErrorKind::Other,
+        format!(
+            "path {} was a file, but must be a directory",
+            path.display()
+        ),
+    ))
+}
+
+fn not_found<T>(path: &Path) -> io::Result<T> {
+    Err(io::Error::new(
+        io::ErrorKind::NotFound,
+        format!("path {} not found", path.display()),
+    ))
+}