Add `route!` macro for early error routing

3 files changed, 50 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f7a2ec2..582cbdb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -38,6 +38,42 @@ fn your_command_help(_prev: YourEntry) {
 }
 ```
 
+7. **\[macros\]** Added the `route!` macro, which allows quick error routing within the `chain!` function. Usage is as follows:
+
+```rust
+// Before
+#[chain]
+fn parse(prev: PickEntry) -> mingling::ChainProcess<ThisProgram> {
+    let picker = Picker::new(prev.inner);
+    let pick_result = picker
+        .pick_or_route((), NoNameProvided::default().to_render())
+        .unpack();
+
+    match pick_result {
+        Ok(name) => {
+            // use name here
+        }
+        Err(e) => {
+            // handle error route here
+            e
+        }
+    }
+}
+
+// After
+#[chain]
+fn parse(prev: PickEntry) -> mingling::ChainProcess<ThisProgram> {
+    let picker = Picker::new(prev.inner);
+    let name: String = route! {
+        picker
+            .pick_or_route((), NoNameProvided::default().to_render())
+            .unpack()
+    };
+
+    // use name here
+}
+```
+
 #### **BREAKING CHANGES**:
 
 1. **\[macros\]** Removed macro `dispatcher_render!` from `mingling_macros`
diff --git a/mingling/src/lib.rs b/mingling/src/lib.rs
index 7496d9d..afc8e90 100644
--- a/mingling/src/lib.rs
+++ b/mingling/src/lib.rs
@@ -113,6 +113,8 @@ pub mod macros {
     pub use mingling_macros::register_type;
     /// Used to generate a struct implementing the `Renderer` trait via a method
     pub use mingling_macros::renderer;
+    /// Used to generate a route that either returns a successful result or early returns an error.
+    pub use mingling_macros::route;
     #[cfg(feature = "comp")]
     /// Used to generate suggestions
     pub use mingling_macros::suggest;
diff --git a/mingling_macros/src/lib.rs b/mingling_macros/src/lib.rs
index f9be1de..cce5eeb 100644
--- a/mingling_macros/src/lib.rs
+++ b/mingling_macros/src/lib.rs
@@ -59,6 +59,18 @@ pub fn pack(input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro]
+pub fn route(input: TokenStream) -> TokenStream {
+    let expr = parse_macro_input!(input as syn::Expr);
+    let expanded = quote! {
+        match #expr {
+            Ok(r) => r,
+            Err(e) => return e,
+        }
+    };
+    TokenStream::from(expanded)
+}
+
+#[proc_macro]
 pub fn dispatcher(input: TokenStream) -> TokenStream {
     dispatcher::dispatcher(input)
 }