Reuse oak_core's is_r_file()

Author: lionel-

Cargo.lock

@@ -1,6 +1,13 @@
 use std::path::Path;
 use std::path::PathBuf;
 
+/// Does this path's name look like an R file (`.R` / `.r` extension)?
+///
+/// Pure name test, no I/O. It doesn't touch the filesystem, so it says
+/// nothing about whether the path exists or is a regular file. A
+/// directory named `foo.R` passes, and so does a path that isn't on disk
+/// at all. Callers that walk a real directory and want to skip such cases
+/// must check `path.is_file()` themselves.
 pub fn is_r_file(path: &Path) -> bool {
     path.extension()
         .and_then(|e| e.to_str())

crates/oak_core/src/file.rs

@@ -3,3 +3,5 @@ pub mod file;
 pub mod identifier;
 pub mod range;
 pub mod syntax_ext;
+
+pub use file::is_r_file;

crates/oak_core/src/lib.rs

@@ -18,6 +18,7 @@ workspace = true
 [dependencies]
 aether_url.workspace = true
 log.workspace = true
+oak_core.workspace = true
 oak_db.workspace = true
 oak_package_metadata.workspace = true
 salsa.workspace = true

crates/oak_scan/Cargo.toml

@@ -107,11 +107,5 @@ fn scan_r_files(r_dir: &Path) -> Vec<FileEntry> {
 }
 
 fn is_r_file(path: &Path) -> bool {
-    if !path.is_file() {
-        return false;
-    }
-    let Some(ext) = path.extension() else {
-        return false;
-    };
-    ext.eq_ignore_ascii_case("r")
+    path.is_file() && oak_core::is_r_file(path)
 }