Add support for extension sort.

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 ## [Unreleased] - ReleaseDate
+### Added
+- Add support for `--extensionsort` `-X` from [aldhsu](https://github.com/aldhsu)
 
 ## [0.18.0] - 2020-08-29
 ### Added

src/app.rs

@@ -154,6 +154,13 @@ pub fn build() -> App<'static, 'static> {
                 .multiple(true)
                 .help("Sort by size"),
         )
+        .arg(
+            Arg::with_name("extensionsort")
+                .short("X")
+                .long("extensionsort")
+                .multiple(true)
+                .help("Sort by file extension"),
+        )
         .arg(
             Arg::with_name("reverse")
                 .short("r")

src/flags.rs

@@ -58,6 +58,8 @@ impl Flags {
             SortFlag::Time
         } else if matches.is_present("sizesort") {
             SortFlag::Size
+        } else if matches.is_present("extensionsort") {
+            SortFlag::Extension
         } else {
             SortFlag::Name
         };
@@ -306,6 +308,7 @@ pub enum SortFlag {
     Name,
     Time,
     Size,
+    Extension,
 }
 
 #[derive(Clone, Debug, Copy, PartialEq, Eq)]

src/sort.rs

@@ -19,6 +19,7 @@ pub fn assemble_sorters(flags: &Flags) -> Vec<(SortOrder, SortFn)> {
         SortFlag::Name => by_name,
         SortFlag::Size => by_size,
         SortFlag::Time => by_date,
+        SortFlag::Extension => by_extension,
     };
     sorters.push((flags.sort_order, other_sort));
     sorters
@@ -55,6 +56,10 @@ fn by_date(a: &Meta, b: &Meta) -> Ordering {
     b.date.cmp(&a.date).then(a.name.cmp(&b.name))
 }
 
+fn by_extension(a: &Meta, b: &Meta) -> Ordering {
+    a.name.extension().cmp(&b.name.extension())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -220,4 +225,42 @@ mod tests {
         let sorter = assemble_sorters(&flags);
         assert_eq!(by_meta(&sorter, &meta_a, &meta_z), Ordering::Greater);
     }
+
+    #[test]
+    fn test_sort_assemble_sorters_by_extension() {
+        let tmp_dir = tempdir().expect("failed to create temp dir");
+
+        // Create the file with rs extension;
+        let path_a = tmp_dir.path().join("aaa.rs");
+        File::create(&path_a).expect("failed to create file");
+        let meta_a = Meta::from_path(&path_a, false).expect("failed to get meta");
+
+        // Create the file with rs extension;
+        let path_z = tmp_dir.path().join("zzz.rs");
+        File::create(&path_z).expect("failed to create file");
+        let meta_z = Meta::from_path(&path_z, false).expect("failed to get meta");
+
+        // Create the file with js extension;
+        let path_j = tmp_dir.path().join("zzz.js");
+        File::create(&path_j).expect("failed to create file");
+        let meta_j = Meta::from_path(&path_j, false).expect("failed to get meta");
+
+        // Create the file with txt extension;
+        let path_t = tmp_dir.path().join("zzz.txt");
+        File::create(&path_t).expect("failed to create file");
+        let meta_t = Meta::from_path(&path_t, false).expect("failed to get meta");
+
+        let mut flags = Flags::default();
+        flags.sort_by = SortFlag::Extension;
+
+        // Sort by extension
+        let sorter = assemble_sorters(&flags);
+        assert_eq!(by_meta(&sorter, &meta_a, &meta_z), Ordering::Equal);
+
+        let sorter = assemble_sorters(&flags);
+        assert_eq!(by_meta(&sorter, &meta_a, &meta_j), Ordering::Greater);
+
+        let sorter = assemble_sorters(&flags);
+        assert_eq!(by_meta(&sorter, &meta_a, &meta_t), Ordering::Less);
+    }
 }