Expose filtering by file type in glob (#7834)

# Description

Add flags for filtering the output of `glob` by file type. I find myself
occasionally wanting to do this, and getting a file's
[file_type](https://docs.rs/wax/latest/wax/struct.WalkEntry.html#method.file_type)
is presumably fast to do as it doesn't have to go through the fallible
metadata method.

The design of the signature does concern me; it's not as readable as a
filter or "include" type list would be. They have to be filtered one by
one, which can be annoying if you only want files `-D -S`, or only want
folders `-F -S`, or only want symlinks `--butwhy?`. I considered
SyntaxShape::Keyword for this but I'll just defer to comments on this PR
if they pop up.

I'd also like to bring up performance since including these flags
technically incurs a `.filter` penalty on all glob calls, which could be
optimized out if we added a branch for the no-filters case. But in
reality I'd expect the file system to be the bottleneck and the flags to
be pretty branch predictor friendly, so eh

# User-Facing Changes
Three new flags when using `glob` and a slightly more cluttered help
page. No breaking changes, I hope.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/src/filesystem/glob.rs

@@ -26,6 +26,21 @@ impl Command for Glob {
                 "directory depth to search",
                 Some('d'),
             )
+            .switch(
+                "no-dir",
+                "Whether to filter out directories from the returned paths",
+                Some('D'),
+            )
+            .switch(
+                "no-file",
+                "Whether to filter out files from the returned paths",
+                Some('F'),
+            )
+            .switch(
+                "no-symlink",
+                "Whether to filter out symlinks from the returned paths",
+                Some('S'),
+            )
             .category(Category::FileSystem)
     }
 
@@ -81,6 +96,11 @@ impl Command for Glob {
                 example: "glob <[a-d]:1,10>",
                 result: None,
             },
+            Example {
+                description: "Search for folders that begin with an uppercase ASCII letter, ignoring files and symlinks",
+                example: r#"glob "[A-Z]*" --no-file --no-symlink"#,
+                result: None,
+            },
         ]
     }
 
@@ -100,6 +120,10 @@ impl Command for Glob {
         let glob_pattern: Spanned<String> = call.req(engine_state, stack, 0)?;
         let depth = call.get_flag(engine_state, stack, "depth")?;
 
+        let no_dirs = call.has_flag("no-dir");
+        let no_files = call.has_flag("no-file");
+        let no_symlinks = call.has_flag("no-symlink");
+
         if glob_pattern.item.is_empty() {
             return Err(ShellError::GenericError(
                 "glob pattern must not be empty".to_string(),
@@ -139,6 +163,13 @@ impl Command for Glob {
                 },
             )
             .flatten()
+            .filter(|entry| {
+                let file_type = entry.file_type();
+
+                !(no_dirs && file_type.is_dir()
+                    || no_files && file_type.is_file()
+                    || no_symlinks && file_type.is_symlink())
+            })
             .map(|entry| Value::String {
                 val: entry.into_path().to_string_lossy().to_string(),
                 span,

crates/nu-command/tests/commands/glob.rs

@@ -37,3 +37,84 @@ fn nonempty_glob_lists_matching_paths() {
         assert_eq!(actual.out, "3");
     })
 }
+
+#[test]
+fn glob_subdirs() {
+    Playground::setup("glob_subdirs", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("yehuda.txt"),
+            EmptyFile("jonathan.txt"),
+            EmptyFile("andres.txt"),
+        ]);
+        sandbox.mkdir("children");
+        sandbox.within("children").with_files(vec![
+            EmptyFile("timothy.txt"),
+            EmptyFile("tiffany.txt"),
+            EmptyFile("trish.txt"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline("glob '**/*' | length"),
+        );
+
+        assert_eq!(
+            actual.out, "8",
+            "count must be 8 due to 6 files and 2 folders, including the cwd"
+        );
+    })
+}
+
+#[test]
+fn glob_subdirs_ignore_dirs() {
+    Playground::setup("glob_subdirs_ignore_directories", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("yehuda.txt"),
+            EmptyFile("jonathan.txt"),
+            EmptyFile("andres.txt"),
+        ]);
+        sandbox.mkdir("children");
+        sandbox.within("children").with_files(vec![
+            EmptyFile("timothy.txt"),
+            EmptyFile("tiffany.txt"),
+            EmptyFile("trish.txt"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline("glob '**/*' -D | length"),
+        );
+
+        assert_eq!(
+            actual.out, "6",
+            "directory count must be 6, ignoring the cwd and the children folders"
+        );
+    })
+}
+
+#[test]
+fn glob_ignore_files() {
+    Playground::setup("glob_ignore_files", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("yehuda.txt"),
+            EmptyFile("jonathan.txt"),
+            EmptyFile("andres.txt"),
+        ]);
+        sandbox.mkdir("children");
+        sandbox.within("children").with_files(vec![
+            EmptyFile("timothy.txt"),
+            EmptyFile("tiffany.txt"),
+            EmptyFile("trish.txt"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(),
+            pipeline("glob '*' -F | length"),
+        );
+
+        assert_eq!(
+            actual.out, "1",
+            "should only find one folder; ignoring cwd, files, subfolders"
+        );
+    })
+}