feat(xatu): add lint architecture

src/xatu/rules.rs

@@ -0,0 +1,54 @@
+use crate::FileId;
+use crate::ast;
+use crate::rules::empty_inherit::EmptyInherit;
+
+pub mod empty_inherit;
+
+pub struct Finding {
+    pub rule_id: &'static str,
+    pub range: ast::SourceRange,
+    pub message: &'static str,
+}
+
+pub struct Diagnostic {
+    pub file_id: FileId,
+    pub finding: Finding,
+}
+
+pub trait NodeRule {
+    type Node;
+
+    const ID: &'static str;
+
+    fn select(data: &ast::NodeData) -> Option<&Self::Node>;
+    fn check(node: &Self::Node) -> Option<&'static str>;
+}
+
+fn run_node_rule<R>(node: &ast::Node) -> Option<Finding>
+where
+    R: NodeRule,
+{
+    let typed_node = R::select(&node.data)?;
+    let message = R::check(typed_node)?;
+
+    Some(Finding {
+        rule_id: R::ID,
+        range: node.range,
+        message,
+    })
+}
+
+pub fn run_rules(file: &ast::ParsedFile) -> Vec<Diagnostic> {
+    file.nodes
+        .iter()
+        .flat_map(|node| {
+            [run_node_rule::<EmptyInherit>(node)]
+                .into_iter()
+                .flatten()
+                .map(|finding| Diagnostic {
+                    file_id: file.file_id,
+                    finding,
+                })
+        })
+        .collect()
+}