Add mounter abstraction, enable minimal GVfs support

src/mounter/mod.rs

@@ -0,0 +1,33 @@
+use cosmic::widget;
+use std::error::Error;
+use std::{collections::BTreeMap, path::PathBuf, sync::Arc};
+
+#[cfg(feature = "gvfs")]
+mod gvfs;
+
+pub trait MounterItem {
+    fn name(&self) -> String;
+    fn icon(&self, size: u16) -> widget::icon::Handle;
+    fn path(&self) -> Option<PathBuf>;
+}
+
+pub type MounterItems = Vec<Box<dyn MounterItem>>;
+
+pub trait Mounter {
+    fn items(&self) -> Result<MounterItems, Box<dyn Error>>;
+}
+
+pub type MounterKey = &'static str;
+pub type MounterMap = BTreeMap<MounterKey, Box<dyn Mounter>>;
+pub type Mounters = Arc<MounterMap>;
+
+pub fn mounters() -> Mounters {
+    let mut mounters = MounterMap::new();
+
+    #[cfg(feature = "gvfs")]
+    {
+        mounters.insert("gvfs", Box::new(gvfs::Gvfs::new()));
+    }
+
+    Mounters::new(mounters)
+}