Working example

src/project/loading/mod.rs

@@ -0,0 +1,61 @@
+mod file_loader;
+mod ext_loader;
+mod string_loader;
+mod map_loader;
+mod fnlib_loader;
+mod overlay_loader;
+mod prefix_loader;
+
+pub use file_loader::file_loader;
+pub use ext_loader::ext_loader;
+pub use fnlib_loader::fnlib_loader;
+pub use string_loader::string_loader;
+pub use map_loader::map_loader;
+pub use overlay_loader::overlay_loader;
+pub use prefix_loader::prefix_loader;
+
+use std::{rc::Rc, io};
+
+use crate::parse::FileEntry;
+
+#[derive(Clone, Debug)]
+pub enum LoadingError {
+  /// An IO operation has failed (i.e. no read permission)
+  IOErr(Rc<io::Error>),
+  /// The leaf does not exist
+  UnknownNode(String),
+  /// The leaf and at least the immediately containing namespace don't exist
+  Missing(String)
+}
+
+impl From<io::Error> for LoadingError {
+  fn from(inner: io::Error) -> Self {
+    LoadingError::IOErr(Rc::new(inner))
+  }
+}
+
+#[derive(Debug, Clone)]
+pub enum Loaded {
+  Module(String),
+  Namespace(Vec<String>),
+  External(Vec<FileEntry>)
+}
+
+pub trait Loader {
+  fn load<'s, 'a>(&'s mut self, path: &'a [&'a str]) -> Result<Loaded, LoadingError>;
+  fn boxed<'a>(self) -> Box<dyn 'a + Loader> where Self: 'a + Sized {
+    Box::new(self)
+  }
+}
+
+impl<T> Loader for T where T: for<'a> FnMut(&'a [&'a str]) -> Result<Loaded, LoadingError> {
+  fn load(&mut self, path: &[&str]) -> Result<Loaded, LoadingError> {
+    (self)(path)
+  }
+}
+
+impl Loader for Box<dyn Loader> {
+  fn load<'s, 'a>(&'s mut self, path: &'a [&'a str]) -> Result<Loaded, LoadingError> {
+    self.as_mut().load(path)
+  }
+}