Add Buffer::outline method

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/outline/src/outline.rs

@@ -0,0 +1,53 @@
+use editor::{display_map::ToDisplayPoint, Autoscroll, Editor, EditorSettings};
+use gpui::{
+    action, elements::*, geometry::vector::Vector2F, keymap::Binding, Axis, Entity,
+    MutableAppContext, RenderContext, View, ViewContext, ViewHandle,
+};
+use postage::watch;
+use std::sync::Arc;
+use text::{Bias, Point, Selection};
+use workspace::{Settings, Workspace};
+
+action!(Toggle);
+action!(Confirm);
+
+pub fn init(cx: &mut MutableAppContext) {
+    cx.add_bindings([
+        Binding::new("cmd-shift-O", Toggle, Some("Editor")),
+        Binding::new("escape", Toggle, Some("GoToLine")),
+        Binding::new("enter", Confirm, Some("GoToLine")),
+    ]);
+    cx.add_action(OutlineView::toggle);
+    cx.add_action(OutlineView::confirm);
+}
+
+struct OutlineView {}
+
+impl Entity for OutlineView {
+    type Event = ();
+}
+
+impl View for OutlineView {
+    fn ui_name() -> &'static str {
+        "OutlineView"
+    }
+
+    fn render(&mut self, cx: &mut RenderContext<'_, Self>) -> ElementBox {
+        todo!()
+    }
+}
+
+impl OutlineView {
+    fn toggle(workspace: &mut Workspace, _: &Toggle, cx: &mut ViewContext<Workspace>) {
+        let editor = workspace
+            .active_item(cx)
+            .unwrap()
+            .to_any()
+            .downcast::<Editor>()
+            .unwrap();
+        let buffer = editor.read(cx).buffer().read(cx);
+        dbg!(buffer.read(cx).outline());
+    }
+
+    fn confirm(&mut self, _: &Confirm, cx: &mut ViewContext<Self>) {}
+}