Implement a version control component for the statusline

book/src/configuration.md

@@ -110,6 +110,7 @@ The following statusline elements can be configured:
 | `position-percentage` | The cursor position as a percentage of the total number of lines |
 | `separator` | The string defined in `editor.statusline.separator` (defaults to `"│"`) |
 | `spacer` | Inserts a space between elements (multiple/contiguous spacers may be specified) |
+| `version-control` | The current branch name or detached commit hash of the opened workspace |
 
 ### `[editor.lsp]` Section
 

helix-term/src/ui/statusline.rs

@@ -1,4 +1,4 @@
-use helix_core::{coords_at_pos, encoding, Position};
+use helix_core::{coords_at_pos, encoding, find_root, Position};
 use helix_lsp::lsp::DiagnosticSeverity;
 use helix_view::{
     document::{Mode, SCRATCH_BUFFER_NAME},
@@ -155,6 +155,7 @@ where
         helix_view::editor::StatusLineElement::TotalLineNumbers => render_total_line_numbers,
         helix_view::editor::StatusLineElement::Separator => render_separator,
         helix_view::editor::StatusLineElement::Spacer => render_spacer,
+        helix_view::editor::StatusLineElement::VersionControl => render_version_control,
     }
 }
 
@@ -466,3 +467,18 @@ where
 {
     write(context, String::from(" "), None);
 }
+
+fn render_version_control<F>(context: &mut RenderContext, write: F)
+where
+    F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
+{
+    let path = find_root(None, &[]);
+
+    let current_branch_name = context
+        .editor
+        .diff_providers
+        .get_current_head_name(&path)
+        .unwrap_or_default();
+
+    write(context, current_branch_name, None);
+}

helix-vcs/src/git.rs

@@ -88,6 +88,18 @@ impl DiffProvider for Git {
         }
         Some(data)
     }
+
+    fn get_current_head_name(&self, file: &Path) -> Option<String> {
+        // TODO cache repository lookup
+        let repo = Git::open_repo(file, None)?.to_thread_local();
+        let head_ref = repo.head_ref().ok()?;
+        let head_commit = repo.head_commit().ok()?;
+
+        match head_ref {
+            Some(reference) => Some(reference.name().shorten().to_string()),
+            None => Some(head_commit.id.to_hex_with_len(8).to_string()),
+        }
+    }
 }
 
 /// Finds the object that contains the contents of a file at a specific commit.

helix-vcs/src/lib.rs

@@ -18,6 +18,7 @@ pub trait DiffProvider {
     /// The data is returned as raw byte without any decoding or encoding performed
     /// to ensure all file encodings are handled correctly.
     fn get_diff_base(&self, file: &Path) -> Option<Vec<u8>>;
+    fn get_current_head_name(&self, file: &Path) -> Option<String>;
 }
 
 #[doc(hidden)]
@@ -26,6 +27,10 @@ impl DiffProvider for Dummy {
     fn get_diff_base(&self, _file: &Path) -> Option<Vec<u8>> {
         None
     }
+
+    fn get_current_head_name(&self, _file: &Path) -> Option<String> {
+        None
+    }
 }
 
 pub struct DiffProviderRegistry {
@@ -38,6 +43,12 @@ impl DiffProviderRegistry {
             .iter()
             .find_map(|provider| provider.get_diff_base(file))
     }
+
+    pub fn get_current_head_name(&self, file: &Path) -> Option<String> {
+        self.providers
+            .iter()
+            .find_map(|provider| provider.get_current_head_name(file))
+    }
 }
 
 impl Default for DiffProviderRegistry {

helix-view/src/editor.rs

@@ -445,6 +445,9 @@ pub enum StatusLineElement {
 
     /// A single space
     Spacer,
+
+    /// Current version control information
+    VersionControl,
 }
 
 // Cursor shape is read and used on every rendered frame and so needs