add shallow_find_files helper to run_make_support

Author: Oneirical

src/tools/run-make-support/src/lib.rs

@@ -261,6 +261,40 @@ pub fn test_while_readonly<P: AsRef<Path>, F: FnOnce() + std::panic::UnwindSafe>
     success.unwrap();
 }
 
+/// Browse the directory `path` non-recursively and return all files which respect the parameters
+/// outlined by `closure`.
+#[track_caller]
+pub fn shallow_find_files<P: AsRef<Path>, F: Fn(&PathBuf) -> bool>(
+    path: P,
+    closure: F,
+) -> Vec<PathBuf> {
+    let mut matching_files = Vec::new();
+    for entry in fs_wrapper::read_dir(path) {
+        let entry = entry.expect("failed to read directory entry.");
+        let path = entry.path();
+
+        if path.is_file() && closure(&path) {
+            matching_files.push(path);
+        }
+    }
+    matching_files
+}
+
+/// Returns true if the filename at `path` starts with `prefix`.
+pub fn has_prefix<P: AsRef<Path>>(path: P, prefix: &str) -> bool {
+    path.as_ref().file_name().is_some_and(|name| name.to_str().unwrap().starts_with(prefix))
+}
+
+/// Returns true if the filename at `path` has the extension `extension`.
+pub fn has_extension<P: AsRef<Path>>(path: P, extension: &str) -> bool {
+    path.as_ref().extension().is_some_and(|ext| ext == extension)
+}
+
+/// Returns true if the filename at `path` is not in `expected`.
+pub fn name_not_among<P: AsRef<Path>>(path: P, expected: &[&'static str]) -> bool {
+    path.as_ref().file_name().is_some_and(|name| !expected.contains(&name.to_str().unwrap()))
+}
+
 /// Use `cygpath -w` on a path to get a Windows path string back. This assumes that `cygpath` is
 /// available on the platform!
 #[track_caller]