1 files changed, 72 insertions, 0 deletions
diff --git a/mingling_pathf/src/patterns/chain.rs b/mingling_pathf/src/patterns/chain.rs
new file mode 100644
index 0000000..10d698e
--- /dev/null
+++ b/mingling_pathf/src/patterns/chain.rs
@@ -0,0 +1,72 @@
+use syn::Item;
+
+use crate::pattern_analyzer::{AnalyzeItem, AnalyzePattern};
+
+/// Match `#[chain]` functions, extract the generated internal struct name.
+///
+/// `#[chain] fn handle_greet(...)` → `__internal_chain_handle_greet`
+///
+/// Covered forms:
+/// - `#[chain] fn handle(args: EntryType) -> Next { ... }`
+/// - `#[chain] fn handle(args: EntryType, res: &mut Res) -> Next { ... }`
+/// - async version
+pub struct ChainPattern;
+
+impl AnalyzePattern for ChainPattern {
+    fn contains(&self, content: &str) -> bool {
+        content.contains("chain]")
+    }
+
+    fn analyze(&self, content: &str) -> Vec<AnalyzeItem> {
+        let Ok(syntax) = syn::parse_file(content) else {
+            return Vec::new();
+        };
+
+        let mut items = Vec::new();
+
+        for item in &syntax.items {
+            collect_from_item(item, "", &mut items);
+        }
+
+        items
+    }
+}
+
+fn internal_name(fn_name: &str) -> String {
+    format!("__internal_chain_{fn_name}")
+}
+
+fn collect_from_item(item: &Item, current_mod: &str, items: &mut Vec<AnalyzeItem>) {
+    match item {
+        Item::Fn(f) if has_attr(&f.attrs, "chain") => {
+            let fn_name = f.sig.ident.to_string();
+            items.push(AnalyzeItem {
+                module: current_mod.to_string(),
+                item_name: internal_name(&fn_name),
+            });
+        }
+        Item::Mod(item_mod) => {
+            if let Some((_, nested)) = &item_mod.content {
+                let mod_name = &item_mod.ident.to_string();
+                let nested_mod = if current_mod.is_empty() {
+                    mod_name.clone()
+                } else {
+                    format!("{current_mod}::{mod_name}")
+                };
+                for n in nested {
+                    collect_from_item(n, &nested_mod, items);
+                }
+            }
+        }
+        _ => {}
+    }
+}
+
+fn has_attr(attrs: &[syn::Attribute], name: &str) -> bool {
+    attrs.iter().any(|a| {
+        a.path()
+            .segments
+            .last()
+            .is_some_and(|s| s.ident == name)
+    })
+}