Add no-detach option

src/args.rs

@@ -63,6 +63,9 @@ pub struct Args {
     #[structopt(long)]
     pub no_confirm: bool,
 
+    #[structopt(long)]
+    pub no_detach: bool,
+
     /// Comma separated values of [all, merged, gone, local, remote, merged-local, merged-remote, gone-local, gone-remote].
     /// 'all' is equivalent to 'merged-local,merged-remote,gone-local,gone-remote'.
     /// 'merged' is equivalent to 'merged-local,merged-remote'.

src/lib.rs

@@ -56,12 +56,34 @@ pub struct MergedOrGone {
     pub merged_locals: HashSet<String>,
     pub gone_locals: HashSet<String>,
 
+    pub kept_back_locals: HashSet<String>,
+
     /// remote refs
     pub merged_remotes: HashSet<String>,
     pub gone_remotes: HashSet<String>,
 }
 
 impl MergedOrGone {
+    pub fn adjust_not_to_detach(&mut self, repo: &Repository) -> Result<()> {
+        if repo.head_detached()? {
+            return Ok(());
+        }
+        let head = repo.head()?;
+        let head_name = head.name().ok_or("non-utf8 head ref name")?;
+        assert!(head_name.starts_with("refs/heads/"));
+        let head_name = &head_name["refs/heads/".len()..];
+
+        if self.merged_locals.contains(head_name) {
+            self.merged_locals.remove(head_name);
+            self.kept_back_locals.insert(head_name.to_string());
+        }
+        if self.gone_locals.contains(head_name) {
+            self.gone_locals.remove(head_name);
+            self.kept_back_locals.insert(head_name.to_string());
+        }
+        Ok(())
+    }
+
     pub fn print_summary(&self, filter: &DeleteFilter) {
         fn print(branches: &HashSet<String>, filter: &DeleteFilter, category: Category) {
             if filter.contains(&category) && !branches.is_empty() {
@@ -78,6 +100,14 @@ impl MergedOrGone {
         }
         print(&self.merged_locals, filter, Category::MergedLocal);
         print(&self.merged_remotes, filter, Category::MergedRemote);
+
+        if !self.kept_back_locals.is_empty() {
+            println!("Kept back not to become detached HEAD:");
+            for branch in &self.kept_back_locals {
+                println!("  {}", branch);
+            }
+        }
+
         print(&self.gone_locals, filter, Category::GoneLocal);
         print(&self.gone_remotes, filter, Category::GoneRemote);
     }
@@ -370,17 +400,36 @@ fn resolve_config_base_ref(repo: &Repository, base: &str) -> Result<String> {
         .to_string())
 }
 
-pub fn delete_local_branches(branches: &[&str], dry_run: bool) -> Result<()> {
+pub fn delete_local_branches(repo: &Repository, branches: &[&str], dry_run: bool) -> Result<()> {
     if branches.is_empty() {
         return Ok(());
     }
     let mut args = vec!["branch", "--delete", "--force"];
     args.extend(branches);
+
+    let detach_to = if repo.head_detached()? {
+        None
+    } else {
+        let head = repo.head()?;
+        let head_name = head.name().ok_or("non-utf8 head ref name")?;
+        if branches.contains(&head_name) {
+            Some(head_name.to_string())
+        } else {
+            None
+        }
+    };
+
     if dry_run {
+        if let Some(detach_to) = detach_to {
+            println!("Note: switching to '{}' (dry run)", detach_to);
+        }
         for branch in branches {
             println!("Delete branch {} (dry run).", branch);
         }
     } else {
+        if let Some(detach_to) = detach_to {
+            git(&["checkout", &detach_to])?;
+        }
         git(&args)?;
     }
     Ok(())
@@ -422,7 +471,7 @@ fn get_remote_name_and_ref_on_remote(
         let remote_name = remote_name.ok_or("non-utf8 remote name")?;
         let remote = repo.find_remote(&remote_name)?;
         for refspec in remote.refspecs() {
-            if let Direction::Fetch = refspec.direction() {
+            if let Direction::Push = refspec.direction() {
                 continue;
             }
             let src = refspec.src().ok_or("non-utf8 src dst")?;

src/main.rs

@@ -21,7 +21,11 @@ fn main(args: Args) -> ::std::result::Result<(), Box<dyn std::error::Error>> {
 
     let repo = Repository::open_from_env()?;
     let base = get_config_base(&repo, args.base)?;
-    let branches = get_merged_or_gone(&repo, &base)?;
+    let mut branches = get_merged_or_gone(&repo, &base)?;
+
+    if args.no_detach {
+        branches.adjust_not_to_detach(&repo)?;
+    }
 
     branches.print_summary(&args.delete);
 
@@ -36,6 +40,7 @@ fn main(args: Args) -> ::std::result::Result<(), Box<dyn std::error::Error>> {
     }
 
     delete_local_branches(
+        &repo,
         &branches.get_local_branches_to_delete(&args.delete),
         args.dry_run,
     )?;