From 8f1e196d0a98a48cd2923c94f488ca69691ee5fe Mon Sep 17 00:00:00 2001
From: 魏曹先生 <1992414357@qq.com>
Date: Thu, 23 Jul 2026 08:38:56 +0800
Subject: 4

---
 src/lib.rs | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
index 02871bb..7d82100 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,13 +3,74 @@ use proc_macro::TokenStream;
 mod args;
 pub(crate) mod func;
 pub(crate) mod invoke;
+pub(crate) mod select;
 
+/// Attribute macro that generates both a sync and an async version of a function,
+/// gated by a Cargo feature flag.
+///
+/// # Usage
+///
+/// ```ignore
+/// /// Doc comments are preserved
+/// #[might_be_async::func]
+/// pub fn my_function<T: Clone>(arg: T) -> ReturnType
+/// where T: Debug
+/// {
+///     // body — written as a regular (non-async) function
+/// }
+/// ```
+///
+/// Expands to:
+/// - `#[cfg(not(feature = "async"))] fn my_function(...)` — sync version
+/// - `#[cfg(feature = "async")] async fn my_function(...)` — async version
+///
+/// An explicit feature name can be provided:
+///
+/// ```ignore
+/// #[might_be_async::func("tokio_rt")]
+/// pub fn my_function() { ... }
+/// ```
 #[proc_macro_attribute]
 pub fn func(attr: TokenStream, item: TokenStream) -> TokenStream {
     func::func(attr, item)
 }
 
+/// Wraps a call expression, adding `.await` when the async feature is enabled.
+///
+/// # Usage
+///
+/// ```ignore
+/// // Default feature name ("async"):
+/// let result = might_be_async::invoke!(some_async_fn(args));
+///
+/// // Explicit feature name:
+/// let result = might_be_async::invoke!("tokio_rt" => some_async_fn(args));
+/// ```
 #[proc_macro]
 pub fn invoke(input: TokenStream) -> TokenStream {
     invoke::invoke(input)
 }
+
+/// Select between sync and async expressions based on a Cargo feature flag.
+///
+/// # Usage
+///
+/// ## Explicit mode (with feature names)
+///
+/// ```ignore
+/// select!["async" => expr_async().await, "sync" => expr_sync()];
+/// select!["async" => { expr_async().await }, "sync" => { expr_sync() }];
+/// select!["async" => expr_async().await, !        => expr_sync()];
+/// select![!        => expr_async().await, "sync" => expr_sync()];
+/// ```
+///
+/// ## Implicit mode (auto-detect `.await`)
+///
+/// ```ignore
+/// select![expr_async().await, expr_sync()];
+/// select![{ expr_async().await }, { expr_sync() }];
+/// ```
+#[proc_macro]
+pub fn select(input: TokenStream) -> TokenStream {
+    select::select(input)
+}
-- 
cgit