feat(pathf): add build-time type path resolution system

Add `mingling_pathf` sub-crate and `pathf` feature for automatic
resolution of Mingling type module paths at build time. Scans source
files, identifies macro invocations via pattern matchers, and generates
mapping files consumed by `gen_program!()`.

1 files changed, 116 insertions, 0 deletions

diff --git a/mingling_pathf/src/patterns/dispatcher.rs b/mingling_pathf/src/patterns/dispatcher.rs
new file mode 100644
index 0000000..7bb076c
--- /dev/null
+++ b/mingling_pathf/src/patterns/dispatcher.rs
@@ -0,0 +1,116 @@
+use syn::Item;
+
+use crate::pattern_analyzer::{AnalyzeItem, AnalyzePattern};
+
+/// Matches the `dispatcher!` macro, extracts the entry type name.
+///
+/// Supported forms:
+/// - `dispatcher!("greet", CMDGreet => EntryGreet)` — explicit
+/// - `dispatcher!("greet")` — implicit, infers EntryType
+/// - `dispatcher! { ... }` — with braces
+pub struct DispatcherPattern;
+
+impl AnalyzePattern for DispatcherPattern {
+    fn contains(&self, content: &str) -> bool {
+        content.contains("dispatcher!")
+    }
+
+    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 {
+            match item {
+                Item::Macro(m) => {
+                    let macro_name = macro_simple_name(m);
+                    if macro_name != "dispatcher" {
+                        continue;
+                    }
+                    if let Some(entry_name) = extract_dispatcher_entry(&m.mac.tokens) {
+                        items.push(AnalyzeItem {
+                            module: String::new(),
+                            item_name: entry_name,
+                        });
+                    }
+                }
+                Item::Mod(item_mod) => {
+                    if let Some((_, nested)) = &item_mod.content {
+                        for n in nested {
+                            if let Item::Macro(m) = n {
+                                if macro_simple_name(m) != "dispatcher" {
+                                    continue;
+                                }
+                                if let Some(entry_name) = extract_dispatcher_entry(&m.mac.tokens) {
+                                    items.push(AnalyzeItem {
+                                        module: item_mod.ident.to_string(),
+                                        item_name: entry_name,
+                                    });
+                                }
+                            }
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        items
+    }
+}
+
+fn macro_simple_name(m: &syn::ItemMacro) -> String {
+    m.mac
+        .path
+        .segments
+        .last()
+        .map(|s| s.ident.to_string())
+        .unwrap_or_default()
+}
+
+/// Extracts the entry type name from the `dispatcher!` macro arguments.
+///
+/// Input examples:
+/// - `"greet", CMDGreet => EntryGreet` → `EntryGreet`
+/// - `"remote.add"` → `EntryRemoteAdd` (implicit inference)
+fn extract_dispatcher_entry(tokens: &proc_macro2::TokenStream) -> Option<String> {
+    let stream = tokens.to_string();
+
+    // Explicit form: look for `=>`
+    if let Some(arrow_idx) = stream.find("=>") {
+        let after_arrow = stream[arrow_idx + 2..].trim();
+        let entry_name = after_arrow
+            .split(|c: char| c.is_whitespace() || c == ',' || c == ')' || c == '}')
+            .next()?;
+        if !entry_name.is_empty() {
+            return Some(entry_name.trim().to_string());
+        }
+    }
+
+    // Implicit form: infer from command name
+    let stream = stream.trim();
+    if let Some(start) = stream.find('"') {
+        let rest = &stream[start + 1..];
+        let cmd_name = rest.split('"').next()?;
+        let last_segment = cmd_name.split('.').next_back()?;
+        let entry = format!("Entry{}", to_pascal_case(last_segment));
+        Some(entry)
+    } else {
+        None
+    }
+}
+
+fn to_pascal_case(s: &str) -> String {
+    s.split(['-', '_', '.'])
+        .filter(|s| !s.is_empty())
+        .map(|s| {
+            let mut c = s.chars();
+            match c.next() {
+                None => String::new(),
+                Some(f) => f.to_uppercase().collect::<String>() + c.as_str(),
+            }
+        })
+        .collect()
+}