feat(xatu): add lint architecture

src/xatu/file_store.rs

@@ -0,0 +1,33 @@
+use std::path::PathBuf;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FileId(usize);
+
+#[derive(Debug)]
+pub struct SourceFile {
+    pub path: PathBuf,
+    pub source: String,
+}
+
+#[derive(Debug, Default)]
+pub struct FileStore {
+    files: Vec<SourceFile>,
+}
+
+impl FileStore {
+    pub fn add(&mut self, file: SourceFile) -> FileId {
+        let id = FileId(self.files.len());
+        self.files.push(file);
+        id
+    }
+
+    pub fn get(&self, id: FileId) -> &SourceFile {
+        &self.files[id.0]
+    }
+}
+
+impl From<Vec<SourceFile>> for FileStore {
+    fn from(files: Vec<SourceFile>) -> Self {
+        Self { files }
+    }
+}