[red-knot] Merge the semantic and module-resolver crates (#12751)

crates/red_knot_python_semantic/src/module_resolver/mod.rs

@@ -0,0 +1,45 @@
+use std::iter::FusedIterator;
+
+pub(crate) use module::Module;
+pub use resolver::resolve_module;
+use ruff_db::system::SystemPath;
+pub use typeshed::vendored_typeshed_stubs;
+
+use crate::Db;
+use resolver::{module_resolution_settings, SearchPathIterator};
+
+mod module;
+mod path;
+mod resolver;
+mod state;
+mod typeshed;
+
+#[cfg(test)]
+mod testing;
+
+/// Returns an iterator over all search paths pointing to a system path
+pub fn system_module_search_paths(db: &dyn Db) -> SystemModuleSearchPathsIter {
+    SystemModuleSearchPathsIter {
+        inner: module_resolution_settings(db).search_paths(db),
+    }
+}
+
+pub struct SystemModuleSearchPathsIter<'db> {
+    inner: SearchPathIterator<'db>,
+}
+
+impl<'db> Iterator for SystemModuleSearchPathsIter<'db> {
+    type Item = &'db SystemPath;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            let next = self.inner.next()?;
+
+            if let Some(system_path) = next.as_system_path() {
+                return Some(system_path);
+            }
+        }
+    }
+}
+
+impl FusedIterator for SystemModuleSearchPathsIter<'_> {}