Altered directory api for optimisations when -t is not specified

src/directory.rs

@@ -31,14 +31,18 @@ impl Directory {
         // NOTE: I go back and forth on canonicalize()ing all the time.
         // I feel like it changes every commit. The performance loss seems
         // to be negligible, even when I do crazy things like `hb -p /`
-        let name = match path.canonicalize() {
+        let name = if args.tree() {
-            Ok(path) => path,
+            match path.canonicalize() {
-            Err(_) if args.persistant() => return Ok(None),
+                Ok(path) => path,
-            Err(e) => return Err(e.into()),
+                Err(_) if args.persistant() => return Ok(None),
-        }
+                Err(e) => return Err(e.into()),
-            .file_name()
+            }
-            .map_or_else(|| OsString::from("/"), ToOwned::to_owned)
+                .file_name()
-            .into();
+                .map_or_else(|| OsString::from("/"), ToOwned::to_owned)
+                .into()
+        } else {
+            PathBuf::new()
+        };
 
         // symlink_metadata() is the same as metadata() but it doesn't
         // traverse symlinks, so that we can exclude them if necessary
@@ -94,7 +98,7 @@ impl Directory {
                     (Err(e), false) => return Err(e),
                 };
                 size += dir.size;
-                if args.should_print(dir.path()) {
+                if args.tree() && args.should_print(dir.path()) {
                     // since size was increased, this just prevents
                     // the directory from appearing in printing
                     children.push(dir);
@@ -109,7 +113,7 @@ impl Directory {
         .try_reduce(
             || (0, Vec::new()),
             |(asize, mut avec), (bsize, bvec)| {
-                avec.extend(bvec);
+                if args.tree() { avec.extend(bvec); }
                 Result::Ok((asize + bsize, avec))
             }
         ) {

src/main.rs

@@ -4,16 +4,29 @@ mod args;
 mod directory;
 mod unit;
 
+use clap::Parser;
+
 use args::Args;
 use directory::Directory;
+use rayon::ThreadPoolBuilder;
 
 use std::process::ExitCode;
 
 fn main() -> ExitCode {
-    let args = Args::parse_and_process();
+    let args = Args::parse().post_process();
+
+    match ThreadPoolBuilder::new().num_threads(args.threads()).build_global() {
+        Ok(()) => (),
+        Err(e) => {
+            if !args.minimal() && !args.quiet() {
+                eprintln!("hb: {e}");
+            }
+            return ExitCode::FAILURE;
+        }
+    };
 
     let mut total = 0;
-    for path in args.iter() {
+    for path in args.paths() {
         let dir_structure = match Directory::new(path, &args) {
             Ok(Some(ds)) => ds,
             // this only ever returns None when persistant,
@@ -39,7 +52,7 @@ fn main() -> ExitCode {
         } else {
             println!(
                 "{}: {}",
-                dir_structure.path().display(),
+                path,
                 args.unit().convert(dir_structure.size())
             );
         }