Add file metadata to AssetIo (#2123)

This is a replacement for #2106

This adds a `Metadata` struct which contains metadata information about a file, at the moment only the file type.
It also adds a `get_metadata` to `AssetIo` trait and an `asset_io` accessor method to `AssetServer` and `LoadContext`

I am not sure about the changes in `AndroidAssetIo ` and `WasmAssetIo`.

crates/bevy_asset/src/asset_server.rs

@@ -124,7 +124,7 @@ impl AssetServer {
     /// Enable watching of the filesystem for changes, if support is available, starting from after
     /// the point of calling this function.
     pub fn watch_for_changes(&self) -> Result<(), AssetServerError> {
-        self.server.asset_io.watch_for_changes()?;
+        self.asset_io().watch_for_changes()?;
         Ok(())
     }
 
@@ -301,7 +301,7 @@ impl AssetServer {
         };
 
         // load the asset bytes
-        let bytes = match self.server.asset_io.load_path(asset_path.path()).await {
+        let bytes = match self.asset_io().load_path(asset_path.path()).await {
             Ok(bytes) => bytes,
             Err(err) => {
                 set_asset_failed();
@@ -313,7 +313,7 @@ impl AssetServer {
         let mut load_context = LoadContext::new(
             asset_path.path(),
             &self.server.asset_ref_counter.channel,
-            &*self.server.asset_io,
+            self.asset_io(),
             version,
             &self.server.task_pool,
         );
@@ -361,8 +361,7 @@ impl AssetServer {
             }
         }
 
-        self.server
-            .asset_io
+        self.asset_io()
             .watch_path_for_changes(asset_path.path())
             .unwrap();
         self.create_assets_in_load_context(&mut load_context);
@@ -403,15 +402,15 @@ impl AssetServer {
         path: P,
     ) -> Result<Vec<HandleUntyped>, AssetServerError> {
         let path = path.as_ref();
-        if !self.server.asset_io.is_directory(path) {
+        if !self.asset_io().is_dir(path) {
             return Err(AssetServerError::AssetFolderNotADirectory(
                 path.to_str().unwrap().to_string(),
             ));
         }
 
         let mut handles = Vec::new();
-        for child_path in self.server.asset_io.read_directory(path.as_ref())? {
-            if self.server.asset_io.is_directory(&child_path) {
+        for child_path in self.asset_io().read_directory(path.as_ref())? {
+            if self.asset_io().is_dir(&child_path) {
                 handles.extend(self.load_folder(&child_path)?);
             } else {
                 if self.get_path_asset_loader(&child_path).is_err() {

crates/bevy_asset/src/io/android_asset_io.rs

@@ -1,7 +1,8 @@
-use crate::{AssetIo, AssetIoError};
+use crate::{AssetIo, AssetIoError, Metadata};
 use anyhow::Result;
 use bevy_utils::BoxedFuture;
 use std::{
+    convert::TryFrom,
     ffi::CString,
     path::{Path, PathBuf},
 };
@@ -46,7 +47,17 @@ impl AssetIo for AndroidAssetIo {
         Ok(())
     }
 
-    fn is_directory(&self, path: &Path) -> bool {
-        self.root_path.join(path).is_dir()
+    fn get_metadata(&self, path: &Path) -> Result<Metadata, AssetIoError> {
+        let full_path = self.root_path.join(path);
+        full_path
+            .metadata()
+            .and_then(Metadata::try_from)
+            .map_err(|e| {
+                if e.kind() == std::io::ErrorKind::NotFound {
+                    AssetIoError::NotFound(full_path)
+                } else {
+                    e.into()
+                }
+            })
     }
 }

crates/bevy_asset/src/io/file_asset_io.rs

@@ -1,6 +1,6 @@
 #[cfg(feature = "filesystem_watcher")]
 use crate::{filesystem_watcher::FilesystemWatcher, AssetServer};
-use crate::{AssetIo, AssetIoError};
+use crate::{AssetIo, AssetIoError, Metadata};
 use anyhow::Result;
 #[cfg(feature = "filesystem_watcher")]
 use bevy_ecs::system::Res;
@@ -15,6 +15,7 @@ use parking_lot::RwLock;
 #[cfg(feature = "filesystem_watcher")]
 use std::sync::Arc;
 use std::{
+    convert::TryFrom,
     env, fs,
     io::Read,
     path::{Path, PathBuf},
@@ -128,8 +129,18 @@ impl AssetIo for FileAssetIo {
         Ok(())
     }
 
-    fn is_directory(&self, path: &Path) -> bool {
-        self.root_path.join(path).is_dir()
+    fn get_metadata(&self, path: &Path) -> Result<Metadata, AssetIoError> {
+        let full_path = self.root_path.join(path);
+        full_path
+            .metadata()
+            .and_then(Metadata::try_from)
+            .map_err(|e| {
+                if e.kind() == std::io::ErrorKind::NotFound {
+                    AssetIoError::NotFound(full_path)
+                } else {
+                    e.into()
+                }
+            })
     }
 }
 

crates/bevy_asset/src/io/metadata.rs

@@ -0,0 +1,77 @@
+use std::convert::{TryFrom, TryInto};
+
+/// A enum representing a type of file.
+#[non_exhaustive]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+pub enum FileType {
+    Directory,
+    File,
+}
+
+impl FileType {
+    #[inline]
+    pub const fn is_dir(&self) -> bool {
+        matches!(self, Self::Directory)
+    }
+
+    #[inline]
+    pub const fn is_file(&self) -> bool {
+        matches!(self, Self::File)
+    }
+}
+
+impl TryFrom<std::fs::FileType> for FileType {
+    type Error = std::io::Error;
+
+    fn try_from(file_type: std::fs::FileType) -> Result<Self, Self::Error> {
+        if file_type.is_dir() {
+            Ok(Self::Directory)
+        } else if file_type.is_file() {
+            Ok(Self::File)
+        } else {
+            Err(std::io::Error::new(
+                std::io::ErrorKind::Other,
+                "unknown file type",
+            ))
+        }
+    }
+}
+
+/// Metadata information about a file.
+///
+/// This structure is returned from the [`AssetIo::get_metadata`](crate::AssetIo) method.
+#[derive(Debug, Clone)]
+pub struct Metadata {
+    file_type: FileType,
+}
+
+impl Metadata {
+    pub fn new(file_type: FileType) -> Self {
+        Self { file_type }
+    }
+
+    #[inline]
+    pub const fn file_type(&self) -> FileType {
+        self.file_type
+    }
+
+    #[inline]
+    pub const fn is_dir(&self) -> bool {
+        self.file_type.is_dir()
+    }
+
+    #[inline]
+    pub const fn is_file(&self) -> bool {
+        self.file_type.is_file()
+    }
+}
+
+impl TryFrom<std::fs::Metadata> for Metadata {
+    type Error = std::io::Error;
+
+    fn try_from(metadata: std::fs::Metadata) -> Result<Self, Self::Error> {
+        Ok(Self {
+            file_type: metadata.file_type().try_into()?,
+        })
+    }
+}

crates/bevy_asset/src/io/mod.rs

@@ -5,13 +5,17 @@ mod file_asset_io;
 #[cfg(target_arch = "wasm32")]
 mod wasm_asset_io;
 
+mod metadata;
+
 #[cfg(target_os = "android")]
 pub use android_asset_io::*;
 #[cfg(all(not(target_arch = "wasm32"), not(target_os = "android")))]
 pub use file_asset_io::*;
 #[cfg(target_arch = "wasm32")]
 pub use wasm_asset_io::*;
 
+pub use metadata::*;
+
 use anyhow::Result;
 use bevy_utils::BoxedFuture;
 use downcast_rs::{impl_downcast, Downcast};
@@ -39,9 +43,23 @@ pub trait AssetIo: Downcast + Send + Sync + 'static {
         &self,
         path: &Path,
     ) -> Result<Box<dyn Iterator<Item = PathBuf>>, AssetIoError>;
-    fn is_directory(&self, path: &Path) -> bool;
+    fn get_metadata(&self, path: &Path) -> Result<Metadata, AssetIoError>;
     fn watch_path_for_changes(&self, path: &Path) -> Result<(), AssetIoError>;
     fn watch_for_changes(&self) -> Result<(), AssetIoError>;
+
+    fn is_dir(&self, path: &Path) -> bool {
+        self.get_metadata(path)
+            .as_ref()
+            .map(Metadata::is_dir)
+            .unwrap_or(false)
+    }
+
+    fn is_file(&self, path: &Path) -> bool {
+        self.get_metadata(path)
+            .as_ref()
+            .map(Metadata::is_file)
+            .unwrap_or(false)
+    }
 }
 
 impl_downcast!(AssetIo);

crates/bevy_asset/src/io/wasm_asset_io.rs

@@ -1,8 +1,11 @@
-use crate::{AssetIo, AssetIoError};
+use crate::{AssetIo, AssetIoError, Metadata};
 use anyhow::Result;
 use bevy_utils::BoxedFuture;
 use js_sys::Uint8Array;
-use std::path::{Path, PathBuf};
+use std::{
+    convert::TryFrom,
+    path::{Path, PathBuf},
+};
 use wasm_bindgen::JsCast;
 use wasm_bindgen_futures::JsFuture;
 use web_sys::Response;
@@ -50,7 +53,17 @@ impl AssetIo for WasmAssetIo {
         Ok(())
     }
 
-    fn is_directory(&self, path: &Path) -> bool {
-        self.root_path.join(path).is_dir()
+    fn get_metadata(&self, path: &Path) -> Result<Metadata, AssetIoError> {
+        let full_path = self.root_path.join(path);
+        full_path
+            .metadata()
+            .and_then(Metadata::try_from)
+            .map_err(|e| {
+                if e.kind() == std::io::ErrorKind::NotFound {
+                    AssetIoError::NotFound(full_path)
+                } else {
+                    e.into()
+                }
+            })
     }
 }

crates/bevy_asset/src/loader.rs

@@ -147,6 +147,10 @@ impl<'a> LoadContext<'a> {
     pub fn task_pool(&self) -> &TaskPool {
         self.task_pool
     }
+
+    pub fn asset_io(&self) -> &dyn AssetIo {
+        self.asset_io
+    }
 }
 
 /// The result of loading an asset of type `T`

examples/asset/custom_asset_io.rs

@@ -1,5 +1,5 @@
 use bevy::{
-    asset::{AssetIo, AssetIoError},
+    asset::{AssetIo, AssetIoError, Metadata},
     prelude::*,
     utils::BoxedFuture,
 };
@@ -26,11 +26,6 @@ impl AssetIo for CustomAssetIo {
         self.0.read_directory(path)
     }
 
-    fn is_directory(&self, path: &Path) -> bool {
-        info!("is_directory({:?})", path);
-        self.0.is_directory(path)
-    }
-
     fn watch_path_for_changes(&self, path: &Path) -> Result<(), AssetIoError> {
         info!("watch_path_for_changes({:?})", path);
         self.0.watch_path_for_changes(path)
@@ -40,6 +35,11 @@ impl AssetIo for CustomAssetIo {
         info!("watch_for_changes()");
         self.0.watch_for_changes()
     }
+
+    fn get_metadata(&self, path: &Path) -> Result<Metadata, AssetIoError> {
+        info!("get_metadata({:?})", path);
+        self.0.get_metadata(path)
+    }
 }
 
 /// A plugin used to execute the override of the asset io