[tui] Add ComponentOf trait.

I think it will help with fetching a component by type from the
Components vector attached to App?

src/tui/app.rs

@@ -24,6 +24,59 @@ pub enum AppComponents<'a> {
     AppComponent(Box<dyn Component>),
 }
 
+/// Usage: get_component_mut::<Editor>() OR get_component::<Editor>()
+///
+/// Implementing this trait for each AppComponent allows for easy lookup in the vector.
+trait ComponentOf<T> {
+    fn as_ref(&self) -> Option<&T>;
+    fn as_mut(&mut self) -> Option<&mut T>;
+}
+
+impl<'a> ComponentOf<Logger> for AppComponents<'a> {
+    fn as_ref(&self) -> Option<&Logger> {
+        if let AppComponents::AppLogger(ref e) = *self {
+            return Some(e);
+        }
+        None
+    }
+    fn as_mut(&mut self) -> Option<&mut Logger> {
+        if let AppComponents::AppLogger(ref mut e) = *self {
+            return Some(e);
+        }
+        None
+    }
+}
+
+impl<'a> ComponentOf<Editor> for AppComponents<'a> {
+    fn as_ref(&self) -> Option<&Editor> {
+        if let AppComponents::AppEditor(ref e) = *self {
+            return Some(e);
+        }
+        None
+    }
+    fn as_mut(&mut self) -> Option<&mut Editor> {
+        if let AppComponents::AppEditor(ref mut e) = *self {
+            return Some(e);
+        }
+        None
+    }
+}
+
+impl<'a> ComponentOf<Explorer<'a>> for AppComponents<'a> {
+    fn as_ref(&self) -> Option<&Explorer<'a>> {
+        if let AppComponents::AppExplorer(ref e) = *self {
+            return Some(e);
+        }
+        None
+    }
+    fn as_mut(&mut self) -> Option<&mut Explorer<'a>> {
+        if let AppComponents::AppExplorer(ref mut e) = *self {
+            return Some(e);
+        }
+        None
+    }
+}
+
 pub struct App<'a> {
     components: Vec<AppComponents<'a>>,
 }
@@ -37,7 +90,7 @@ impl<'a> App<'a> {
                 AppComponents::AppLogger(Logger::new()),
             ],
         };
-        app.get_editor_mut()
+        app.get_component_mut::<Editor>()
             .unwrap()
             .set_contents(&root_path.join("src/tui/app.rs"))
             .context(format!(
@@ -47,44 +100,18 @@ impl<'a> App<'a> {
         Ok(app)
     }
 
-    fn get_explorer(&self) -> Result<&Explorer<'a>> {
-        for component in &self.components {
-            if let AppComponents::AppExplorer(explorer) = component {
-                return Ok(explorer);
-            }
-        }
-        bail!("Failed to find project explorer widget.")
+    fn get_component<T>(&self) -> Option<&T>
+    where
+        AppComponents<'a>: ComponentOf<T>,
+    {
+        self.components.iter().find_map(|c| c.as_ref())
     }
 
-    fn get_explorer_mut(&mut self) -> Result<&mut Explorer<'a>> {
-        for component in &mut self.components {
-            if let AppComponents::AppExplorer(explorer) = component {
-                return Ok(explorer);
-            }
-        }
-        bail!("Failed to find project explorer widget.")
-    }
-
-    fn get_editor(&self) -> Option<&Editor> {
-        for component in &self.components {
-            if let AppComponents::AppEditor(editor) = component {
-                return Some(editor);
-            }
-        }
-
-        // There is no editor currently opened.
-        None
-    }
-
-    fn get_editor_mut(&mut self) -> Option<&mut Editor> {
-        for component in &mut self.components {
-            if let AppComponents::AppEditor(editor) = component {
-                return Some(editor);
-            }
-        }
-
-        // There is no editor currently opened.
-        None
+    fn get_component_mut<T>(&mut self) -> Option<&mut T>
+    where
+        AppComponents<'a>: ComponentOf<T>,
+    {
+        self.components.iter_mut().find_map(|c| c.as_mut())
     }
 
     pub fn run(mut self, mut terminal: DefaultTerminal) -> Result<()> {
@@ -121,7 +148,7 @@ impl<'a> App<'a> {
     fn draw_tabs(&self, area: Rect, buf: &mut Buffer) {
         // Determine the tab title from the current file (or use a fallback).
         let mut title: Option<&str> = None;
-        if let Some(editor) = self.get_editor() {
+        if let Some(editor) = self.get_component::<Editor>() {
             title = editor
                 .file_path
                 .as_ref()
@@ -144,12 +171,12 @@ impl<'a> App<'a> {
     /// If the selected item is not a file, this does nothing.
     fn refresh_editor_contents(&mut self) -> Result<()> {
         // Use the currently selected TreeItem or get an absolute path to this source file.
-        let selected_pathbuf = match self.get_explorer()?.selected() {
+        let selected_pathbuf = match self.get_component::<Explorer>().unwrap().selected() {
             Ok(path) => PathBuf::from(path),
             Err(_) => PathBuf::from(std::path::absolute(file!())?.to_string_lossy().to_string()),
         };
         let editor = self
-            .get_editor_mut()
+            .get_component_mut::<Editor>()
             .context("Failed to get active editor while refreshing contents.")?;
         if let Some(current_file_path) = editor.file_path.clone() {
             if selected_pathbuf == current_file_path || !selected_pathbuf.is_file() {
@@ -194,15 +221,15 @@ impl<'a> Widget for &mut App<'a> {
 
         self.draw_status(vertical[0], buf);
         self.draw_tabs(editor_layout[0], buf);
+        let id = self.id().to_string();
         for component in &mut self.components {
             match component {
                 AppComponents::AppEditor(editor) => editor.render(editor_layout[1], buf),
                 AppComponents::AppExplorer(explorer) => {
-                    // TODO: What to do about errors during rendering?
-                    // Once there is a debug console, maybe log it and discard? Panic isn't great.
                     explorer
                         .render(horizontal[0], buf)
-                        .expect("Failed to render Explorer");
+                        .context("Failed to render Explorer")
+                        .unwrap_or_else(|e| error!(target:id.as_str(), "{}", e));
                 }
                 AppComponents::AppLogger(logger) => logger.render(vertical[2], buf),
                 AppComponents::AppComponent(_) => {}