Walk all commits reachable from a refspec

src/git/mod.rs

@@ -24,3 +24,14 @@ pub fn fetch_or_find(repo: &str) -> eyre::Result<gix::Repository> {
         Ok(repo)
     }
 }
+
+pub fn walk_reference<'w>(
+    reference: &str,
+    repo: &'w gix::Repository,
+) -> eyre::Result<gix::revision::Walk<'w>> {
+    let reference = repo.find_reference(reference)?;
+    let revision = reference.id();
+    let platform = repo.rev_walk([revision]);
+    let walk = platform.all()?;
+    Ok(walk)
+}

src/main.rs

@@ -10,6 +10,11 @@ struct CliArgs {
     /// A path to a work tree or bare repository, or a clone URL
     repository: String,
 
+    /// The branch to search for achievements
+    ///
+    /// Technically, this argument is allowed to be any refspec, remote or local.
+    branch: String,
+
     /// Set the application log level
     ///
     /// You can also set the value of the HEROSTRATUS_LOG environment variable like so
@@ -30,7 +35,11 @@ fn main() -> eyre::Result<()> {
         .from_env_lossy();
     tracing_subscriber::fmt().with_env_filter(filter).init();
 
-    let _repo = git::fetch_or_find(&args.repository)?;
+    let repo = git::fetch_or_find(&args.repository)?;
+    let _walk = match git::walk_reference(&args.branch, &repo) {
+        Ok(w) => w,
+        Err(e) => return Err(e.wrap_err(format!("Could not walk reference '{}'", args.branch))),
+    };
 
     Ok(())
 }