refactor(natu): rename xatu

src/natu/rules/let_order.rs

@@ -0,0 +1,71 @@
+use crate::{
+    ast,
+    scope_graph::{LetScope, NodeId, ScopeGraph},
+};
+
+pub struct Finding {
+    pub range: ast::SourceRange,
+    pub binding: String,
+}
+
+pub fn check(graph: &ScopeGraph) -> Vec<Finding> {
+    graph
+        .let_scopes()
+        .iter()
+        .flat_map(|let_scope| {
+            let expected = expected_order(graph, let_scope);
+            let positions = expected
+                .iter()
+                .enumerate()
+                .map(|(position, declaration)| (*declaration, position))
+                .collect::<Vec<_>>();
+
+            let_scope
+                .bindings
+                .iter()
+                .enumerate()
+                .filter_map(move |(position, binding)| {
+                    positions
+                        .iter()
+                        .find(|(declaration, _)| *declaration == binding.declaration)
+                        .filter(|(_, expected_position)| position != *expected_position)
+                        .map(|_| Finding {
+                            range: binding.range,
+                            binding: binding.name.clone(),
+                        })
+                })
+        })
+        .collect()
+}
+
+fn expected_order(graph: &ScopeGraph, let_scope: &LetScope) -> Vec<NodeId> {
+    let mut order = Vec::new();
+    visit_references(graph, &let_scope.entry_references, let_scope, &mut order);
+    order
+}
+
+fn visit_references(
+    graph: &ScopeGraph,
+    references: &[NodeId],
+    let_scope: &LetScope,
+    order: &mut Vec<NodeId>,
+) {
+    for reference in references {
+        for declaration in graph.resolve(*reference) {
+            let Some(binding) = let_scope
+                .bindings
+                .iter()
+                .find(|binding| binding.declaration == declaration)
+            else {
+                continue;
+            };
+
+            if order.contains(&declaration) {
+                continue;
+            }
+
+            order.push(declaration);
+            visit_references(graph, &binding.references, let_scope, order);
+        }
+    }
+}